A prefabricated variable diameter hole pipe pile structure for soft foundation treatment and its construction method

Abstract

The present invention discloses a prefabricated variable diameter hole pipe pile structure for soft foundation treatment and a construction method thereof, which relates to the field of prefabricated pipe piles. The existing pile body small holes with equal apertures cannot quickly discharge the increased pore water in the soil around the deeper pile body into the pipe cavity, and the soil around the pile is easy to block the pile body small holes while discharging the pore water during the pile sinking process, and cause the soil around the pile to be lost. The present invention can discharge the super pore water more quickly and prevent pile sinking accidents by setting a plurality of pile body small holes, i.e., variable diameter holes, whose apertures gradually increase from the pile top to the pile bottom along the axial direction of the pipe pile, on the pipe pile wall; by wrapping a geotextile on the outer side of the pipe pile wall, utilizing the anti-filtration and drainage effects of the geotextile, the super pore water and gas in the soil around the pile are discharged into the pipe cavity through the pores of the geotextile, and at the same time, soil particles are intercepted to prevent the soil from blocking the pile body small holes, and can maintain the stability of the water and soil engineering within the range of the pile body small holes, and prevent soil and water loss in a local range.

Description

Technical Field

[0001] The invention relates to the field of prefabricated pipe piles, and in particular to a prefabricated variable-diameter hole pipe pile structure for soft foundation treatment and a construction method thereof. Background Art

[0002] There are deep soft foundations in my country's riverside and coastal areas. Prefabricated pipe piles are widely used in foundation treatment of various construction projects in my country due to their superiority. However, the soil squeezing effect produced by the pipe pile sinking process will cause the excess pore water pressure in the soil around the pile to rise rapidly, and it will continue to increase with the increase of the pile penetration depth, thus causing adverse effects such as broken piles and soil displacement.

[0003] Existing technology: In order to reduce the soil squeezing effect generated during pile sinking and accelerate the dissipation of excess pore water pressure, the existing technology is to open a number of small holes of equal diameter on the wall of the pile. During the pile sinking process, the excess pore water in the soil around the pile can be discharged into the pipe cavity through the small holes of the pile body, and at the same time pumped out by a water pump to reduce the soil squeezing effect, reduce the excess pore water pressure value, and accelerate its dissipation, so as to achieve the purpose of reducing pile sinking accidents. However, the existing technology still has the following shortcomings:

[0004] 1. The existing pile bodies have the same diameter of small holes, and the relationship between the excess pore water pressure and the depth and the diameter of the small holes in the pile body during the pile sinking process is not considered. For long-length perforated pipe piles, the small holes in the pile body with equal diameters cannot quickly discharge the increased pore water in the soil around the deeper pile body into the pipe cavity at the same time.

[0005] 2. The reason why the existing technology can effectively reduce the soil squeezing effect is that during the pile sinking process, the excess 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 a water pump to reduce the excess pore water pressure in the soil. However, during the pile sinking process, the soil around the pile will block the small holes in the pile body. If the small holes in the pile body are completely blocked by the soil, the function of the pile body opening is lost.

[0006] 3. The existing technology will cause the loss of soil (such as silty soil) in different soil layers around the pile while draining pore water, and there will also be a certain risk of pile sinking. Summary of the invention

[0007] 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, so as to solve the problem that the existing small holes of the pile body with equal apertures cannot quickly discharge the pore water increased in the soil around the deeper pile body into the pipe cavity, and the soil around the pile is likely to block the small holes of the pile body while discharging the pore water during the pile sinking process, thereby causing the soil around the pile to be lost.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] A prefabricated variable diameter hole pipe pile structure for soft foundation treatment comprises a pipe pile and a geotextile. The pipe pile comprises a pipe pile wall, wherein the pipe pile wall has a pipe cavity penetrating the pile top and the pile bottom, and the pipe pile wall is provided with a plurality of pile body small holes, wherein the diameter of the pile body small holes gradually increases from the pile top to the pile bottom along the axial direction of the pipe pile, and the geotextile is wrapped around the outer side of the pipe pile wall.

[0010] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, the diameter of the pile body small hole is 1 / 12 to 1 / 8 larger than the diameter of the adjacent pile body small hole at the previous level.

[0011] Preferably, in the above-mentioned prefabricated variable diameter hole pipe pile structure for soft foundation treatment, the geotextile is wrapped around the periphery of the pipe pile wall, the overlapping part of the geotextile is fixed by soil nails, and the geotextile is flush with both ends of the pipe pile wall.

[0012] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, the overlapping width of the geotextile is greater than 0.2 m.

[0013] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, the geotextile is a polyester staple fiber needle-punched geotextile.

[0014] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, there is only one pile body small hole located at the same horizontal height, and the connecting line of all the pile body small holes is parallel to the central axis of the pipe pile.

[0015] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, there are two small holes in the pile body located at the same horizontal height, including a first through hole and a second through hole, the first through hole and the second through hole are relatively arranged on the pipe pile wall to form a one-way through hole, and the connecting line of all the first through holes and the connecting line of all the second through holes on the pipe pile wall are parallel to the central axis of the pipe pile.

[0016] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, there are three small holes in the pile body located at the same horizontal height, including a first through hole, a second through hole and a third through hole, and the first through hole, the second through hole and the third through hole are distributed on the pipe pile wall in an equilateral triangle, and the connecting line of all the first through holes, the connecting line of all the second through holes and the connecting line of all the third through holes on the pipe pile wall are parallel to the central axis of the pipe pile.

[0017] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, there are two small holes in the pile body located at the same horizontal height, including a first through hole and a second through hole, and the second through hole is rotated 90 degrees clockwise or counterclockwise on the pipe pile wall relative to the first through hole, and the connecting line of all the first through holes and the connecting line of all the second through holes on the pipe pile wall are parallel to the central axis of the pipe pile.

[0018] Preferably, in the above-mentioned prefabricated variable-diameter hole pipe pile structure for soft foundation treatment, there are four pile body holes located at the same horizontal height, including a first through hole, a second through hole, a third through hole and a fourth through hole, and each pile body hole is rotated 90 degrees clockwise or counterclockwise on the pipe pile wall relative to the adjacent pile body hole at the same horizontal height, and the connecting line of all the first through holes, the connecting line of all the second through holes, the connecting line of all the third through holes and the connecting line of all the fourth through holes on the pipe pile wall are parallel to the central axis of the pipe pile.

[0019] The present invention also discloses a construction method of the prefabricated variable diameter hole pipe pile structure for soft foundation treatment as described above, comprising the following steps:

[0020] Step 1: A plurality of small pile body holes with gradually increasing diameters are opened from top to bottom on the wall of the pipe pile;

[0021] Step 2: Determine the required cutting size of the geotextile according to the outer perimeter of the pile wall, the required overlap length of the geotextile, and the length of the pile;

[0022] Step 3: Wrap the geotextile around the outer periphery of the pile wall and fix the overlapping parts of the geotextile with soil nails, and the overlapping width of the geotextile is more than 0.2m;

[0023] Step 4: transport the prefabricated pipe piles to the site;

[0024] Step 5: measuring and positioning the pipe piles;

[0025] Step 6: Static pile driver is in place;

[0026] Step 7, hanging piles;

[0027] Step eight, statically press the piles to the designed elevation, and use a water pump to discharge the pore water in the pipe cavity during the pile pressing process.

[0028] It can be seen from the technical solutions disclosed above that, compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The prefabricated variable-diameter hole pipe pile structure for soft foundation treatment provided by the present invention utilizes the principle that the excess pore water pressure of the soil increases linearly along the depth direction, and the larger the diameter of the pile body opening at the same depth, the faster the excess pore water pressure dissipates. By arranging a plurality of pile body small holes, i.e., variable-diameter holes, whose diameters gradually increase from the pile top to the pile bottom along the axial direction of the pipe pile, on the pipe pile wall, it can be ensured that the pore water of different depths encountered in the pile pressing process can be quickly discharged, thereby preventing pile sinking accidents. In addition, by wrapping a geotextile on the outer side of the pipe pile wall and utilizing the anti-filtration and drainage effects of the geotextile, the excess pore water and gas in the soil around the pile are discharged into the pipe cavity through the pores of the geotextile, while effectively intercepting particles, fine sand, and small stones, thereby preventing the pile body small holes from being blocked, and the pore water in the pipe cavity can be discharged by using a water pump, thereby achieving the purpose of optimally reducing the soil squeezing effect of pile sinking. Furthermore, by utilizing the good air permeability and water permeability of the geotextile, the present invention can effectively intercept soil particles, fine sand, small stones, etc. when the water flow around the pile flows into the inner lumen of the pile, thereby maintaining the stability of the water and soil engineering within the small hole range of the pile body and preventing soil and water loss in a local area.

[0030] The construction method of the prefabricated variable-diameter hole pipe pile structure for soft foundation treatment provided by the present invention can quickly discharge pore water at different depths by opening a plurality of pile body small holes with gradually increasing apertures from top to bottom on the pipe pile wall, thereby effectively preventing the occurrence of pile sinking accidents; a geotextile is wrapped around the outer periphery of the pipe pile wall, and the overlapping parts of the geotextile are fixed with soil nails, and the overlapping width of the geotextile is more than 0.2m, thereby utilizing the anti-filtration and drainage effects of the geotextile, so that the super-pore water and gas in the soil around the pile are discharged into the pipe cavity through the pores of the geotextile, and the pore water in the pipe cavity is discharged by a water pump, thereby achieving the purpose of optimally reducing the soil squeezing effect of pile sinking, and at the same time being able to effectively intercept soil particles, fine sand, small stones, etc., thereby being able to maintain the stability of water and soil engineering within the range of the pile body small holes, and preventing soil and water loss in a local range. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a cross-sectional view of a prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to an embodiment of the present invention.

[0032] Figure 2 It is a schematic diagram of the structure of a pipe pile in one embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the deployment of a geotextile in one embodiment of the present invention.

[0034] Figure 4 Schematic diagram of geotextile overlap in one embodiment of the present invention.

[0035] Figure 5 This is one of the distribution diagrams of the small holes in the pile body at the same horizontal height of the pipe pile (one-way non-perforation).

[0036] Figure 6 This is the second schematic diagram of the distribution of small holes in the pile body at the same horizontal height of the pipe pile (one-way through holes).

[0037] Figure 7 This is the third schematic diagram of the distribution of small holes in the pile body at the same horizontal height of the pipe pile (bidirectional non-perforation).

[0038] Figure 8 This is the fourth diagram of the distribution of the small holes in the pile body at the same horizontal height of the pipe pile (bidirectional through-holes). Figure 2 AA section view.

[0039] Fig. 9 Schematic diagram of the distribution of small holes in the pile body at the same horizontal height of the pipe pile (star-shaped openings) No. 5.

[0040] In the figure: 1. Small hole in the pile body; 2. Pile wall; 3. Pipe cavity; 4. Geotextile; 5. Soil nails. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The technical content and features of the present invention will be described in detail below by combining the enumerated embodiments with the accompanying drawings. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and 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 "upper" and "lower" described below are consistent with the upper and lower directions of the accompanying drawings, but this cannot be a limitation of the technical solution of the present invention.

[0042] See also Figures 1 to 9 The present embodiment discloses a prefabricated variable diameter hole pipe pile structure for soft foundation treatment, including a pipe pile and a geotextile 4, wherein the pipe pile includes a pipe pile wall 2, wherein the pipe pile wall has a tubular cavity 3 that passes through the pile top and the pile bottom, and the pipe pile wall 2 is provided with a plurality of pile body small holes 1, wherein the diameter of the pile body small holes 1 gradually increases from the pile top to the pile bottom along the axial direction of the pipe pile to form the variable diameter hole, and the geotextile 4 is wrapped around the outer side of the pipe pile wall 2.

[0043] The prefabricated variable-diameter hole pipe pile structure for soft foundation treatment provided by the present invention utilizes the principle that the excess pore water pressure of the soil increases linearly along the depth direction, and the larger the diameter of the pile body opening at the same depth, the faster the excess pore water pressure dissipates. By providing a plurality of pile body small holes 1, i.e., variable-diameter holes, whose diameters gradually increase from the pile top to the pile bottom along the axial direction of the pipe pile, on the pipe pile wall 2, it can be ensured that the pore water of different depths encountered in the pile pressing process can be quickly discharged, thereby effectively preventing the occurrence of pile sinking accidents. In addition, the present invention wraps a geotextile 4 on the outer side of the pipe pile wall 2, utilizes the anti-filtration and drainage effects of the geotextile 4, so that the excess pore water and gas in the soil around the pile are discharged into the pipe cavity 3 in the pipe through the pores of the geotextile 4, and at the same time intercepts soil particles, effectively preventing the soil from blocking the pile body small holes 1, and can use a water pump to discharge the pore water in the pipe cavity 3, thereby achieving the purpose of optimally reducing the soil squeezing effect of pile sinking. Furthermore, the present invention utilizes the good air permeability and water permeability of the geotextile 4 to effectively intercept soil particles, fine sand, small stones, etc. when the water flow around the pile flows into the inner tube cavity 3 of the pile, thereby maintaining the stability of the water and soil engineering within the small hole 1 of the pile body and preventing soil and water loss in a local area.

[0044] During the pile sinking process: the excess pore water pressure at the same depth is inversely proportional to the hole diameter of the pile body small hole 23. The larger the hole diameter of the pile body small hole 23, the smaller the excess pore water pressure. When the hole diameters of the pile body small holes 23 are the same, the excess pore water pressure is proportional to the depth, and the excess pore water pressure increases linearly with the increase of depth. After repeated experiments and demonstrations by the invention team, when the vertical spacing of the pile body small holes 23 is 1 / 5 to 1 / 8 times the pile length, and the hole diameter of the pile body small hole 23 is 1 / 12 to 1 / 8 larger than the hole diameter of the pile body small hole 23 at the adjacent upper horizontal height, the pipe pile 2 has sufficient strength, and the excess pore water pressure of the pipe pile 2 is small and balanced during the entire pile-making process, and the drainage is smooth, stable and timely, which can maintain the stability of the water and soil engineering within the range of the pile body small hole 23 and prevent soil and water loss in a local range. Furthermore, in this embodiment, the vertical spacing of the pile body holes 23 is 1 / 6 of the pile length, and the diameter of the pile body holes 23 is 1 / 10 larger than the diameter of the adjacent pile body holes 23 at the previous level, which achieves the best overall effect.

[0045] Preferably, in the above-mentioned prefabricated variable diameter hole 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 both 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 firmly fix the solid geotextile 4.

[0046] In order to achieve full coverage of the outer surface of the pile wall 2 by the geotextile 4 and to achieve reliable fixation of the geotextile 4, preferably, in the above-mentioned prefabricated variable diameter hole pile structure for soft foundation treatment, the overlap width D of the geotextile 4 is greater than 0.2 m.

[0047] Preferably, in the above-mentioned prefabricated variable diameter hole pipe pile structure for soft foundation treatment, the geotextile 4 is made of polyester staple fiber needle-punched geotextile, which has good air permeability and water permeability, and can effectively intercept soil particles, fine sand, small stones, etc. when the water flow around the pile flows into the pile cavity 3, thereby maintaining the stability of the water and soil engineering within the small hole 1 of the pile body and preventing soil and water loss in a local area.

[0048] In order to ensure that the pipe pile structure has sufficient strength while meeting drainage requirements, in this embodiment, the vertical small hole spacing is 1 / 6 times the pile length, the pipe pile wall thickness is 1 / 8 times the pile diameter, and the pile diameter of the pipe pile is 1 / 12 times the pile length.

[0049] The opening forms of the small holes on the pile body at the same horizontal height can be diversified, and can be unidirectional opening, bidirectional opening, star-shaped opening, and spiral opening.

[0050] The one-way opening includes one-way non-through opening and one-way through opening. Figure 5 , the pile body holes 1 at the same level are one, and the connecting line of all the pile body holes 1 is parallel to the central axis of the pile. For the one-way through hole form, please refer to Figure 5 There are two small holes 1 on the pile body at the same horizontal height, 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 on the pipe pile wall 2 to form a one-way through hole. The connecting line of all the first through holes and the connecting line of all the second through holes on the pipe pile wall 2 are parallel to the central axis of the pipe pile.

[0051] The bidirectional opening includes bidirectional non-intersecting opening and bidirectional intersecting opening. Figure 7 There are two small holes 1 on 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 relative to the first through hole on the pile wall 2. The connecting line of all the first through holes and the connecting line of all the second through holes on the pile wall 2 are parallel to the central axis of the pile. For bidirectional through holes, please refer to Figure 8There are four small holes 1 on the pile body at the same horizontal height, including a first through hole, a second through hole, a third through hole and a fourth through hole. Each small hole 1 on the pile body is rotated 90 degrees clockwise or counterclockwise on the pipe pile wall 2 relative to the adjacent small hole 1 on the same horizontal height. The connecting lines of all the first through holes, all the second through holes, all the third through holes and all the fourth through holes on the pipe pile wall 2 are parallel to the central axis of the pipe pile. In other words, the four small holes on the pile body are interpenetrated in pairs, and the connecting lines of the centers of the two groups of interpenetrating small holes are perpendicular to each other. The use of a two-way opening form can solve the problem of super-porous water seepage in the soil around the two or four sides of the pile, so that it can flow into the official cavity as quickly as possible. At the same time, the two-way interpenetrating opening can reasonably avoid the stress concentration effect of the small holes at the pile body opening, which may cause cracking and sinking at the pile opening due to the asymmetric opening.

[0052] The star-shaped openings are shown in Fig. 9 , there are three pile body holes 1 located at the same horizontal height, including a first through hole, a second through hole and a third through hole, the first through hole, the second through hole and the third through hole are distributed on the pipe pile wall 2 in an equilateral triangle, and the connecting lines of all the first through holes, the connecting lines of all the second through holes and the connecting lines of all the third through holes on the pipe pile wall 2 are parallel to the central axis of the pipe pile. In other words, the three pile body holes 1 are combined into a star-shaped opening, and the star-shaped opening is distributed with three small holes on the same cross section, the three small holes are obliquely intersecting each other, and the connecting lines of the centers of the three small holes are an equilateral triangle. Compared with unidirectional openings and bidirectional openings, star-shaped openings not only have the smallest maximum value of excess pore water pressure, but also have the smallest influence of stress concentration effect generated at the opening, which is the optimal opening method, and can make the excess pore water generated during the pile sinking process flow into the pipe cavity of the pipe pile from three directions in an even manner, accelerate the dissipation of excess pore water pressure or reduce the maximum value of excess pore water pressure of pile groups, effectively reduce the soil squeezing effect of pile sinking, and reduce the occurrence of pile sinking accidents.

[0053] Please continue reading Figures 1 to 9 The present invention also discloses a construction method of a prefabricated variable diameter hole pipe pile structure for soft foundation treatment as described above, comprising the following steps:

[0054] Step 1: a plurality of pile body small holes 1 with gradually increasing diameters are opened from top to bottom on the pipe pile wall 2;

[0055] Step 2, determining the size of the geotextile 4 to be cut according to the outer perimeter of the pile wall 2, the required overlap length of the geotextile 4, and the pile length;

[0056] Step 3: Wrap the geotextile 4 around the outer periphery of the 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 more than 0.2m;

[0057] Step 4: transport the prefabricated pipe piles to the site;

[0058] Step 5: measuring and positioning the pipe piles;

[0059] Step 6: Static pile driver is in place;

[0060] Step 7, hanging piles;

[0061] Step eight, statically press the piles to the designed elevation, and use a water pump to discharge the pore water in the pipe cavity during the pile pressing process.

[0062] The construction method of the prefabricated variable-diameter hole pipe pile structure for soft foundation treatment provided in the present embodiment can quickly discharge pore water of different depths by opening a plurality of pile body small holes 1 with gradually increasing apertures from top to bottom on the pipe pile wall 2, thereby effectively preventing the occurrence of pile sinking accidents; a geotextile 4 is wrapped around the outer periphery of the pipe pile wall 2, and the overlapping part of the geotextile 4 is fixed with soil nails 5, and the overlapping width of the geotextile 4 is more than 0.2m, thereby utilizing the anti-filtration and drainage effects of the geotextile 4, so that the super-pore water and gas in the soil around the pile are discharged into the pipe cavity 3 in the pipe through the pores of the geotextile 4, and the pore water in the pipe cavity 3 is discharged by a water pump, so as to achieve the purpose of optimally reducing the soil squeezing effect of pile sinking, and at the same time can effectively intercept soil particles, fine sand, small stones, etc., so as to maintain the stability of the water and soil engineering within the range of the pile body small hole 1, and prevent soil and water loss in a local range.

[0063] In summary, the beneficial effects of the present invention are as follows:

[0064] For the existing pile body, the hole diameter of the pile body small hole 1 is equal, and the relationship between the excess pore water pressure and the depth and the hole diameter of the pile body small hole 1 during the pile sinking process is not considered. For the long-length perforated pipe pile, the pile body small hole 1 with equal hole diameter cannot well discharge the increased pore water in the soil around the deeper pile body into the tube cavity 3 at the same time. The present invention derives through theoretical formulas that the excess pore water pressure is closely related to the pile sinking depth and the hole diameter of the pile body small hole 1. The excess pore water pressure in the pile sinking process increases linearly with the deepening of the depth, and the excess pore water pressure decreases with the increase of the hole diameter. Therefore, after the prefabricated pipe pile is completed, the excess pore water pressure of the soil around the pile bottom is much greater than the pore pressure in the soil around the pile top. The present invention sets a variable diameter hole with a gradually increasing hole diameter from top to bottom on the pipe pile wall 2. Compared with the perforated pipe pile with equal hole diameter of the pile body small hole 1, it can more effectively reduce the maximum value of the excess pore water pressure, further accelerate the dissipation of the excess pore water pressure, and more effectively prevent the occurrence of pile sinking accidents.

[0065] 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 tube cavity 3 through the pile body small hole 1 on the pipe pile wall 2, and then the water is discharged by a water pump to reduce the super pore water pressure in the soil. However, during the pile sinking process, the soil around the pile can block the pile body small hole 1. If the pile body small hole 1 is completely blocked by the soil, the function of the pile body opening is lost. The present invention wraps a circle of geotextile 4 around the outer periphery of the pipe pile. The geotextile 4 has high strength and can maintain sufficient strength and elongation in both dry and wet states; it has good corrosion resistance and can resist corrosion for a long time in soil and water with different pH values; it also has the characteristics of good water permeability, good antimicrobial property, and convenient construction. The present invention utilizes the filtration and drainage functions of the geotextile 4, which can form a drainage channel inside the soil. The super-pore water and gas in the soil around the pile are discharged into the tube cavity 3 in the pipe through the small holes 1 in the pile body, and soil particles are intercepted, effectively preventing the soil from blocking the small holes 1 in the pile body. Finally, a water pump is used to discharge the pore water in the tube cavity 3, thereby achieving the purpose of optimally reducing the soil squeezing effect of pile sinking.

[0066] The existing technology will cause the loss of soil (such as muddy soil) in different soil layers around the pile while draining pore water, and there will also be a certain risk of pile sinking. The present invention uses the good air permeability and water permeability of polyester staple needle-punched geotextile 4 to allow water to flow through and effectively intercept soil particles, fine sand, small stones, etc., so as to maintain the stability of water and soil engineering within the small hole 1 of the pile body and prevent soil and water loss in a local area.

[0067] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A prefabricated variable diameter hole pipe pile structure for soft foundation treatment, characterized in that: The invention comprises a pipe pile and a geotextile. The pipe pile comprises a pipe pile wall. The pipe pile wall has a tube cavity penetrating the pile top and the pile bottom. The pipe pile wall is provided with a plurality of pile body small holes. The diameter of the pile body small holes gradually increases from the pile top to the pile bottom along the axial direction of the pipe pile. The geotextile is wrapped around the outer side of the pipe pile wall. When the vertical spacing of the pile body small holes is 1 / 5 to 1 / 8 times the pile length, the diameter of the pile body small holes is 1 / 12 to 1 / 8 larger than the diameter of the adjacent pile body small holes at the previous horizontal height.

2. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, characterized in that: The geotextile is wrapped around the periphery of the pipe pile wall, 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.

3. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 2, characterized in that: The overlapping width of the geotextile is more than 0.2m.

4. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, characterized in that: The geotextile is a polyester staple fiber needle-punched geotextile.

5. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, characterized in that: There is one pile body small hole located at the same horizontal height, and the connecting line of all the pile body small holes is parallel to the central axis of the pipe pile, or there are two pile body small holes located at the same horizontal height, including a first through hole and a second through hole, the first through hole and the second through hole are arranged on the wall of the pipe pile opposite to each other to form a one-way through hole, and the connecting line of all the first through holes and the connecting line of all the second through holes on the wall of the pipe pile are parallel to the central axis of the pipe pile.

6. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, characterized in that: There are three small holes on the pile body located at the same horizontal height, including a first through hole, a second through hole and a third through hole. The first through hole, the second through hole and the third through hole are distributed on the wall of the pipe pile in the form of an equilateral triangle. The connecting line of all the first through holes, the connecting line of all the second through holes and the connecting line of all the third through holes on the wall of the pipe pile are parallel to the central axis of the pipe pile.

7. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, characterized in that: There are two small holes on the pile body located at the same horizontal height, 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. The connecting line of all the first through holes and the connecting line of all the second through holes on the wall of the pipe pile are parallel to the central axis of the pipe pile.

8. The prefabricated variable diameter hole pipe pile structure for soft foundation treatment according to claim 1, characterized in that: There are four pile body holes located at the same horizontal height, including a first through hole, a second through hole, a third through hole and a 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 hole at the same horizontal height. The connecting line of all the first through holes, the connecting line of all the second through holes, the connecting line of all the third through holes and the connecting line of all the fourth through holes on the pipe pile wall are parallel to the central axis of the pipe pile.

9. A construction method for a prefabricated variable diameter hole pipe pile structure for soft foundation treatment as claimed in any one of claims 1 to 8, characterized in that: The steps include: Step 1: A plurality of small pile body holes with gradually increasing diameters are opened from top to bottom on the wall of the pipe pile; Step 2: Determine the size of the geotextile to be cut according to the outer circumference of the pile wall, the required overlap length of the geotextile, and the length of the pile; Step 3: Wrap the geotextile around the outer periphery of the pile wall and fix the overlapping parts of the geotextile with soil nails, and the overlapping width of the geotextile is more than 0.2m; Step 4: transport the prefabricated pipe piles to the site; Step 5: measuring and positioning the pipe piles; Step 6: Static pile driver is in place; Step 7, hanging piles; Step eight, statically press the piles to the designed elevation, and use a water pump to discharge the pore water in the pipe cavity during the pile pressing process.

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