A composite foundation structure and construction method

Abstract

The present invention relates to the technical field of foundation reinforcement, and specifically to a composite foundation structure and a construction method. A concrete reinforcement member for horizontally connecting adjacent pipe piles is cast in the inner cavity surrounded by a head connecting member and a mold connecting member. A sunken hole is provided at the upper end of the pipe pile, and the inner cavity of the sunken hole is integrally cast with a high-strength adhesion layer. A deformation coordination layer is cast on the upper end of the high-strength adhesion layer. The beneficial effects are as follows: By setting the cast concrete reinforcement member, the connection between the ends of adjacent pipe piles is realized, and thus the force on the pipe piles is evenly distributed to each pipe pile, avoiding the extrusion of soft soil by a single pipe pile, improving the stability of the foundation. At the same time, by setting the connection between the sunken hole and the cushion layer, the vertical force on the pipe piles is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation reinforcement, and specifically to a composite foundation structure and a construction method thereof. Background Art

[0002] In traditional foundation treatment technologies, pipe piles (such as prestressed concrete pipe piles) are often used to improve bearing capacity. However, when used alone, they are prone to differential settlement due to the weakness of the soil between piles; cement mixing piles can improve the properties of the soil around the piles, but it is difficult to meet high bearing capacity requirements when used alone. In the prior art, the combination of pipe piles and mixing piles mostly adopts a parallel arrangement or a simple alternating manner, with insufficient synergistic effect, and the combination with the upper cushion layer is mostly loose filling, which is prone to uneven stress transfer. In addition, the traditional cushion layer has a single material and is difficult to meet the deformation coordination requirements of the composite foundation.

[0003] Moreover, the existing pipe pile reinforcement method is to insert the pipe piles into the soft soil, but the soft soil gap between adjacent pipe piles is still very large. Therefore, when the pipe piles are inclined and stressed or the installation verticality of the pipe piles is insufficient, it will cause the extrusion of the soft soil between adjacent pipe piles, and then cause the instability of the foundation. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite foundation structure and a construction method thereof to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A composite foundation structure, the composite foundation structure includes a reinforcement area, a surrounding area and a cushion layer. A plurality of groups of pipe piles densely distributed in a matrix are vertically inserted in the reinforcement area. A plurality of groups of cement mixing piles sleeved with each other are arranged on the outer contour of the reinforcement area. The plurality of groups of cement mixing piles form the surrounding area. The upper ends of the reinforcement area and the surrounding area are filled with a cushion layer. The cushion layer includes a high-strength adhesion layer and a deformation coordination layer. The upper end of the pipe pile is fixedly provided with a head component located at the upper end of the reinforcement area. A head connecting piece is sleeved on the head component. Adjacent head connecting pieces are connected by a die connecting piece. A concrete reinforcement member connecting adjacent pipe piles horizontally is poured in the inner cavity surrounded by the head connecting piece and the die connecting piece. A sinkhole is provided at the upper end of the pipe pile. The inner cavity of the sinkhole is integrally poured with the high-strength adhesion layer. The deformation coordination layer is poured on the upper end of the high-strength adhesion layer.

[0007] Preferably, a plurality of groups of connecting bars distributed in a circumferential array are provided at the upper end of the pipe pile, and connecting holes matched with the connecting bars for fixed sleeving are provided at the lower end of the head component.

[0008] Preferably, a stepped platform is provided on the inner wall of the middle section of the end component. The inner cavity at the upper end of the stepped platform is set as an upper hole, and the inner cavity at the lower end of the stepped platform is set as a lower hole. The upper hole and the lower hole communicate with each other, the lower hole communicates with the counterbore, and the inner diameter of the lower hole is smaller than the inner diameter of the counterbore.

[0009] Preferably, a plurality of lower through grooves communicating with the inner cavity of the lower hole are provided on the outer wall of the lower arc of the end component, and the lower through grooves are distributed in a staggered manner with the mold connecting piece.

[0010] Preferably, the end connecting piece includes a positioning collar and an extension die frame, and a positioning ring for fitting and sleeving with the positioning collar is provided at the upper end of the stepped platform.

[0011] Preferably, the outer diameter of the positioning collar is equal to the outer diameter of the positioning ring, and a circular ring gap is left between the inner wall of the positioning collar and the upper hole. The circular ring gap communicates with the extension die frame.

[0012] Preferably, one end of the extension die frame is attached to the outer wall of the circular ring of the end component, and the other end of the extension die frame is fixedly connected to the mold connecting piece.

[0013] Preferably, a T-shaped insert is provided at one end of the extension die frame close to the mold connecting piece, and a slot for cooperating with the T-shaped insert is provided at the end of the mold connecting piece.

[0014] Preferably, a positioning pin is installed on the side wall of the mold connecting piece by means of threaded rotation, and a pin hole facing the positioning pin is provided on the T-shaped insert.

[0015] A construction method according to the composite foundation structure described above, the construction method comprising the following steps:

[0016] Step 1: Fill and compact a 1m thick soil layer on the surface of the original soft formation as a construction platform; Core reinforcement area construction: Use PHC prepared pipe piles to drive piles from the middle to the surrounding, and drive the end of the pipe pile into the bottom bedrock.

[0017] Step 2: Enclosure area construction: Use cement-soil mixing piles for sealing, arrange them in a socket connection, overlap each other, and the cement content ratio of the pile body is 18%.

[0018] Step 3: Install the end component at the upper end of the pipe pile, and use the mold connecting piece and the end connecting piece to realize the connection between adjacent pipe piles. Then, pour concrete into the gap between the end connecting piece and the mold connecting piece to form a concrete reinforcement member, and then remove the end connecting piece and the mold connecting piece.

[0019] Step 4: Construction of the cushion layer area. Excavate the soil layer filled at the top, chisel off the pile segments with poor quality at the upper 0.5 m of the cement mixing piles, fill self-compacting concrete as the high-strength adhesion layer. The self-compacting concrete fills the sunken holes at the upper ends of the pipe piles along the pores after the end connectors are removed, fills the gaps between adjacent concrete reinforcement members, and the high-strength adhesion layer covers the upper ends of the concrete reinforcement members. Fill cement soil at the upper end of the high-strength adhesion layer as the deformation coordination layer.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] In the present invention, pipe piles are set to bear vertical loads, and mixing piles provide lateral constraints to reduce the differential deformation between the piles and the soil; the mixing piles are enclosed to block the penetration of external groundwater and improve the comprehensive anti-seepage capacity of the foundation; the multi-layer cushion layers are combined with self-compacting concrete and cement soil to achieve uniform transfer of loads to the reinforcement area;

[0022] At the same time, cast concrete reinforcement members are set to realize the connection between the end heads of adjacent pipe piles, and then evenly distribute the forces of the pipe piles to each pipe pile, avoiding the extrusion of soft soil by a single pipe pile, improving the stability of the foundation. At the same time, the connection between the sunken holes and the cushion layer is set to ensure the vertical force of the pipe piles. Description of the Drawings

[0023] Figure 1 It is a top view of the installation of the end connector and the mold connector of the present invention;

[0024] Figure 2 It is a sectional view of the present invention;

[0025] Figure 3 It is a schematic structural diagram of the installation of the end component of the present invention at the upper end of the pipe pile;

[0026] Figure 4 It is a schematic pouring structural diagram of the present invention;

[0027] Figure 5 It is a three-dimensional structural diagram of the installation of the end connector of the present invention on the end component;

[0028] Figure 6 It is a schematic structural diagram of the end component of the present invention;

[0029] Figure 7 It is a three-dimensional structural diagram of the end component of the present invention;

[0030] Figure 8 It is a three-dimensional structural diagram of the installation of the end component of the present invention on the pipe pile.

[0031] In the figure: 1. Enclosure area; 2. Pipe pile; 3. End component; 4. Mold connecting piece; 5. End connecting piece; 6. Deformation coordination layer; 7. High-strength adhesion layer; 8. Cement mixing pile; 9. Concrete reinforcement; 10. Counterbore; 11. Connecting bar; 31. Lower through groove; 32. Lower hole; 33. Upper hole; 34. Step platform; 35. Positioning ring; 36. Connecting hole; 51. Positioning sleeve ring; 52. Extended mold frame; 53. T-shaped insert; 54. Pin hole. Detailed implementation manners

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Please refer to Figures 1 to 8 , the present invention provides a technical solution:

[0034] A composite foundation structure, the composite foundation structure includes a reinforcement area, an enclosure area 1 and a cushion layer. A plurality of groups of pipe piles 2 densely distributed in a matrix are vertically inserted in the reinforcement area, and the pipe piles provide lateral restraint to reduce the differential deformation between the pile and the soil.

[0035] A plurality of groups of cement mixing piles 8 sleeved with each other are arranged on the outer contour of the reinforcement area, and the plurality of groups of cement mixing piles 8 form the enclosure area 1. The mixing piles enclose to block the penetration of external groundwater and improve the comprehensive anti-seepage capacity of the foundation.

[0036] The upper ends of the reinforcement area and the enclosure area 1 are filled with a cushion layer, and the cushion layer includes a high-strength adhesion layer 7 and a deformation coordination layer 6. The multi-layer cushion layer is combined with self-compacting concrete and cement soil to achieve uniform transfer of the load to the reinforcement area.

[0037] The upper end of the pipe pile 2 is fixedly provided with an end component 3 located at the upper end of the reinforcement area. An end connecting piece 5 is sleeved on the end component 3. Adjacent end connecting pieces 5 are connected by a mold connecting piece 4. A concrete reinforcement 9 for horizontally connecting adjacent pipe piles 2 is poured in the inner cavity surrounded by the end connecting piece 5 and the mold connecting piece 4. A counterbore 10 is provided at the upper end of the pipe pile 2, and the inner cavity of the counterbore 10 is integrally poured with the high-strength adhesion layer 7. The deformation coordination layer 6 is poured on the upper end of the high-strength adhesion layer 7.

[0038] Working principle: By setting the cooperation of the end component 3, the end connecting piece 5 and the mold connecting piece 4, it is convenient to pour the concrete reinforcement 9, and the connection between the ends of adjacent pipe piles 2 is realized. When the pipe pile 2 is laterally stressed due to the setting of an inclined pressure or insufficient verticality of the pipe pile, the lateral stress is evenly transmitted to each pipe pile 2;

[0039] Meanwhile, a counterbore 10 is provided to realize the connection between the pipe pile 2 and the high-strength adhesion layer 7, and further accurately transfer the pressure to the pipe pile 2 to achieve high-strength bearing support.

[0040] Embodiment 2: On the basis of Embodiment 1, a plurality of groups of connecting ribs 11 distributed in a circumferential array are provided at the upper end of the pipe pile 2, and a connecting hole 36 for fitting and fixing sleeving with the connecting ribs 11 is provided at the lower end of the end component 3.

[0041] Through the cooperation of the connecting ribs 11 and the connecting holes 36, the fixed limit installation of the end component 3 on the pipe pile 2 is realized.

[0042] A stepped platform 34 is provided on the inner wall of the middle section of the end component 3. The inner cavity at the upper end of the stepped platform 34 is set as an upper hole 33, and the inner cavity at the lower end of the stepped platform 34 is set as a lower hole 32. The upper hole 33 and the lower hole 32 communicate with each other. The lower hole 32 communicates with the counterbore 10, and the inner diameter of the lower hole 32 is smaller than the inner diameter of the counterbore 10.

[0043] By limiting the inner diameter size, a dislocation is formed after pouring to ensure the stable connection between the pipe pile 2 and the high-strength adhesion layer 7.

[0044] A plurality of groups of lower through grooves 31 communicating with the inner cavity of the lower hole 32 are provided on the outer wall of the lower end arc of the end component 3, and the lower through grooves 31 are misaligned with the mold connecting member 4.

[0045] By providing the lower through grooves 31, the end component 3 is cast and wrapped in the high-strength adhesion layer 7.

[0046] Embodiment 3: On the basis of Embodiment 2, the end connecting member 5 includes a positioning collar 51 and an extension mold frame 52. A positioning ring 35 for fitting and sleeving with the positioning collar 51 is provided at the upper end of the stepped platform 34. The outer diameter of the positioning collar 51 is equal to the outer diameter of the positioning ring 35, and a circular ring gap is left between the outer wall of the positioning collar 51 and the inner wall of the upper hole 33, and the circular ring gap communicates with the extension mold frame 52.

[0047] Through the cooperation of the positioning collar 51 and the positioning ring 35, the positioning installation of the end connecting member 5 is realized.

[0048] One end of the extension mold frame 52 is attached to the circular ring outer wall of the end component 3, the other end of the extension mold frame 52 is fixedly connected to the mold connecting member 4, a T-shaped insert 53 is provided at one end of the extension mold frame 52 close to the mold connecting member 4, a slot for cooperating with the T-shaped insert 53 is provided at the end of the mold connecting member 4, a positioning pin is provided on the side wall of the mold connecting member 4 for threaded rotation installation, and a pin hole 54 opposite to the positioning pin is provided on the T-shaped insert 53.

[0049] By setting the mold connecting piece 4 to adapt to the lateral interval between adjacent pipe piles 2. Furthermore, after the concrete reinforcement 9 is poured, it is connected laterally into one body. By means of the matching insertion of the T-shaped insert 53, the positioning connection between the end connecting piece 5 and the mold connecting piece 4 is realized. By means of the insertion of the positioning pin into the pin hole 54, the fixed connection between the end connecting piece 5 and the mold connecting piece 4 is realized.

[0050] A construction method for realizing the above composite foundation structure, characterized in that the construction method comprises the following steps:

[0051] Step 1: Fill and compact a 1m soil layer on the surface of the original soft stratum as the construction platform; Construction of the core reinforcement area: Use PHC to prepare pipe piles 2 with a diameter of 50cm, a wall thickness of 125mm, a pile length of 16m, and a pile spacing of 1.75m. Drive the piles from the middle to the periphery, and drive the ends of the pipe piles 2 into the bottom bedrock.

[0052] Step 2: Construction of the enclosure area: Use a cement-soil mixing pile with a diameter of 60cm for sealing, arranged in a socket connection, with a lap length of 15cm, an average pile length of 15m, and a cement (quality) incorporation ratio of 18% in the pile body.

[0053] Step 3: Install the end component 3 at the upper end of the pipe pile 2, and use the mold connecting piece 4 and the end connecting piece 5 to realize the connection between adjacent pipe piles 2. Then, pour concrete into the gap between the end connecting piece 5 and the mold connecting piece 4 to form the concrete reinforcement 9, and then remove the end connecting piece 5 and the mold connecting piece 4.

[0054] Step 4: Construction of the cushion layer area, excavate the soil layer filled at the top, chisel off the pile sections with poor quality at the upper 0.5m of the cement mixing pile 8, fill self-compacting concrete as the high-strength adhesion layer 7. The self-compacting concrete fills the sunken holes 10 at the upper ends of the pipe piles 2 along the pores after the removal of the end connecting piece 5, fills the gaps between adjacent concrete reinforcements 9, and the high-strength adhesion layer 7 covers the upper ends of the concrete reinforcements 9. Fill cement soil at the upper end of the high-strength adhesion layer 7 as the deformation coordination layer 6.

[0055] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite foundation structure, the composite foundation structure comprising a reinforcement area, a surrounding area (1) and a cushion layer. A plurality of groups of pipe piles (2) densely distributed in a matrix are vertically inserted in the reinforcement area. A plurality of groups of cement mixing piles (8) are arranged in a sleeved manner on the outer contour of the reinforcement area. The plurality of groups of cement mixing piles (8) form the surrounding area (1). The reinforcement area and the surrounding area (1) are filled with a cushion layer at the upper end. It is characterized in that: The cushion layer includes a high-strength adhesion layer (7) and a deformation coordination layer (6). At the upper end of the pipe pile (2), a head component (3) located at the upper end of the reinforcement area is fixedly arranged. A head connector (5) is sleeved on the head component (3). Adjacent head connectors (5) are connected by a die connector (4). In the inner cavity surrounded by the head connector (5) and the die connector (4), a concrete reinforcement member (9) for horizontally connecting adjacent pipe piles (2) is poured. A sunken hole (10) is arranged at the upper end of the pipe pile (2). The inner cavity of the sunken hole (10) is integrally poured with the high-strength adhesion layer (7). The deformation coordination layer (6) is poured on the upper end of the high-strength adhesion layer (7). A stepped platform (34) is arranged on the inner wall of the middle section of the head component (3). The inner cavity at the upper end of the stepped platform (34) is set as an upper hole (33), and the inner cavity at the lower end of the stepped platform (34) is set as a lower hole (32). The upper hole (33) and the lower hole (32) are communicated with each other. The lower hole (32) is communicated with the sunken hole (10), and the inner diameter of the lower hole (32) is smaller than the inner diameter of the sunken hole (10). The head connector (5) includes a positioning collar (51) and an extension die frame (52). A positioning ring (35) for mating and sleeving with the positioning collar (51) is arranged at the upper end of the stepped platform (34). One end of the extension die frame (52) is attached to the circular outer wall of the head component (3), and the other end of the extension die frame (52) is fixedly connected to the die connector (4).

2. A composite foundation structure according to claim 1, characterized in that: Multiple groups of connecting bars (11) distributed in a circumferential array are arranged at the upper end of the pipe pile (2). Connecting holes (36) for mating and fixedly sleeving with the connecting bars (11) are arranged at the lower end of the head component (3).

3. A composite foundation structure according to claim 2, characterized in that: Multiple groups of lower through grooves (31) for communicating the inner cavity of the lower hole (32) are arranged on the lower arc outer wall of the head component (3) in a circumferential array. The lower through grooves (31) and the die connector (4) are misaligned.

4. A composite foundation structure according to claim 3, characterized in that: The outer diameter of the positioning collar (51) is equal to the outer diameter of the positioning ring (35), and a circular gap is left between the inner wall of the positioning collar (51) and the upper hole (33). The circular gap is communicated with the extension die frame (52).

5. A composite foundation structure according to claim 4, characterized in that: A T-shaped insert (53) is arranged at one end of the extension die frame (52) close to the die connector (4). A slot for mating with the T-shaped insert (53) is arranged at the end of the die connector (4).

6. The composite foundation structure according to claim 5, characterized in that: A positioning pin is rotatably installed on the side wall of the die connector (4) by threads. A pin hole (54) facing the positioning pin is arranged on the T-shaped insert (53).

7. A construction method of the composite foundation structure according to any one of claims 1-6, characterized in that: The construction method comprises the following steps: Step 1: Fill 1 m of soil layer on the surface of the original soft formation and compact it to serve as a construction platform; Construction of the core reinforcement area: Use PHC to prepare pipe piles (2), drive the piles from the middle to the surrounding, and drive the ends of the pipe piles (2) into the bottom bedrock; Step 2: Construction of the enclosure area: Use cement-soil mixing piles for sealing, arrange them in a socket connection, overlap each other, and the cement mixing ratio of the pile body is 18%; Step 3: Install the end component (3) at the upper end of the pipe pile (2), and use the mold connecting piece (4) and the end connecting piece (5) to realize the connection between adjacent pipe piles (2). Then, pour concrete into the gap between the end connecting piece (5) and the mold connecting piece (4) to form a concrete reinforcement member (9), and then remove the end connecting piece (5) and the mold connecting piece (4). Step 4: Construction of the cushion layer area. Excavate the soil layer filled at the top, chisel off the pile segments with poor pile head quality in the upper 0.5 m of the cement mixing pile (8), and fill self-compacting concrete as the high-strength adhesion layer (7). The self-compacting concrete fills the sunken hole (10) at the upper end of the pipe pile (2) along the pores after the removal of the end connecting piece (5), and the self-compacting concrete fills the gap between adjacent concrete reinforcement members (9). Moreover, the high-strength adhesion layer (7) covers the upper end of the concrete reinforcement member (9). Fill cement soil at the upper end of the high-strength adhesion layer (7) as the deformation coordination layer (6).

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