A soft soil slope pile foundation inclination correction structure and construction method

Abstract

The present application belongs to the technical field of pile foundation engineering construction, and relates to a soft soil slope pile foundation inclination correction structure and a construction method. The soft soil slope pile foundation inclination correction structure comprises a deviation pile, a pile top force device, a grid-gravel composite pile, a grouting pipe and a pile side reinforcement area, wherein the grid-gravel composite pile is composed of a grid casing and gravel. By setting the grid-gravel composite pile in front of the pile, on the one hand, it can serve as a stress release hole, and by pumping and draining water in the hole, the passive side soil pressure during correction is reduced; on the other hand, by grouting reinforcement, the soft soil characteristics are improved, a rigid gravel pile is formed in front of the pile, the pile side reinforcement area is combined, the bearing capacity of the deviation pile is improved, the landslide thrust borne by the deviation pile is reduced, and then the reliability and stability of the deviation pile during service are increased. The present application overcomes the problems of large correction difficulty and incomplete correction of the traditional correction measures, and has good economy and implementability.

Description

Technical Field

[0001] This invention belongs to the field of pile foundation engineering construction technology, and relates to a tilt correction structure and construction method for pile foundations on soft soil slopes. Background Technology

[0002] Soft soil has adverse engineering characteristics such as high natural water content, large natural void ratio, high compressibility, low shear strength, small consolidation coefficient, long consolidation time, high sensitivity, large disturbance, poor permeability, complex layered distribution, and large differences in physical and mechanical properties between layers. These characteristics lead to pile foundation tilting and deviation during the construction of soft soil slopes near rivers and lakes under the action of unbalanced soil and water pressure. When the deviation value exceeds the allowable value in the specification, correction is required before the soil can be used.

[0003] The existing methods for correcting the deviation of soft soil pile foundations often use the chain hoisting method, which directly applies a reverse force to the top of the pile to reset the pile foundation. However, due to the high water content in soft soil, the water cannot be effectively drained during the correction process, resulting in significant water pressure and making correction difficult. At the same time, the properties of the soft soil are not improved after correction, and the deviation may recur after a period of time, resulting in incomplete correction. This seriously affects the progress and quality of the project, while also consuming a lot of manpower, material resources, and financial resources, increasing the project cost. Summary of the Invention

[0004] Based on this, the present invention provides a simple, easy-to-operate, and economical soft soil slope pile foundation tilt correction structure and construction method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A tilt correction structure for soft soil slope pile foundations includes a deflection pile, a pile top force generating device, a grid-gravel composite pile, a grouting pipe, and a pile side reinforcement zone.

[0007] Preferably, the pile top force-generating device used in this invention applies force in the opposite direction to the tilt direction of the offset pile. The pile top force value is determined by theoretical calculation or numerical simulation, and the force is applied using a graded slow loading method, with real-time monitoring of the pile foundation's return to its original position during the loading process.

[0008] Preferably, the grid-gravel composite pile used in this invention is composed of a grid casing and gravel; the grid-gravel composite pile is located on the uphill side of the offset pile, and the net distance between the two is no more than 2.5 times the diameter of the grid-gravel composite pile.

[0009] Preferably, the grid-crushed stone composite piles used in this invention are one or more piles. When there are multiple piles, they are arranged in an arc shape with the center of the offset pile as the center and at equal intervals.

[0010] Preferably, the grid-gravel composite pile used in this invention has a pre-embedded grouting pipe, which is one or more pipes. When there are multiple pipes, they are arranged at equal intervals along the circumference of the grid-gravel composite pile. The bottom of the grouting pipe is perforated and also serves as a drainage pipe.

[0011] Preferably, the pile side reinforcement zone used in this invention is located on the inclined side of the offset pile, and is circular in shape, with a fan-shaped angle of not less than 180 degrees with the center of the offset pile; the pile side reinforcement zone adopts the form of grouting or powder jetting, and the reinforcement depth is greater than the thickness of the soft soil layer on the pile side, and enters the relatively dense layer.

[0012] Preferably, the correction construction method adopted in this invention includes the following steps: 1) Excavate and clear the soil around the offset pile so that the pile head is at least 0.5m above the ground. 2) Locate the position of the grid-crushed stone composite pile and perform hole drilling; 3) After drilling is completed, place an annular geogrid casing tightly against the borehole wall; 4) Pre-embed grouting pipes and fill them with crushed stone. No vibration is required to form a loose grid-crushed stone composite pile. No grouting is required at this time. 5) Use the grouting pipe as a pumping pipe to pump out the groundwater collected in the grid-gravel composite pile; 6) While pumping out groundwater, apply a reaction force opposite to the direction of the pile's inclination to the top of the misaligned pile to correct its deviation. 7) After the misaligned piles are corrected, keep the force output of the power generation device unchanged and construct the reinforcement zone; 8) Stop pumping groundwater from the loose grid-crushed stone composite pile, and carry out grouting operation in the grid-crushed stone composite pile through the grouting pipe. Use a segmented lifting high-pressure grouting method to make the cement grout gradually rise from the bottom of the test pile until it fills the entire pile hole, forming a rigid grid-crushed stone composite pile. 9) Remove the power generation device, backfill to restore the original slope, and end the correction operation.

[0013] Advantages of this invention: This invention, by installing a grid-gravel composite pile in front of the pile, serves two purposes: firstly, it acts as a stress relief hole, and by pumping water from within the hole, it reduces passive lateral earth pressure during the correction process; secondly, through grouting reinforcement, it improves the properties of soft soil, forming a rigid gravel pile in front of the pile. Combined with the pile side reinforcement zone, this enhances the bearing capacity of the misaligned pile, reduces the landslide thrust behind the pile, and thus increases the reliability and stability of the misaligned pile during service. The method proposed in this invention overcomes the difficulties of traditional correction measures, such as high correction difficulty and incomplete correction, avoiding resource waste and unnecessary rework. It has good operability, is economical and reasonable, and the construction quality is easily guaranteed. Attached Figure Description

[0014] Figure 1 This is a cross-sectional schematic diagram of the tilt correction structure of the soft soil slope pile foundation provided by the present invention; Figure 2 This is a top view schematic diagram of the tilt correction structure of the soft soil slope pile foundation used in this invention.

[0015] Wherein: 1-Offset pile; 2-Pile top force generating device; 3-Grid-gravel composite pile; 4-Grouting pipe; 5-Pile side reinforcement zone; 31-Grid casing; 32-Gravel. Detailed Implementation

[0016] See Figure 1 and Figure 2 This invention provides a tilt correction structure and construction method for pile foundations on soft soil slopes, including a tilt pile 1, a pile top force generating device 2, a grid-gravel composite pile 3, a grouting pipe 4, and a pile side reinforcement zone 5. The grid-gravel composite pile 3 is composed of a grid casing 31 and gravel 32.

[0017] The present invention will be further described in detail below with reference to specific embodiments: Example

[0018] The abutment piles of a certain cross-river bridge have a diameter of 1.2m and a length of 22m. Shortly after the pile foundation was completed, the piles began to tilt and deviate, with the maximum deviation at the top of the pile reaching 18cm, far exceeding the specification limit, making it impossible to construct the bridge superstructure. Investigation revealed that the soil within 9 meters below the pile top was silty clay, soft, with high water content and high compressibility, locally containing thin layers of silt, exhibiting a soft plastic to fluid plastic state.

[0019] For this specific project example, the following steps were taken to correct the deviation: 1) Excavate and clear the soil around the offset pile 1 so that the pile head of the offset pile 1 is 0.8 m above the ground; 2) On the opposite side of the tilt of the offset pile 1, at a position 2 m away from the center of the offset pile 1, a drilling rig is used to drill the grid-gravel composite pile 3. The drilling diameter is 0.6 m and the length is 10 m, penetrating the soft soil layer and entering the medium-dense silty clay layer below by 1 m.

[0020] 3) After drilling is completed, place the annular geogrid casing 31 tightly against the hole wall from bottom to top. The sections and joints of the geogrid casing are connected with wire or cable ties. 4) Two grouting pipes 4 with bottom openings are pre-embedded in the borehole and crushed stone 32 is added. The crushed stone 32 is naturally graded, with a mud content of no more than 10% and a maximum particle size of no more than 5 cm. No vibration is required during the filling of crushed stone. After the filling is completed, a loose grid-crushed stone composite pile 3 is formed. At this time, no grouting is required. 5) Use the grouting pipe 4 as a pumping pipe to pump out the groundwater collected in the grid-gravel composite pile 3; 6) While pumping out groundwater, correction work is carried out on the misaligned pile 1. First, a force-generating device 2 is installed on the top of the misaligned pile 1, and a reaction force opposite to the direction of the pile's inclination is applied. The force value at the pile top is determined using theoretical calculations and numerical simulations. During the application of force, a graded slow loading method is used, and the pile's return to its original position is monitored in real time. The force is dynamically adjusted according to the actual situation until the pile's misalignment meets the specifications. After that, the applied force value remains unchanged. 7) After the deviation pile 1 is corrected, the pile side reinforcement zone 5 is constructed in the form of jet grouting. The reinforcement zone 5 is located on the inclined side of the pile foundation, and is in the shape of a ring. The angle between the ring and the center of the deviation pile 1 is 210°. The length of the jet grouting pile is 12 meters. 8) Stop pumping the groundwater in the loose grid-crushed stone composite pile 3, and grout the grid-crushed stone composite pile (3) through the grouting pipe 4. Use the segmented lifting high pressure grouting method to make the cement grout gradually rise from the bottom of the test pile until it fills the entire pile hole, forming a rigid grid-crushed stone composite pile 3. 9) 15 days after the grouting is completed, remove the top force-generating device 2 of the misaligned pile, backfill to restore the original slope, and end the correction operation.

[0021] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any equivalent modifications or substitutions to the technical solutions of the present invention that do not depart from the spirit and scope of the technical solutions of the present invention should fall within the scope of the patent of the present invention.

Claims

1. A tilt correction structure for pile foundations on soft soil slopes, characterized in that: The correction structure includes a misaligned pile (1), a pile top force generating device (2), a grid-crushed stone composite pile (3), a grouting pipe (4), and a pile side reinforcement zone (5). The force-generating device (2) at the top of the pile exerts force in the opposite direction to the tilting direction of the offset pile (1); The grid-crushed stone composite pile (3) is composed of a grid casing (31) and crushed stone (32); the grid-crushed stone composite pile (3) is located on the opposite side of the tilt direction of the offset pile (1), and the net distance between the two is no more than 2.5 times the diameter of the grid-crushed stone composite pile (3); The grid-crushed stone composite pile (3) is pre-embedded with grouting pipes (4). The grouting pipes (4) are one or more. When there are multiple pipes, they are arranged at equal intervals around the grid-crushed stone composite pile (3). The bottom of the grouting pipe (4) is opened and also serves as a drainage pipe. The pile side reinforcement zone (5) is located on the inclined side of the offset pile (1), and is circular. The fan-shaped angle formed by the pile side reinforcement zone (5) and the center of the offset pile (1) is not less than 180 degrees. The pile side reinforcement zone (5) adopts the form of grouting or powder jetting. The reinforcement depth should be greater than the thickness of the soft soil layer on the side of the offset pile (1) and enter the relatively dense layer.

2. The tilt correction structure for soft soil slope pile foundations according to claim 1, characterized in that: The grid-gravel composite pile (3) is one or more piles. When there are multiple piles, they are arranged in an arc shape with the center of the offset pile (1) as the center and at equal intervals.

3. The construction method of the inclined correction structure for soft soil slope pile foundation according to claim 1, characterized in that: The construction method includes the following steps: 1) Excavate and clear the soil around the offset pile (1) so that the pile head of the offset pile (1) is not less than 0.5m above the ground; 2) Locate the position of the grid-crushed stone composite pile (3) and perform hole drilling; 3) After drilling is completed, place an annular geogrid casing (31) close to the hole wall. 4) Pre-embed grouting pipes (4) and fill them with crushed stone (32). No vibration is required to form a loose grid-crushed stone composite pile (3). No grouting is required at this time. 5) Use the grouting pipe (4) as a pumping pipe to pump out the groundwater collected in the grid-gravel composite pile (3); 6) Install a force-generating device (2) on the top of the offset pile (1) and apply a reaction force opposite to the direction of the pile foundation inclination. Use graded slow loading and monitor the pile foundation return to its original position in real time during the loading process. 7) After the misaligned pile (1) is corrected, keep the force value of the force generating device (2) unchanged and construct the reinforcement area (5). 8) Stop pumping groundwater in the loose grid-crushed stone composite pile (3), and carry out grouting operation in the grid-crushed stone composite pile (3) through the grouting pipe (4). Use the segmented lifting high pressure grouting method to make the cement grout gradually rise from the bottom of the test pile until it fills the entire pile hole and forms a rigid grid-crushed stone composite pile (3). 9) After grouting is completed and no less than 7 days later, remove the pile top force device (2) of the deviated pile (1), backfill to restore the original slope, and end the correction operation.

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