CN119145893B - Mutual embedded type tunnel yielding supporting structure and construction method - Google Patents
Mutual embedded type tunnel yielding supporting structure and construction method Download PDFInfo
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- CN119145893B CN119145893B CN202411650493.3A CN202411650493A CN119145893B CN 119145893 B CN119145893 B CN 119145893B CN 202411650493 A CN202411650493 A CN 202411650493A CN 119145893 B CN119145893 B CN 119145893B
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- 238000010276 construction Methods 0.000 title claims abstract description 26
- 239000011435 rock Substances 0.000 claims abstract description 99
- 239000010410 layer Substances 0.000 claims description 136
- 239000011229 interlayer Substances 0.000 claims description 29
- 238000009412 basement excavation Methods 0.000 claims description 23
- 230000006835 compression Effects 0.000 claims description 18
- 238000007906 compression Methods 0.000 claims description 18
- 238000007789 sealing Methods 0.000 claims description 17
- 229910000831 Steel Inorganic materials 0.000 claims description 13
- 239000010959 steel Substances 0.000 claims description 13
- 238000005507 spraying Methods 0.000 claims description 12
- 238000009434 installation Methods 0.000 claims description 11
- 210000001503 joint Anatomy 0.000 claims description 3
- 239000002344 surface layer Substances 0.000 claims description 3
- 239000002184 metal Substances 0.000 description 35
- 238000003825 pressing Methods 0.000 description 11
- 230000007423 decrease Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 230000009471 action Effects 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 4
- 239000006260 foam Substances 0.000 description 4
- 238000003466 welding Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
- E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/23—Dune restoration or creation; Cliff stabilisation
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Lining And Supports For Tunnels (AREA)
Abstract
本发明提供了一种互嵌式隧道让压支护结构及施工方法，属于隧道施工技术领域，其中互嵌式隧道让压支护结构包括径向让压支护结构和环向让压支护结构；径向让压支护结构包括混凝土缓冲层和径向支护组件；混凝土缓冲层覆盖在围岩的表层；支护组件包括嵌于混凝土缓冲层内的预应力锚杆和支护壳体，支护壳体为开口朝向围岩一侧的弧形结构，预应力锚杆连接支护壳体并固定于围岩内；环向让压支护结构包括多段支护架体、若干个预应力放张结构和若干个让压支撑结构，环向让压支护结构围设成支护环。本发明提供的互嵌式隧道让压支护结构，通过沿径向和环向联合让压协同变形，确保径向与环向让压支护结构稳定安全，提高了支护结构的稳定性。
The present invention provides an interlocking tunnel pressure-yielding support structure and a construction method, which belongs to the technical field of tunnel construction, wherein the interlocking tunnel pressure-yielding support structure includes a radial pressure-yielding support structure and an annular pressure-yielding support structure; the radial pressure-yielding support structure includes a concrete buffer layer and a radial support assembly; the concrete buffer layer covers the surface of the surrounding rock; the support assembly includes a prestressed anchor rod and a support shell embedded in the concrete buffer layer, the support shell is an arc-shaped structure with an opening toward one side of the surrounding rock, the prestressed anchor rod is connected to the support shell and fixed in the surrounding rock; the annular pressure-yielding support structure includes a multi-section support frame, a plurality of prestressed tensioning structures and a plurality of pressure-yielding support structures, and the annular pressure-yielding support structure is arranged to form a support ring. The interlocking tunnel pressure-yielding support structure provided by the present invention ensures the stability and safety of the radial and annular pressure-yielding support structures through joint pressure-yielding cooperative deformation in radial and annular directions, thereby improving the stability of the support structure.
Description
Technical Field
The invention belongs to the technical field of tunnel construction, and particularly relates to a mutual embedded type tunnel yielding support structure and a construction method.
Background
The problem of high ground stress soft rock large deformation tunnel surrounding rock and support stability becomes a major engineering problem facing tunnel engineering construction, and the problems of tunnel collapse, support cracking and the like caused by large deformation amount, high deformation rate, long deformation duration and the like of the soft rock large deformation tunnel surrounding rock become one of the main problems affecting tunnel construction and operation safety. The tunnel yielding supporting measure is a supporting measure commonly accepted by tunnel engineering construction, but under extremely high ground stress, the deformation of the tunnel is large, and the requirement of the tunnel construction is difficult to be met by a single yielding measure.
Disclosure of Invention
The invention aims to provide a mutual embedded type tunnel yielding support structure and a construction method, and aims to realize radial and annular combined yielding active bearing support for a soft rock large-deformation tunnel.
In order to achieve the aim, the technical scheme adopted by the invention is that the mutual embedded type tunnel yielding support structure comprises a radial yielding support structure and a circumferential yielding support structure;
The radial yielding support structure comprises a concrete buffer layer and a radial support assembly; the support assembly comprises a prestressed anchor rod and a support shell, wherein the prestressed anchor rod and the support shell are embedded in the concrete buffer layer, the support shell is of an arc-shaped structure with an opening facing one side of the surrounding rock, and the prestressed anchor rod is connected with the support shell and is fixed in the surrounding rock;
the annular yielding support structure comprises a multi-section support frame body, a plurality of prestress tension releasing structures and a plurality of yielding support structures, wherein the annular yielding support structure is enclosed to form a support ring, and the prestress tension releasing structures and the yielding support structures all have tangential degrees of freedom along the support ring.
The concrete buffer layer comprises a primary concrete buffer layer and a secondary concrete buffer layer which are sprayed in sequence along the thickness direction, wherein the primary concrete buffer layer is sprayed on the surface of surrounding rock, the primary concrete buffer layer comprises a first concrete buffer layer and a second concrete buffer layer, the prestressed anchor rod and the supporting shell are arranged on the outer side of the first concrete buffer layer, the second concrete buffer layer is sprayed on the outer side of the first concrete buffer layer and is in scarf joint with the supporting shell and the annular yielding supporting structure, the secondary concrete buffer layer is sprayed on the outer sides of the second concrete buffer layer and the supporting shell, and the secondary concrete buffer layer is solidified to cover the supporting shell and the prestressed anchor rod in the concrete buffer layer.
As another embodiment of the present application, the support casing includes an outer arc plate, an inner arc plate and a yielding filling layer, the inner arc plate is located at one side close to the surrounding rock, the inner arc plate and the outer arc plate are arranged in parallel, an interlayer space is formed between the inner arc plate and the outer arc plate, the yielding filling layer is located in the interlayer space, and the yielding filling layer has a degree of freedom of buckling along a thickness direction.
According to the application, the support shell is of a hemispherical structure, the end face of the opening end of the support shell is attached to surrounding rock at the top of a tunnel, the closed end of the support shell faces downwards, one side, facing the opening end, of the outer arc-shaped plate and the inner arc-shaped plate is provided with a sealing end plate, the sealing end plate is used for sealing the interlayer space, the edge, close to the outer arc-shaped plate, of the sealing end plate is provided with an outer edge bulge protruding outwards, and the outer edge bulge is attached to the surrounding rock wall.
In another embodiment of the application, the cross section direction of the supporting shell and the length direction of the tunnel form an included angle, the two supporting shells are connected in a cross mode to form a cross beam structure, the interlayer space in the two supporting shells is connected, the prestressed anchor rod in the interlayer space vertically penetrates through the center of the connecting position of the two supporting shells, and vertical end plates are arranged around the sides of the supporting shells and are concave towards the interlayer space.
The prestress tension structure comprises a first positioning plate, a second positioning plate and a plurality of telescopic pieces, wherein two end parts of each telescopic piece are respectively connected with the first positioning plate and the second positioning plate, the telescopic pieces are respectively connected with the support frame body and the yielding support structure by means of the first positioning plate and the second positioning plate, the telescopic pieces are always in a contracted state when being assembled and constructed with the support frame body, and when the telescopic pieces are in a plurality of telescopic pieces, the telescopic pieces are uniformly distributed between the two positioning plates.
In another embodiment of the present application, the yielding support structure includes a first bearing plate, a second bearing plate, and a yielding element, where two stress ends of the yielding element are respectively connected to the first bearing plate and the second bearing plate, and the yielding element is respectively connected to the yielding support structure and the next section of the support frame by means of the first bearing plate and the second bearing plate.
The pressing element comprises two concave pressing plates which are symmetrically arranged, a pressing space is formed between the first bearing plate and the second bearing plate, and the concave pressing plates are positioned at the edge of the pressing space and convexly deform towards the center direction of the pressing space in a pressed state;
And buckling pieces which are arranged in pairs are arranged between the two concave yielding plates, the two buckling pieces are arc-shaped plates, and the opening ends of the two buckling pieces face the first bearing plate and the second bearing plate respectively and the closed ends of the two buckling pieces are attached.
In another embodiment of the present application, the yielding element is a metal block, and the metal block is provided with a plurality of rows of yielding holes along a length direction, and the diameters of the yielding holes gradually decrease or gradually increase from the first bearing plate to the second bearing plate.
Compared with the prior art, the inter-embedded type tunnel yielding support structure has the advantages that the inter-embedded type tunnel yielding support structure is internally provided with the annular yielding support structure and the radial yielding support structure, the annular prestressing releasing structure and the yielding support structure of the annular yielding support structure respectively realize the annular prestressing releasing and yielding retraction of the support ring in a coordinated mode, the radial prestressing releasing anchor rod and the support shell of the radial yielding support respectively realize the radial prestressing releasing and yielding retraction of the support ring in a coordinated mode, when the tunnel is deformed, the radial yielding support structure and the annular yielding support structure are ensured to be stable and safe through the combined yielding in the radial direction and the annular direction, the stability of the support structure is improved, and the problem that the existing single yielding measure cannot meet the supporting measure of a soft rock large-deformation tunnel is solved.
The construction method of the mutual embedded tunnel yielding support structure is also provided, which is characterized in that, the mutual embedded tunnel yielding supporting structure comprises the following steps:
S1, excavating an upper step of a tunnel, and spraying a first layer of radial yielding concrete on the excavation contour surface;
S2, mounting a prestress anchor rod and a support shell on the radial yielding concrete surface of the first layer, applying anchor rod prestress, simultaneously mounting a support frame body, shi Zuosuo feet of anchor rods, and assembling a prestress tension structure and a yielding support structure;
s3, spraying a second layer of radial yielding concrete, and embedding the support shell and the support frame body in the second layer of radial yielding concrete to form a steel frame embedded structure;
S4, excavating a tunnel lower step, and repeating the installation of the support frame body, the prestress tension releasing structure and the yielding support structure in the step S1 and the step S2 aiming at the excavation contour surface of the lower step;
S5, the yielding support structure is annular, and the prestressing force is released, so that the yielding support structure is extruded and deformed towards surrounding rock, the diameter of the yielding support structure is outwards extended to be large, and an active support force is formed;
S6, spraying a secondary concrete buffer layer to form an integral supporting structure;
s7, continuously extruding and deforming surrounding rock to the excavation contour surface, when the pressure of the surrounding rock is larger than that of the main power, bearing the load by the prestress tension structure, starting compression deformation, extruding and deforming along with the surrounding rock to the excavation contour surface, and reducing the diameter of the pressure support structure;
S8, continuously extruding and deforming surrounding rock to the excavation contour surface, continuously increasing supporting pressure of the surrounding rock, starting compression deformation of the pressure-yielding supporting structure when the pressure of the surrounding rock is larger than the pressure-yielding initial force of the pressure-yielding supporting structure, simultaneously, carrying out compression deformation on the supporting shell, and carrying out cooperative deformation on the annular pressure-yielding supporting structure and the radial pressure-yielding supporting structure until the pressure of the surrounding rock and the supporting force reach stress balance.
Compared with the prior art, the construction method of the mutual-embedded type tunnel yielding support structure has the advantages that the mutual-embedded type tunnel yielding support structure has all the beneficial effects, when the tunnel is deformed, the radial and circumferential yielding support structure is ensured to be stable and safe through combined yielding and cooperative deformation along the radial and circumferential directions, the yielding limit state is synchronously entered, the stability of the support structure is improved, and the problem that the existing single yielding measure cannot meet the support measure of a soft rock large-deformation tunnel is solved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a pressure-yielding support structure of an embedded tunnel according to an embodiment of the present invention;
FIG. 2 is an enlarged schematic cross-sectional view of a pressure-relieving support structure for a mutually embedded tunnel according to an embodiment of the present invention;
Fig. 3 is a schematic structural diagram of a prestressed anchor rod according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view of a pre-stressed anchor provided by an embodiment of the present invention;
Fig. 5 is a schematic structural view of a first supporting shell according to an embodiment of the present invention;
fig. 6 is a schematic structural view of a second supporting shell according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a first prestressed releasing structure according to an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of a second pre-stress tension structure according to an embodiment of the present invention;
FIG. 9 is a schematic structural diagram of a first yielding support structure according to an embodiment of the invention;
FIG. 10 is a schematic structural diagram of a second yielding support structure according to an embodiment of the invention;
FIG. 11 is a schematic view of a retractable housing according to an embodiment of the present invention;
Fig. 12 is a schematic view of a stress state of a support ring in an active support state according to an embodiment of the present invention;
fig. 13 is a schematic view of a stress state of a support ring in a yielding support state according to an embodiment of the present invention.
In the figure, 100 parts, a supporting frame body, 200 parts, a prestress anchor rod, 201 parts, a lower part, 202 parts, 203 parts, an upper part, 204 parts, a yielding member, 205 parts, a precompressed disc spring, 300 parts, a supporting shell, 301 parts, an outer arc plate, 302 parts, an inner arc plate, 303 parts, a yielding filling layer, 304 parts, a sealing end plate, 400 parts, an anchor expanding sleeve, 500 parts, a prestress releasing structure, 501 parts, a mechanical jack, 502 parts, an oil pressure type jack, 503 parts, a first positioning plate, 504 parts, a second positioning plate, 505 parts, a precompressed spring structure, 506 parts, a grouting hole, 507 parts, a vertical side plate, 508 parts, a fixing plate, 600 parts, a yielding supporting structure, 601 parts, an inward concave yielding plate, 602 parts, a first bearing plate, 603 parts, a second bearing plate, 604 parts, an arc plate body, 605 parts, a supporting plate, 606 parts, a metal block, 607 parts, a yielding hole, 700 parts, a sleeve structure, 701 parts, an inner cylinder, 702 parts, an outer cylinder, 703 parts, a flange part, 800 parts, a first concrete buffer layer, 801 parts, a second concrete buffer layer, 802 parts, a second concrete buffer layer, a rock-filling layer, a first mounting plate, 803 parts, a steel reinforcement cage, 803 parts, and a steel reinforcement cage.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1 to 13, the structure and the construction method of the present invention for the pressure-yielding support of the embedded tunnel will now be described. The embedded tunnel yielding support structure comprises a radial yielding support structure and a circumferential yielding support structure, wherein the radial yielding support structure comprises a concrete buffer layer and a radial support component, the concrete buffer layer covers the surface layer of a surrounding rock 803, the support component comprises a prestressed anchor rod 200 and a support shell 300 which are embedded in the concrete buffer layer, the support shell 300 is an arc-shaped structure with an opening facing one side of the surrounding rock 803, the prestressed anchor rod 200 is connected with the support shell 300 and is fixed in the surrounding rock 803, the circumferential yielding support structure comprises a plurality of sections of support frames 100, a plurality of prestressed release structures 500 and a plurality of yielding support structures 600, the circumferential yielding support structures are arranged to form support rings, and the prestressed release structures 500 and the yielding support structures 600 are provided with tangential degrees of freedom along the support rings.
Compared with the prior art, the embedded type tunnel yielding support structure provided by the invention has the advantages that the annular yielding support structure and the radial yielding support structure are arranged in the support ring, the prestress releasing structure 500 and the yielding support structure 600 of the annular yielding support structure respectively realize the releasing and yielding retraction of the annular prestress of the support ring in a coordinated manner, the radial yielding support concrete buffer layer, the prestress anchor rod 200 and the support shell 300 respectively realize the releasing and yielding retraction of the radial prestress of the support ring in a coordinated manner, and when the tunnel is deformed, the radial yielding support structure and the annular yielding support structure are ensured to be stable and safe and synchronously enter a yielding limit state through the combined yielding deformation along the radial direction and the annular direction, so that the stability of the support structure is improved, and the problem that the existing single yielding measure cannot meet the supporting measure of a soft rock large-deformation tunnel is solved.
The concrete buffer layer comprises a primary concrete buffer layer and a secondary concrete buffer layer 801 which are sprayed in sequence along the thickness direction, the primary concrete buffer layer is sprayed on the surface of the surrounding rock 803, the primary concrete buffer layer comprises a first concrete buffer layer 800 and a second concrete buffer layer 802, the prestressed anchor rod 200 and the support shell 300 are arranged on the outer side of the first concrete buffer layer 800, the second concrete buffer layer 802 is sprayed on the outer side of the first concrete buffer layer 800 and is in scarf joint with the support shell 300 and the annular yielding support structure, the secondary concrete buffer layer 801 is sprayed on the outer sides of the second concrete buffer layer 802 and the support shell 300, the secondary concrete buffer layer 801 is solidified, and the support shell 300 and the prestressed anchor rod 200 are coated in the concrete buffer layer.
The method comprises the steps of firstly spraying a first concrete buffer layer 800 on the surface of surrounding rock 803, then installing a prestressed anchor rod 200 and a supporting shell 300, and after the installation is completed, forming an embedded structure on the outer sides of the first concrete buffer layer 800 and the surface layers of the installed prestressed anchor rod 200 and the supporting shell 300 until a second concrete buffer layer 802 covers the first concrete buffer layer 800 and the supporting shell. And finally, spraying the secondary concrete buffer layer 801 to completely cover the concrete after yielding.
Sets of pre-stressed anchor rods 200 and support shells 300 are disposed between the first concrete buffer layer 800 and the second concrete buffer layer 802. The concrete buffer layer and the prestressed anchor rods and the supporting shell form an integral structure, so that radial yielding supporting is realized.
Referring to fig. 3 to 6, the radial yielding support includes a prestressed anchor 200 and a support housing 300, wherein the prestressed anchor 200 may be an existing anchor, and the prestressed anchor 200 extends into the first concrete buffer layer 800 and the surrounding rock 803 along the radial direction of the tunnel to form a radial support for the tunnel. The first end of the prestressed anchor rod 200 is fixed in the surrounding rock 803, the second end of the prestressed anchor rod 200 extends out of the surrounding rock 803 into the tunnel, the supporting shell 300 is installed at the second end of the prestressed anchor rod 200, the opening end of the supporting shell 300 is attached to the surface of the first layer of concrete buffer layer of the tunnel, and the middle part of the arc-shaped supporting shell 300 protrudes towards the inside of the tunnel.
The prestressed anchor 200 may employ a rod member or an anchor tube. The first end of the pre-stressed anchor rod 200 is anchored in the rock mass and the second end of the pre-stressed anchor rod 200 is secured to the surface of the surrounding rock 803 by means of an anchor bolt after passing through the support housing 300. The anchor bolts are located in the circumferential direction of the supporting housing 300.
Elastic pieces can be arranged in the rods of the prestress anchor rods 200, and the prestress is released through releasing the elastic pieces. The prestressed anchor rod 200 can be set to be of a telescopic loop bar structure, an elastic piece is added in the inner cavity of the loop bar, the elastic piece is always kept in a compressed state during construction, after the construction is completed, the elastic piece is stretched, and the loop bar is driven by the elastic piece to stretch so as to apply prestress to surrounding rock 803.
The pre-stressed anchor 200 may also be implemented by installing hydraulic or pneumatic jacks within a hollow sleeve. After the installation of the prestressed anchor 200 is completed, the jack is opened to release the prestress.
The second end of the prestressed anchor rod 200 is provided with a limiting annular step, the prestressed anchor rod 200 penetrates through the supporting shell 300 from top to bottom, the limiting annular step is attached to the outer end face of the supporting shell 300, the lower end of the prestressed anchor rod 200 extends out of the lower end of the supporting shell 300, and limiting structures such as nuts are installed on the extending portion. Optionally, a gasket is added to the limit annular step, and the gasket increases the contact area between the limit annular step and the supporting housing 300. A washer is also provided at the lower end of the support housing 300, and is fixed to the pre-stressing bolt 200 by means of a nut or the like.
As shown in fig. 3 and 4, the prestressed anchor 200 comprises a multi-section sleeve, specifically comprising a lower section 201, a middle section 202 and an upper section 203, wherein the lower section 201 is a pipe body with uniform diameters up and down, the lower part of the lower section 201 is closed, and the lower end is opened. The middle section 202 and the upper section 203 are of a two-section structure, wherein the pipe diameter of the lower section is smaller than that of the upper section, the outer diameter of the upper section is identical with that of the lower section 201, the outer diameter of the lower section is smaller than that of the upper section, the lower section of the middle section 202 extends into the inner cavity of the upper part of the lower section 201, and the lower section of the upper section 203 extends into the inner cavity of the upper section of the middle section 202. A limiting piece is arranged in the cavity of the lower section 201, the limiting piece is coaxial with the lower section 201, and the upper end of the limiting piece does not exceed the upper end face of the lower section 201. The outside cover of limiter is equipped with lets press the component 204, lets press the component 204 to be annular structure, lets press the component 204 to be located the inner chamber of lower section 201, and the lower extreme of well section 202 supports and lets press the up end of component 204. A precompression disc spring 205 is arranged in a cavity at the upper end of the middle section 202, the lower end of the precompression disc spring 205 abuts against a limit step formed at the joint of the upper section and the lower section of the middle section 202, and the upper end of the precompression disc spring 205 is sleeved outside the lower section of the upper section 203 and abuts against a limit step formed at the upper section and the lower section of the upper section 203. Alternatively, the pressure-releasing member 204 may be made of foam metal or the like.
After the construction and installation of the prestressed anchor rod 200 are completed, the prestressed disc spring 205 is firstly expanded, the prestressed anchor rod 200 applies a prestress to the surrounding rock 803, the surrounding rock 803 applies a larger force than the prestress of the prestressed anchor rod 200 along with the deformation of the surrounding rock 803, the prestressed anchor rod 200 is compressed under the stress, the prestressed disc spring 205 and the compression member 204 are compressed, and the prestressed anchor rod 200 is shortened.
The radial pressure-yielding supporting shell 300 comprises an outer arc plate 301, an inner arc plate 302 and a pressure-yielding filling layer 303, wherein the inner arc plate 302 is positioned on one side close to the surrounding rock 803, the inner arc plate 302 and the outer arc plate 301 are arranged in parallel, an interlayer space is formed between the inner arc plate 302 and the outer arc plate 301, the pressure-yielding filling layer 303 is positioned in the interlayer space, and the pressure-yielding filling layer 303 has the flexibility along the thickness direction.
The interlayer space between the outer arc plate 301 and the inner arc plate 302 is filled with a yielding filling layer 303. The yielding filling layer 303 can realize buckling deformation in the thickness direction under the action of external force and form resilience force to the outside, so as to achieve the purpose of yielding. After the outer arc plate 301 is deformed by extrusion, the outer arc plate 301 deforms towards the interlayer space, the outer arc plate 301 extrudes the pressure-yielding filling layer 303 positioned in the interlayer space, the pressure-yielding filling layer 303 deforms, but as the pressure-yielding filling layer 303 deforms and simultaneously applies a reverse extrusion force to the surrounding rock 803, the deformation of the pressure-yielding filling layer 303 reaches the maximum along with the maximum force applied by the surrounding rock 803, and finally the pressure-yielding filling layer 303 and the surrounding rock 803 reach a balanced state.
The thickness and strength of inner arcuate plate 302 are greater than outer arcuate plate 301. In the yielding process, the outer arc plate 301, the yielding filling layer 303 and the inner arc plate 302 are integrally deformed, and the deformation amount of the inner arc plate 302 is minimum.
The yielding fill layer 303 in the interlayer space of the supporting case 300 is of a porous structure. Or the pressure filling layer 303 is made of metal, the pressure filling layer 303 is compressible along the thickness direction of the shell, and the pressure filling layer 303 is of a honeycomb plate-shaped structure or a plurality of corrugated plate-shaped structures which are connected in sequence.
The material selected for the crush-fill 303 is a material having support strength and compressibility. In the first embodiment, the yielding fill layer 303 may be made of a non-metallic material, such as artificial SAP hole concrete. In the second embodiment, the yielding filler layer 303 may be made of a metal material such as a foam metal, a honeycomb metal plate, a corrugated metal plate, and a metal block 606 structure.
The porosity of the foam metal reaches more than 90 percent, and the foam metal is porous metal with certain strength and rigidity. Which has compressible properties.
When the honeycomb metal plate is provided in the yielding fill layer 303, the aperture direction of the honeycomb metal plate is perpendicular to the thickness direction of the yielding fill layer 303, and the aperture of the honeycomb metal plate gradually decreases from outside to inside in the thickness direction. The honeycomb metal plate can be steel plate. The honeycomb metal plates are formed by combining a plurality of blocks, and when the honeycomb metal plates are combined by the plurality of blocks, two adjacent honeycomb metal plates are welded and fixed. The honeycomb metal plate is welded or bolted to the inside arcuate plate 302, the honeycomb metal plate and the outside arcuate plate 301.
When letting to press and set up the ripple metal sheet in the filling layer 303, a plurality of ripple metal sheets set up along thickness direction stack, and a plurality of ripple metal sheets are crisscross to be overlapped, make and form the hole between two adjacent ripple metal sheets, avoid two ripple metal sheets to closely laminate, lose and let the pressure deformation volume. The arcuate diameters corresponding to the corrugations of the plurality of corrugated metal sheets gradually decrease from outside to inside in the thickness direction of the yielding fill layer 303. The adjacent two corrugated metal plates, the corrugated metal plate and the inner arc plate 302, and the corrugated metal plate and the outer arc plate 301 can be welded.
The inside of the metal block 606 structure is provided with relief holes 607 distributed in an array, and the relief holes 607 can realize the compression deformation of the metal block 606. The hole diameter of the relief hole 607 gradually decreases from outside to inside along the radial direction of the support housing 300, so that the bearing capacity of the pressure-filling layer 303 gradually increases from outside to inside, and when the pressure is applied, the outer arc 301 and the outer structure of the pressure-filling layer 303 are compressed and deformed first.
The supporting shell 300 achieves a gradient structure with rigidity outside and flexibility inside by filling the pressure-yielding filling layer 303 in the interlayer space of the shell, so that the supporting shell can bear the load of surrounding rock 803 and can deform orderly.
For the case structure of the supporting case 300, the thickness of the outer arc 301 is smaller than that of the inner arc 302, and the thickness of the outer arc 301 is gradually thinner from the center toward the edge.
The outer arc plate 301 and the inner arc plate 302 of the supporting shell 300 are made of steel plates, the thickness of the outer arc plate 301 is gradually changed from edge to center, and a gradual change gradient structure of the anchor in the horizontal direction is formed. The thickness of the outer arc plate 301 of the supporting shell 300 is slightly thinner than that of the inner arc plate 302, under the action of load, the outer arc plate 301 can reach yield strength first, and the buckling deformation of the outer arc plate 301 realizes the compression deformation of an anchor.
When being pressed by the surrounding rock 803, the outer arc plate 301 is deformed first, and transmits force into the yielding filling layer 303, and the pressure of the surrounding rock 803 is buffered and the supporting balance is achieved by the yielding filling layer 303, so that the supporting shell 300 forms a stable state.
When the load reaches a certain value, the thinner part of the outer arc plate 301 of the supporting shell 300 starts to buckle and deform, so that the whole anchor is deformed relatively to the surrounding rock 803, and the whole anchor is deformed in a compression mode relatively to the surrounding rock 803. When the anchor continuously bears the load, the outer arc 301 and the inner arc 302 of the supporting case 300 deform to a certain extent when the load is further increased to a certain value, and the buckling deformation thereof stops. At this time, the outer arc plate 301 of the support case 300 reaches a flexed state.
In some possible embodiments, referring to fig. 5, the supporting shell 300 has a hemispherical structure, the end face of the opening end of the supporting shell 300 is attached to the surrounding rock 803 at the top of the tunnel, the closed end of the supporting shell 300 faces downward, the sides of the outer arc plate 301 and the inner arc plate 302 facing the opening end are provided with a sealing end plate 304, the sealing end plate 304 is used for sealing the interlayer space, the edge of the sealing end plate 304, which is close to the outer arc plate 301, is provided with an outer edge bulge protruding outwards, and the outer edge bulge is attached to the wall of the surrounding rock 803.
The edge of the outer arc plate 301 of the supporting shell 300 and the edge of the inner arc plate 302 are positioned on the same horizontal plane, the outer arc plate 301 and the inner arc plate 302 are parallel, the outer arc plate 301 and the inner arc plate 302 are hemispherical, an interlayer space is formed between the outer arc plate 301 and the inner arc plate 302, a sealing end plate 304 for connecting the outer arc plate 301 and the inner arc plate 302 is arranged at the edge of the interlayer space, and the sealing end plate 304 is attached to the wall of the surrounding rock 803. The outer edge of the sealing end plate 304 is convexly attached to the wall of the surrounding rock 803 to increase the attaching degree. Deformation reservation grooves allowing deformation of the supporting shell 300 are formed in the wall of the surrounding rock 803.
In another embodiment, as shown in fig. 6, the cross section direction of the supporting shell 300 and the length direction of the tunnel form an included angle, the two supporting shells 300 connected in a cross way form a cross beam structure, an interlayer space in the two supporting shells 300 is connected, the prestressed anchor rod 200 in the interlayer space vertically penetrates through the center of the joint of the two supporting shells 300, and vertical end plates are arranged around the sides of the supporting shells 300 and are concave towards the interlayer space.
The two supporting shells 300 are of arc-shaped structures, the circumferences of the two supporting shells 300 are arranged at an included angle with the axial direction of the tunnel, and the two supporting shells 300 are symmetrically arranged along the axial direction of the tunnel. The length direction of the two supporting cases 300 is perpendicular. The two supporting shells 300 are in cross connection to form a cross beam structure, the outer arc surfaces of the two supporting shells 300 are flush, the inner arc surfaces of the two supporting shells are flush, the interlayer spaces are communicated, and an integral yielding filling layer 303 is formed in the communicated interlayer spaces. Corrugated steel plates can be adopted in the yielding filling layer 303, the corrugated steel plates are horizontally arranged and are overlapped in a longitudinal staggered mode, and the yielding filling layer 303 formed by stacking the corrugated steel plates can be compressed and deformed under the load effect.
The supporting shell 300 further comprises vertical end plates which are arranged on two sides of the supporting shell 300 in the width direction, the vertical end plates are steel plates which are sunken towards the inner side of the interlayer space, under the action of pressure, the vertical end plates are buckled and deform towards the inner side of the interlayer space, and the problems that the supporting shell 300 is expanded outwards and deformed, concrete is sprayed on the side face of an extrusion anchor device and the like are avoided.
To ensure that the anchors are in close proximity to the surrounding rock 803, the lengthwise ends of the inner and outer arcuate plates 302, 301 are also wrapped with vertical end plates that conform to the vertical end plate structure in the widthwise direction of the support housing 300. The edges of the vertical end plates, which are close to one side of the outer arc plate 301, are respectively provided with an outer edge bulge protruding outwards, and the outer edge bulges are attached to surrounding rocks 803.
Or the end of the outer arc 301 extends down to be flush with the end of the inner arc 302, and the ends in the longitudinal direction of the two are connected by means of a sealing end plate 304, the outer edge of the sealing end plate 304 is provided with a bulge protruding outwards, and the bulge is attached to the surrounding rock 803.
The support frame 100 is a single-layer support structure or a multi-layer support structure. The support frame 100 may be H-steel, or a combination thereof. The support frame body 100 can be fixedly connected with the annular yielding support structure and the radial yielding support structure by adopting modes of welding, bolt fixing, concrete pouring and the like. In particular to a radial yielding support structure, an anchor expansion sleeve 400 is sleeved on the outer side of the radial yielding support structure, and the anchor expansion sleeve is connected with a support frame body 100. The prestressed tension structure 500 of the circumferential yielding support structure is connected with the yielding support structure 600.
In some possible embodiments, referring to fig. 7 to 8, the prestressed stretching structure 500 includes a first positioning plate 503, a second positioning plate 504, and a plurality of telescopic members, wherein two ends of the telescopic members are respectively connected to the first positioning plate 503 and the second positioning plate 504, the telescopic members are respectively connected to the support frame 100 and the yielding support structure 600 by means of the first positioning plate 503 and the second positioning plate 504, the telescopic members are always in a contracted state when assembled with the support frame 100, and the telescopic members are one or more, and when the telescopic members are a plurality of telescopic members, the telescopic members are uniformly distributed between the two positioning plates.
The first positioning plate 503 and the second positioning plate 504 face the support frame 100 and the yielding support structure 600 respectively, the first positioning plate 503 is connected with the support frame 100, and the second positioning plate 504 is connected with the yielding support structure 600. The telescopic member is located between the first positioning plate 503 and the second positioning plate 504, and stretches along the length direction of the telescopic member to drive the first positioning plate 503 and the second positioning plate 504 to approach or separate.
When the telescopic piece stretches along the length direction of the telescopic piece, the first positioning plate 503 and the second positioning plate 504 are driven to be far away, and further expansion of the support ring is achieved, and pressure of the support ring to surrounding rocks 803 is achieved.
When the force exerted by the surrounding rock 803 is larger than the pre-stressing force of the expansion piece, the expansion piece contracts under the pressure of the surrounding rock 803, and drives the first positioning plate 503 and the second positioning plate 504 to approach, so that the support ring retracts, the inner diameter of the support ring is reduced, and meanwhile the yielding action on the surrounding rock 803 is realized.
A yielding space for installing the telescopic members is formed between the first positioning plate 503 and the second positioning plate 504, and the number of the telescopic members in the yielding space can be one or more, so that the problem that the supporting force is suddenly lost when one telescopic member is adopted is avoided, and a plurality of telescopic members are adopted for supporting simultaneously in actual construction.
As shown in fig. 7, the plurality of telescoping members may include pneumatic jacks, hydraulic jacks 502, and mechanical jacks 501. In construction, the pneumatic jack or the hydraulic jack 502 is installed in the middle of the abdication space, the mechanical jack 501 is installed on two sides of the abdication space respectively, and the active supporting force is provided by the combination mode of the pneumatic/hydraulic jack 502 and the mechanical jack 501, so that the problem that the active supporting force is suddenly lost due to pressure failure when a single jack is adopted is avoided. Such as a telescoping member comprising a hydraulic jack 502 and mechanical jacks 501 located on either side of the hydraulic jack 502. The locating plates can be one or more groups, a plurality of telescopic pieces can be arranged on the same group of locating plates, and a group of locating plates can be arranged on each telescopic piece.
In order to facilitate the installation, the prestress device further comprises a telescopic shell, the telescopic shell comprises two flange mounting plates 703 and a sleeve structure 700, the sleeve structure 700 comprises an inner cylinder 701 and an outer cylinder 702 which are sleeved and connected, the outer cylinder 702 is in sliding fit along the length direction of the inner cylinder 701, and the inner cavity of the telescopic shell is used for accommodating the prestress releasing structure 500. As shown in fig. 11.
The prestress releasing structure 500 is located in an inner cavity of the telescopic shell, the first positioning plate 503 and the second positioning plate 504 are respectively connected to two flange mounting plates 703, bolt holes are formed in the two flange mounting plates 703, and the two flange mounting plates 703 are respectively connected to the ends of the support frame body 100 and the yielding support structure 600 by means of bolts or welding.
In addition, as shown in fig. 8, the telescopic member may also adopt a pre-compression spring structure 505, and the pre-compression spring is pre-compressed during construction and installation, so that the pre-compression spring is kept in a compressed state. And after the construction of the support ring is completed, the support ring is stretched, and the stretched spring applies force to the support ring and drives the support ring to expand outwards, so that the surrounding rock 803 is extruded. Specifically, the sleeve structure 700 is divided into three layers, and two adjacent layers can slide relatively. Wherein, a pre-pressing spring structure 505 is arranged in the inner cavity between the first layer and the second layer, a pressing piece is arranged in the inner cavity between the second layer and the third layer, the pressing piece comprises an upper fixing plate 508, a lower fixing plate 508 and two vertical side plates 507 connected with the two fixing plates 508, and the two vertical side plates 507 are symmetrically arranged at two sides of the fixing plates 508. The vertical side plate 507 is an arc plate which is sunken inwards, and when the vertical side plate 507 is extruded by external force, the vertical side plate 507 can be sunken inwards to deform, so that the structure of the outer side of the pressing piece is prevented from being influenced.
In some possible embodiments, referring to fig. 9 to 10, the yielding support structure 600 includes a first bearing plate 602, a second bearing plate 603 and a yielding element, wherein two stress ends of the yielding element are respectively connected to the first bearing plate 602 and the second bearing plate 603, and the yielding element is respectively connected to the yielding support structure 600 and the next section of support frame 100 by means of the first bearing plate 602 and the second bearing plate 603.
The first bearing plate 602 and the second bearing plate 603 are arranged in parallel at intervals, a yielding space is formed between the first bearing plate 602 and the second bearing plate 603, and a yielding element is installed in the yielding space. The two ends of the yielding element are respectively connected to the first bearing plate 602 and the second bearing plate 603, and the yielding element has a deformation tendency along a direction perpendicular to the connecting line of the first bearing plate 602 and the second bearing plate 603. When the yielding element is extruded by the first bearing plate 602 and the second bearing plate 603, the yielding element is compressively deformed, and deforms along the direction perpendicular to the connecting line of the first bearing plate 602 and the second bearing plate 603, so that the displacement of the first bearing plate 602 and the second bearing plate 603 is met, and meanwhile the first bearing plate 602 and the second bearing plate 603 are pressed, and the stress stability of the support ring is further maintained.
The yielding element comprises two concave yielding plates 601 which are symmetrically arranged, a yielding space is formed between the first bearing plate 602 and the second bearing plate 603, and the concave yielding plate 601 is positioned at the edge of the yielding space and protrudes and deforms towards the center direction of the yielding space in a pressed state.
And buckling pieces which are arranged in pairs are further arranged between the two concave yielding plates 601, the two buckling pieces are arc-shaped plate pieces, and the open ends of the two buckling pieces face the first bearing plate 602 and the second bearing plate 603 respectively, and the closed ends of the two buckling pieces are attached.
Both ends in the longitudinal direction of the concave yielding plate 601 are respectively connected to a first bearing plate 602 and a second bearing plate 603. The two indent plates of stepping down are set up in letting two edges in the space of pressing symmetrically, and the bulge direction of indent plate of stepping down is towards the space between two indent plates of stepping down. The concave abdication plate deforms towards the middle part of the abdication space under the extrusion force application effect of the first bearing plate 602 and the second bearing plate 603. As the amount of deformation of the concave yielding plate increases, the spacing of the first bearing plate 602 and the second bearing plate 603 decreases.
Alternatively, the concave shape allows the thickness of the platen 601 to gradually decrease from both ends toward the middle.
And buckling pieces which are arranged in pairs are further arranged between the two concave yielding plates 601, the two buckling pieces are arc-shaped plate bodies 604, and the opening ends of the two buckling pieces face the first bearing plate 602 and the second bearing plate 603 respectively, and the closed ends of the two buckling pieces are attached.
The two flexures are located in the yielding space between the two concave yielding plates 601. The two buckling pieces are arc-shaped plates which are reversely arranged, namely a first arc-shaped plate and a second arc-shaped plate, the opening of the first arc-shaped plate faces the first bearing plate 602, and two end parts of the first arc-shaped plate are connected to the first bearing plate 602. In contrast, the opening of the second arc plate faces the second bearing plate 603, and both ends of the second arc plate are connected to the second bearing plate 603. The middle parts of the first arc-shaped plate and the second arc-shaped plate extend towards the middle part of the yielding space. The middle parts of the first arc-shaped plate and the second arc-shaped plate are abutted or welded and fixed. Optionally, the first arc-shaped plate and the second arc-shaped plate have the same structure, and the thicknesses of the first arc-shaped plate and the second arc-shaped plate gradually decrease from two ends to the middle part.
Further, a support plate 605 having a semicircular cross section is provided on the inner side of the buckling member. Two semicircular support plates 605 are respectively positioned on the inner sides of the first arc-shaped plate and the second arc-shaped plate. The two support plates 605 are respectively a first support plate and a second support plate, the first support plate is correspondingly arranged in an inner cavity surrounded by the first arc-shaped plate and the first bearing plate 602, and the second straight plate is correspondingly arranged in an inner cavity surrounded by the second arc-shaped plate and the second bearing plate 603.
Taking the first support plate as an example, the first support plate is an arc plate body 604 with a semicircular section, the opening end of the arc plate body 604 faces one side of the first bearing plate, and both ends of the arc plate body are connected to the first bearing plate. The arc plate 604 protrudes towards the middle of the yielding space, and a gap is reserved between the middle of the first support plate and the middle of the first arc plate.
The second support plate is consistent with the first support plate, and the second support plate and the first support plate are symmetrically arranged.
When the first arc-shaped plate and the second arc-shaped plate are extruded and deformed to the middle of the first arc-shaped plate and the second arc-shaped plate to be attached to the first support plate and the second support plate, the first support plate and the second support plate play a supporting role on the first arc-shaped plate and the second arc-shaped plate, and the supporting stability is improved.
As shown in fig. 10, the yielding element is a metal block 606, and the metal block 606 is provided with a plurality of rows of yielding holes 607 along the length direction, and the diameters of the yielding holes 607 gradually decrease or gradually increase from the first bearing plate 602 to the second bearing plate 603. The metal block 606 is welded or bolted to the first and second bearing plates 602 and 603.
In order to facilitate installation, the yielding support structures comprise telescopic shells, each telescopic shell comprises two flange mounting plates 703 and a sleeve structure 700, each sleeve structure 700 comprises an inner cylinder 701 and an outer cylinder 702, each outer cylinder 702 is sleeved on the outer side of each inner cylinder 701 and slides along the length direction of each inner cylinder 701, and the inner cavity of each telescopic shell is used for accommodating the yielding support structure 600. As shown in fig. 11.
The yielding support structure is located in an inner cavity of the telescopic shell, the first bearing plate 602 and the second bearing plate 603 are respectively connected to the two flange mounting plates 703, bolt holes are formed in the two flange mounting plates 703, and the two flange mounting plates 703 are respectively connected to the prestress device and the support frame body 100 by means of bolts or welding.
Grouting holes 506 are formed at both ends of the telescopic shells of the prestressed releasing structure 500 and the yielding support structure 600, and the grouting holes 506 are used for pouring yielding concrete.
As shown in fig. 1 to 13, a construction method of a mutual-embedded tunnel yielding support structure is further provided, the mutual-embedded tunnel yielding support structure is adopted, and the construction method comprises the following steps:
S1, excavating an upper step of a tunnel, and spraying a first layer of radial yielding concrete on the excavation contour surface;
s2, installing a prestress anchor rod 200 and a support shell 300 on the radial yielding concrete surface of a first layer, applying anchor rod prestress, installing a support frame body 100 at the same time, applying a foot locking anchor rod, and assembling a prestress releasing structure 500 and a yielding support structure 600;
S3, spraying a second layer of radial yielding concrete, and embedding the support shell 300 and the support frame body 100 in the second layer of radial yielding concrete to form a steel frame embedded structure;
S4, excavating a tunnel lower step, and repeating the installation of the support frame body 100, the prestress tension releasing structure 500 and the yielding support structure 600 in the steps S1 and S2 aiming at the excavation contour surface of the lower step;
S5, the yielding support structure is annular, and the prestressing force is released, namely the yielding support structure 500 is extruded and deformed towards the surrounding rock 803, so that the diameter of the yielding support structure is outwards extended to be larger, and an active support force is formed;
S6, spraying a secondary concrete buffer layer 801 to form an integral support structure;
S7, continuously extruding and deforming the surrounding rock 803 towards the excavation outline surface, when the pressure of the surrounding rock 803 is larger than that of the main power, bearing the load by the prestress tension structure 500, starting compression deformation, extruding and deforming along with the surrounding rock 803 towards the excavation outline surface, and reducing the diameter of the pressure support structure;
S8, continuously extruding and deforming the surrounding rock 803 towards the excavation outline surface, continuously increasing the supporting pressure of the surrounding rock 803, starting compression deformation of the pressure-yielding supporting structure 600 when the pressure of the surrounding rock 803 is larger than the pressure-yielding initial force of the pressure-yielding supporting structure 600, simultaneously, carrying out compression deformation on the supporting shell 300, and carrying out cooperative deformation on the annular pressure-yielding supporting structure and the radial pressure-yielding supporting structure until the pressure and the supporting force of the surrounding rock 803 reach the stress balance.
Compared with the prior art, the construction method of the mutual embedded type tunnel yielding support structure has the advantages that when the tunnel is deformed, the radial and annular yielding support structure is ensured to be stable and safe, the yielding limit state is synchronously entered, the stability of the support structure is improved, and the problem that the existing single yielding measure cannot meet the support measure of a soft rock large-deformation tunnel is solved.
Specifically, after the step on the tunnel is excavated, a primary concrete layer 804 is sprayed on the excavation contour surface, and after solidification, a first layer of radial yielding concrete is sprayed to form a first concrete buffer layer. Then the surface of the first layer of radial yielding concrete is provided with a prestressed anchor rod 200 and a supporting shell 300, and after the installation is completed, the prestressed anchor rod 200 is released, meanwhile, the supporting frame body 100 is installed, a foot locking anchor rod is installed at the supporting frame body 100, and the prestressed releasing structure 500 and the yielding supporting structure 600 are assembled while the supporting frame body 100 is installed.
And spraying a second layer of radial yielding concrete on the support frame body 100 after the installation is completed to form a second concrete buffer layer, so as to complete the radial yielding structure. The support housing 300 and the support frame 100 are embedded in a concrete structure layer to form a steel frame embedded structure. A reinforcing mesh 805 is also laid in the second concrete buffer layer.
And after the supporting of the upper step of the tunnel is completed, excavating the lower step of the tunnel. After the tunnel is excavated down to the step, a first layer of radial yielding concrete is sprayed on the excavation contour surface, and the support frame body 100, the prestressed tension structure 500 and the yielding support structure 600 are installed. Namely, the excavation contour surface of the tunnel which is stepped down does not need to be provided with a radial yielding supporting structure.
And after the support ring is assembled, the prestress tension structure 500 is tensioned, so that the support ring is extruded and deformed towards the surrounding rock 803, the diameter of the support ring is extended outwards, and the support ring actively applies supporting force to the surrounding rock 803 to form active supporting force. Then, a secondary concrete buffer layer 801 is sprayed on the support ring to form an overall support structure.
The surrounding rock 803 continuously extrudes and deforms towards the excavation outline surface, the supporting pressure of the surrounding rock 803 continuously increases, when the pressure of the surrounding rock 803 is larger than that of the main power, the prestress tension structure 500 bears load, begins to compress and deform, and extrudes and deforms towards the excavation outline surface along with the surrounding rock 803, the diameter of the supporting ring is reduced, and the supporting ring begins to deform and yielding.
As the surrounding rock 803 continues to squeeze and deform toward the excavation contour surface, the supporting pressure of the surrounding rock 803 continues to increase, when the pressure of the surrounding rock 803 is greater than the yielding initial force of the yielding support structure 600, the yielding support structure 600 begins to compress and deform, and under the common compression deformation of the prestressed tension structure 500 and the yielding support structure 600, the surrounding rock 803 continues to squeeze and deform toward the excavation contour surface, and the diameter of the supporting ring continues to shrink. Along with the continuous shrinkage deformation of the support ring, the surrounding rock 803 continuously extrudes deformation to the excavation outline surface to release energy, so that the pressure of the surrounding rock 803 to the support structure is reduced, and the energy of the surrounding rock 803 is continuously released until the pressure of the surrounding rock 803 and the support force reach the stress balance, and the support structure is in a stable state.
When the tunnel is deformed, the annular yielding supporting structure and the radial yielding supporting structure cooperatively deform, so that the annular yielding supporting structure and the radial yielding supporting structure are ensured to be stable and safe, and synchronously enter a yielding limit state.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (6)
1. The mutual embedded type tunnel yielding support structure is characterized by comprising a radial yielding support structure and an annular yielding support structure;
The radial yielding support structure comprises a concrete buffer layer and a radial support assembly, wherein the concrete buffer layer covers the surface layer of surrounding rock, the support assembly comprises a prestressed anchor rod (200) and a support shell (300) which are embedded in the concrete buffer layer, the support shell (300) is of an arc-shaped structure with an opening facing one side of the surrounding rock, and the prestressed anchor rod (200) is connected with the support shell (300) and is fixed in the surrounding rock;
The support shell (300) comprises an outer arc plate (301), an inner arc plate (302) and a yielding filling layer (303), wherein the inner arc plate (302) is positioned on one side close to surrounding rock, the inner arc plate (302) and the outer arc plate (301) are arranged in parallel, an interlayer space is formed between the inner arc plate (302) and the outer arc plate (301), the yielding filling layer (303) is positioned in the interlayer space, the yielding filling layer (303) has the degree of freedom of buckling along the thickness direction, the bearing capacity of the yielding filling layer (303) gradually increases from outside to inside, and when the bearing capacity is stressed, the outer arc plate (301) and the outer structure of the yielding filling layer (303) are subjected to compression deformation;
the annular yielding support structure comprises a plurality of sections of support frame bodies (100), a plurality of prestress tension releasing structures (500) and a plurality of yielding support structures (600), wherein the annular yielding support structures are enclosed to form a support ring, and the prestress tension releasing structures (500) and the yielding support structures (600) have the degree of freedom along the tangential direction of the support ring;
The yielding support structure (600) comprises a first bearing plate (602), a second bearing plate (603) and a yielding element, wherein two stress ends of the yielding element are respectively connected with the first bearing plate (602) and the second bearing plate (603), and the yielding element is respectively connected with the yielding support structure (600) and the next section of the support frame body (100) by means of the first bearing plate (602) and the second bearing plate (603);
the yielding element comprises two concave yielding plates (601) which are symmetrically arranged, wherein a yielding space is formed between the first bearing plate (602) and the second bearing plate (603), and the concave yielding plates (601) are positioned at the edge of the yielding space and convexly deform towards the central direction of the yielding space in a pressed state;
And buckling pieces which are arranged in pairs are further arranged between the two concave yielding plates (601), the two buckling pieces are arc-shaped plates, the opening ends of the two buckling pieces face the first bearing plate (602) and the second bearing plate (603) respectively, and the closed ends of the two buckling pieces are attached.
2. The mutual embedded tunnel yielding support structure according to claim 1, wherein the concrete buffer layer comprises a primary concrete buffer layer and a secondary concrete buffer layer (801) which are sequentially sprayed along the thickness direction, the primary concrete buffer layer is sprayed on the surface of the surrounding rock (803), the primary concrete buffer layer comprises a first concrete buffer layer (800) and a second concrete buffer layer (802), the prestressed anchor rod (200) and the support shell (300) are installed on the outer side of the first concrete buffer layer (800), the second concrete buffer layer (802) is sprayed on the outer side of the first concrete buffer layer (800) and is in scarf joint with the support shell (300) and the circumferential yielding support structure, the secondary concrete buffer layer (801) is sprayed on the outer sides of the second concrete buffer layer (802) and the support shell (300), and the secondary concrete buffer layer (801) is solidified to cover the prestressed anchor rod (300) and the prestressed anchor rod (300) in the concrete buffer layer.
3. The pressure-yielding supporting structure of the mutually embedded tunnel according to claim 1, wherein the supporting shell (300) is of a hemispherical structure, the end face of the opening end of the supporting shell (300) is attached to surrounding rocks at the top of the tunnel, the closed end of the supporting shell (300) faces downwards, a sealing end plate (304) is arranged on one side, facing the opening end, of the outer arc plate (301) and the inner arc plate (302), and is used for sealing the interlayer space, an outer edge bulge protruding outwards is arranged on the edge, close to the outer arc plate (301), of the sealing end plate (304), and the outer edge bulge is attached to the surrounding rock wall.
4. The pressure-yielding supporting structure of the mutually embedded tunnel according to claim 1, wherein the cross section direction of the supporting shell (300) is arranged at an included angle with the length direction of the tunnel, the cross beam structure is formed by the two supporting shells (300) which are connected in a cross mode, the interlayer space in the two supporting shells (300) is connected, the prestressed anchor rod (200) in the interlayer space vertically penetrates through the center of the connecting position of the two supporting shells (300), and vertical end plates are arranged around the side of the supporting shells (300) and are inwards concave towards the interlayer space.
5. The tunnel yielding support structure according to claim 1, wherein the prestress releasing structure (500) comprises a first positioning plate (503), a second positioning plate (504) and a plurality of telescopic pieces, two end parts of each telescopic piece are respectively connected with the first positioning plate (503) and the second positioning plate (504), the telescopic pieces are respectively connected with the support frame body (100) and the yielding support structure (600) by means of the first positioning plate (503) and the second positioning plate (504), the telescopic pieces are always in a contracted state when being assembled with the support frame body (100), and when the telescopic pieces are in a plurality of telescopic pieces, the telescopic pieces are uniformly distributed between the two positioning plates.
6. The construction method of the mutual embedded type tunnel yielding support structure is characterized in that the mutual embedded type tunnel yielding support structure as claimed in any one of claims 1 to 5 is adopted, and the construction method comprises the following steps:
S1, excavating an upper step of a tunnel, and spraying a first layer of radial yielding concrete on the excavation contour surface;
S2, mounting a prestress anchor rod (200) and a support shell (300) on the radial yielding concrete surface of a first layer, applying anchor rod prestress, simultaneously mounting a support frame body (100), shi Zuosuo pin anchor rods, and assembling a prestress tension structure (500) and a yielding support structure (600);
s3, spraying a second layer of radial yielding concrete, and embedding the support shell (300) and the support frame body (100) in the second layer of radial yielding concrete to form a steel frame embedded structure;
S4, excavating a tunnel in a lower step, and repeating the installation of the support frame body (100), the prestress tension structure (500) and the yielding support structure (600) in the step S1 and the step S2 aiming at the excavation contour surface of the lower step;
S5, the yielding support structure is annular, and the prestressing force is released to release the tension structure (500), so that the yielding support structure is extruded and deformed towards surrounding rock, the diameter of the yielding support structure is outwards extended to be larger, and active support force is formed;
S6, spraying a secondary concrete buffer layer to form an integral supporting structure;
s7, continuously extruding and deforming surrounding rock to the excavation outline surface, when the pressure of the surrounding rock is larger than that of the main power, bearing the load by the prestress tension structure (500), starting compression deformation, extruding and deforming along with the surrounding rock to the excavation outline surface, and reducing the diameter of the pressure support structure;
S8, continuously extruding and deforming surrounding rock to the excavation outline surface, continuously increasing supporting pressure of the surrounding rock, starting compression deformation of the pressure-yielding supporting structure (600) when the pressure of the surrounding rock is larger than the pressure-yielding initial force of the pressure-yielding supporting structure (600), simultaneously, carrying out compression deformation on the supporting shell (300), and carrying out cooperative deformation on the annular pressure-yielding supporting structure and the radial pressure-yielding supporting structure until the pressure of the surrounding rock and the supporting force reach stress balance.
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| CN110118091B (en) * | 2019-06-26 | 2024-01-30 | 河北丞璐建设工程有限公司 | Tunnel support lining with buffer performance and construction method |
| CN110847930A (en) * | 2019-12-09 | 2020-02-28 | 中交第一公路勘察设计研究院有限公司 | Multi-level yield-resisting support structure and construction method of extremely high in-situ stress soft rock large deformation tunnel |
| CN115596466B (en) * | 2022-10-18 | 2025-05-06 | 衡水奇佳工程材料有限公司 | Buffering and pressure-yielding composite support structure and support method for soft surrounding rock tunnels |
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| CN205638510U (en) * | 2016-04-22 | 2016-10-12 | 华北水利水电大学 | Stock lets presses pallet means |
| CN111119958A (en) * | 2019-12-27 | 2020-05-08 | 常州工学院 | Coal mine tunnel anchor rope supporting system |
| CN118640037A (en) * | 2024-06-11 | 2024-09-13 | 中铁一局集团有限公司 | A tunnel initial support method |
| CN118881407A (en) * | 2024-07-04 | 2024-11-01 | 安徽理工大学 | A prestressed arch support structure and construction method |
| CN118933935A (en) * | 2024-07-31 | 2024-11-12 | 中铁第一勘察设计院集团有限公司 | Flexible initial support structure and construction method for tunnels in high-energy geological environments |
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