WO2021027664A1

WO2021027664A1 - Prefabricated pipe pile structure having variable-diameter holes for soft foundation treatment and construction method therefor

Info

Publication number: WO2021027664A1
Application number: PCT/CN2020/107261
Authority: WO
Inventors: 柳俊; 万梦华; 张振礼; 程波; 杨赵停; 沈湘
Original assignee: 上海建工二建集团有限公司
Priority date: 2019-08-12
Filing date: 2020-08-06
Publication date: 2021-02-18
Also published as: CN110397021A

Abstract

A prefabricated pipe pile structure having variable-diameter holes for soft foundation treatment and a construction method therefor. A pipe pile wall (2) is provided with a plurality of pile body small holes (1), i.e., variable-diameter holes, having the hole diameters gradually increased from a pile top to a pile bottom in an axial direction of a pipe pile, so that excess pore water can be more rapidly discharged, and the pile sinking accident is prevented; an outer side of the pipe pile wall (2) is wrapped by geotextile (4), and the functions of reverse filter and water discharging of the geotextile (4) are utilized, so that excess pore water and gas in a soil body around the pile are discharged into a pipe cavity (3) in a pipe by means of pores of the geotextile (4), meanwhile, soil particles and the like are intercepted, the soil body is prevented from blocking the pile body small holes (1), stability of water and soil engineering within the range of the pile body small holes (1) can be kept, and water and soil losses in the local range are prevented.

Description

Prefabricated variable-diameter bore pipe pile structure for soft foundation treatment and construction method thereof

Technical field

The invention relates to the field of prefabricated pipe piles, in particular to a prefabricated variable-diameter bore pipe pile structure for soft foundation treatment and a construction method thereof.

Background technique

There are deep and thick soft foundations along the rivers and coastal areas of our country. Prefabricated pipe piles are widely used in foundation treatment of various construction projects in our country because of their advantages. However, the soil squeezing effect produced by the pipe pile driving process will cause the excess pore water pressure in the soil around the pile to rise rapidly, and it will increase with the increase of the penetration depth of the pile, resulting in undesirable effects such as broken piles and soil displacement.

Existing technology: In order to reduce the soil squeezing effect generated during the pile sinking process and accelerate the dissipation of excess pore water pressure, the existing technology is to open some small holes of the same diameter in the pipe wall of the pipe pile. The super pore water in the soil around the pile can be discharged into the tube cavity through the small hole of the pile body, and at the same time, it can be pumped out to reduce the soil squeezing effect, reduce the value of super pore water pressure, accelerate its dissipation, and achieve the purpose of reducing pile sinking accidents. The existing technology still has the following shortcomings:

1. The diameters of the small holes of the existing piles are equal, and the relationship between the excess pore water pressure and the depth during the pile sinking process and the hole diameter of the small holes of the pile is not considered. For the long-pile pipe piles, The small holes of the pile body of the same diameter can not discharge the increased pore water in the soil around the deeper pile body quickly into the tube cavity at the same time.

2. The reason that the existing technology can effectively reduce the soil squeezing effect is that during the pile sinking process, the super-pore water in the soil around the pile can flow into the pipe cavity through the small holes on the pile wall, and then the water is discharged by the water pump. Reduce the excess pore water pressure in the soil. However, in the process of pile sinking, the soil around the pile will block the small holes of the pile. If the small holes of the pile are completely blocked by the soil, the function of opening the pile is lost.

3. Existing technology will cause soil loss in different soil layers around the pile (such as silty soil) while draining pore water, and there will also be a certain risk of pile sinking.

Summary of the invention

The purpose of the present invention is to provide a prefabricated variable-diameter hole pipe pile structure for soft foundation treatment and a construction method thereof, which is used to solve the problem that the existing small holes of the pile body with the same diameter cannot increase the soil around the deeper pile body. The problem of rapid drainage of pore water into the pipe cavity. When the pore water is drained during the pile sinking process, the soil around the pile is easy to block the small holes of the pile and cause the problem of soil loss around the pile.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, comprising pipe piles and geotextiles. The pipe piles include a pipe pile wall. The pipe pile wall has a pipe cavity that penetrates the pile top and the pile bottom. , The pipe pile wall is provided with a number of small pile holes, the diameter of the small holes of the pile body gradually increases from the top of the pile to the bottom of the pile along the axial direction of the pipe pile, and the geotextile is wrapped around the pipe pile The outside of the wall.

Preferably, in the above-mentioned prefabricated variable diameter pipe pile structure for soft foundation treatment, the diameter of the small hole of the pile body is 1/12~1 larger than the diameter of the small hole of the adjacent pile body at the previous level. /8.

Preferably, in the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, the geotextile is wrapped around the periphery of the pipe pile wall, and the overlapping part of the geotextile is fixed by soil nails, and the geotextile The cloth is flush with both ends of the pipe pile wall.

Preferably, in the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, the overlapping width of the geotextile is 0.2 m or more.

Preferably, in the aforementioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, the geotextile is a polyester staple fiber needle-punched geotextile.

Preferably, in the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, there is one pile body small hole at the same level, and the connecting lines of all the pile body small holes are parallel to the central axis of the pipe pile.

Preferably, in the above-mentioned prefabricated variable diameter pipe pile structure for soft foundation treatment, there are two small holes in the pile body at the same level, including a first through hole and a second through hole. The second through holes are arranged oppositely on the pipe pile wall to form a one-way pair of perforations, and the lines of all the first through holes on the pipe pile wall and the lines of all the second through holes are parallel to the central axis of the pipe pile .

Preferably, in the above-mentioned prefabricated variable diameter pipe pile structure for soft foundation treatment, there are three small holes in the pile body at the same level, including a first through hole, a second through hole and a third through hole, The first through holes, the second through holes, and the third through holes are distributed on the pipe pile wall in an equilateral triangle, and the connection lines of all the first through holes on the pipe pile wall and all the second through holes The connection line and the connection lines of all the third through holes are parallel to the central axis of the pipe pile.

Preferably, in the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, there are two small holes in the pile body at the same level, including a first through hole and a second through hole. The hole is rotated 90 degrees clockwise or counterclockwise on the wall of the pipe pile relative to the first through hole, and the connection lines of all the first through holes and the connection lines of all the second through holes on the pipe pile wall are aligned with the central axis of the pipe pile parallel.

Preferably, in the above-mentioned prefabricated variable diameter pipe pile structure for soft foundation treatment, there are four small holes in the pile body at the same level, including a first through hole, a second through hole, a third through hole and The fourth through hole, each pile body hole is rotated 90 degrees clockwise or counterclockwise on the pipe pile wall relative to the adjacent pile body holes of the same level, and all the first through holes on the pipe pile wall are connected The line, all second through holes, all third through holes, and all fourth through holes are parallel to the central axis of the pipe pile.

The invention also discloses a construction method of the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, including the following steps:

Step 1: Open a number of small holes with gradually increasing diameters on the pipe pile wall from top to bottom;

Step 2: Determine the cutting size of the geotextile according to the outer perimeter of the pipe pile wall, the lap length required by the geotextile, and the length of the pipe pile;

Step 3: Wrap the geotextile around the periphery of the pipe pile wall, and fix the overlapping part of the geotextile with soil nails, and the overlapping width of the geotextile is 0.2m or more;

Step 4: Transport the prefabricated pipe piles to the site;

Step 5, pipe pile measurement and positioning;

Step six, the static pile driver is in place;

Step seven, hang the pile;

Step 8, statically press the pile to the designed height, and use the water pump to drain the pore water in the tube cavity during the process of pile pressing.

From the technical solutions disclosed above, compared with the prior art, the beneficial effects of the present invention are as follows:

The prefabricated variable-diameter pore pipe pile structure for soft foundation treatment provided by the present invention utilizes the excess pore water pressure of the soil to increase linearly in the depth direction, and the larger the hole diameter of the pile body at the same depth, the more the excess pore water pressure dissipates The principle of quickness is that by setting up a number of small holes in the pile body that gradually increase in diameter from the top of the pile to the bottom of the pile along the axial direction of the pile, the different depths encountered in the process of pile pressing can be guaranteed The pore water can be discharged quickly to prevent pile sinking accidents; and the present invention wraps geotextile on the outer side of the pipe pile wall, and utilizes the filtering and drainage effects of the geotextile to make the super pore water in the soil around the pile While the gas is discharged into the tube cavity through the pores of the geotextile, the particles, fine sand, and small stones are effectively intercepted to prevent the small holes of the pile body from clogging, and the pore water in the tube cavity can be discharged by a water pump to achieve optimal reduction The purpose of pile driving and soil squeezing effect. In addition, with the good air permeability and water permeability of the geotextile, the present invention can effectively intercept soil particles, fine sand, small rocks, etc. when the water flows around the pile into the pipe cavity of the pile, thereby maintaining the water and soil within the small hole of the pile body. The stability of the project prevents soil erosion in a local area.

The construction method of the prefabricated variable-diameter pore pipe pile structure for soft foundation treatment provided by the present invention can quickly reduce the pore water of different depths by opening a number of small holes with gradually increasing diameters on the pipe pile wall. It can effectively prevent the occurrence of pile sinking accidents; wrap a circle around the pipe pile wall with geotextile, and fix the overlapping part of the geotextile with soil nails, and the overlapping width of the geotextile is more than 0.2m, so as to use the reverse of the geotextile. The function of filtration and drainage makes the super-porous water and gas in the soil around the pile drain into the tube cavity through the pores of the geotextile, and the pore water in the tube cavity is discharged by the water pump, so as to achieve the purpose of optimally reducing the pile sinking soil squeezing effect At the same time, it can effectively intercept soil particles, fine sand, small stones, etc., so as to maintain the stability of water and soil engineering within the small hole of the pile body and prevent water and soil loss in a local area.

Description of the drawings

Figure 1 is a structural cross-sectional view of a prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of the structure of a pipe pile in an embodiment of the present invention.

Fig. 3 is a schematic diagram of an unfolded geotextile in an embodiment of the invention.

Figure 4 is a schematic diagram of geotextile overlap in an embodiment of the invention.

Figure 5 is one of the schematic diagrams of the distribution of small holes in the pile body at the same level of the pipe pile (one-way misaligned perforation).

Figure 6 is the second schematic diagram of the distribution of small holes in the pile body at the same level of the pipe pile (one-way perforation).

Figure 7 is the third schematic diagram of the distribution of small holes in the pile body at the same level of the pipe pile (two-way misaligned perforation).

Fig. 8 is the fourth schematic diagram of the distribution of small holes in the pile body at the same level of the pipe pile (two-way perforation), that is, the A-A sectional view of Fig. 2.

Figure 9 is the fifth (star-shaped opening) of the distribution of small holes in the pile body at the same level of the pipe pile.

In the picture: 1. Small hole on the pile body; 2. Pipe pile wall; 3. Pipe cavity; 4. Geotextile; 5. Soil nails.

detailed description

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments. Hereinafter, the technical content and features of the present invention will be described in detail by the listed embodiments in combination with the accompanying drawings. It should be additionally noted that the drawings are in a very simplified form and all use imprecise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. For the convenience of description, the "up" and "down" described below are consistent with the directions of the upper and lower directions of the drawings, but this cannot be a limitation of the technical solution of the present invention.

1-9, this embodiment discloses a prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, including pipe piles and geotextiles 4, the pipe piles include a pipe pile wall 2, the The pipe pile wall has a pipe cavity 3 that penetrates the pile top and the pile bottom. The pipe pile wall 2 is provided with a number of small pile holes 1. The diameter of the pile body small holes 1 extends along the axial direction of the pipe pile. The pile top and the pile bottom gradually increase to form the variable diameter hole, and the geotextile 4 is wrapped on the outside of the pipe pile wall 2.

The prefabricated variable-diameter pore pipe pile structure for soft foundation treatment provided by the present invention utilizes the excess pore water pressure of the soil to increase linearly in the depth direction, and the larger the hole diameter of the pile body at the same depth, the more the excess pore water pressure dissipates The principle of quickness, by setting up a number of small holes 1 in the pile body that gradually increase in diameter from the top of the pile to the bottom of the pile along the axial direction of the pile by setting up a number of holes in the wall 2 of the pipe pile, that is, the variable diameter hole, which can ensure that the pile is pressed The pore water of different depths can be discharged quickly, which can effectively prevent the occurrence of pile sinking accidents; and the present invention utilizes the filtering and drainage effects of the geotextile 4 by wrapping the geotextile 4 on the outside of the pipe pile wall 2. The super-porous water and gas in the soil around the pile are discharged into the tube cavity 3 through the pores of the geotextile 4, while soil particles are intercepted, effectively preventing the soil from blocking the small holes 1 of the pile body, and can be discharged from the tube cavity 3 by a water pump The internal pore water achieves the purpose of optimally reducing the pile-squeezing effect. In addition, the present invention utilizes the good air permeability and water permeability of the geotextile 4, which can effectively intercept soil particles, fine sand, small rocks, etc. when the water flows around the pile into the pile cavity 3, thereby maintaining the small holes 1 of the pile body. The stability of water and soil engineering within the scope, to prevent soil erosion in a local area.

In the process of pile sinking: the excess pore water pressure at the same depth is inversely proportional to the hole diameter of the hole 23 of the pile body. The larger the hole diameter of the pile body 23, the smaller the excess pore water pressure; When the pore size is the same, the excess pore water pressure is proportional to the depth, and the excess pore water pressure increases linearly with the depth. The invention team has repeatedly tested and demonstrated that when the vertical spacing of the pile holes 23 is 1/5 to 1/8 times the pile length, the diameter of the pile holes 23 is larger than that of the adjacent piles of the previous level. When the aperture of the small hole 23 is 1/12～1/8 larger, the pipe pile 2 has sufficient strength, and the super-void water pressure of the pipe pile 2 is small and balanced during the entire pile formation process, and the drainage is smooth and stable in time, which can maintain the pile body The stability of the water and soil engineering within the small hole 23 prevents soil erosion in a local area. Further, in this embodiment, the vertical spacing of the pile holes 23 is 1/6 times the pile length, and the hole diameter of the pile holes 23 is larger than that of the adjacent pile holes 23 at the previous level. The aperture is 1/10 larger and the overall effect is the best.

Preferably, in the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, the geotextile 4 is wrapped around the periphery of the pipe pile wall 2, and the overlapping part of the geotextile 4 is fixed by soil nails 5, And the geotextile 4 is flush with the two ends of the pipe pile wall 2. The overlapping part of the geotextile 4 is fixed by soil nails 5, which is not only convenient for construction, but also can be firmly fixed by the solid geotextile 4.

In order to achieve full coverage of the outer surface of the pipe pile wall 2 by the geotextile 4, and to achieve reliable fixation of the geotextile 4, preferably, in the above-mentioned prefabricated variable diameter pipe pile structure for soft foundation treatment, the geotextile The overlap width D of the cloth 4 is 0.2 m or more.

Preferably, in the above-mentioned prefabricated variable-diameter bored pipe pile structure for soft foundation treatment, the geotextile 4 adopts polyester staple fiber needle-punched geotextile, and the polyester staple fiber needle-punched geotextile has good air permeability and water permeability. The water around the pile can effectively intercept soil particles, fine sand, small stones, etc. when it flows into the pipe cavity 3 of the pile, thereby maintaining the stability of water and soil engineering within the small hole 1 of the pile body and preventing water and soil loss in a local area.

In order to make the pipe pile structure have sufficient strength while meeting the drainage requirements, in this embodiment, the vertical hole spacing is 1/6 times the pile length, and the pipe pile wall thickness is 1/8 times the pile length. The pile diameter of the pipe pile is 1/12 times the pile length.

The opening forms of the small holes in the pile body at the same level can be diversified, and can be unidirectional opening, bidirectional opening, star-shaped opening, and spiral opening.

The unidirectional openings include unidirectional misaligned openings and unidirectional opposed openings. Among them, the one-way misaligned hole type, please refer to Figure 5. There is one pile hole 1 at the same level, and the connecting line of all pile holes 1 is parallel to the central axis of the pipe pile. One-way through hole form, please refer to Figure 5. There are two small holes 1 in the pile body at the same level, including a first through hole and a second through hole. The first through hole and the second through hole are arranged opposite to each other. The pipe pile wall 2 is formed with a one-way pair of perforations, and the connection lines of all the first through holes and the connection lines of all the second through holes on the pipe pile wall 2 are parallel to the central axis of the pipe pile.

The bidirectional openings include bidirectional misaligned openings and bidirectional opposing openings. Among them, the two-way mismatched through hole form, please refer to Figure 7. There are two pile holes 1 at the same level, including a first through hole and a second through hole. The second through hole is opposite to the first through hole. The pipe pile wall 2 is rotated 90 degrees clockwise or counterclockwise, and the connection lines of all the first through holes and the connection lines of all the second through holes on the pipe pile wall 2 are parallel to the central axis of the pipe pile. Two-way through holes, please refer to Figure 8. There are four pile holes 1 at the same level, including the first through hole, the second through hole, the third through hole and the fourth through hole. The small hole 1 is rotated 90 degrees clockwise or counterclockwise on the pipe pile wall 2 relative to the adjacent pile hole 1 of the same level. The connection lines of all the first through holes and all the second holes on the pipe pile wall 2 The connection lines of the through holes, all the third through holes, and all the fourth through holes are parallel to the central axis of the pipe pile. That is to say, the four small holes of the pile body are pierced in pairs, and the lines of the centers of the two pairs of piercing holes are perpendicular to each other. The use of two-way openings can solve the problem of excessive pore water seepage in the soil around the two or four sides of the pipe pile, so that it can flow into the official cavity as quickly as possible. At the same time, the two-way butt-through opening can reasonably avoid the pile The stress concentration effect of the small hole at the body opening may cause the cracking and sinking of the pipe pile opening due to the asymmetry of the opening.

Please refer to FIG. 9 for the star-shaped openings. There are three pile holes 1 at the same level, including a first through hole, a second through hole, and a third through hole. The through holes and the third through holes are distributed on the pipe pile wall 2 in an equilateral triangle. The connection lines of all the first through holes, the connection lines of all the second through holes and all the third through holes on the pipe pile wall 2 The connecting lines of the holes are parallel to the central axis of the pipe pile. That is to say, the three small holes 1 of the pile body are combined into a star-shaped opening, and the star-shaped openings are distributed with three small holes on the same cross section, and the three small holes pass diagonally in pairs, and the three small holes The line connecting the center of the circle is an equilateral triangle. Compared with unidirectional openings and bidirectional openings, star-shaped openings not only have the smallest maximum excess pore water pressure, but also have the least impact on the stress concentration effect at the opening. It is the optimal opening method and can make the pile sinking process The super pore water generated in the pores flows into the pipe pile’s cavity from three directions in a balanced manner, accelerating the dissipation of the super pore water pressure or reducing the maximum value of the pile group super pore water pressure, effectively reducing the pile-squeezing effect and reducing The occurrence of pile sinking accidents.

Please continue to refer to Figures 1-9. The present invention also discloses a construction method of the above-mentioned prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, including the following steps:

Step 1: Open a number of small holes 1 with gradually increasing diameters on the pipe pile wall 2 from top to bottom;

Step 2: Determine the cut size of the geotextile 4 according to the outer circumference of the pipe pile wall 2, the lap length required by the geotextile 4, and the length of the pipe pile;

Step 3: Wrap the geotextile 4 around the periphery of the pipe pile wall 2 and fix the overlapping part of the geotextile 4 with soil nails 5, and the overlapping width of the geotextile 4 is 0.2m or more;

Step 4: Transport the prefabricated pipe piles to the site;

Step 5, pipe pile measurement and positioning;

Step six, the static pile driver is in place;

Step seven, hang the pile;

The construction method of the prefabricated variable-diameter bore pipe pile structure for soft foundation treatment provided by the present embodiment, by opening a number of small pile holes 1 with gradually increasing diameters on the pipe pile wall 2 from top to bottom, different depths The pore water is discharged quickly to effectively prevent the occurrence of pile sinking accidents; the geotextile 4 is wrapped around the pipe pile wall 2 in a circle, and the overlapping part of the geotextile 4 is fixed with soil nails 5, and the overlapping width of the geotextile 4 is 0.2m As mentioned above, by using the filtering and drainage effects of the geotextile 4, the super-porous water and gas in the soil around the pile are discharged into the tube cavity 3 through the pores of the geotextile 4, and the pore water in the cavity 3 is discharged by a water pump , To achieve the purpose of optimally reducing the effect of pile sinking and soil squeezing, while effectively intercepting soil particles, fine sand, small stones, etc., so as to maintain the stability of the water and soil engineering within the small hole 1 of the pile body and prevent soil erosion in a local area .

In summary, the beneficial effects of the present invention are as follows:

For the existing process piles, the diameter of the small hole 1 of the pile body is equal, and the relationship between the excess pore water pressure and depth during the pile sinking process and the hole diameter of the small hole 1 of the pile body is not considered. The problem that the small holes 1 of the pile body with the same diameter can not well drain the increased pore water in the soil around the deeper pile body into the tube cavity 3 at the same time. According to the theoretical formula, the present invention knows that the excess pore water pressure is closely related to the pile driving depth and the opening diameter of the small hole 1 of the pile body. During the pile driving process, the excess pore water pressure increases linearly with the deepening of the depth, and the excess pore water pressure increases with the opening The hole diameter increases and decreases. Therefore, the excess pore water pressure of the soil around the bottom of the pile after the completion of the precast pipe pile is much greater than the pore pressure of the soil around the top of the pile. In the present invention, a variable-diameter hole with a diameter gradually increasing from top to bottom is arranged on the pipe pile wall 2. Compared with the open-hole pipe pile with the same diameter of the small hole 1 of the pile body, the maximum value of the excess pore water pressure can be effectively reduced, and the super pore can be further accelerated The dissipation of water pressure can more effectively prevent pile sinking accidents.

The reason why the existing technology can effectively reduce the soil squeezing effect is that during the pile sinking process, the super-pore water in the soil around the pile can flow into the pipe cavity 3 through the pile body small hole 1 on the pipe pile wall 2, and then the water is discharged by the water pump , To reduce the excess pore water pressure in the soil, but during the process of pile sinking, the soil around the pile will block the small hole 1 of the pile body. If the small hole 1 of the pile body is completely blocked by the soil, the hole of the pile body will be lost. The question of role. In the present invention, a circle of geotextile 4 is wrapped around the pipe pile. The geotextile 4 has high strength and can maintain sufficient strength and elongation in dry and wet conditions; it has good corrosion resistance and can be used in soil and water with different pH levels. It can resist corrosion for a long time; at the same time, it has the characteristics of good water permeability, good antimicrobial performance, and convenient construction. The invention utilizes the filtering and drainage effects of the geotextile 4, which can form a drainage channel in the soil. The super-porous water and gas in the soil around the pile are discharged into the tube cavity 3 through the small holes 1 of the pile body, and the soil Particles and other interception can effectively prevent the soil from blocking the small hole 1 of the pile body, and finally use a water pump to drain the pore water in the tube cavity 3 to achieve the purpose of optimally reducing the pile-squeezing effect.

For the existing technology, while draining the pore water, the soil body (such as silty soil) in different soil layers around the pile will be lost, and there will also be a certain problem of pile sinking risk. The invention utilizes the good air permeability and water permeability of the polyester staple fiber needle-punched geotextile 4 to allow water to pass through while effectively intercepting soil particles, fine sand, small stones, etc., so as to maintain the stability of the water and soil engineering within the small hole 1 of the pile body. Prevent soil erosion in a local area.

The foregoing description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes or modifications made by persons of ordinary skill in the field of the present invention based on the foregoing disclosure shall fall within the protection scope of the claims.

Claims

A prefabricated variable-diameter bore pipe pile structure for soft foundation treatment, which is characterized in that it comprises a pipe pile and a geotextile. The pipe pile includes a pipe pile wall, and the pipe pile wall has a through pile top and a pile The bottom of the tube cavity, the pipe pile wall is provided with a number of small pile holes, the hole diameter of the pile body gradually increases from the pile top to the bottom of the pile along the axial direction of the pipe pile, and the geotextile is wrapped in The outside of the pipe pile wall.
The prefabricated variable-diameter hole pipe pile structure for soft foundation treatment according to claim 1, wherein the hole diameter of the pile body is larger than the hole diameter of the adjacent pile body of the previous level. /12～1/8.
The prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to claim 1, wherein the geotextile is wrapped around the periphery of the pipe pile wall, and the overlapping part of the geotextile is fixed by soil nails, And the geotextile is flush with the two ends of the pipe pile wall.
The prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to claim 3, wherein the overlap width of the geotextile is 0.2 m or more.
The prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to claim 1, wherein the geotextile is a polyester staple fiber needle-punched geotextile.
The prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to claim 1, wherein there is one small hole in the pile body at the same level, and the connection line of all the small holes in the pile body is connected to the center of the pipe pile. There are two small holes in the pile body with parallel axes or at the same level, including a first through hole and a second through hole. The first through hole and the second through hole are oppositely arranged on the pipe pile wall to form a unidirectional pair For perforation, the connection lines of all the first through holes and the connection lines of all the second through holes on the pipe pile wall are parallel to the central axis of the pipe pile.
The prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to claim 1, wherein there are three small holes in the pile body at the same level, including a first through hole, a second through hole, and a second through hole. Three through holes, the first through holes, the second through holes, and the third through holes are distributed on the pipe pile wall in an equilateral triangle, and the connecting lines of all the first through holes on the pipe pile wall and all the first through holes The connection line of the two through holes and the connection line of all the third through holes are parallel to the central axis of the pipe pile.
The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, wherein there are two small holes in the pile body at the same level, including a first through hole and a second through hole. The second through hole is rotated 90 degrees clockwise or counterclockwise on the wall of the pipe pile relative to the first through hole, and the connections of all the first through holes on the pipe pile wall and the connections of all the second through holes are connected to the pipe The central axis of the pile is parallel.
The prefabricated variable-diameter hole pipe pile structure for soft foundation treatment according to claim 1, wherein there are four small holes in the pile body at the same level, including a first through hole, a second through hole, and a second through hole. For the three through holes and the fourth through hole, each pile body hole is rotated 90 degrees clockwise or counterclockwise on the pipe pile wall relative to the adjacent pile body holes of the same level. The connection lines of the through holes, all the second through holes, all the third through holes, and all the fourth through holes are parallel to the central axis of the pipe pile.
A construction method of a prefabricated variable-diameter bore pipe pile structure for soft foundation treatment according to any one of claims 1-9, characterized in that it comprises the following steps:

Step 1: Open a number of small holes with gradually increasing diameters on the pipe pile wall from top to bottom;

Step 2: Determine the size of the geotextile to be cut according to the outer circumference of the pipe pile wall, the lap length required by the geotextile, and the length of the pipe pile;

Step 3: Wrap the geotextile around the periphery of the pipe pile wall, and fix the overlapping part of the geotextile with soil nails, and the overlapping width of the geotextile is 0.2m or more;

Step 4: Transport the prefabricated pipe piles to the site;

Step 5, pipe pile measurement and positioning;

Step 6, the static pile driver is in place;

Step seven, hang the pile;

Step eight: statically press the pile to the design height, and use a water pump to drain the pore water in the cavity during the process of pile pressing.