CN108019209B - The drawing anchor construction method of upper overburden layer sedimentation and deformation suitable for shallow tunnel - Google Patents

Abstract

The anchor pulling construction method suitable for the settlement and deformation of the overlying soil layer of the shallow buried tunnel disclosed by the present invention comprises the following steps: Step 1, pretreatment before excavating the tunnel; Applying a grouting anchor; step 3, constructing a foundation beam near the surface above the tunnel to fix the anchor head; step 4, excavating the tunnel by using the method of upper, middle and lower steps. The anchor pulling construction method of the present invention applies an anchor force to the overlying soil layer of the tunnel by applying an anchor rod at the spandrel of the tunnel and connecting it with the foundation beam, thereby playing the role of pulling the anchor; effectively reinforcing the loose, and shallowly burying the ground The settlement and deformation of the overlying soil layer on the tunnel can play a very good role in limiting and reducing the construction period. This construction method has short construction period, low cost and high construction efficiency. It can dissipate the unbalanced force caused by tunnel excavation, adjust the strain state, and slow down the development of deformation. , realize self-restriction effect, and have very good practical value.

Description

Anchor construction method suitable for settlement and deformation of overlying soil layer in shallow buried tunnel

technical field

The invention belongs to the technical field of excavation methods for shallow-buried tunnels, and in particular relates to an anchor-drawing construction method suitable for the settlement deformation of the overlying soil layer of shallow-buried tunnels.

Background technique

In recent years, the intensification of urban population has made the ground use area more and more limited, and the ground traffic has become more and more congested, thus promoting the rapid popularization and progress of urban underground railways. With the maturity of urban rail transit, both subway tunnels and highway tunnels have been well developed in various regions, but there are more and more problems arising therefrom.

The rapid development of the subway has undoubtedly alleviated the considerable traffic congestion problem in major cities and brought great convenience to people. But there is a worry here. The buried depth of the subway is generally 10-20 meters, and most of the tunnels are shallow. The excavation will inevitably cause disturbance and damage to the surrounding soil, causing the overlying soil layer on the tunnel to have different degrees of settlement and deformation. It directly affects the safe use of dense buildings on the ground, road pavement and municipal engineering, and this phenomenon is more prominent in loose and weak strata. Therefore, in order to ensure the safety of ground buildings and the normal order of ground traffic, the settlement and deformation of the overlying soil layer caused by tunnel excavation must be strictly controlled. There are many methods to control the settlement and deformation, including improving the soil properties, reducing the discharge of groundwater, selecting the construction method according to the stratum conditions, reasonably determining the excavation footage, timely support measures and engineering reinforcement measures, etc. The selection should be as reasonable and effective as possible, otherwise There will be serious consequences.

Contents of the invention

The purpose of the present invention is to provide an anchoring construction method suitable for the settlement and deformation of the overlying soil layer of the shallow buried tunnel, which solves the problem that the existing shallow buried tunnel is prone to the settlement and deformation of the overlying soil layer during excavation.

The technical scheme adopted in the present invention is a construction method for drawing anchors suitable for the settlement and deformation of the overlying soil layer of shallow buried tunnels, comprising the following steps:

Step 1, pretreatment before tunnel excavation

Above the excavation surface of the tunnel within the scope of reinforcement treatment, use ordinary drilling rigs to carry out hole-forming operations, and then insert the advanced small conduit into the formed holes and inject grout to form a pre-consolidated layer;

Step 2, apply grouting anchor

Step 2.1, at the spandrel position of the tunnel processed in step 1, use an ordinary drilling rig to drill a group of boreholes symmetrically along the direction that forms an angle of 30°-45° with the vertical centerline of the tunnel, and then clean the boreholes;

Step 2.2, use the head to install the hollow grouted anchor rod of the anchor head, and then insert it into the drilled hole in step 2.1, and at the same time hang the hollow grouted anchor rod with the barb on the anchor head; Install the sleeve, grout stopper, backing plate and nut on the anchor rod in sequence, and then connect the grouting hole at the end of the hollow grouting anchor rod to the grouting machine;

Step 2.3, grouting the hollow grouting anchor rod through the grouting machine and the grouting hole to obtain the grouting anchor rod;

Step 3, fixing the anchor head of the grouted anchor treated in step 2

Step 3.1, build a concrete cushion above the tunnel treated in step 2, and then draw the centerline and sideline of the foundation beam to be constructed as the reference line for the post support formwork;

Step 3.2, making steel bars that meet the requirements and binding the steel bars at the corresponding parts according to the requirements, and then installing the wooden formwork according to the center line and side line of step 3.1;

Step 3.3: Sprinkle and wet the wooden formwork, then use reinforced concrete to pour and tamp the wooden formwork and the embedded anchor head, so that the anchor head is fixed in the foundation beam in the wooden formwork, and remove the wooden formwork after solidification for no less than 24 hours. mold, even if the anchor head is fixed in the foundation beam;

Step 4: Excavate the tunnel treated in step 3 by using the upper, middle and lower steps method to obtain a shallow buried tunnel that prevents deformation of the overlying soil layer.

The present invention is also characterized in that,

In step 1, the leading small conduits are all seamless steel pipes, specifically including grouting inlets, grouting section steel pipes and grout stop section steel pipes which are successively connected to each other;

The grouting inlet is conical, and grouting holes arranged in a quincunx shape are arranged in the steel pipe of the grouting section.

The inner diameter of the leading small conduit is 30-50mm, the length is 3-5mm, the distance between adjacent grouting holes is 100-150mm, and the distance between adjacent small leading conduits is 300-500mm.

The specific installation operation of the advanced small conduit is as follows:

The advanced small conduit is installed after being jacked with a pick or machined into a hole, and drilled outward along the longitudinal excavation contour line of the tunnel at an angle of 10°-30°, and then driven into the formation; after installation, Use hemp silk and anchoring agent to block the gap between the nozzle of the leading small conduit and the hole, and install a head and an orifice valve at the nozzle of the leading small conduit.

In step 2, the length of the hollow grouting anchor rod inserted into the borehole is not less than 95% of its total length; the backing plate is close to the air surface of the tunnel.

In step 3, the surface of the wooden mold is cleaned before use, then brushed with release grease, and the wooden mold is supported after it is dry.

In step 3, the pouring operation uses a plug-in vibrator, and the vibrating time is 10-15s.

The specific steps of step 4 are:

In step 4.1, adopt the circular excavation reserve core soil method for the upper steps, first dig an arc-shaped pit on the upper section of the tunnel, then excavate the core soil in the middle and erect a steel arch frame, and set the primary support and arch foot of the corresponding part in it Grouting lock foot anchor pipe to control the settlement deformation of the initial lining;

In step 4.2, the middle steps are excavated on the left and right sides, and the steel arches are erected in time, and the corresponding part of the primary support and the wall corner grouting lock foot anchor pipe are installed to control the settlement deformation of the initial lining;

Step 4.3: Excavate the lower steps to construct the inverted arch of the tunnel, and set the primary support for the corresponding part, so that the initial lining of the arch wall, the initial lining of the vault and the initial lining of the inverted arch are connected as a whole to form a closed ring-shaped initial lining;

Step 4.4: Set up a plastic sheet isolation layer as a waterproof layer, perform molding concrete operations on the tunnel inverted arch and arch wall in turn, and complete the secondary lining and vault backfill grouting.

The beneficial effects of the present invention are: the anchoring construction method suitable for the settlement and deformation of the overlying soil layer of the shallow buried tunnel, by applying anchor rods at the spandrels of the tunnel and connecting them with the foundation beams near the surface, the tunnel An anchor force is applied to the overlying soil layer to play the role of pulling the anchor; it can effectively reinforce the loose and weak stratum structure, and play a good role in restricting and reducing the settlement and deformation of the overlying soil layer of the shallow tunnel buried in the stratum. The construction period of this construction method is Short, low cost, high construction efficiency, can dissipate the unbalanced force caused by tunnel excavation, adjust the strain state, slow down or delay the development of deformation, realize self-control effect, have high economic and social benefits, and have great potential Good practical value.

Description of drawings

Fig. 1 is the excavation construction flowchart of tunnel in the anchor drawing construction method of the present invention;

Fig. 2 is the structural representation of A-A section among Fig. 1 of the present invention;

Fig. 3 is a schematic diagram of tunnel anchor construction in the anchor construction method of the present invention;

Fig. 4 is the structural representation of the hollow grouting anchor rod in the anchor pulling construction method of the present invention;

Fig. 5 is a flow chart of the hollow grouting bolt construction process in the anchor pulling construction method of the present invention.

In the figure, 1. Advanced small conduit, 2. Steel arch frame, 3. Arch foot grouting lock foot anchor pipe, 4. Wall foot grouting lock foot anchor pipe, 5. Primary support, 6. Plastic sheet isolation layer, 7 .Molded concrete, 8. Hollow grouting anchor rod, 9. Foundation beam, 10. Grouting hole, 11. Nut, 12. Vent hole, 13. Grout stopper, 14. Backing plate, 15. Sleeve, 16. Anchor head, 17. Drilling.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention is suitable for the anchoring construction method of the overlying soil settlement deformation of the shallow buried tunnel, comprising the following steps:

Step 1, pretreatment before tunnel excavation

Above the excavation surface of the tunnel within the scope of reinforcement treatment, ordinary drilling rigs are used to carry out hole-forming operations, as shown in Figures 1 and 2, and then the advanced small conduit 1 is inserted into the formed hole and grouted to form a pre-reinforced tunnel. knot layer;

Among them, the leading small conduit 1 is a seamless steel pipe, specifically including the grouting inlet, the steel pipe of the grouting section and the steel pipe of the grouting section connected to each other in sequence; Grouting holes; the inner diameter of the leading small conduit 1 is 30-50mm, the length is 3-5mm, the distance between every two adjacent grouting holes is 100-150mm, and the distance between every two adjacent leading small conduits 1 is 300-500mm; , the grouting fluid is determined according to the formation conditions;

The specific installation operation of the advanced small conduit 1 is as follows: the advanced small conduit 1 is installed after being jacked with a pick or machined into a hole, and drilled outward along the longitudinal excavation contour of the tunnel at an external insertion angle of 10°-30°. Then drive it into the formation; after the installation is completed, use hemp silk and anchoring agent to seal the gap between it and the hole at the nozzle of the leading small conduit 1, and install a head and an orifice valve at the nozzle of the leading small conduit 1 .

Step 2, apply grouting anchor

Step 2.1, at the spandrel position of the tunnel processed in step 1, use an ordinary drilling rig to drill a group of boreholes 17 symmetrically along the direction that forms an angle of 30°-45° with the vertical centerline of the tunnel, and then clean the boreholes 17;

Step 2.2, as shown in Figure 3 and Figure 4, use the head to install the hollow grouting anchor rod 8 of the anchor head 16, and then insert it into the drill hole 17 in step 2.1, while using the barb on the anchor head 16 to insert the hollow The grouting anchor 8 is hung up; at this time, the sleeve 15, the grout stopper 13, the backing plate 14 and the nut 11 are installed sequentially on the hollow grouting anchor 8, and then the grouting hole 10 at the end of the hollow grouting anchor 8 is It is connected with the grouting machine; the tail of the hollow grouting anchor rod 8 is also provided with an exhaust hole 12; the length of the hollow grouting anchor rod 8 inserted into the drill hole 17 is not less than 95% of its total length; the backing plate 14 is pasted tight tunnel airside;

Step 2.3, grouting the hollow grouting anchor rod 8 through the grouting machine and the grouting hole 10, if you want to perform pressure grouting to improve the soil structure, you only need to wait for the pointer on the pressure gauge to rise to the designed pressure That is, the grouting anchor rod can be obtained, as shown in FIG. 5 for details.

Step 3, fixing the grouted anchor head 16 processed in step 2

Step 3.1, build a concrete cushion above the tunnel processed in step 2, and then pop up the center line and side line of the foundation beam 9 to be constructed on it with ink lines, as the reference line of the later formwork;

Step 3.2: Make steel bars that meet the requirements and bind the steel bars at the corresponding parts according to the requirements, and then install the wooden formwork according to the centerline and sideline of step 3.1; the surface of the wooden formwork should be cleaned before use, and then brushed with release grease. After it dries, support the wooden formwork;

In step 3.3, the wooden formwork is sprayed and wetted, and then the wooden formwork and the embedded anchor head 16 are poured and tamped with reinforced concrete, so that the anchor head 16 is fixed in the foundation beam 9 in the wooden formwork, and solidified for no less than 24 hours. Finally remove the wooden formwork, even if the anchor head 16 is fixed in the foundation beam 9, wherein the pouring and ramming operation adopts a plug-in vibrator, and the ramming time is 10-15s;

The construction of the foundation beam 9 should be outside the stress action space after the excavation of the underground tunnel, so as to exert the anchoring effect through the grouting bolt; the position, size and reinforcement of the foundation beam 9 should be determined according to the size of the tunnel, and use The reinforced concrete foundation beam 9 is used to fix the anchor rod; the steel bars of the foundation beam 9 are all connected by binding, and binding should be carried out in sequence during binding.

Step 4: Excavate the tunnel treated in step 3 by using the upper, middle and lower steps method to obtain a shallow buried tunnel that prevents deformation of the overlying soil layer:

In step 4.1, adopt circular excavation and reserve core soil method for the upper steps, as shown in Figure 1-3, first dig arc-shaped pit ① on the upper section of the tunnel, then excavate the core soil ② in the middle and erect steel arch 2. Corresponding parts of primary support 5 and arch foot grouting lock foot anchor pipe 3 are set inside to control the settlement deformation of the initial lining;

In step 4.2, the middle steps are excavated on the left and right sides, the left side ③ is excavated first, and then the right side ④ is excavated, the steel arch 2 is erected in time and the corresponding part of the primary support 5 and the wall corner grouting locking foot anchor pipe 4 are set. Control the settlement deformation of the initial lining;

Step 4.3: Excavate the lower steps to construct the tunnel inverted arch ⑤, and set the primary support 5 for the corresponding part, so that the initial lining of the arch wall, the initial lining of the vault and the initial lining of the inverted arch are connected as a whole to form a closed annular initial lining;

In step 4.4, the plastic thin plate isolation layer 6 is set up as a waterproof layer, and the molded concrete 7 operation is performed on the inverted arch and arch wall of the tunnel in turn to complete the secondary lining and backfill grouting on the vault.

In the construction method of the present invention, the tunnel excavation adopts the upper, middle and lower three-step method, wherein the upper step adopts the method of reserving the core soil for circular excavation. Since the core soil is left in the upper part to support the excavation surface during the excavation process, it can be quickly and timely. Do the primary support for the vault to increase the stability of the excavation surface; the core soil and the excavation of the lower part are carried out under the protection of the primary support of the arch, which is safe; the middle steps are constructed on the left and right sides, The excavation section is reduced, the scope of excavation disturbed soil layer is relatively small, the closure time is short, and the structure will soon be in a good stress state as a whole; Settlement deformation also plays a certain role in control.

Claims (8)

1. being suitable for the drawing anchor construction method of the upper overburden layer sedimentation and deformation of shallow tunnel, which comprises the following steps:

Step 1, it is pre-processed before tunneling

It will be done above the tunnel excavation face within the scope of consolidation process shortly, and carry out pore-forming operation using ordi-nary drilling machine, then will Advanced tubule (1) is inserted into hole and slip casting, forms preparatory bonding course；

Step 2, grouted anchor bar is applied

Step 2.1, at the spandrel position in the tunnel handled through step 1, using ordi-nary drilling machine along with Vertical tunnel middle line at One group of drilling (17) is symmetrically crept into the direction of 30 ° of -45 ° of angles, then cleaning drilling (17)；

Step 2.2, using the hollow grouting anchor (8) of head installation anchor head (16), it is then inserted into the drilling of step 2.1 (17) in, while hollow grouting anchor (8) being tangled with the hangnail on anchor head (16)；At this time on hollow grouting anchor (8) according to Secondary installation sleeve (15), stop grouting plug (13), backing plate (14) and nut (11), then by the slip casting of hollow grouting anchor (8) tail portion Hole (10) is connected with slip casting machine；

Step 2.3, slip casting operation is carried out to hollow grouting anchor (8) by slip casting machine and injected hole (10), obtains grouted anchor bar；

Step 3, the fixed grouted anchor bar anchor head (16) handled through step 2

Step 3.1, concrete cushion is being built through step 2 treated tunnel upper, is then drawing the grade beam that will be applied (9) center line and sideline, the reference line as later period formwork supporting plate；

Step 3.2, production meets defined reinforcing bar and according to demand in corresponding site assembling reinforcement, then according to step 3.1 Wooden model is installed in center line and sideline；

Step 3.3, wet processing of sprinkling water is carried out to wooden model, is then carried out with anchor head (16) of the armored concrete to wooden model and insertion It pours and smashes operation, be fixed on anchor head (16) in the grade beam in wooden model (9), no less than wooden model is removed afterwards for 24 hours in solidification, even if anchor Head (16) is fixed in grade beam (9)；

Step 4, the tunnel handled through step 3 is excavated using three benching tunnelling method of upper, middle and lower to get shallow to preventing upper overburden layer from deforming Bury tunnel.

2. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 1 suitable for shallow tunnel, feature It is, advanced tubule (1) is seamless steel pipe in the step 1, specifically includes successively slip casting entrance interconnected, slip casting Duan Gangguan and only slurry section steel pipe；

Wherein slip casting entrance is in coniform, and the slip casting hole arranged in plum blossom-shaped is provided in slip casting section steel pipe.

3. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 2 suitable for shallow tunnel, feature It is, advanced tubule (1) the internal diameter 30-50mm, the spacing of the adjacent slip casting hole is 100-150mm, adjacent described The spacing of advanced tubule (1) is 300-500mm.

4. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 1 to 3 suitable for shallow tunnel, It is characterized in that, the specific installation of the advanced tubule (1) operates are as follows:

Advanced tubule (1) is headed into using pneumatic pick or with installing after mechanical hole building, and outside along tunnel longitudinal direction excavation contour line With 10 ° -30 ° of extrapolation angular bit hole, stratum is then squeezed into；After the installation is completed, in advanced tubule (1) nozzle flax silk and Anchor Agent blocks its gap between hole, and end socket and orifice valves are installed at advanced tubule (1) nozzle.

5. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 1 suitable for shallow tunnel, feature It is, the length of hollow grouting anchor (8) insertion drilling (17) is no less than the 95% of its total length in the step 2；The pad Plate (14) is adjacent to tunnel free face.

6. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 1 suitable for shallow tunnel, feature It is, wooden model is first clean by its surface clean before using in the step 3, then paints demoulding grease, after its drying again Zhi Mumo.

7. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 1 suitable for shallow tunnel, feature It is, is poured in the step 3 and smash operation using poker vibrator, vibrating time 10-15s.

8. the drawing anchor construction method of the upper overburden layer sedimentation and deformation according to claim 1 suitable for shallow tunnel, feature It is, the specific steps of the step 4 are as follows:

Step 4.1, top bar uses Ring Cutting provided core soil method, and on tunnel top, section first digs arc hole, then excavates Central core soil is simultaneously set up steel arch-shelf (2), locks foot anchor tube in the once supporting (5) that corresponding portion is arranged inside and arch springing slip casting (3), the sedimentation and deformation of initial stage lining cutting is controlled；

Step 4.2, middle step divides left and right sides to excavate, in time set up steel arch-shelf (2) and be arranged corresponding portion once supporting (5) and Foot anchor tube (4) are locked in corner slip casting, control the sedimentation and deformation of initial stage lining cutting；

Step 4.3, the excavation that carries out getting out of a predicament or an embarrassing situation constructs tunnel inverted arch, and the once supporting (5) of corresponding portion is arranged, and serves as a contrast arch wall initial stage It builds, vault initial stage lining cutting and inverted arch initial stage lining cutting are connected as an entirety, formation closed circular initial stage lining cutting；

Step 4.4, sheet plastic separation layer (6) are set up as waterproof layer, successively tunnel inverted arch and arch wall are carried out building mould coagulation Native (7) operation, completes secondary lining and vault backfills slip casting.