Expanded-base special-shaped pile capable of eliminating negative frictional resistance of foundation pile and construction method
By using expanded base-expanded special-shaped piles and specific construction methods in foundation pile engineering in wet loess areas, and using steel casings, water storage devices and HCSA concrete expansion devices, the negative friction resistance problem caused by wet loess is solved, and the effect of reducing pile length, reducing construction cost and improving foundation pile bearing capacity is achieved.
Patent Information
- Application Number
- CN202510159186.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2025-04-15
AI Technical Summary
In the wet loess area, the pile project causes negative friction resistance to the pile side due to the wet loess of the wet loess, which affects the bearing capacity of the foundation pile and the settlement of the pile body. The existing technology deals with it by increasing the pile length and pile diameter, but this is not only uneconomical, but also increases the construction difficulty.
A special-shaped pile with a bottom-expanded bottom that eliminates the negative friction resistance of the foundation pile and a construction method are adopted. By setting up a steel casing, a water reservoir and an HCSA concrete expansion device above the neutral point of the pile body, the combination of expansion agent and water is used to eliminate the negative friction resistance on the pile side, and the pile end resistance and static pressure pile sinking are increased.
It effectively reduces the pile length, reduces the construction cost, improves the bearing capacity of the foundation pile and the settlement stability of the pile body, and reduces the construction difficulty.
Smart Images
Figure CN119824899A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of building foundation engineering, and in particular to a bottom-enlarged special-shaped pile for eliminating negative friction resistance of a foundation pile and a construction method. Background Art
[0002] There are large areas of deep and collapsible loess layers in the central and western regions of my country. Loess has a significant problem of collapsing when it encounters water. Engineering structures in collapsible loess areas often produce additional settlement deformation due to the collapse of the foundation soil. For pile foundations, it is because of the collapse of collapsible loess that negative friction is generated on the pile side. The influence of negative friction on the bearing capacity and pile settlement in collapsible loess areas cannot be ignored. When the sinking rate (or settlement) of the soil on the pile side is greater than the sinking rate (or settlement) of the pile itself, negative friction will be generated on the surface of the pile, which will cause the settlement of the building pile foundation and even endanger the safety of the upper structure.
[0003] At present, when designing pile foundation projects in collapsible loess areas, negative friction is applied to the pile body in the form of a pull-down load, which forces the pile length and diameter to be increased during design. This method is not only uneconomical, but also increases the difficulty of construction as the pile length and diameter increase.
[0004] In order to solve the above problems, the present invention proposes a bottom-enlarged special-shaped pile and a construction method for eliminating the negative friction resistance of the foundation pile. The setting of the bottom-enlarged, wedge-shaped and expansion device can increase the positive friction resistance of the foundation pile and effectively reduce the negative friction resistance, thereby achieving the purpose of reducing the pile length and reducing the construction cost. Summary of the invention
[0005] The purpose of the present invention is to solve the above-mentioned problems and to provide a bottom-enlarged special-shaped pile and a construction method for eliminating the negative friction resistance of the foundation pile.
[0006] To achieve the above object, the technical solution adopted by the present invention is: The present invention provides a bottom-enlarged special-shaped pile for eliminating the negative friction of the foundation pile and a construction method, comprising a cap, a pile body, a steel casing, a water storage tank, a HCSA concrete expansion device, and a bottom-enlarged component, characterized in that: The pile body is a prefabricated concrete pile, and a steel bar is reserved at the top of the pile. The part above the neutral point of the pile body is cylindrical, and the part below the neutral point is wedge-shaped. A notch is reserved at the end of the wedge-shaped section of the pile body. The water storage device is composed of a rubber piston and a water storage tank. The bottom of the water storage tank is provided with a water outlet hole connected to the lower water injection pipe. The HCSA concrete expansion device includes an inner and outer double-layer steel casing and an HCSA concrete storage bin arranged between the double-layer steel casing. The HCSA concrete storage bin is a multi-bin arrangement and is symmetrical around the center position of the double-layer steel casing. Holes corresponding to the positions of the HCSA concrete storage bins are reserved on the outer side of the double-layer steel casing and geotextiles are arranged on the holes. Water injection pipe holes are correspondingly arranged on the multiple HCSA concrete storage bins, and water outlets are reserved at corresponding positions of the water injection pipes and the HCSA concrete storage bins.
[0007] Furthermore, the cross-sectional area of the top of the wedge-shaped section of the pile body is larger than the cross-sectional area of the cylinder.
[0008] Furthermore, the inner diameter of the steel casing is the same as the diameter of the cylindrical pile body above the neutral point.
[0009] Furthermore, the number of the water outlet holes, water injection pipes and HCSA concrete storage bins on each layer is the same.
[0010] Furthermore, the bottom expansion component is cast by manually digging a hole, and a protruding end is prefabricated on the top, and the protruding end is connected to a reserved recess of the pile body.
[0011] A construction method for a bottom-enlarged special-shaped pile for eliminating negative friction of a foundation pile, the steps of which are as follows: S1: Prefabricated pile body: The pile body size and neutral point position are determined according to the design requirements. The part above the neutral point of the pile body is cylindrical, and the part below the neutral point is wedge-shaped. Reinforcement is reserved at the top of the pile, and a notch is reserved at the end of the pile. S2: Prefabricated HCSA concrete expansion device: According to the design requirements, steel materials of different radii are selected for cutting and drilling to make the inner and outer double-layer steel casings, HCSA concrete storage bins, and water injection pipes of the HCSA concrete expansion device. After the production is completed, welding is carried out and geotextiles are laid to complete the production of the HCSA concrete expansion device; S3: Prefabricated water storage tank and steel casing: Determine the diameter and length of the steel casing according to the design requirements; determine the volume of the water storage tank, make it, and install the steel casing, water storage tank, and HCSA concrete expansion device on the pile in sequence; S4: Pre-drilling: Drill holes to the designed elevation. The diameter of the drilling steel pipe used for drilling holes is the same as the diameter of the end of the wedge section of the pile body, ensuring that the wedge section below the neutral point of the pile body can fully exert its compaction effect during the static pressure pile sinking process; S5: Casting the bottom expansion component: After the drilling is completed, the bottom is expanded manually to form an expanded head at the bottom of the pile, and the steel cage in a contracted state is lowered. When the steel cage is lowered to the design elevation, it is expanded and the bottom expansion component is cast to form a regular shape, ensuring that the protruding end of the bottom expansion component is well connected with the reserved notch of the pile body; S6: Static pressure pile formation and cap casting: Static pressure pile sinking, ensure that the reserved notch of the pile body is well connected with the protruding end of the bottom expansion member, reserve steel bars at the top of the pile, weld steel cages, and cast the cap; S7: Repeat steps S4, S5, and S6 to construct the next pile.
[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention arranges a steel casing, a water reservoir, and an HCSA concrete expansion device on the part of the pile body above the neutral point. When the pile and the soil around the pile generate relative displacement, causing negative friction, the steel casing slides downward under the action of the negative friction, pushing the piston of the water reservoir, so that the water in the water reservoir flows from the water injection pipe to the HCSA concrete storage bin. At the same time, HCSA, as a high-performance concrete expansion agent, can also absorb a certain amount of water from the soil on the side of the pile, so that the dry powder mixture of HCSA and cement in the HCSA storage bin expands to form an expansion body, thereby eliminating the negative friction on the side of the pile body above the neutral point.
[0013] (2) The pile end resistance is increased by pre-drilling, artificial bottom expansion and static pressure pile sinking. Since the diameter of the bored steel pipe used in the pre-drilling is the same as the diameter of the pile end of the wedge-shaped section of the pile body, the wedge-shaped section of the pile body has a certain compacting effect on the soil around the pile during the static pressure pile sinking process, which improves the density of the soil around the pile. At the same time, due to the unique shape of the wedge-shaped section of the pile body, the positive friction resistance of the pile side below the neutral point is increased. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 This is a schematic diagram of a special-shaped pile with an expanded bottom; Figure 2 It is a schematic diagram of the pile; Figure 3 It is a schematic diagram of steel casing; Figure 4 is a schematic diagram of a water storage tank; Figure 5 It is a top view of the HCSA concrete expansion device; Figure 6 It is a schematic diagram of the HCSA concrete expansion device; Figure 7 It is a schematic diagram of the bottom expansion component; Figure 8 Drilling steel pipe diagram.
[0015] In the figure: 1. foundation; 2. steel casing; 3. rubber piston; 4. water storage tank; 5. water storage vessel; 6. HCSA concrete expansion device; 7. HCSA concrete storage tank; 8. water outlet; 9. water injection pipe; 10. pile body; 11. notch; 12. protruding end; 13. bottom expansion member; 14. water outlet hole; 15. reserved steel bar; 16. drilled steel pipe; 17. double-layer steel pipe sleeve. DETAILED DESCRIPTION
[0016] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.
[0017] The present invention provides a bottom-enlarged special-shaped pile and a construction method for eliminating the negative friction of the foundation pile. Figures 1 to 8 As shown, a bottom-enlarged special-shaped pile for eliminating the negative friction resistance of the foundation pile includes a cap 1, a pile body 10, a steel casing 2, a water storage tank 5, a HCSA concrete expansion device 6, and a bottom-enlarged component 13.
[0018] The pile body 10 is a prefabricated concrete pile, and a steel bar 15 is reserved at the top of the pile. The part above the neutral point of the pile body 10 is cylindrical, and the part below the neutral point is wedge-shaped. A notch 11 is reserved at the end of the wedge-shaped section of the pile body 10. The water storage device 5 is composed of a rubber piston 3 and a water storage tank 4. The bottom of the water storage tank 4 is provided with a water outlet 14 which is connected to the lower water injection pipe 9. The HCSA concrete expansion device 6 includes an inner and outer double-layer steel casing 17, and a HCSA concrete storage bin 7 is arranged between the double-layer steel casing 17. The HCSA concrete storage bin 7 is a multi-layer multi-bin arrangement and is symmetrical around the center of the double-layer steel casing 17. The outer side of the double-layer steel casing 17 is reserved with HCSA concrete storage bin 7 holes and geotextiles are laid on the holes. Multiple HCSA concrete storage bins 7 are provided with corresponding water injection pipe 9 holes, and the corresponding positions of the water injection pipe 9 and the HCSA concrete storage bin 7 are reserved with water outlets 8. Drill holes to the designed elevation, perform manual digging, cast the bottom expansion component 13, static pressure pile sinking, and cast the cap 1.
[0019] like Figure 1 , 2 As shown, the pile body 10 is a precast concrete pile, the portion above the neutral point is cylindrical, the portion below the neutral point is wedge-shaped, and there is a small cap at the neutral point for carrying the HCSA concrete expansion device 6.
[0020] like Figure 1 , 3 As shown, the inner diameter of the steel casing 2 is the same as the diameter of the pile body 10 above the neutral point.
[0021] like Figure 1 , 4 As shown, the water reservoir 5 is composed of a rubber piston 3 and a water storage tank 4. The rubber piston 3 and the inner and outer walls of the water storage tank 4 are tightly squeezed to ensure that there is enough pressure in the water reservoir 5, so that when the rubber piston 3 is located at the top position of the water reservoir 5, the water in the water reservoir 5 will not flow out. The bottom of the water reservoir 5 is sealed and 6 to 8 water outlet holes 14 are reserved.
[0022] like Figure 1, 5 As shown in , 6, the HCSA concrete expansion device 6 is composed of an inner double-layer steel pipe 17, a HCSA concrete storage bin 7, and a water injection pipe 9; the inner and outer double-layer steel casings 17 of the HCSA concrete expansion device 6 are welded and connected by the HCSA concrete storage bin 7, and holes corresponding to the positions of the HCSA concrete storage bin 7 are reserved on the outer side of the double-layer steel casing 17, and geotextiles are arranged on the holes to prevent the dry powder mixture of HCSA and cement from flowing out, and holes for the water injection pipe 9 are reserved in the HCSA concrete storage bin 7, and the inner diameter of the holes of the water injection pipe 9 is the same as the outer diameter of the water injection pipe 9 to ensure that no water will seep out during the water injection process, and the water injection pipe 9 is reserved with a water outlet 8 at the corresponding position of the HCSA concrete storage bin 7.
[0023] The number of the water injection pipe 9, the water outlet 8, and the HCSA concrete storage bins in each layer along the radial direction of the pile body is the same as the number of the water outlet holes 14, and 6 to 8 are arranged. Figure 6 .
[0024] like Figure 1 , 2 As shown in 7, the bottom expansion member 13 is a manually dug hole, and the steel cage in a contracted state is lowered and then poured. The top of the expanded member 13 is prefabricated with a protruding end 12, which is regularly shaped and well connected with the reserved notch 11 of the pile body 10.
[0025] The construction method of the expanded bottom special-shaped pile for eliminating the negative friction resistance of the foundation pile comprises the following steps: S1: Prefabricated pile body 10: The pile body size and neutral point position are determined according to the design requirements. The part above the neutral point of the pile body 10 is cylindrical, and the part below the neutral point is wedge-shaped. The wedge angle of the wedge section is 1 / 60, and a steel bar 15 is reserved at the pile top position, and a notch 11 is reserved at the pile end position; S2: Prefabricate HCSA concrete expansion device 6: According to the design requirements, steel materials with different radii are selected for cutting and drilling to manufacture the inner and outer double-layer steel casings 17, HCSA concrete storage bin 7, and water injection pipe 9 of HCSA concrete expansion device 6. After the manufacture is completed, welding is performed. After the welding is completed, geotextile is pasted on the hole position of HCSA concrete storage bin 7 reserved on the outer side of the double-layer steel casing 17 to prevent the HCSA concrete dry powder mixture from flowing out, thereby completing the manufacture of HCSA concrete expansion device 6; S3: Prefabricate water storage tank 5 and steel casing 2: According to the design requirements, determine the diameter and length of steel casing 2; determine the volume of water storage tank 5 and make it. Install steel casing 2, water storage tank 5 and HCSA concrete expansion device 6 on the pile body, ensure that steel casing 2 can slide downward under the action of negative friction resistance, and push piston 3 of water storage tank 5 to inject water in water storage tank 5 into HCSA concrete expansion device, so that HCSA concrete dry powder mixture in HCSA concrete storage bin 7 expands when it meets water.
[0026] S4: Pre-drilling: Drill to the designed elevation; the diameter of the drilling steel pipe 16 used for drilling is the same as the diameter of the end of the wedge-shaped section of the pile body 10, to ensure that the wedge section below the neutral point of the pile body 10 can fully compact the surrounding soil during the static pressure pile sinking process and increase the positive friction resistance; S5: Casting the bottom expansion component 13: After the drilling is completed, the bottom is expanded manually to form an enlarged head at the bottom of the pile, and the steel cage in a contracted state is lowered. When the steel cage is lowered to the designed elevation, it is expanded and the bottom expansion component 13 is cast to form a regular shape, ensuring that the protruding end 12 of the bottom expansion component 13 is well connected with the reserved notch 11 of the pile body 10; S6: Static pressure pile formation and pouring of the cap 1: Static pressure pile sinking, ensuring that the reserved notch 11 of the pile body 10 is well connected with the protruding end 12 of the bottom expansion member 13, the steel bar 15 is reserved at the top of the pile, the steel cage is welded, and the cap 1 is poured; S7: Repeat steps S4, S5, and S6 to construct the next pile.
[0027] Working principle: (1) Reducing or even eliminating the negative friction on the pile side of the part above the neutral point: In collapsible loess areas, the loess foundation will produce additional displacement when it encounters water, and the pile-soil interface will produce relative displacement changes, causing negative friction. The present invention arranges a casing, a water reservoir, and HCSA concrete expansion on the part of the pile body above the neutral point, so that after the soil around the pile collapses and settles when it encounters water, it drives the steel casing to slide downward, thereby pushing the piston, so that the water in the water reservoir flows from the water injection pipe to the HCSA concrete storage bin. At the same time, HCSA, as a high-performance concrete expansion agent, can also absorb a certain amount of moisture from the soil around the pile. The dry powder mixture of HCSA and cement in the HCSA concrete storage bin expands when it encounters water to form an expansion body, thereby eliminating the negative friction on the pile side above the neutral point.
[0028] (2) Increasing pile end resistance: By manually digging a hole, an enlarged head is formed at the pile end, and the bottom expansion component is cast to increase the contact area between the pile and the soil at the pile end, thereby improving the pile end resistance.
[0029] (3) Compacting the soil around the pile and increasing the positive friction resistance of the pile side below the neutral point: Since the part below the neutral point is a wedge-shaped pile, the pile must overcome the tangential friction along the direction of the pile and the vertical support force perpendicular to the direction of the pile to produce vertical displacement during the static pressure pile sinking process. Therefore, compared with piles with equal cross-section, the pile has a certain compacting effect on the soil around the pile, compacting the soil around the pile and improving the density of the soil around the pile. After the pile is sunk, due to the unique shape of the wedge-shaped pile body, the pile body is simultaneously subjected to the tangential friction force and vertical support force of the soil around the pile, and the positive friction resistance of the pile side is greater than that of piles with equal cross-section.
[0030] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.
[0031] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.
Claims
1. A bottom-enlarged special-shaped pile for eliminating negative friction resistance of a foundation pile, comprising a cap (1), a pile body (10), a steel casing (2), a water storage tank (5), a HCSA concrete expansion device (6), and a bottom-enlarged component (13), characterized in that: The pile body (10) is a prefabricated concrete pile, and a steel bar (15) is reserved at the pile top; the portion above the neutral point of the pile body (10) is cylindrical, and the portion below the neutral point is wedge-shaped; a notch (11) is reserved at the end of the wedge-shaped section of the pile body (10); The water storage device (5) is composed of a rubber piston (3) and a water storage tank (4); a water outlet hole (14) is provided at the bottom of the water storage tank (4) and is connected to a lower water injection pipe (9); The HCSA concrete expansion device (6) comprises an inner and outer double-layer steel casing (17) and an HCSA concrete storage bin (7) arranged between the double-layer steel casing (17). The HCSA concrete storage bin (7) is radially arranged in multiple layers at equal intervals and each layer of the HCSA concrete storage bin (7) is symmetrically arranged around the center of the double-layer steel casing (17). Holes corresponding to the positions of the HCSA concrete storage bins (7) are reserved on the outer side of the double-layer steel casing (17) and geotextiles are arranged on the holes. Holes for water injection pipes (9) are correspondingly arranged on the plurality of HCSA concrete storage bins (7), and water outlets (8) are reserved at corresponding positions of the water injection pipes (9) and the HCSA concrete storage bins (7).
2. According to claim 1, a base-enlarged special-shaped pile for eliminating negative friction of foundation piles is characterized by: The cross-sectional area of the top of the wedge-shaped section of the pile body (10) is larger than the cross-sectional area of the cylinder.
3. The bottom-enlarged special-shaped pile for eliminating the negative friction of the foundation pile according to claim 2, characterized in that: The inner diameter of the steel casing (2) is the same as the diameter of the cylindrical pile body (10) above the neutral point.
4. The bottom-enlarged special-shaped pile for eliminating the negative friction of the foundation pile according to claim 3, characterized in that: The number of the water outlet holes (14), the water injection pipes (9) and the HCSA concrete storage bins (7) on each layer is the same.
5. The bottom-enlarged special-shaped pile for eliminating the negative friction of the foundation pile according to claim 4, characterized in that: The bottom expansion component (13) is cast by manually digging a hole, and a protruding end (12) is prefabricated on the top thereof, and the protruding end (12) is connected to a reserved notch (11) of the pile body (10).
6. A construction method for base-enlarged special-shaped piles for eliminating negative friction of foundation piles according to claim 5, characterized in that: The steps are: S1: Prefabricated pile body (10): The pile body size and neutral point position are determined according to design requirements. The portion above the neutral point of the pile body (10) is cylindrical, and the portion below the neutral point is wedge-shaped. A steel bar (15) is reserved at the pile top position, and a notch (11) is reserved at the pile end position. S2: Prefabricate the HCSA concrete expansion device (6): According to the design requirements, steel materials with different radii are selected for cutting and drilling to manufacture the inner and outer double-layer steel casings (17), the HCSA concrete storage bin (7), and the water injection pipe (9) of the HCSA concrete expansion device (6). After the manufacture is completed, welding is performed and geotextiles are laid, thereby completing the manufacture of the HCSA concrete expansion device (6); S3: Prefabricate the water storage tank (5) and the steel casing (2): according to the design requirements, determine the diameter and length of the steel casing (2); determine the volume of the water storage tank (5), make it, and install the steel casing (2), the water storage tank (5), and the HCSA concrete expansion device (6) on the pile body (10) in sequence; S4: Pre-drilling: Drilling to the designed elevation, the diameter of the drilling steel pipe (16) used for drilling is the same as the diameter of the end of the wedge-shaped section of the pile body (10), ensuring that the wedge-shaped section below the neutral point of the pile body (10) can fully exert its compaction effect during the static pressure pile sinking process; S5: Casting the bottom expansion component (13): After the drilling is completed, the bottom is expanded manually to form an expanded head at the bottom of the pile, and the steel cage in a contracted state is lowered. When the steel cage is lowered to the designed elevation, it is expanded and the bottom expansion component (13) is cast to form a regular shape, ensuring that the protruding end (12) of the bottom expansion component (13) is well connected to the reserved notch (11) of the pile body (10); S6: Static pressure pile formation and pouring of the cap (1): Static pressure pile sinking, ensuring that the reserved notch (11) of the pile body (10) and the protruding end (12) of the bottom expansion member (13) are well connected, steel bars (15) are reserved at the top of the pile, a steel cage is welded, and the cap (1) is poured; S7: Repeat steps S4, S5, and S6 to construct the next pile.