Bored pile and pile protection system construction method near subway shield construction section

Abstract

This invention provides a construction method for bored piles and their protective pile system in a section of subway tunnel construction. The method includes steps such as construction preparation, pile location layout, high-pressure jet grouting pile construction, guide support fixing, protective pile steel pipe driving, mud preparation and its circulation system construction, drilling, hole cleaning, reinforcement cage processing and installation, sonic logging pipe installation, guide pipe installation and concrete pouring, and bored pile testing. This invention can provide vibration reduction for completed bored piles and reduce the compressive stress on the pile body caused by tunnel construction.

Description

Technical Field

[0001] This invention relates to the field of bored pile construction technology, specifically a construction method for bored piles and their protective pile system in a section of subway tunnel construction. Background Technology

[0002] With the development of urbanization, more and more urban rail transit bridges are being built, and the requirements of the engineering environment are becoming increasingly stringent for construction constraints. In particular, the construction of pile foundations, main structures and other structures near the subway shield tunneling section is complex and difficult. Therefore, it is especially important to minimize the impact of subway shield tunneling on the completed pile foundations, main structures and other structures. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention proposes a construction method for bored cast-in-place piles and their protective pile system in the adjacent subway shield tunneling section.

[0004] This invention provides a construction method for bored piles and their protective pile system in a section of subway tunnel construction, comprising the following steps:

[0005] S1. Construction preparation: Conduct a site survey, level the site, and draw the shield shell edge line of the tunnel boring machine.

[0006] S2. Pile location layout: The center of the bored pile foundation is laid out to determine the location of the guide support's pile protection point, the axis of the high-pressure jet grouting pile, and the center point of the pile protection steel pipe. The centers of the bored pile, the guide support, and the pile protection steel pipe coincide.

[0007] S3. High-pressure jet grouting pile construction: A row of high-pressure jet grouting piles parallel to the direction of subway tunnel construction is driven in the middle position between the outer wall of the tunnel boring machine and the outer wall of the bored pile.

[0008] S4. Guide bracket fixing: The guide bracket includes a grid-shaped bracket and a square bracket with the same inner diameter. The square bracket is placed on the grid-shaped bracket, so that the diagonal of the square bracket coincides with the two center lines of the grid-shaped bracket, and the center of the grid-shaped bracket coincides with the center of the square bracket. After the placement position meets the requirements, the two brackets are fully welded. One through hole is opened at each of the four intersections of the grid-shaped bracket. Four pile protection points are set according to the pile core of the bored pile and the distance between the four through holes of the guide bracket. The guide bracket is placed at the pile protection points.

[0009] S5. Insertion of protective pile steel pipe: Align the center of the protective pile steel pipe with the center of the guide support, and correct the deviation of the protective pile steel pipe in real time through the guide support during the insertion process;

[0010] S6. Construction of mud preparation and circulation system: According to the site conditions, a mud storage pool is set up, and a mud sedimentation pool is set up next to the mud storage pool. The pile protection steel pipe is connected to the mud storage pool and the mud sedimentation pool through pipelines respectively. During the drilling process, the mud storage pool replenishes fresh mud into the hole through a mud pump. When cleaning the hole, the mud in the hole settles in the mud sedimentation pool and then flows back to the mud storage pool through the pipeline.

[0011] S7. Drilling and Hole Cleaning: After the drilling rig is installed and in place, drilling is carried out. After the hole depth reaches the design elevation, the hole depth, hole diameter and inclination are checked.

[0012] S8. Reinforcing cage fabrication and installation: After the reinforcing cage is fabricated, the frame is installed using a truck crane to ensure that the frame does not deform during lifting.

[0013] S9. Installation of sonic logging pipes: Install sonic logging pipes on the installed steel cage;

[0014] S10. Conduit Installation and Concrete Pouring: Install the conduit into the installed reinforcing cage and pour concrete.

[0015] S11. Inspection of bored piles: After construction is completed, the guide support is removed and the integrity of the bored piles is inspected.

[0016] Preferably, in S4, an installation trench is excavated downward at the pile protection point, and a steel bar is pre-embedded in the installation trench. The steel bar is above the ground, and the steel bar above the ground is threaded. The four through holes of the guide bracket are aligned with the steel bars at the four pile protection points and inserted. The guide bracket is placed in place. After verifying that the center of the guide bracket coincides with the center of the pile protection steel pipe and the core of the bored pile, it is tightened with nuts to fix it.

[0017] Preferably, in S4, the mounting groove is configured as a convex shape.

[0018] Preferably, in S5, the protective pile steel pipe is driven by a fully hydraulic vibratory hammer.

[0019] Preferably, in S5, the protective pile steel pipe includes an inner steel pipe and an outer steel pipe; the inner diameter of the inner steel pipe is the same as the outer diameter of the bored pile; the inner diameter of the outer steel pipe is larger than the outer diameter of the inner steel pipe, and the length of the outer steel pipe is shorter than that of the inner steel pipe; the middle of the inner and outer steel pipes is a shock-absorbing interlayer, which is filled tightly with natural rubber; the top of the shock-absorbing interlayer is sealed by welding a steel plate flush with the inner and outer steel pipes, and the bottom of the shock-absorbing interlayer is formed by welding a steel plate to the inner and outer steel pipes to form a cutting edge.

[0020] Preferably, in S9, a clamp-type sonic logging pipe is used. The U-shaped groove at the end of the clamp-type sonic logging pipe is equipped with an O-ring rubber sealing ring. During installation, the spigot end of the sonic logging pipe is inserted into the socket end to the marking position. A special hydraulic clamp is used to simultaneously squeeze the U-shaped groove and one side of the U-shaped groove. After being squeezed, the rubber sealing ring plays a sealing role. The pipe material at both the spigot end and the socket end of the clamped part shrinks and deforms at the same time, which plays a positioning and fixing role, thereby effectively realizing the connection of the sonic logging pipe.

[0021] Preferably, in S10, the guide pipe is a steel guide pipe with a diameter of 30cm, a smooth and round inner wall, and a consistent inner diameter. Its standard section length is 2.5m, and it is equipped with 1.5m and 1m non-standard sections to adjust the length of the guide pipe to meet the construction needs of different hole depths. The bored pile concrete is pumped commercial concrete. During construction, the concrete mix ratio, slump and workability are strictly controlled to ensure that the concrete in the whole hole is poured before the first batch of concrete sets.

[0022] Compared to existing technologies, the beneficial effects of this invention are as follows: This invention provides a construction method for bored piles and their protective pile system near a subway shield tunneling section, which innovates in materials and construction technology for bored pile construction near a subway shield tunneling section. Through a guide support, it innovatively and precisely positions the bored piles and their protective pile system, enabling real-time and precise control of the pile foundation center point, pile verticality, protective pile steel pipe center point, and other protective pile system axes during construction. Secondly, it serves as a warning for the subway shield tunneling construction area. Thirdly, it achieves a vibration reduction effect on the completed bored piles and reduces the compressive stress on the piles caused by shield tunneling during subway shield tunneling and subway operation. Attached Figure Description

[0023] Figure 1 This is a planar schematic diagram of an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the guide bracket in an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the mounting slot in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the structure of the protective pile steel pipe in an embodiment of the present invention.

[0027] In the diagram: 1. High-pressure jet grouting pile; 2. Well-shaped support; 3. Square support; 4. Through hole; 5. Installation groove; 6. Reinforcing bar; 7. Protective steel pipe; 71. Inner steel pipe; 72. Outer steel pipe; 73. Vibration damping interlayer; 74. Cutting edge; 8. Shield edge line. Detailed Implementation

[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations. Example

[0029] A construction method for bored piles and their protective pile system near a subway shield tunneling section includes the following steps:

[0030] S1. Construction preparation: Conduct a site survey, level the site, and draw the edge line of the shield shell of the tunnel boring machine.

[0031] S2. Pile location layout: The center of the bored pile foundation is laid out to determine the location of the guide support's pile protection point, the axis of the high-pressure jet grouting pile, and the center point of the pile protection steel pipe. The centers of the bored pile, the guide support, and the pile protection steel pipe coincide.

[0032] S3. High-pressure jet grouting pile construction: such as... Figure 1 As shown, a row of φ800mm high-pressure jet grouting piles 1 are driven in the middle position between the outer wall of the tunnel boring machine and the outer wall of the bored pile, parallel to the direction of the subway tunnel construction. The driving range is no less than 10m from the first high-pressure jet grouting pile 1 at the entrance of the tunnel boring machine and no less than 5m from the exit of the tunnel boring machine to the last high-pressure jet grouting pile 1. The bottom of the high-pressure jet grouting pile 1 penetrates into the subway tunnel construction section by less than 5mm. 15% iron oxide red pigment is added to the cement grout used for the high-pressure jet grouting pile 1 to dye the cement grout red.

[0033] A row of high-pressure jet grouting piles 1 is added between the subway tunnel boring machine and the cast-in-place piles. Red dye is added to the mud of the high-pressure jet grouting piles 1. On the one hand, it can serve as a warning during the tunnel boring machine's construction. When the tunnel boring machine hits the high-pressure jet grouting piles 1, the excavated mud will turn red, indicating that the tunnel boring machine has deviated and is very close to the cast-in-place piles. On the other hand, adding a row of high-pressure jet grouting piles 1 can reduce the soil pressure on the cast-in-place piles during the subway tunnel boring process and ensure the overall safety of the drilled cast-in-place piles.

[0034] S4. Guide bracket fixing: such as Figure 2 As shown, the guide support includes a grid-shaped support 2 and a square support 3 made of 8 I20 steel sections with the same inner diameter. The inner diameter of the square support 3 is 10mm larger than the outer diameter of the protective pile steel pipe 7. The square support 3 is placed on the grid-shaped support 2, so that the diagonal of the square support 3 coincides with the two center lines of the grid-shaped support 2, and the center of the grid-shaped support coincides with the center of the square support. After the placement position meets the requirements, the two supports are fully welded. A 28mm through hole 4 is opened at each of the four intersection points of the grid-shaped support 2.

[0035] Four pile protection points are set according to the distance between the pile core and the four through holes 4 of the guide support. The direction of the four pile protection points is parallel to the row of high-pressure jet grouting piles. An installation groove 5 with a depth of 1.5mm is excavated downward at each pile protection point. Figure 3 As shown, the installation groove 5 is set in the shape of a convex character. A steel bar 6 with a diameter of 28mm is pre-embedded at the vertical center axis position in the installation groove 5. The steel bar 6 is 200mm above the ground, and the steel bar above the ground is threaded. The four through holes of the guide bracket are aligned with the steel bar 6 at the four pile protection points and inserted. The guide bracket is placed in place. After verifying that the center of the guide bracket coincides with the center of the pile protection steel pipe and the core of the drilled pile, it is tightened with nuts to fix it.

[0036] S5. Driving of protective pile steel pipes: such as Figure 2 As shown, the center of the protective pile steel pipe is aligned with the center of the guide support. During the driving process, the guide support is used to correct the deviation of the protective pile steel pipe 7 in real time, ensuring that the deviation between the center of the protective pile steel pipe and the center of the bored pile is no more than 5mm and the inclination is no more than 1%. The protective pile steel pipe 7 is driven into the ground using a fully hydraulic vibratory hammer (such as APE200-6). During construction, the sinking speed is controlled and the frequency of the vibratory hammer is gradually increased to ensure that the pile sinking is carried out after the soil around the pile has liquefied. During the hammering process, the protective pile steel pipe 7 penetrates 5m below the subway shield tunneling section to enhance the shear resistance of the bored pile, reduce the impact of unbalanced soil pressure on the bored pile during shield tunneling, and ensure construction quality. Sand is poured in while hammering the protective pile steel pipe 7.

[0037] like Figure 4 As shown, the protective pile steel pipe 7 includes an inner steel pipe 71 and an outer steel pipe 72. The inner diameter of the inner steel pipe 71 is the same as the outer diameter of the bored pile, and the wall thickness is 16mm. The inner diameter of the outer steel pipe 72 is 100mm larger than the outer diameter of the inner steel pipe 71, and the wall thickness is 16mm. The length of the outer steel pipe 72 is 1000mm shorter than the inner steel pipe. The middle of the inner steel pipe 71 and the outer steel pipe 72 is a shock-absorbing interlayer 73 with a thickness of 100mm. The shock-absorbing interlayer is filled with natural rubber. The top of the shock-absorbing interlayer 73 is welded and sealed flush with the inner and outer steel pipes using a 16mm thick steel plate. The bottom of the shock-absorbing interlayer 73 is welded with the inner and outer steel pipes using a 16mm thick steel plate to form a cutting edge 74. The length of the protective pile steel pipe 7 is the same as the length of the bored pile. Considering the limitations of road transportation conditions, the protective pile steel pipe is transported to the construction site in sections according to the actual situation.

[0038] Through the above measures, the drilling piles can be protected against vibration and the soil pressure on the piles can be reduced during the construction of the subway tunnel and the operation of the ground.

[0039] S6. Construction of Mud Preparation and Circulation System: Based on the site conditions, a truncated quadrangular mud storage tank is reasonably set up, 3m high (1.5m below the original ground level, 1.5m of embankment, and 0.5m wide at the top of the embankment). The slope of both the inner and outer sides is 1:1. The external bottom dimensions are 20×14m, the top dimensions are 16×10m, and the internal bottom dimensions are 10×4m. The mud surface is 0.5m from the top of the mud tank. A single mud tank can store 120m³ of mud. Fresh mud is stored here after preparation. A mud sedimentation tank is set up next to the mud storage tank. The protective pile steel pipe 7 is connected to the mud storage tank and the mud sedimentation tank through pipelines. During drilling, the mud storage tank replenishes fresh mud into the hole through a mud pump. When cleaning the hole, the mud in the hole settles in the mud sedimentation tank and then flows back to the mud storage tank through pipelines. The circulating mud is treated by a mud-sand separator before it can be used.

[0040] S7. Drilling and Hole Cleaning: After the drilling rig is installed and in place, drilling is carried out. After the hole depth reaches the design elevation, the hole depth, diameter and inclination are checked with a graduated measuring rope and a cage-type hole inspector. A hole inspector with an outer diameter of φ1.5m and a length of 6m (for φ1.5m pile foundations) is processed. During the inspection, the hole inspector is lifted by a crane and placed vertically into the hole. A measuring rope is tied to the top of the hole inspector and it is lowered in an attached manner. After checking whether the hole depth and diameter meet the requirements, the hole is cleaned.

[0041] S8. Rebar Cage Processing and Installation: Rebar cages are processed in a semi-automated centralized manner on the rebar factory assembly line. From raw rebar material cutting to finished product storage, standardized and procedural management requirements are followed. Each construction process is completed by specialized machinery and equipment and dedicated construction personnel, with division of responsibilities and assembly line operation. Construction and acceptance standards are established for each process to ensure the proceduralization of "people, machines, and methods". After the rebar cage is fabricated, the frame is installed using a truck crane to ensure that the frame does not deform during lifting.

[0042] S9. Installation of sonic logging pipes: Install sonic logging pipes on the installed reinforcing cage; use crimp-type sonic logging pipes, with an O-ring rubber seal inside the U-groove at the end of the crimp-type sonic logging pipe. During installation, insert the spigot end of the sonic logging pipe into the socket end to the marked position, and use a special hydraulic crimper to simultaneously squeeze the U-groove and one side of the U-groove. The rubber seal acts as a seal after being squeezed, and the pipe material at both the spigot end and the socket end of the crimped part shrinks and deforms at the same time (forming a hexagonal shape in cross-section), which plays a positioning and fixing role, thereby effectively realizing the connection of the sonic logging pipes.

[0043] S10. Installation of guide pipe and concrete pouring: Install the guide pipe in the installed reinforcing cage and pour concrete. The guide pipe is a steel guide pipe with a diameter of 30cm, smooth and round inner wall, and uniform inner diameter. Its standard section length is 2.5m, and it is equipped with 1.5m and 1m non-standard sections to adjust the length of the guide pipe to meet the construction needs of different hole depths. The concrete for the bored pile is pumped commercial concrete. During construction, the concrete mix ratio, slump and workability are strictly controlled to minimize the time for removing the guide pipe and ensure that the concrete in the whole hole is poured before the first batch of concrete sets.

[0044] S11. Inspection of bored piles: After construction is completed, the guide support will be removed; after construction is completed, 100% integrity inspection of the bored piles will be carried out. All tests and construction requirements for the hole formation and pile body construction quality of the bored piles shall be strictly implemented in accordance with the "Technical Specification for Building Pile Foundations" (JGJ94-2008). During the construction of the subway shield tunnel, the integrity monitoring of the bored piles and high-pressure jet grouting piles shall be strengthened.

[0045] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structures made using the contents of the present invention specification and drawings, whether directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of the present invention.

Claims

1. A construction method for bored piles and their protective pile system near a subway shield tunneling section, characterized in that, Includes the following steps: S1. Construction preparation: Conduct a site survey, level the site, and draw the shield shell edge line of the tunnel boring machine. S2. Pile location layout: The center of the bored pile foundation is laid out to determine the location of the guide support's pile protection point, the axis of the high-pressure jet grouting pile, and the center point of the pile protection steel pipe. The centers of the bored pile, the guide support, and the pile protection steel pipe coincide. S3. High-pressure jet grouting pile construction: A row of high-pressure jet grouting piles parallel to the direction of subway tunnel construction is driven in the middle position between the outer wall of the tunnel boring machine and the outer wall of the bored pile. S4. Guide bracket fixing: The guide bracket includes a grid-shaped bracket and a square bracket with the same inner diameter. The square bracket is placed on the grid-shaped bracket, so that the diagonal of the square bracket coincides with the two center lines of the grid-shaped bracket, and the center of the grid-shaped bracket coincides with the center of the square bracket. After the placement position meets the requirements, the two brackets are fully welded. One through hole is opened at each of the four intersections of the grid-shaped bracket. Four pile protection points are set according to the pile core of the bored pile and the distance between the four through holes of the guide bracket. The guide bracket is placed at the pile protection points. S5. Insertion of the protective pile steel pipe: Align the center of the protective pile steel pipe with the center of the guide support. During the insertion process, the guide support is used to correct the deviation of the protective pile steel pipe in real time. The protective pile steel pipe includes an inner steel pipe and an outer steel pipe. The inner diameter of the inner steel pipe is the same as the outer diameter of the bored pile. The inner diameter of the outer steel pipe is larger than the outer diameter of the inner steel pipe, and the length of the outer steel pipe is shorter than that of the inner steel pipe. The middle of the inner and outer steel pipes is a shock-absorbing interlayer, which is filled with natural rubber. The top of the shock-absorbing interlayer is sealed by welding a steel plate flush with the inner and outer steel pipes. The bottom of the shock-absorbing interlayer is formed by welding a steel plate to the inner and outer steel pipes to form a cutting edge. S6. Construction of mud preparation and circulation system: According to the site conditions, a mud storage pool is set up, and a mud sedimentation pool is set up next to the mud storage pool. The pile protection steel pipe is connected to the mud storage pool and the mud sedimentation pool through pipelines respectively. During the drilling process, the mud storage pool replenishes fresh mud into the hole through a mud pump. When cleaning the hole, the mud in the hole settles in the mud sedimentation pool and then flows back to the mud storage pool through the pipeline. S7. Drilling and Hole Cleaning: After the drilling rig is installed and in place, drilling is carried out. After the hole depth reaches the design elevation, the hole depth, hole diameter and inclination are checked. S8. Reinforcing cage fabrication and installation: After the reinforcing cage is fabricated, the frame is installed using a truck crane to ensure that the frame does not deform during lifting. S9. Installation of sonic logging pipes: Install sonic logging pipes on the installed steel cage; S10. Conduit Installation and Concrete Pouring: Install the conduit into the installed reinforcing cage and pour concrete. S11. Inspection of bored piles: After construction is completed, the guide support is removed and the integrity of the bored piles is inspected.

2. The construction method of bored piles and their protective pile system in the adjacent subway shield tunneling section as described in claim 1, characterized in that, In S4, an installation trench is excavated downwards at the protection pile point, and a steel bar is pre-embedded in the installation trench. The steel bar is above the ground, and the steel bar above the ground is threaded. The four through holes of the guide bracket are aligned with the steel bars at the four protection pile points and inserted. The guide bracket is placed in place. After verifying that the center of the guide bracket coincides with the center of the protection pile steel pipe and the core of the drilled pile, it is tightened with nuts to fix it.

3. The construction method of bored piles and their protective pile system in the adjacent subway shield tunneling section as described in claim 2, characterized in that, In S4, the mounting groove is configured as a convex shape.

4. The construction method of bored piles and their protective pile system in the adjacent subway shield tunneling section as described in claim 1 or 2, characterized in that, In S5, the protective pile steel pipe is driven by a fully hydraulic vibratory hammer.

5. The construction method for bored piles and their protective pile system in the adjacent subway shield tunneling section as described in claim 1 or 2, characterized in that, In S9, a clamp-type sonic logging pipe is used. The U-shaped groove at the end of the clamp-type sonic logging pipe is equipped with an O-ring rubber sealing ring. During installation, the spigot end of the sonic logging pipe is inserted into the socket end to the marked position. A special hydraulic clamp is used to simultaneously squeeze the U-shaped groove and one side of the U-shaped groove. After being squeezed, the rubber sealing ring plays a sealing role. The pipe material at both the spigot end and the socket end of the clamp-type part shrinks and deforms at the same time, which plays a positioning and fixing role, thereby effectively realizing the connection of the sonic logging pipe.

6. The construction method for bored piles and their protective pile system in the adjacent subway shield tunneling section as described in claim 1 or 2, characterized in that, In S10, the guide pipe is a steel guide pipe with a diameter of 30cm. The inner wall is smooth and round, and the inner diameter is uniform. Its standard section length is 2.5m, and it is equipped with 1.5m and 1m non-standard sections to adjust the length of the guide pipe to meet the construction needs of different hole depths. The bored pile concrete is pumped commercial concrete. During construction, the concrete mix ratio, slump and workability are strictly controlled to ensure that the concrete in the whole hole is poured before the first batch of concrete sets.

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