CN110486021B - Construction method for converting large-section tunnel into two small-section tunnels - Google Patents
Construction method for converting large-section tunnel into two small-section tunnels Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 52
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- 229910000831 Steel Inorganic materials 0.000 claims description 38
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- 239000011435 rock Substances 0.000 claims description 13
- 238000009415 formwork Methods 0.000 claims description 7
- 238000005422 blasting Methods 0.000 claims description 3
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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
- E21D11/14—Lining predominantly with metal
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- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
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- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/001—Improving soil or rock, e.g. by freezing; Injections
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/006—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries by making use of blasting methods
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Abstract
The invention discloses a construction method for converting a large-section tunnel into two small-section tunnels, which is characterized in that the large-section tunnel is divided into a first small-section tunnel and a second small-section tunnel forwards at a fork position, the large-section tunnel is constructed by adopting a double-side-wall pit guiding method, a guide tunnel of one side, leading to the first small-section tunnel, of the large-section tunnel is firstly excavated to the fork position, then a gradual change tunnel section is excavated at the tail end of the guide tunnel, the gradual change tunnel section is positioned in the outline of the first small-section tunnel, and when the section of the gradual change tunnel section is enlarged to be consistent with the section of the first small-section tunnel, the gradual change tunnel section is reversely excavated to form a part of the tunnel section of the first small-section tunnel. By designing the gradual change tunnel section, the safety support can be realized, and the construction safety in the process of converting the large-section tunnel into the small-section tunnel is improved; and then the gradual change tunnel section is reversely excavated, so that the stable transition from the large-section tunnel to the small-section tunnel is realized.
Description
Technical Field
The invention relates to the technical field of tunnel construction, in particular to a construction method for converting a large-section tunnel into two small-section tunnels.
Background
In the tunnel engineering, in order to make the road or the railway in the tunnel lead to different directions, a tunnel needs to be divided into two or more than two tunnels at the fork position, and generally, a large-section tunnel is divided into two or more than two small-section tunnels.
In the construction process, the major cross-section tunnel is repaired into the minor cross-section tunnel mainly with the following difficulties: firstly, there is great section difference in big section tunnel and the little section tunnel, and the section conversion difficulty of fork position. Secondly, because the rock pillar of two small cross section tunnels at the fork position is little, intensity is low, and very easy emergence damage even collapses in the work progress has great construction degree of difficulty and risk. Thirdly, the construction difficulty of the fork position is high, the work amount is relatively large, and the construction progress is easily delayed.
Chinese patent publication No. CN104265305A describes an expanding excavation method for merging two small-section caverns into one large-section cavern, and although the method in this patent publication can also achieve section conversion, it is not suitable for converting a large-section cavern into two small-section caverns.
Chinese patent publication No. CN109779653A describes a construction method for a crossing of a soft rock large-section tunnel, in which a tunnel turns and then leads to another tunnel, an advanced large pipe shed needs to be constructed, and the construction of the advanced large pipe shed needs a large space.
Disclosure of Invention
The invention aims to provide a construction method for converting a large-section tunnel into two small-section tunnels, and solves the technical problem that the section is difficult to convert in the construction process of converting the large-section tunnel into the small-section tunnel in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme:
designing a construction method for converting a large-section tunnel into two small-section tunnels, wherein the large-section tunnel is divided and repaired into a first small-section tunnel and a second small-section tunnel forwards at a fork position, the large-section tunnel is constructed by adopting a double-side-wall pit guiding method, a guide tunnel, which leads to one side of the first small-section tunnel, of the large-section tunnel is excavated to the fork position in advance, then a gradual change tunnel section is excavated at the tail end of the guide tunnel, the gradual change tunnel section is positioned in the outline of the first small-section tunnel, and when the section of the gradual change tunnel section is expanded to be consistent with the section of the first small-section tunnel, the gradual change tunnel section is reversely excavated into a part of the tunnel section of the first small-section tunnel.
Preferably, one side of the gradual change tunnel section, which is far away from the second small-section tunnel, is excavated along the profile of the first small-section tunnel, and the other side of the gradual change tunnel section gradually extends and is excavated towards the second small-section tunnel so as to increase the section.
Preferably, in the back excavation process, the blastholes arranged on the tunnel face close to one side of the second small-section tunnel inwardly converge for a certain distance along the excavation profile of the first small-section tunnel, and the explosive loading is reduced, so that the rock pillar between the first small-section tunnel and the second small-section tunnel is prevented from being damaged due to drilling and blasting construction.
Preferably, the gradual change tunnel section is reversely excavated by adopting a short footage mode, and the underexcavated part in the first small-section tunnel profile is chiseled off manually.
Preferably, in the excavation process of the gradual change tunnel section, the small advancing duct which is arranged on the arch waist and the arch part of one side wall of the gradual change tunnel section far away from the second small-section tunnel is arranged at a larger external differential angle, and the small advancing duct is not arranged on one side wall of the gradual change tunnel section close to the second small-section tunnel.
Preferably, the steel frame is timely supported by the gradual change tunnel section in the excavation process, wherein the steel frame close to one side of the second small-section tunnel in the gradual change tunnel section is a temporary steel frame, and the other side of the gradual change tunnel section is a steel frame matched with the section of the first small-section tunnel.
Preferably, in the excavation process of the first small-section tunnel, the number of the locking anchor pipes which are arranged on the side wall of the first small-section tunnel, close to the second small-section tunnel, of the first small-section tunnel is increased, and the driving depth is reduced.
Preferably, before the gradual change tunnel section is excavated, the gradual change tunnel section enters the second small-section tunnel through a flat pilot tunnel and is positioned at the non-excavated part in front of the fork position to perform reverse excavation, and lining is timely applied until the gradual change tunnel section is reversely excavated to the fork position.
Preferably, an end wall which is connected with the lining of the large-section tunnel and the lining of the first small-section tunnel and the lining of the second small-section tunnel is constructed at the fork position.
Preferably, when the end wall is constructed, the lining trolleys in the first small-section tunnel and the second small-section tunnel both travel to the fork position to be used as a part of a template for constructing the end wall.
The invention has the beneficial technical effects that:
1. according to the construction method for converting the large-section tunnel into the two small-section tunnels, safety support can be realized in the gradual-change tunnel sections, so that the construction safety in the process of converting the large-section tunnel into the small-section tunnels is improved; and then the gradual change tunnel section is reversely excavated, so that the stable transition from the large-section tunnel to the small-section tunnel is realized.
2. In the excavation process of the gradual change tunnel section and the first small-section tunnel, the support strength is improved by changing the laying mode of the advanced small guide pipe and the locking anchor pipe, and the damage to rock pillars between the two small-section tunnels is avoided.
3. The gradual change tunnel is reversely dug in a short-advancing ruler mode, the position of the blast hole of the tunnel face and the charging amount are controlled in the reverse digging process, and damage to a rock pillar is effectively avoided.
4. The second small-section tunnel is reversely excavated after the flat pilot tunnel reaches the front of the fork position, so that excavation and supporting of the second small-section tunnel can be realized before construction of the first small-section tunnel, the construction progress is accelerated, and the difficulty in excavation and supporting of the first small-section tunnel and the second small-section tunnel at the front of the fork position is avoided simultaneously.
5. The lining trolley in the first small-section tunnel and the second small-section tunnel is used as a foundation, and the difficulty of formwork support in end wall construction is reduced.
Drawings
FIG. 1 is a schematic structural diagram of a tunnel constructed in an embodiment of a construction method for converting a large-section tunnel into two small-section tunnels according to the present invention;
FIG. 2 is a cross-sectional view of a large cross-sectional tunnel excavated by a double-side-wall heading method in an embodiment of the construction method for converting a large cross-sectional tunnel into two small cross-sectional tunnels according to the present invention;
FIG. 3 is a schematic cross-sectional view of a large cross-section tunnel at a fork position in an embodiment of a construction method for converting the large cross-section tunnel into two small cross-section tunnels according to the present invention;
FIG. 4 is a construction diagram of an embodiment of a construction method for converting a large-section tunnel into two small-section tunnels according to the present invention;
FIG. 5 is a schematic construction diagram of another embodiment of the construction method for converting a large-section tunnel into two small-section tunnels according to the present invention;
FIG. 6 is a cross-sectional view of an end wall in an embodiment of the construction method for converting a large-section tunnel into two small-section tunnels according to the present invention.
In the drawings, each reference numeral means: the main tunnel 10, the large-section tunnel 11, the left guide tunnel 111, the middle guide tunnel 112, the right guide tunnel 113, the left side wall 114, the right side wall 115, the large-section tunnel lining 116, the first small-section tunnel 12, the first small-section tunnel profile 121, the upper steel frame 122, the normal-section steel frame 1221, the temporary support steel frame 1222, the back-excavated space 123, the first small-section tunnel lining 124, the second small-section tunnel 13, the second small-section tunnel lining 131, the fork position 14, the rock pillar 15, the gradual-change tunnel section 16, the branch tunnel 17, the head wall 18 and the flat guide tunnel 20.
Detailed Description
The following examples are intended to illustrate the invention in detail and are not intended to limit the scope of the invention in any way.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Example 1:
a construction method for converting a large cross section tunnel into two small cross section tunnels, please refer to fig. 1 to fig. 4.
In fig. 1, a main tunnel 10 is used for building a tunnel of a railway, a horizontal pilot tunnel 20 is built in the main tunnel 10 during the building process, and the horizontal pilot tunnel 20 is used for assisting the construction of the main tunnel 10, and in the embodiment of the invention, a large-section tunnel 11, a first small-section tunnel 12 and a second small-section tunnel 13 are part of the main tunnel 10. The large section tunnel 11 needs to be divided into a first small section tunnel 12 and a second small section tunnel 13 in front of the fork position 14 for the train to pass to different directions.
As shown in fig. 2, the large-section tunnel 11 is constructed by a double-side-wall pilot tunnel method, the whole tunnel is divided into three pilot tunnels of a left pilot tunnel 111, a middle pilot tunnel 112 and a right pilot tunnel 113 which are respectively excavated forwards, the left pilot tunnel 111 and the right pilot tunnel 113 are constructed by a three-step method, the middle pilot tunnel 112 is constructed by four steps, specifically, in fig. 2, three construction steps of a left step (r), a step (r) and a step (c) are three construction steps of the left pilot tunnel 111, a step (r), a step (c) and a step (c) are three construction steps of the right pilot tunnel 113, and a step (c), a step (r), a step (ninu) and a step (r) in the middle are four construction steps of the middle pilot tunnel 112.
The construction steps in each pilot tunnel are sequentially excavated forwards from top to bottom, and the depths of the forwards excavated left pilot tunnel 111, middle pilot tunnel 112 and right pilot tunnel 113 are staggered, so that the mutual influence of the excavated surfaces is prevented, and the safety of excavation work is ensured. The left side wall 114 and the right side wall 115 are made of steel frames and concrete, and can play a role of temporary support, and after the left side wall 114 and the right side wall 115 are dismantled in the later period, the three guide holes are converged into the large-section tunnel 11.
As shown in fig. 3, of the three pilot tunnels, i.e., the left pilot tunnel 111, the middle pilot tunnel 112, and the right pilot tunnel 113, the left pilot tunnel 111 may directly lead to the first small cross-section tunnel 12, in this embodiment, the left pilot tunnel 111 is first excavated to the fork position 14, then the construction of the first small cross-section tunnel 12 is performed from the end of the left pilot tunnel 111, and the middle pilot tunnel 112 and the right pilot tunnel 113 are followed up subsequently, so as to prevent multiple construction operations from being performed at the fork position 14 at the same time, thereby reducing the construction risk and the support difficulty at the fork position 14.
Since the cross section of the left pilot tunnel 111 is smaller than the cross section of the first small cross section tunnel 12, when the left pilot tunnel 111 is excavated to the fork position 14, it is difficult to directly excavate the first small cross section tunnel 12 from the end of the left pilot tunnel 111, for this reason, as shown in fig. 4, a gradual change tunnel section 16 is excavated first, the gradual change tunnel section 16 is located within the first small cross section tunnel profile 121, and when the cross section of the gradual change tunnel section 16 is enlarged to be consistent with the cross section of the first small cross section tunnel 12, the gradual change tunnel section 16 is reversely excavated to be a part of the first small cross section tunnel 12.
Through the design gradual change tunnel section 16, the transition to first little section tunnel 12 that left guide hole 111 can be steady, and safety support can be realized to the hole wall of gradual change tunnel section 16, ensures the security of left guide hole 111 to first little section tunnel 12 section conversion in-process.
In this embodiment, the gradual transition tunnel section 16 needs to pay attention to the following requirements during the construction process:
(1) gradual change tunnel section 16 is in the excavation process, and its one side of keeping away from second small cross section tunnel 13 excavates along first small cross section tunnel profile 121, and gradual opposite side of gradual change tunnel section 16 extends to the direction of second small cross section tunnel 13 and expands to dig to the increase section. According to this kind of mode excavation, can directly regard as the partly hole section of first small cross section tunnel 12 after the later stage is to 16 right sides anti-excavations in gradual change hole section, can improve the efficiency of construction, guarantee the order of construction.
(2) The steel frame is to be supported in time in the excavation process of the gradual change tunnel section 16, wherein the steel frame near one side of the second small-section tunnel 13 in the gradual change tunnel section 16 is a temporary steel frame, and the other side of the gradual change tunnel section is a steel frame matched with the section of the first small-section tunnel 12. When the gradual change hole section 16 later stage is dug conversely, the interim steelframe that its was strutted is removable, and remaining steelframe need not to dismantle, reduces the work load when digging conversely.
(3) Because the narrowest part of the rock pillar 15 between the first small-section tunnel 12 and the second small-section tunnel 13 is about 1.1 m, the rock pillar is easy to damage, in order to prevent the rock pillar 15 from being damaged, a small advance guide pipe is not arranged on the side wall of the gradual change tunnel section 16 close to the second small-section tunnel 13, and the rock pillar 15 is prevented from being damaged by the small advance guide pipe; however, in order to enhance the supporting strength of the transition tunnel section 16, a small advance conduit is required to be arranged at the arch waist and the arch part of the tunnel wall on the side of the transition tunnel section 16 far away from the second small-section tunnel 13, and the small advance conduit is arranged at a larger angle of difference so as to enhance the supporting strength.
(4) After the gradual change tunnel section 16 is turned over and is dug to and follow-up follow gradual change tunnel section 16 and continue to excavate first little section tunnel 12 in-process forward, increase the quantity of the lock foot anchor pipe of doing and reduce the degree of depth of driving into on first little section tunnel 12 is close to second little section tunnel 13 a lateral wall, can prevent damage rock pillar 15 after the lock foot anchor pipe shortens, and increase the quantity of lock foot anchor pipe then can strengthen the support intensity of lock foot anchor pipe to erectting the steelframe.
The excavation and reverse excavation method of the gradual change tunnel section 16 is as follows:
the first step is as follows: as shown in fig. 3, the gradual hole section 16 is divided into an upper step, a middle step, and a lower step, and the gradual hole section 16 is excavated according to the upper, middle, and lower steps.
Excavating an upper step of the gradual change tunnel section 16 in advance, wherein the left side of the upper step is consistent with the profile 121 of the first small-section tunnel; in the excavation process, the upper steel frame 122 is timely supported at the arch part of the upper step, and a small advanced guide pipe and a lock pin anchor pipe for fixing the upper steel frame 122 are timely constructed; as shown in fig. 3, the left portion of the upper steel frame 122 is a normal-section steel frame 1221, the right gradual change section is a temporary support steel frame 1222, and the temporary support steel frame 1222 is fixed by a temporary foot-locking anchor pipe; after 7 upper steel frames 122 are supported, the section of the gradual change tunnel section 16 is enlarged to be consistent with the section of the first small-section tunnel 12.
The second step is that: the middle step of the gradual change tunnel section 16 lags behind the upper step by a distance (about 5 meters) for excavation supporting, and the left side of the middle step is excavated and supported for 2 meters according to the normal section of the first small-section tunnel 12 and then is excavated and supported on the right side of the middle step; corresponding middle steel frames are supported in time in the middle step excavation process, a small advanced guide pipe and a foot locking anchor pipe used for fixing the middle steel frames are constructed in time, the steel frames supported on the left side of the middle step are lengthened along the normal section steel frame 1221 in the step one, the temporary middle steel frame supported on the right side is lengthened along the temporary support steel frame 1222 in the step one, the section of the middle step is gradually changed to be the same as the section of the first small-section tunnel 12 according to 7 steel frames, and the temporary middle steel frame on the right side of the middle step is fixed through the temporary foot locking anchor pipe.
The third step: and after the middle step of the gradual change tunnel section 16 is excavated and supported to the same size as the section of the first small-section tunnel 12, spraying concrete on the tunnel face of the upper step and the middle step of the gradual change tunnel section 16 for sealing, and then reversely excavating the upper step and the middle step of the gradual change tunnel section 16 from the position, in the gradual change tunnel section 16, of the same size as the section of the first small-section tunnel 12.
The gradual change tunnel section 16 is reversely excavated by adopting a short-cut-in mode, in the reverse excavation process, blastholes arranged on the tunnel face close to one side of the second small-section tunnel 13 are converged by 60 centimeters inwards along the first small-section tunnel profile 121, the explosive loading is reduced, the damage to rock pillars 15 between the first small-section tunnel 12 and the second small-section tunnel 13 caused by drilling and blasting construction is prevented, and the underexcavated part in the first small-section tunnel profile 121 is chiseled manually. In the process of reversely digging, the temporary support steel frame 1222, the temporary middle steel frame and the temporary lock anchor pipe are gradually removed, a replacement steel frame corresponding to the right profile of the first small-section tunnel 12 is timely supported, and a short lock anchor pipe for fixing the replacement steel frame is driven in.
The back cut space 123 and the transition section 16 of fig. 4 together form a portion of the first small cross section tunnel 12.
The fourth step: and excavating the lower steps of the gradual change tunnel section 16 and the reverse excavation space 123, and gradually excavating and supporting the lower steps from the left side to the right side until the gradual change tunnel section 16 and the upper steps, the middle steps and the lower steps in the reverse excavation space 123 form a three-step section layout. The lower steel frame for supporting the lower step is lengthened along the replacement steel frame, and a lock foot anchor pipe is arranged for fixing the lower steel frame.
At this point, the excavation and reverse excavation of the gradual change tunnel section 16 are completed. Then, a three-step section layout can be formed along the transition tunnel section 16 and the upper step, the middle step and the lower step in the reverse excavation space 123 to continue the forward excavation of the first small-section tunnel 12, and the construction of the rest of the pilot tunnel of the large-section tunnel 11 and the second small-section tunnel 13.
Example 2:
a construction method for converting a large cross-section tunnel into two small cross-section tunnels, please refer to fig. 1 to 6.
Considering that the construction speed at the fork position 14 is slow, the construction progress of the whole tunnel project is affected, the section of the flat pilot tunnel 20 is smaller than that of the main tunnel 10, and the excavation speed of the flat pilot tunnel 20 is fast, therefore, the difference between the embodiment and the embodiment 1 is that before the gradual change tunnel section 16 is excavated, the branch tunnel 17 is excavated through the flat pilot tunnel 20 to enter the unearthed part of the second small section tunnel 13 located in front of the fork position 14 for backward excavation, and lining is timely applied until the fork position 14 is excavated in the backward direction.
When waiting for large cross section tunnel 11 to excavate to fork position 14, the hole section of the anti-excavation of second small cross section tunnel 13 can directly dock with large cross section tunnel 11, and the excavation work of second small cross section tunnel 13 is just carried out when not waiting for large cross section tunnel 11 to excavate to fork position 14, has consequently accelerated the construction progress.
On the other hand, since the first small-section tunnel 12 and the second small-section tunnel 13 are adjacent in front of the fork position 14 and have a large influence on each other, the reverse excavation and support of the second small-section tunnel 13 are performed first, which is equivalent to that the excavation work of the second small-section tunnel 13 and the excavation work of the first small-section tunnel 12 are staggered near the fork position 14, so that the mutual influence between the two constructions is avoided.
Further, a headwall 18 connecting the large cross-section tunnel lining 116 with the first small cross-section tunnel lining 124 and the second small cross-section tunnel lining 131 is constructed at the bifurcation site 14.
The construction method of the end wall 18 is as follows:
the first step is as follows: when the large-section tunnel 11 is excavated to the fork position 14, the air pick is used for chiseling 80 cm in thickness forwards on the tunnel face, the waterproof plate of the end wall is paved after chiseling is completed, the waterproof plate is paved on the tunnel face, and the waterproof plate is connected with the waterproof plate reserved at the side lining end of the first small-section tunnel 12 and the second small-section tunnel 13 into a whole, so that the waterproof effect is ensured.
The second step is that: the reinforcing mesh is laid in the chiseled space, the outer edge of the reinforcing mesh is correspondingly supported on the inner circumferential surface of the large cross section tunnel lining 116, and the edge of the reinforcing mesh contacting the first small cross section tunnel lining 124 and the second small cross section tunnel lining 131 is supported on the outer circumferential surface of the first small cross section tunnel lining 124 and the second small cross section tunnel lining 131.
The third step: the lining trolleys in the first small-section tunnel 12 and the second small-section tunnel 13 are all moved to a fork position 14 to be used as a part of a template for building an end wall; and then installing an end template and an end wall template of the lining trolley on the basis of the lining trolley in the first small-section tunnel 12 and the second small-section tunnel 13.
The fifth step: and after the end wall formwork is supported, performing lining pouring at the lining trolley and end wall pouring, removing the formwork after the poured concrete reaches 75% strength, and polishing and maintaining the surface of the end wall 18 in time after the formwork is removed.
The thickness of end wall is 80 centimetres, can stabilize and connect and support first little section tunnel lining cutting, the little section tunnel lining cutting of second and big section tunnel lining cutting end position, prevents that the end position earthwork from collapsing, and through the lining cutting platform truck in first little section tunnel and the little section tunnel of second for basic formwork, makes the formwork of end wall more convenient.
While the present invention has been described in detail with reference to the drawings and the embodiments, those skilled in the art will understand that various specific parameters in the above embodiments can be changed without departing from the spirit of the present invention, and a plurality of specific embodiments are formed, which are common variation ranges of the present invention, and will not be described in detail herein.
Claims (8)
1. A construction method for converting a large-section tunnel into two small-section tunnels, the large-section tunnel is divided and repaired into a first small-section tunnel and a second small-section tunnel forwards at a fork position, which is characterized in that,
the large-section tunnel is constructed by adopting a double-side-wall pit guiding method, a guide tunnel, leading to one side of the first small-section tunnel, of the large-section tunnel is firstly excavated to the fork position, then a gradual change tunnel section is excavated at the tail end of the guide tunnel, one side, far away from the second small-section tunnel, of the gradual change tunnel section is excavated along the profile of the first small-section tunnel, the other side of the gradual change tunnel section gradually extends and expands towards the direction of the second small-section tunnel to increase the section, the gradual change tunnel section is located in the profile of the first small-section tunnel, and when the section of the gradual change tunnel section is expanded to be consistent with the section of the first small-section tunnel, the gradual change tunnel section is reversely excavated into a part of the first small-section tunnel;
before the gradual change tunnel section is excavated, the gradual change tunnel section enters the un-excavated part of the second small section tunnel positioned in front of the fork position through a flat pilot tunnel to perform reverse excavation, and lining is timely performed until the gradual change tunnel section is reversely excavated to the fork position.
2. The method of claim 1, wherein during reverse excavation, the blastholes arranged on the tunnel face near the second small-section tunnel are inwardly converged for a certain distance along the excavation profile of the first small-section tunnel, and the loading is reduced to prevent damage to the rock pillar between the first small-section tunnel and the second small-section tunnel caused by drilling and blasting.
3. The method for converting a large-section tunnel into two small-section tunnels according to claim 2, wherein the gradual-change tunnel sections are reversely excavated by adopting a short-cut-length mode, and the underexcavated parts in the first small-section tunnel profile are manually excavated.
4. The method for transforming a large-section tunnel into two small-section tunnels according to claim 1, wherein in the excavation process of the transition tunnel section, the leading small ducts formed on the arch waist and the arch part of one side wall of the transition tunnel section far away from the second small-section tunnel are arranged at a larger external differential angle, and the leading small ducts formed on one side wall of the transition tunnel section near the second small-section tunnel are not formed.
5. The method for transforming a large-section tunnel into two small-section tunnels according to claim 1, wherein the gradual transition section supports steel frames in time during excavation, wherein the steel frames of the gradual transition section on one side close to the second small-section tunnel are temporary steel frames, and the steel frames on the other side are matched with the section of the first small-section tunnel.
6. The method for transforming a large-section tunnel into two small-section tunnels according to claim 1, wherein during the excavation of the first small-section tunnel, the number of the locking anchor pipes applied to one side wall of the first small-section tunnel, which is close to the second small-section tunnel, is increased, and the driving depth is reduced.
7. The method for transforming a large-section tunnel into two small-section tunnels according to claim 1, wherein an end wall connecting a lining of the large-section tunnel with linings of the first small-section tunnel and the second small-section tunnel is constructed at the position of the fork.
8. The method of claim 7, wherein during construction of the headwall, the lining trolleys in both the first and second low profile tunnels travel to the bifurcation position for use as part of a formwork for constructing the headwall.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910791817.8A CN110486021B (en) | 2019-08-26 | 2019-08-26 | Construction method for converting large-section tunnel into two small-section tunnels |
Applications Claiming Priority (1)
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| CN110924974B (en) * | 2019-11-28 | 2022-03-04 | 云南省建设投资控股集团有限公司 | A construction method of a bifurcated tunnel |
| CN113431588B (en) * | 2021-07-30 | 2022-07-22 | 中铁十四局集团第三工程有限公司 | Construction method for branch tunnel |
| CN114320319B (en) * | 2021-11-09 | 2024-05-03 | 珠海华昕开发建设有限公司 | Construction method for expanding tunnel from minimum section to extra-large section |
| CN114109447A (en) * | 2021-12-03 | 2022-03-01 | 中铁隧道局集团有限公司 | Construction method for separately repairing end wall of tunnel |
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| CN103244130A (en) * | 2013-05-31 | 2013-08-14 | 中南大学 | Quick excavation and expanding construction method of herringbone tunnel section |
| CN109057807A (en) * | 2018-09-28 | 2018-12-21 | 北京市市政三建设工程有限责任公司 | A kind of gradual change Large span tunnel reversely digs method |
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| JPH06294280A (en) * | 1993-04-06 | 1994-10-21 | Yoshio Kusakabe | Method for constructing underground structure crossing under traffic road |
| CN101709651A (en) * | 2009-12-21 | 2010-05-19 | 中铁隧道勘测设计院有限公司 | Grouting water blocking method for undersea tunnel |
| CN103244130A (en) * | 2013-05-31 | 2013-08-14 | 中南大学 | Quick excavation and expanding construction method of herringbone tunnel section |
| CN109057807A (en) * | 2018-09-28 | 2018-12-21 | 北京市市政三建设工程有限责任公司 | A kind of gradual change Large span tunnel reversely digs method |
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