CN106149733A - Tunnel immediately adjacent to bridge section deep foundation pit supporting structure and construction method - Google Patents

Abstract

The invention relates to a support structure for deep foundation pits in bridge-tunnel joints, which mainly includes tunnels, reinforced beams at tunnel sides, cement-soil walls, prefabricated square piles, connecting vertical pipes, steel cages, mold bags, supports, and cast-in-place walls. It is composed of slab walls, side slopes, horizontal cover beams, shaped guide frames, and large caps; the lower part of the tunnel floor is equipped with tunnel edge reinforcement beams, and the outer side of the large caps is equipped with prefabricated square piles and cast-in-place wall panels. The lower part of the cast-in-place siding wall is provided with a cement-soil wall, the construction guide wall is provided with a stereotyped guide frame, and the side slope and the upward slope are provided with mortar anchors and shotcrete. The present invention has the following characteristics and beneficial effects: the safety and stability of the deep foundation pit support in the bridge-tunnel connecting section are improved by means of tunnel reinforcement beams, cement-soil walls, cast-in-place siding walls, etc., and the entire construction process is easy to operate , the benefit is remarkable. The tensile strength of the cast-in-place siding wall can be improved by the tension anchor cable inside the prefabricated square pile and the mold bag outside the steel cage.

Description

Support structure and construction method of deep foundation pit in bridge-tunnel connection section

technical field

The invention relates to a support structure and a construction method of a bridge-tunnel joint section, in particular to a bridge-tunnel joint section deep foundation pit support structure and a construction method, which belong to highway municipal engineering.

Background technique

With the rapid development of China's economy, the construction of expressways has increasingly penetrated into mountainous areas, the proportion of bridges and tunnels has increased significantly, and the connection of bridges and tunnels has become a new landscape of expressways. The design section of the bridge-tunnel connecting section is small, the terrain is relatively narrow, the construction site is cramped, the line is high, the abutment is close to the tunnel entrance, and the construction of the portal and the erection of the beam and slab are relatively difficult. During the excavation of the deep foundation pit at the bridge-tunnel junction, it will have a great impact on the stability of the side slope and the structure of the dark tunnel. Corresponding support needs to be strengthened to ensure that the side slope at the exit of the tunnel, the structure of the dark hole and the The stability and safety of the side wall of the foundation pit.

In the existing deep foundation pit support construction of the bridge-tunnel connection structure at the exit of the tunnel, the support scheme of enclosure piles + micro steel pipe piles and temporary anchor shotcrete nets is adopted. At the same time, the tunnel side slope and upside slope adopt the general bolt-spray reinforcement method, the bridge-tunnel connection section adopts retaining piles, and the bottom of the tunnel adopts the supporting technology of micro-steel pipe pile grouting reinforcement. The displacement and deformation monitoring of the tunnel side slope and the tunnel body show that the overall stability and support effect of the tunnel are good. However, the construction of this kind of support method is relatively complicated, the number of enclosure piles is large, and the construction period is long.

In view of this, in order to improve the safety and stability of the foundation pit at the bridge-tunnel junction, it is urgent to invent a simple and effective deep foundation pit support structure and construction method at the bridge-tunnel junction to improve the construction quality of the bridge-tunnel junction and construction efficiency.

Contents of the invention

The purpose of the invention is to improve the safety and stability of the foundation pit of the connecting section of the bridge and tunnel, and has better technical and economic benefits.

To achieve the above object, the present invention adopts the following technical solutions:

The deep foundation pit supporting structure of the bridge-tunnel connecting section is characterized in that the structure mainly includes tunnels, tunnel side reinforcement beams, cement-soil walls, prefabricated square piles, connecting vertical pipes, steel cages, mold bags, supports, existing It is composed of pouring siding wall, side slope, horizontal cover beam, shaped guide frame, large cap, etc.; the lower part of the tunnel floor is equipped with tunnel edge reinforcement beams, and the outer side of the large cap is equipped with prefabricated square piles and cast-in-place wall panels The lower part of the cast-in-place siding wall is provided with a cement-soil wall, the construction guide wall is provided with a stereotyped guide frame, and the slope and the upward slope are provided with mortar anchors and shotcrete.

Further, the reinforced beam at the side of the tunnel is pre-embedded near the side of the prefabricated square pile and then connected with horizontal reinforcement.

The prefabricated square piles are provided with a shelving groove, and the prefabricated square piles are provided with three grooves at the corner, and the other prefabricated square piles are provided with two grooves, and the connecting vertical pipes are arranged in the grooves. Bottom plate, with pre-buried connection ends on the bottom plate, horizontal connection holes on the side of the prefabricated square piles, horizontal screw rods in the holes, steel pipe supports between the prefabricated square piles, horizontal cover beams on the top of the prefabricated square piles, and rear A screw connection end is provided at a corresponding position connected to the horizontal rib.

There is an anchor cable inside the connecting vertical pipe, a top fixing piece on the top, an anchor cable connecting steel plate on the top of the anchor cable, a steel plate embedded key between the horizontal and vertical steel plates, a grouting hole at the bottom of the connecting vertical pipe, and a grouting hole outside the hole. Lay out geotextiles.

The cast-in-place siding wall is equipped with a reinforcement cage, the bottom of the reinforcement cage is provided with a reinforcement cage bottom plate, the bottom plate is embedded with bolts, the side is provided with a mold bag, and the inside of the mold bag is provided with supports fixed on the reinforcement cage. The cap is fixed on the bottom plate of the steel cage.

Horizontal stiffeners are arranged on the reinforcement cage, steel bar connecting collars are arranged at the ends of the horizontal stiffening ribs, and connecting vertical pipes are arranged inside the reinforcing bar connecting collars.

The present invention also provides a construction method for the deep foundation pit supporting structure of the bridge-tunnel connecting section, which is characterized in that it includes the following steps:

1) Reinforcing beams at the side of the tunnel: Excavate the lower part of the tunnel floor that has been constructed, cast the post formwork, reserve horizontal ribs on the sides, and then set up the set guide frame;

2) Construction of cement-soil wall: After the excavation of the foundation pit is completed, the cement-soil wall is constructed by mixing or slotting.

3) Binding reinforcement cages: Binding reinforcement cages according to the design requirements, then binding horizontal reinforcing ribs every 30-50cm, welding the steel bar connection collar at the end of the horizontal reinforcing ribs, and binding supports every 50-100cm;

4) Set the mold bag: put the mold bag outside the reinforcement cage, bind the mold bag with the support, put the bottom into the pre-embedded bolts on the bottom plate of the reinforcement cage, and tighten and fix it with the L-shaped pressure plate and the nut.

5) Implantation of prefabricated square piles: fix the connecting vertical pipe with anchor cables on the pre-embedded connection end, then lift and implant the prefabricated square piles, and weld steel pipe support between the two prefabricated square piles after implantation;

6) Connection between the reinforced beam at the side of the tunnel and the prefabricated square pile: the horizontal screw reserved for the prefabricated square pile is welded with the reserved horizontal reinforcement on the reinforced beam at the side of the tunnel;

7) Pouring the cast-in-place siding wall: lifting the reinforcement cage so that the reinforcement ring passes through the connecting vertical pipe, controlling the verticality and position of the reinforcement cage in real time, and pouring concrete while placing the reinforcement cage;

8) Fix the anchor cable: After the anchor cable is stretched, inject mortar into the connecting vertical pipe, use the anchor cable connecting steel plate to connect the anchor cable as a whole, and interlock the vertical and horizontal sections through the steel plate fitting key;

9) Construction of horizontal cover beams: Formwork pouring of horizontal cover beams on top of prefabricated square piles;

10) Construction slope and upward slope: Construction mortar anchors and sprayed concrete form slope protection.

The present invention has following characteristics and beneficial effect:

(1) The present invention improves the safety and stability of deep foundation pit support at bridge-tunnel junctions by means of tunnel reinforcement beams, cement-soil walls, cast-in-place slab walls, etc. The entire construction process is simple to operate and has significant benefits.

(2) The tensile strength of the cast-in-place siding wall can be improved by the tension anchor cable inside the prefabricated square pile and the mold bag outside the steel cage.

(3) Horizontal reinforcing ribs are set on the sides of the steel cage, and steel bar connecting collars are set at the ends of the horizontal reinforcing ribs, and the collars are inserted into the connecting vertical pipes, which can increase the integrity of the cast-in-place siding wall.

Description of drawings

Fig. 1 is the plane view of the deep foundation pit supporting structure of bridge-tunnel connecting section of the present invention;

Fig. 2 is a sectional view of the connecting section of the bridge and tunnel of the present invention;

Fig. 3 is a side sectional view of the connecting section of the bridge and tunnel of the present invention;

Figure 4 is a connection diagram between the reinforced beam at the side of the tunnel and the prefabricated square pile;

Fig. 5 is the structural diagram of the second groove of the prefabricated square pile of the present invention;

Fig. 6 is a structural diagram of three grooves of prefabricated square piles of the present invention;

Fig. 7 is a structural representation of the steel cage of the present invention;

Figure 8 is an enlarged view in the circle of Figure 7;

Fig. 9 is a connection diagram of a reinforcement cage of the present invention and a connecting vertical pipe;

Figure 10 is a partially enlarged view of Figure 2;

Figure 11 is a partial enlarged view of Figure 3;

Among them: 1. Tunnel 2. Tunnel reinforcement beam 3. Rear connection with horizontal reinforcement 4. Cement-soil wall 5. Prefabricated square pile 6. Shelving groove 7. Connecting vertical pipe 8. Grouting hole 9. Anchor cable 10. Standpipe fixing Plate 11. Embedded connection end 12. Post-grouting body 13. Reinforcement connection collar 14. Reinforcement cage 15. Top fixing piece 16. Mold bag 17. Support piece 18. Cast-in-place wall panel wall 19. Anchor cable connection steel plate 20 .Horizontal cover beam 21. Guide wall 22. Shaped guide frame 23. Nut 24. Large bearing platform 25. Mortar anchor 26. Screen shotcrete 27. Screw connection end 28. Connecting screw 29. Steel pipe support 30. Steel cage bottom plate 31. Horizontal connection hole 32. Horizontal screw rod 33. Horizontal rib 34. Embedded bolt 35. L-shaped pressure plate.

detailed description

Formwork supporting technical requirements, concrete pouring construction technical requirements, steel bar binding technical requirements, etc., will not be repeated in the present invention, and the embodiments of the structure related to the present invention will be focused on.

As shown in Figures 1 to 3, the deep foundation pit support structure at the bridge-tunnel junction is mainly composed of a tunnel with an inner diameter of 6m, a reinforced beam at the side of the tunnel with a height of 1.5m and a width of 8m, cement-soil walls, prefabricated square piles with an outer diameter of 2m, It is composed of connecting vertical pipes with a diameter of 25mm, steel cages, mold bags with a thickness of 5mm, steel plate supports with a thickness of 3mm, cast-in-place wall panels with a thickness of 1.8m, side slopes, horizontal cover beams, shaped guide frames with a diameter of 48mm, and large caps. ; The lower part of the tunnel floor is equipped with tunnel edge reinforcement beams, and the outer side of the 8m×8m large cap is equipped with prefabricated square piles and cast-in-place wall panels. The guide frame, the side slope and the upward slope are provided with a 4m mortar anchor and a 10cm thick sprayed concrete. A reinforcement cage is installed inside the cast-in-place siding wall. The bottom of the reinforcement cage is provided with a reinforcement cage bottom plate with a thickness of 3mm. The bottom plate is pre-embedded with 20mm bolts. The L-shaped pressure plate and the nut are fixed on the bottom plate of the steel cage.

As shown in Figure 4, the reinforced beam at the side of the tunnel is pre-embedded with a diameter of 20mm near the side of the prefabricated square pile and then connected with horizontal reinforcement. A screw connection end with a length of 20cm is provided at the corresponding position of the prefabricated square pile and the rear horizontal reinforcement. When the two are connected, the connection is completed by welding the rear horizontal reinforcement and the screw connection end.

As shown in Figures 5-6, the prefabricated square piles are provided with a 60cm wide shelving groove, the prefabricated square piles are provided with three grooves at the corner, and the other prefabricated square piles are provided with two grooves, and the grooves are equipped with connecting vertical pipes, and the entire shelving groove is equipped with Post-grouting body, the post-grouting body is C30 cement mortar, the bottom is equipped with a vertical pipe to fix the bottom plate, the bottom plate is a 3mm thick steel plate, the bottom plate is equipped with a pre-embedded connection end, and the side of the prefabricated square pile is provided with a horizontal connection hole, the hole diameter is 22mm , set a horizontal screw in the hole, the diameter of the screw is 20mm, there is a steel pipe support with a diameter of 48mm between the prefabricated square piles, and a horizontal cover beam with a width of 2mm and a thickness of 1m is installed on the top of the prefabricated square piles, and the corresponding position of the rear horizontal reinforcement is provided with a length 20cm screw connection end.

There is an anchor cable with a diameter of 2mm inside the connecting vertical pipe, and a 3mm steel plate top fixing piece on the top, and an anchor cable connecting steel plate with a thickness of 3mm on the top of the anchor cable. There are grouting holes with a diameter of 10mm, and geotextiles are arranged outside the holes.

As shown in Figure 7, a horizontal stiffener with a diameter of 18 mm is provided on the reinforcement cage, and a steel bar connection collar is provided at the end of the stiffener. The collar is made of a steel bar with a diameter of 10 mm, and a connecting vertical pipe is arranged inside the collar.

Claims (7)

1. The deep foundation pit supporting structure of the bridge-tunnel connecting section is characterized in that it mainly consists of a tunnel (1), a reinforced beam at the side of the tunnel (2), a cement-soil wall (4), prefabricated square piles (5), and connecting vertical pipes (7), reinforcement cage (14), mold bag (16), support piece (17), cast-in-place siding wall (18), side slope, horizontal cover beam (20), shaping guide frame (22) and large bearing platform (24); the lower part of the tunnel (1) floor is provided with a tunnel reinforcement beam (2), and the outer side of the large cap (24) is provided with prefabricated square piles (5) and cast-in-place wall panels (18) , the lower part of the cast-in-place siding wall (18) is provided with a cement-soil wall (4), the construction guide wall (21) is provided with a stereotyped guide frame (22), and the side slope and the upward slope are provided with a mortar anchor (25) with mesh shotcrete (26). 2. The deep foundation pit supporting structure of the bridge-tunnel junction according to claim 1, characterized in that the reinforced beam (2) at the side of the tunnel is pre-embedded near the side of the prefabricated square pile (5) and then connected with horizontal ribs (3 ). 3. The deep foundation pit supporting structure of the bridge-tunnel junction according to claim 1, characterized in that the prefabricated square pile (5) is provided with a shelving groove (6), and the prefabricated square pile (5) at the corner is provided with three grooves, The rest of the prefabricated square piles (5) are provided with two grooves, the grooves are provided with connecting vertical pipes (7), the entire shelving groove (6) is provided with a rear grouting body (12), and the bottom is provided with a vertical pipe fixing base plate (10), A pre-buried connection end (11) is provided on the bottom plate, a horizontal connection hole (31) is provided on the side of the prefabricated square pile (5), a horizontal screw rod (32) is provided in the hole, and steel pipe supports are provided between the prefabricated square piles (5) (29), the top of the prefabricated square pile (5) is provided with a horizontal cover beam (20), and the corresponding position of the horizontal rib (3) is provided with a screw connection end (27). 4. The deep foundation pit supporting structure of the bridge-tunnel junction according to claim 1, characterized in that the inside of the connecting vertical pipe (7) is provided with an anchor cable, and the top is provided with a top fixing member (16), and the anchor An anchor cable connecting steel plate (20) is provided on the top of the cable, a steel plate embedded key is provided between the horizontal and vertical steel plates (10), and a grouting hole (8) is provided at the bottom of the connecting vertical pipe (7), and a geotextile is arranged outside the hole. 5. The deep foundation pit supporting structure of the bridge-tunnel junction according to claim 1, characterized in that a reinforcement cage (14) is arranged inside the cast-in-place wall (18), and a reinforcement cage (14) is arranged at the bottom of the reinforcement cage (14). There is a steel cage bottom plate (30), the bottom plate is provided with embedded bolts (34), the side is provided with a mold bag (16), and the inside of the mold bag (16) is provided with a support (17) fixed on the steel cage (14), and the bottom Cooperate the nut (23) with the L-shaped pressing plate (35) and be fixed on the reinforcement cage bottom plate (30). 6. The deep foundation pit support structure of the bridge-tunnel junction according to claim 1, characterized in that horizontal reinforcing ribs (33) are provided on the reinforcement cage (14), and the ends of the horizontal reinforcing ribs (33) are provided with A reinforcing bar connecting collar (13) is arranged, and a connecting vertical pipe (7) is arranged in the reinforcing bar connecting collar (13). 7. The construction method of the deep foundation pit support structure of the bridge-tunnel junction as claimed in claim 1, characterized in that it comprises the following steps: 1) Reinforced beams (2) at the construction tunnel side: Excavate the lower part of the tunnel floor that has been constructed, cast the post formwork, reserve horizontal ribs (3) on the sides, and then set up the setting guide frame (22); 2) Construct the cement-soil wall (4): After the excavation of the foundation pit is completed, stir or groove to construct the cement-soil wall (4); 3) Binding the reinforcement cage (14): Bind the reinforcement cage (14) according to the design requirements, then bind the horizontal reinforcing ribs (33) every 30-50 cm, and weld the connecting rings (13) of the reinforcing bars at the ends of the horizontal reinforcing ribs (33), Simultaneously every 50～100cm binding supports (17); 4) Set the mold bag (16): put the mold bag (16) on the outside of the reinforcement cage (24), bind the mold bag (16) with the support (17), and insert the embedded mold on the bottom plate of the reinforcement cage (14) at the bottom. Bolt (34), and use L-shaped pressure plate to match (35) and nut (23) to tighten and fix; 5) Implantation of prefabricated square piles (5): fix the connecting vertical pipe (7) with anchor cables (9) on the pre-embedded connection end (11), then lift and implant the prefabricated square piles (5), and implant Welded steel pipe support (29) between the rear two prefabricated square piles (5); 6) Connection between the reinforced beam at the tunnel side (2) and the prefabricated square pile (5): the horizontal screw rod (32) reserved for the prefabricated square pile (5) and the horizontal reinforcement (32) reserved on the reinforced beam at the tunnel side (2) )welding; 7) Pouring the cast-in-place siding wall (18): Lift the reinforcement cage (14), make the reinforcement ring (13) pass through the connecting vertical pipe (7), control the verticality and position of the reinforcement cage (14) in real time, and set the side Enter reinforcement cage (14) and pour concrete; 8) Fix the anchor cable (9): After the anchor cable (9) is stretched, inject mortar into the connecting vertical pipe (7), and use the anchor cable connecting steel plate (19) to connect the anchor cable (9) into a whole. Interlocking through steel plate fitting key; 9) Constructing the horizontal cover beam (20): pouring the horizontal cover beam (20) on the top of the prefabricated square pile (5); 10) Construction side slope and upside slope: Construction mortar bolts (25) and sprayed concrete (26) form slope protection.