A pile foundation reinforcing structure based on an underwater karst cave environment

Abstract

The application discloses a pile foundation reinforcing structure based on an underwater karst cave environment, a hole is drilled at a pile position, an inner steel pipe is inserted into the hole, the inner steel pipe is inserted into the bottom of the karst cave, a cast-in-place pile is formed by pouring a concrete structure into the inner steel pipe, pile side grouting reinforcement is performed above and / or below the karst cave, a plugging structure is arranged on the pile foundation, and the plugging structure is used for plugging a gap between the pile side and a soil layer. The pile foundation reinforcing structure based on the underwater karst cave environment inserts the inner steel pipe into the hole, inserts the inner steel pipe into the bottom of the karst cave, forms the cast-in-place pile by pouring the concrete structure into the inner steel pipe, can constrain, support and strengthen the concrete in the karst cave, sets the plugging structure above the top of the karst cave or the roof, cooperates the plugging structure with a soil body of the pile side to plug the gap between the pile side and the soil layer, performs grouting reinforcement on the soil body, forms an overall structure, and improves the bonding force of the pile side and the soil body.

Description

Technical Field

[0001] This invention relates to a pile foundation reinforcement structure based on an underwater karst cave environment. Background Technology

[0002] In karst development areas, underground caves exist, and underwater cave environments are even more complex. Pile foundation construction in these areas requires consideration of the influence of water and caves. Current construction methods typically involve drilling holes at the pile location, inserting steel pipes into the boreholes and embedding them into the bottom slab of the cave, and then pouring concrete to form a cast-in-place pile. The bearing capacity of a cast-in-place pile is provided by two factors: first, the support at the pile end (e.g., end-bearing piles); and second, the friction between the pile side and the soil (e.g., friction piles or end-bearing friction piles). Therefore, the friction between the pile side and the soil is also an important form of support. However, the surface of the aforementioned pile foundation is a steel pipe, which easily separates from the soil, resulting in weak bonding between the soil and the pile foundation, i.e., low pile side friction. An improved method is to inject grout into the pile side. After the cement grout hardens, it bonds the soil to the pile foundation, effectively improving the bonding strength between the pile foundation and the soil. The problem is that if the karst cave is not filled, the borehole diameter of the bored pile is generally slightly larger than the diameter of the steel pipe, and the soil and steel pipe are easy to separate. Cement grout is a fluid substance and can easily seep into the karst cave along the cracks on the pile surface, resulting in incomplete grouting around the pile and affecting the reinforcement effect. Summary of the Invention

[0003] To address the above shortcomings, the purpose of this invention is to provide a pile foundation reinforcement structure based on an underwater karst cave environment.

[0004] Therefore, the present invention provides a pile foundation reinforcement structure based on an underwater karst cave environment, wherein a hole is drilled at the pile location, an inner steel pipe is inserted into the hole and inserted to the bottom of the karst cave, a concrete structure is poured into the inner steel pipe to form a cast-in-place pile, grouting is injected to reinforce the pile side above and / or below the karst cave, and a sealing structure is provided on the pile foundation to seal the gap between the pile side and the soil layer.

[0005] Furthermore, grouting holes are opened at predetermined positions in the inner steel pipe, and grouting pipes are connected to the grouting holes. The grouting pipes extend from the inside of the steel pipes to the outside of the steel pipes. A bladder is provided on the pile side corresponding to the grouting hole, surrounding the pile. After the inner steel pipe is filled with concrete and formed, grout is injected into the bladder through the grouting pipe. After the bladder is grouted, it compresses the soil and forms an annular protrusion that bulges into the soil. The annular protrusion is in close contact with the soil to form a sealing structure.

[0006] Furthermore, the annular protrusion is located above the top plate of the cave.

[0007] Furthermore, several protrusions are provided along the length of the pile foundation. These protrusions form a group, creating a sawtooth-like interlaced sealing structure. Grouting holes are set above the sealing structure and connected to grouting pipes to reinforce the pile side and the soil.

[0008] Furthermore, the outer wall of the inner steel pipe is provided with a groove, and the grouting hole and the bladder are both set in the groove. A protective sleeve is provided on the outside of the groove, and a limiting block is provided on the outer wall of the inner steel pipe above the groove. The protective sleeve is fixed to the outer wall of the inner steel pipe by dispensing adhesive and the protective sleeve is at a predetermined distance from the limiting block. When the protective sleeve is fixed to the outer wall of the inner steel pipe by dispensing adhesive and when the protective sleeve is in contact with the limiting block, the protective sleeve covers the groove.

[0009] Furthermore, the protective sleeve is divided into thin-walled and thick-walled sections along the circumference, with the thin-walled and thick-walled sections spaced apart.

[0010] The inner steel pipe has a groove on its outer wall. The grouting hole and the bladder are both located in the groove. A protective sleeve is provided on the outside of the groove. The protective sleeve includes several independent sleeve pieces with no gaps between adjacent sleeve pieces. The sleeve pieces can be flipped to a horizontal state. The protrusion formed after the bladder is grouted is supported on the sleeve piece that has been flipped to a horizontal state.

[0011] Furthermore, a limiting ring is provided on the outer wall of the protective sleeve, and a top rod is connected to the limiting ring. A limiting block is provided on the outer wall of the inner steel pipe above the top rod to limit the upward displacement of the top rod.

[0012] Furthermore, the inner steel pipe is inserted into the borehole. After the top rod enters the karst cave as a whole, the inner steel pipe is rotated at a predetermined angle and lifted upward so that the top rod contacts the top of the karst cave. After the top rod pushes the limiter to move downward, the sleeve is flipped to a horizontal position and grout is injected into the second bag connected to the bottom of the inner steel pipe to fix the inner steel pipe in a predetermined position. Then, grout is injected into the bag above the sleeve. After the first bag is grouted, an annular protrusion is formed to seal the bottom of the karst cave ceiling.

[0013] Furthermore, it also includes an outer steel pipe, with stepped holes drilled at the pile location, the outer steel pipe inserted into the stepped surface to isolate water on the outside of the outer steel pipe, and then an inner steel pipe inserted, with grout injected between the inner and outer steel pipes to form an integral waterproof structure.

[0014] The beneficial technical effects of this invention are as follows: This invention discloses a pile foundation reinforcement structure based on an underwater karst cave environment. An inner steel pipe is inserted into a borehole and reaches the bottom of the karst cave. Concrete is poured into the inner steel pipe to form a cast-in-place pile. The inner steel pipe can constrain, support, and reinforce the concrete in the karst cave. A sealing structure is set at the top of the karst cave or above the top slab. The sealing structure works with the soil on the pile side to seal the gap between the pile side and the soil layer. Then, the soil is reinforced by grouting to form an integral structure, which improves the bonding force between the pile side and the soil. Attached Figure Description

[0015] Figure 1 A schematic diagram of the pile foundation for implementing the present invention; Figure 2 This is a schematic diagram of Embodiment 1 of the sealing structure; Figure 3 A schematic diagram of the sac and grouting hole; Figure 4 A schematic diagram for the protective sleeve; Figure 5 for Figure 4 A top-down view; Figure 6 This is a schematic diagram of Example 2; Figure 7 This is a top view of Example 2; Figure 8 This is a schematic diagram of a longitudinal partial cross-section of Example 2.

[0016] Explanation of reference numerals in the attached drawings: 1. Surface water; 2. Cave; 201. Cave roof; 202. Cave floor; 3. Outer steel pipe; 4. Inner steel pipe; 5. Cast-in-place pile; 6. Grouting hole; 7. Grouting pipe; 8. Bag; 9. Annular protrusion; 10. Groove; 11. Protective sleeve; 111. Thin wall; 112. Thick wall; 113. Sleeve segment; 12. Limiting block; 13. Limiting ring; 14. Top rod; 15. Cable. Detailed Implementation

[0017] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0018] Reference Figures 1 to 8This invention discloses a pile foundation reinforcement structure based on an underwater karst cave environment. A hole is drilled at the pile location, and an inner steel pipe 4 is inserted into the hole, reaching the bottom of the karst cave 2. Concrete is poured into the inner steel pipe 4 to form a cast-in-place pile 5. Grouting is performed on the pile sides above and / or below the karst cave 2 for reinforcement. A sealing structure is provided on the pile foundation to seal the gap between the pile side and the soil layer. In this embodiment, a submersible drill is first used to drill a hole at the predetermined pile location, and then an outer steel pipe 3 is inserted into the hole. The outer steel pipe 3 is inserted into the clay layer at the bottom of the hole. The clay layer has a low permeability coefficient, and the insertion of the outer steel pipe 3 into the clay layer effectively isolates surface water 1. Drilling continues inside the outer steel pipe 3 using a geological drilling rig. The hole diameter is slightly smaller, forming a stepped hole together with the previously drilled hole. When drilling reaches the top slab 201 of the karst cave, a small hole can be used first to drill through the top slab 201 and inject water into it before continuing drilling. This is mainly to prevent excessive pressure difference between the inside and outside from causing the karst cave to collapse and the steel pipe to deform. The inner steel pipe 4 is inserted into the drilled hole to the bottom slab 202 of the karst cave. Grouting can be injected between the inner steel pipe 4 and the outer steel pipe 3 to form an integral waterproof structure. The inner steel pipe 4 has grouting holes 6 on its side, which are connected to grouting pipes 7. Some of the grouting holes 6 have annular bags 8 around the pile on their outer side. The grouting pipes 7 extend from the top of the inner steel pipe 4. After cleaning the drilled hole, the reinforcing cage is placed into the drilled hole through the inner steel pipe 4, and concrete is poured into the inner steel pipe. Connect the grouting pipe 7 to the grouting pump. First, grout is injected into the bladder 8. The bladder 8 expands into the soil, forming an annular protrusion 9. The annular protrusion 9 is pressed into the soil and comes into close contact with the surrounding soil, forming a sealing structure that seals the gap between the inner steel pipe 4 and the soil. Start the grouting pump to grout the remaining grouting holes 6.

[0019] In Example 1, refer to Figures 2 to 4An annular groove 10 is provided on the outer wall of the inner steel pipe 4. Four grouting holes 6 are evenly spaced within the annular groove 10. An annular bag 8 is placed within the groove 10, and cement grout can be injected into the annular bag 8 through the grouting holes 6. To prevent the inner steel pipe 4 from scratching the bag 8 during lowering, a protective sleeve 11 can be provided on the outer side of the bag 8. The protective sleeve 11 is fixed to the outer wall of the inner steel pipe 4 by adhesive application. A limiting block 12 is provided on the outer wall of the inner steel pipe 4 above the groove 10, and the protective sleeve 11 is at a predetermined distance from the limiting block 12. During the insertion of the inner steel pipe 4, the protective sleeve 11 will rub against the soil, disrupting the adhesive connection structure and causing the protective sleeve 11 to move upwards until it contacts the limiting block 12. The limiting block 12 restricts the protective sleeve 11 from moving further upwards. The protective sleeve 11 covers the groove 10 both when it is fixed to the outer wall of the inner steel pipe 4 by adhesive application and when it contacts the limiting block 12. After the inner steel pipe 4 is fully inserted, it is pulled upwards. Under the action of soil friction, the protective sleeve 11 moves relative to the inner steel pipe 4, exposing the bladder 8. The bottom of the inner steel pipe 4 can be connected to another bladder. After the inner steel pipe 4 is pulled upwards a certain distance, grout can be injected into the bottom bladder. This not only expands the bottom of the pile foundation and increases its bearing capacity, but also keeps the bladder 8 in the inner steel pipe 4 in an exposed state.

[0020] In the above embodiment 1, the protective sleeve 11 is divided into a thin-walled section 111 and a thick-walled section 112 along the circumference. The thin-walled section 111 and the thick-walled section 112 are spaced apart. When the inner steel tube 4 is inserted, the protective sleeve 11 squeezes the hole wall to form a hole shape that matches the outer wall of the protective sleeve 11. By rotating the inner steel tube 4 at a certain angle, the thick wall of the protective sleeve 11 rotates to the position of the hole wall where the thin wall was originally located. The area above the thick wall 112 is soil. When the inner steel tube 4 is slowly lifted upward, the force of the soil causes the protective sleeve 11 to move relative to the inner steel tube 4. Of course, in other embodiments, the protective sleeve 11 can also be pushed by inserting a rod along the outer wall of the inner steel tube 4 to expose the bag 8.

[0021] In the above embodiment 1, the annular protrusion 9 is provided above the top plate 201 of the cave. (Refer to...) Figure 2 Several annular protrusions can be provided along the length of the pile foundation. Several annular protrusions form a group to form a sawtooth-like interlaced sealing structure, which has a better sealing effect. A grouting hole 6 is set above the sealing structure and connected to a grouting pipe 7 to grout and reinforce the pile side and the soil.

[0022] In Example 2, refer to Figure 6 , Figure 7 and Figure 8The inner steel pipe 4 has an annular groove 10 on its outer wall. The grouting hole 6 and the bladder 8 are both located in the groove 10. A protective sleeve 11 is provided on the outside of the groove 10. The protective sleeve 11 includes several independent sleeve pieces 113. There is no gap between adjacent sleeve pieces 113. The sleeve pieces 113 can be flipped to a horizontal state. The annular protrusion 9 formed after grouting of the bladder 8 is supported on the sleeve pieces 113 that have been flipped to a horizontal state. The inner side of the sleeve pieces 113 can be connected to the groove 10 of the inner steel pipe 4 by a cable 15. A limiting ring 13 is provided on the outer wall of the protective sleeve 11. A top rod 14 is connected to the limiting ring 13. A limiting block 12 is provided on the outer wall of the inner steel pipe 4 above the top rod 14 to limit the upward displacement of the top rod 14. The inner steel pipe 4 is inserted into the borehole. After the top rod 14 enters the karst cave 2 as a whole, the inner steel pipe 4 is rotated at a predetermined angle and lifted upwards, so that the top rod 14 contacts the top of the karst cave 2. After the top rod 14 pushes the limiter downwards, the sleeve 113 flips to a horizontal position and grouts into the second bag 8 connected to the bottom of the inner steel pipe 4, fixing the inner steel pipe 4 in a predetermined position. Then, grouts are injected into the bag 8 above the sleeve 113. After the first bag 8 is grouted, it forms an annular protrusion 9 that seals the bottom of the karst cave top plate 201. In Example 1, after the bag 8 is grouted, it squeezes the soil layer outwards to form the annular protrusion 9. The soil layer has certain limitations. If there are sharp particles, irregular or hard soil in the soil layer, the effect is poor. Therefore, the annular protrusion 9 is set in a suitable soil layer. The ordinary grouting hole 6 needs to be set above the annular protrusion 9, which results in a relatively short length of the fixed inner steel pipe 4 end. Example 2 can solve this problem. When the sleeve 113 is horizontal, it plays a supporting role. The bladder 8 is elastic and will sag when there is no support, thus failing to achieve the function of sealing on the top wall. This example solves the problem better.

Claims

1. A pile foundation reinforcement structure based on an underwater karst cave environment, characterized in that: Drill holes at the pile location, insert an inner steel pipe into the holes, insert the inner steel pipe into the bottom of the karst cave, pour concrete structure into the inner steel pipe to form a cast-in-place pile, grout the pile sides above and / or below the karst cave for reinforcement, and provide a sealing structure on the pile foundation to seal the gap between the pile side and the soil layer.

2. The pile foundation reinforcement structure based on an underwater karst cave environment according to claim 1, characterized in that: Grouting holes are opened at predetermined positions in the inner steel pipe, and grouting pipes are connected to the grouting holes. The grouting pipes extend from the inside of the steel pipes to the outside of the steel pipes. A bladder is provided on the pile side corresponding to the grouting hole, surrounding the pile. After the inner steel pipe is filled with concrete and formed, grout is injected into the bladder through the grouting pipe. After the bladder is grouted, it compresses the soil and forms an annular protrusion that bulges into the soil. The annular protrusion is in close contact with the soil to form a sealing structure.

3. The pile foundation reinforcement structure based on an underwater karst cave environment according to claim 2, characterized in that: The annular protrusion is located above the top plate of the cave.

4. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 2 or 3, characterized in that: Several protrusions are provided along the length of the pile foundation. These protrusions form a group, creating a sawtooth-like interlaced sealing structure. Grouting holes are set above the sealing structure and connected to grouting pipes to reinforce the pile side and the soil.

5. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 2, characterized in that: The outer wall of the inner steel pipe is provided with a groove, and the grouting hole and the bladder are both set in the groove. A protective sleeve is provided on the outside of the groove. A limiting block is provided on the outer wall of the inner steel pipe above the groove. The protective sleeve is fixed to the outer wall of the inner steel pipe by dispensing adhesive and the protective sleeve is at a predetermined distance from the limiting block. When the protective sleeve is fixed to the outer wall of the inner steel pipe by dispensing adhesive and when the protective sleeve is in contact with the limiting block, the protective sleeve covers the groove.

6. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 5, characterized in that: The protective sleeve is divided into thin-walled and thick-walled sections along the circumference, with the thin-walled and thick-walled sections spaced apart.

7. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 2, characterized in that: The inner steel pipe has a groove on its outer wall. The grouting hole and the bladder are both located in the groove. A protective sleeve is provided on the outside of the groove. The protective sleeve includes several independent sleeve pieces with no gaps between adjacent sleeve pieces. The sleeve pieces can be flipped to a horizontal state. The protrusion formed after the bladder is grouted is supported on the sleeve piece that has been flipped to a horizontal state.

8. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 7, characterized in that: The outer wall of the protective sleeve is provided with a limiting ring, and a top rod is connected to the limiting ring. A limiting block is provided on the outer wall of the inner steel pipe above the top rod to limit the upward displacement of the top rod.

9. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 8, characterized in that: The inner steel pipe is inserted into the borehole. After the top rod enters the karst cave as a whole, the inner steel pipe is rotated to a predetermined angle and lifted upward so that the top rod contacts the top of the karst cave. After the top rod pushes the limiting ring downward, the casing is flipped to a horizontal position and grout is injected into the second bag connected to the bottom of the inner steel pipe to fix the inner steel pipe in a predetermined position. Grout is then injected into the bag above the casing. After the first bag is grouted, an annular protrusion is formed to seal the bottom of the karst cave ceiling.

10. A pile foundation reinforcement structure based on an underwater karst cave environment according to claim 1, 2, or 3, characterized in that: It also includes an outer steel pipe, a stepped hole is drilled at the pile location, the outer steel pipe is inserted into the stepped surface to isolate water on the outside of the outer steel pipe, and then an inner steel pipe is inserted. Grouting is injected between the inner and outer steel pipes to form an integral waterproof structure.

Images