Underpinning construction method for bridge pile foundation intruding into shield section

Abstract

The invention relates to the technical field of tunnel and underground engineering. The invention particularly relates to an intrusive shield section bridge pile foundation underpinning construction method. The construction method specifically comprises the following steps that S1, preparatory work before construction is conducted; s2, construction of a cofferdam; s3, grouting support construction is carried out; s4, excavation of a foundation pit; s5, carrying out joist construction; s6, construction of anchor rod static pressure piles; s7, grouting reinforcement is conducted; s8, pile cutting; and S9, restoring the riverway and the pipeline to the original shape. Vibration-free and low-noise pile foundation underpinning can be achieved in a limited space, it is guaranteed that a shield safely passes through an existing bridge, and meanwhile normal traffic on the bridge is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnels and underground engineering, and in particular to a construction method for replacing a bridge pile foundation in an intrusion shield tunnel section. Background Art

[0002] Pile underpinning is a method of replacing a foundation with a pile foundation. It is generally used for underground foundation reconstruction and is a form of foundation treatment and reinforcement. Pile underpinning is primarily used to address the need for strengthening the foundations of existing buildings, address the need for underground construction or new construction projects under existing building foundations that could impact the safety of existing buildings, and address the need for new construction projects to conflict with existing piles.

[0003] Traditional pile foundation underpinning requires extensive pipeline relocation or traffic disruption, resulting in the following challenges: 1. Long construction periods and high coordination difficulties; 2. Large machinery cannot enter narrow spaces, resulting in low construction efficiency; and 3. Significant vibration and noise impact on the surrounding environment. Therefore, a construction method for bridge pile foundation underpinning within shield tunneling intervals is urgently needed to address these issues. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned prior art, the present invention provides a construction method for underpinning bridge pile foundations in an intrusion shield tunnel section, and specifically discloses the following technical solutions: A construction method for replacing a bridge pile foundation in an intrusion shield tunnel section specifically comprises the following steps: S1. Carry out preparatory work before construction; S2. Construction of cofferdams: Construction of upstream and downstream cofferdams is carried out based on the on-site investigation and survey, pipeline information within the construction area, and riverbed elevation; S3. Grouting support construction: before the excavation of the beam foundation pit, grouting reinforcement construction is carried out on the foundation pit of the replacement base; S4. Excavation of foundation pit: excavate the earth, level the pit bottom, and lay a 200mm thick cushion layer; S5. Joist construction: After the foundation pit is excavated to the designed depth, two L-shaped joists are made at the bottom of the bridge cap beams on both sides. The top of the joists is connected to the cap beam by planting steel bars; S6. Construction of static anchor piles: Strengthen the holes at the static anchor pile locations, clean the pile holes and anchor construction surfaces at the corresponding locations on the caps, install the pile press frames, and press in the steel pipe piles in sections. S7. Grouting reinforcement: According to the design requirements, grouting reinforcement is performed on the bottom of the L-shaped joist and the shield influence area; S8, Pile cutting: After the L-shaped support beam and anchor static pressure pile construction are completed, the original pile and the cap beam are disconnected; S9. Restore the river channel and pipelines to their original state.

[0005] Furthermore, the cofferdam in step S2 is filled with geobags and covered with waterproof geotextiles, and the bottom of the cofferdam is laid according to the shape of the riverbed to ensure density and take anti-seepage measures.

[0006] Furthermore, the slurry used for grouting in step S3 is ordinary Portland cement with a water-cement ratio of 1:0.6, to which 3% water glass is added; the grouting pressure is uniformly set at 2.0-3.0 MPa, and a grouting test is performed before grouting to determine the slurry parameters.

[0007] Furthermore, in step S5, the original piles are roughened in the joist, and the anchor rods are connected to the newly made L-shaped joist by anchor rods. The horizontal portion of the joist is then used to construct the anchor rod static pressure piles.

[0008] Furthermore, in step S6, after the anchor static pressure pile construction is completed, C40 fine stone expansive concrete is poured between the steel pipe pile and the steel casing, vibrated and compacted, and then the cross steel bars are welded to the embedded M32 anchor rods on both sides, and the anchor pile cap is poured to complete the pile sealing.

[0009] Furthermore, in step S7, the slurry used for grouting reinforcement adopts ordinary silicate cement with a water-cement ratio of 1:0.6, to which 3% water glass is added; the design grouting pressure is uniformly 0.5-1.0 MPa, and tests are carried out before grouting to determine the slurry parameters.

[0010] Furthermore, in step S8, the equipment used for cutting the piles is a fully hydraulic diamond wire saw cutting machine.

[0011] Furthermore, before the construction of the L-shaped joist, the pile cutting wire of the diamond wire saw cutting machine is wrapped around the bridge pile to be cut 10 cm below the cushion layer, and the soil is backfilled to cover the wire saw to ensure that the concrete does not contact the wire saw during the cushion layer construction and joist pouring.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. Construction efficiency is significantly improved, construction period is significantly shortened, and construction costs are reduced; 2. The entire construction process is vibration-free and has low noise, which will not cause significant impact on surrounding residents; 3. After the construction is completed, the bridge deck settlement value is small, and the tunnel forming quality is also reliably guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the construction process of the present invention.

[0014] Figure 2 It is a front cross-sectional view of the grouting support construction in the present invention.

[0015] Figure 3 It is a side sectional view of the grouting support construction in the present invention.

[0016] Figure 4 It is a front cross-sectional view of the grouting reinforcement construction in the present invention.

[0017] Figure 5 It is a side sectional view of the grouting reinforcement construction in the present invention.

[0018] 1- cap beam, 2- support beam, 3- original pile, 4- anchor static pressure pile, 5- cushion layer, 6- pile cap, 7- rope saw. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0020] Reference Figure 1-5 A construction method for replacing a bridge pile foundation in an intrusion shield tunnel section specifically comprises the following steps: S1. Carry out preparatory work before construction; S2. Construction of cofferdams: Construction of upstream and downstream cofferdams is carried out based on the on-site investigation and survey, pipeline information within the construction area, and riverbed elevation; S3. Grouting support construction: before the excavation of the beam foundation pit, grouting reinforcement construction is carried out on the foundation pit of the replacement base; S4. Excavation of foundation pit: excavate the earth, level the pit bottom, and lay a 200mm thick cushion layer 5 using C20 plain concrete; S5. Joist construction: After the foundation pit is excavated to the designed depth, two L-shaped joists 2 are made at the bottom of the bridge cap beam 1 on both sides. The top of the joist 2 is connected to the cap beam 1 through embedded reinforcement. S6. Construction of anchor static pressure piles 4: Strengthen the hole at the anchor static pressure pile location, clean the pile hole and anchor construction working surface at the corresponding position of the cap, install the pile frame, and press the steel pipe piles in sections; S7, grouting reinforcement: according to the design requirements, grouting reinforcement is performed on the bottom of the L-shaped joist 2 and the shield influence area; S8, Pile cutting: After the L-shaped joist 2 and anchor static pile 4 are completed, the original pile 3 is disconnected from the cap beam 1 to prevent the thrust generated by the shield pile grinding from affecting the bridge structure; S9. Restore the river channel and pipelines to their original state.

[0021] In this embodiment, the cofferdam in step S2 is filled with geobags and covered with waterproof geotextiles. The bottom of the cofferdam is laid according to the shape of the riverbed to ensure density and take anti-seepage measures.

[0022] In this embodiment, the slurry used for grouting in step S3 is ordinary Portland cement with a water-cement ratio of 1:0.6. To improve the performance of the cement slurry, 3% water glass can be added thereto; the grouting pressure is uniformly set at 2.0 to 3.0 MPa. Before grouting, a grouting test is performed to determine the slurry parameters, which include the diffusion radius and the shotcrete pressure.

[0023] In this embodiment, in step S5, the original pile 3 is roughened in the joist 2 and connected to the newly made L-shaped joist 2 by anchoring reinforcement; and then the horizontal portion of the joist 2 is used to construct the anchor static pressure pile 4.

[0024] In this embodiment, during the construction of the anchor static pressure pile 4, the L-shaped support beam 2 is used as a reaction frame, and the pile driving equipment is only 2.2 m high, which can adapt to the limited height space under the bridge.

[0025] In this embodiment, in step S6, after the construction of the anchor static pressure pile 4 is completed, C40 fine stone expansive concrete is poured between the steel pipe pile and the steel casing and vibrated to make it dense. Then, the cross steel bars are welded to the embedded M32 anchor rods on both sides, and the pile cap 6 for sealing the anchor is poured to complete the pile sealing.

[0026] In this embodiment, in step S7, the slurry used for grouting reinforcement is ordinary Portland cement with a water-cement ratio of 1:0.6. In order to improve the performance of the cement slurry, 3% water glass can be added thereto; the design grouting pressure is uniformly 0.5-1.0 MPa, and experiments are carried out before grouting to determine the slurry parameters, which include diffusion radius and shotcrete pressure.

[0027] In this embodiment, in step S8, the equipment used for cutting the pile is a fully hydraulic diamond wire saw cutting machine, which has the characteristics of straight and neat incision, fast speed, high efficiency, low noise, no dust, and easy operation.

[0028] In this embodiment, before the construction of the L-shaped joist 2, the wire saw 7 of a diamond wire saw cutting machine is wrapped around the bridge pile to be cut 10 cm below the cushion layer 5, and soil is backfilled to cover the wire saw 7 to ensure that concrete does not contact the wire saw 7 during the construction of the cushion layer 5 and the pouring of the joist 2.

[0029] The above description is merely a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A construction method for replacing bridge pile foundations in an intrusion shield tunnel section, characterized in that: The specific steps include: S1. Carry out preparatory work before construction; S2. Construction of cofferdams: Construction of upstream and downstream cofferdams is carried out based on the on-site investigation and survey, pipeline information within the construction area, and riverbed elevation; S3. Grouting support construction: before the excavation of the beam foundation pit, grouting reinforcement construction is carried out on the foundation pit of the replacement base; S4. Excavation of foundation pit: excavate the earth, level the pit bottom, and lay a 200mm thick cushion layer; S5. Joist construction: After the foundation pit is excavated to the designed depth, two L-shaped joists are made at the bottom of the bridge cap beams on both sides. The top of the joists is connected to the cap beam by planting steel bars; S6. Construction of static anchor piles: Strengthen the holes at the static anchor pile locations, clean the pile holes and anchor construction surfaces at the corresponding locations on the caps, install the pile press frames, and press in the steel pipe piles in sections. S7. Grouting reinforcement: According to the design requirements, grouting reinforcement is performed on the bottom of the L-shaped joist and the shield influence area; S8, Pile cutting: After the L-shaped support beam and anchor static pressure pile construction are completed, the original pile and the cap beam are disconnected; S9. Restore the river channel and pipelines to their original state.

2. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 1 is characterized in that: The cofferdam in step S2 is filled with geobags and covered with waterproof geotextiles. The bottom of the cofferdam is laid according to the shape of the riverbed to ensure density and take anti-seepage measures.

3. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 1 is characterized in that: The slurry used for grouting in step S3 is ordinary Portland cement with a water-cement ratio of 1:0.6, to which 3% water glass is added; the grouting pressure is uniformly set at 2.0-3.0 MPa, and a grouting test is performed before grouting to determine the slurry parameters.

4. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 1 is characterized in that: In step S5, the original piles are roughened in the joist, and the original piles are connected to the newly made L-shaped joist by anchoring reinforcement; and then the horizontal part of the joist is used to carry out anchor static pressure pile construction.

5. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 1 is characterized in that: In step S6, after the anchor static pressure pile construction is completed, C40 fine stone expansive concrete is poured between the steel pipe pile and the steel casing, vibrated and compacted, and then the cross steel bars are welded to the embedded M32 anchor rods on both sides, and the anchor pile cap is poured to complete the pile sealing.

6. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 1 is characterized in that: In step S7, the slurry used for grouting reinforcement is ordinary Portland cement with a water-cement ratio of 1:0.6, to which 3% water glass is added; the design grouting pressure is uniformly 0.5-1.0 MPa, and a test is carried out before grouting to determine the slurry parameters.

7. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 1 is characterized in that: In step S8, the equipment used for cutting the pile is a fully hydraulic diamond wire saw cutting machine.

8. The method for underpinning a bridge pile foundation in an intrusion shield tunnel section according to claim 7 is characterized in that: Before the construction of the L-shaped joist, the pile cutting wire of the diamond wire saw cutting machine is used to cover the bridge pile to be cut 10 cm below the cushion layer, and the soil is backfilled to cover the wire saw to ensure that the concrete does not contact the wire saw during the cushion layer construction and joist pouring.

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