Composite steel pipe pile foundation pit support structure and construction method thereof

Abstract

The present invention discloses a composite steel pipe pile foundation pit support structure and a construction method thereof. In the process of foundation pit support reinforcement, the present invention drives steel pipe piles and constructs a crown beam to form an integral structure, and reserves a position for square rib columns on the crown beam. In the process of excavating the foundation pit within the support range surrounded by each steel pipe pile, a plurality of vertically and linearly arranged square rib columns are gradually cast at the reserved position of the crown beam, and the waist beam, anchor cable or anchor rod are used to reinforce the support structure in real time. The process is repeated until the square rib columns reach the designed depth, and the purpose of foundation pit support reinforcement is finally achieved. The present invention can effectively improve the lateral force resistance performance of the foundation pit support structure, ensure the normal service life of the foundation pit, is safe, reduces the project cost, simplifies the process, has simple technology, occupies a small construction area, and is easy to apply and promote.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation pit support, and in particular relates to a composite steel pipe pile foundation pit support structure and a construction method thereof. Background Art

[0002] With the rapid development of infrastructure and the shortage of urban land, buildings are bound to develop in the direction of "higher and deeper". The deeper the building, the more complex the foundation pit will be. At the same time, due to the influence of complex environmental factors such as surrounding buildings and underground structures, the construction space of the foundation pit is getting smaller and smaller, which requires the support structure to strictly control the construction area.

[0003] During the foundation pit construction, in order to ensure the safety of the surrounding environment of the foundation pit, support and reinforcement measures must be taken for the foundation pit. At present, under the premise that the construction area of ​​the support structure is not restricted, most of the support types are pile row composite prestressed anchor cable (rod); however, when the construction area of ​​the support structure is limited, the steel pipe pile composite prestressed anchor cable (rod) support type becomes the preferred method.

[0004] When the construction area of ​​the support structure is limited and the environment around the foundation pit is complex, it is inevitable that a large external load will be generated around the foundation pit. However, the traditional steel pipe pile composite prestressed anchor cable (rod) support type is affected by the deep foundation pit depth and large external load, making the foundation pit lateral force resistance fail to meet the requirements of relevant specifications. Summary of the invention

[0005] In view of the deficiencies in the prior art, an object of the present invention is to provide a composite steel pipe pile foundation pit support structure and a construction method thereof.

[0006] The present invention is achieved in this way: a composite steel pipe pile foundation pit support structure, which includes a plurality of steel pipe piles arranged vertically and linearly, the bottom of the steel pipe piles is driven into the soil layer, self-compacting concrete is poured in the pipe, and a crown beam is poured on the top of each steel pipe pile to form an integral structure, and the poured crown beam is provided with a reserved position on the steel pipe pile side close to the direction of the foundation pit; in the process of excavating the foundation pit layer by layer within the support range surrounded by each steel pipe pile, corresponding to each newly excavated soil layer, a plurality of vertically arranged square rib columns are poured in sections at the reserved position of the crown beam; wherein, after the pouring of each section of square rib column is completed, a horizontally placed waist beam is arranged on the section of square rib column and close to the direction of the foundation pit, each waist beam is provided with a plurality of waist beam anchor holes, an anchor cable or anchor rod is inserted into each waist beam anchor hole, the anchor cable or anchor rod is constructed, and the anchor cable or anchor rod and the waist beam are fastened to the square rib column by using an anchor.

[0007] Preferably, the crown beam is also provided with a plurality of crown beam anchor holes; an anchor cable or anchor rod is inserted into each of the crown beam anchor holes, and the anchor cable or anchor rod is constructed and fastened with an anchor device.

[0008] Preferably, a square rib column is closely attached to a steel pipe pile, and two steel pipe piles are arranged between two adjacent square rib columns.

[0009] Preferably, a groove for embedding steel pipe piles is provided on the side of the square rib column; longitudinal stress-bearing reinforcements are evenly arranged along the straight edge of the square rib column, and each longitudinal stress-bearing reinforcement is fixed by annular stirrups, and the two ends of the annular stirrups are located on the two opposite sides of the groove and are respectively connected to the extended oblique segment stirrups, and the ends of the two oblique segment stirrups are fixed on a longitudinal stress-bearing reinforcement at the edge opposite to the groove, and the two oblique segment stirrups intersect with the middle part of a straight stirrup close to the groove position, and the straight stirrups and the two oblique segments are respectively fastened with a longitudinal stress-bearing reinforcement at each intersection point, and the two ends of the straight stirrups are respectively fixed on the longitudinal stress-bearing reinforcements at the two opposite straight edges of the square rib column.

[0010] Preferably, the distance between two adjacent steel pipe piles is not greater than 500 mm, and the depth at which the bottom of the square rib column is embedded in the soil layer at the bottom of the foundation pit is not less than 500 mm.

[0011] The present invention further discloses a construction method of a composite steel pipe pile foundation pit support structure, the method comprising the following steps:

[0012] (1) A number of steel pipe piles arranged vertically and linearly are driven into the soil layer according to the design requirements, and self-compacting concrete is poured into the pipes. The steel pipe piles are close to the excavation edge of the foundation pit;

[0013] (2) constructing a cap beam on the top of the steel pipe pile, connecting the top of the steel pipe pile with the steel bars inside the cap beam to form an integral skeleton, and providing a reserved position for the cap beam on the side of the steel pipe pile close to the inside of the foundation pit;

[0014] (3) A plurality of crown beam anchor holes are evenly distributed on the crown beam; an anchor cable or anchor rod is inserted into each of the crown beam anchor holes, and the anchor cable or anchor rod is constructed and fastened with an anchor tool;

[0015] (4) A foundation pit is excavated within the support range surrounded by the steel pipe piles. After each layer of soil is excavated from top to bottom, square rib columns are cast in sections at the reserved position of the crown beam in a continuous manner. After each layer of soil is excavated, a waist beam and an anchor cable or anchor rod are constructed at the casting section of the square rib column corresponding to the soil layer. The waist beam is transversely arranged and evenly distributed with a plurality of waist beam anchor holes. An anchor cable or anchor rod is inserted into each waist beam anchor hole, and the anchor cable or anchor rod is constructed. The anchor cable or anchor rod and the waist beam are fastened to the square rib column using an anchor.

[0016] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects: the present invention achieves the purpose of foundation pit support and reinforcement by driving steel pipe piles, constructing crown beams and reserving positions for square rib columns, constructing square rib columns, constructing waist beams and anchor cables or anchor rods, and repeating the steps until the designed bottom is reached during the foundation pit support and reinforcement process. It can effectively improve the lateral force resistance of the foundation pit support structure and ensure the normal service life of the foundation pit. It is safe and reduces project costs, simplifies the process, has simple technology, occupies a small construction area, and is easy to apply and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a front structural schematic diagram of the composite steel pipe pile foundation pit supporting structure of the present invention;

[0018] Figure 2 It is a side structural schematic diagram of the composite steel pipe pile foundation pit supporting structure of the present invention;

[0019] Figure 3 It is a schematic diagram of the reinforcement arrangement in the square rib column of the supporting structure of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] like Figures 1 to 3 As shown, Figure 1 It is a front structural schematic diagram of the composite steel pipe pile foundation pit supporting structure of the present invention; Figure 2 It is a side structural schematic diagram of the composite steel pipe pile foundation pit supporting structure of the present invention; Figure 3 It is a schematic diagram of the reinforcement arrangement in the square rib column of the supporting structure of the present invention.

[0022] A composite steel pipe pile foundation pit support structure, the structure comprises a plurality of steel pipe piles 1 arranged vertically and linearly, the bottom of the steel pipe piles 1 is driven into a soil layer 2, self-compacting concrete is poured in the pipe, and a crown beam 3 is poured on the top of each steel pipe pile 1 to form an integral structure, and the poured crown beam 3 is provided with a reserved position on the side of the steel pipe pile 1 close to the inside of the foundation pit; in the process of excavating the foundation pit layer by layer within the support range surrounded by each steel pipe pile 1, corresponding to each newly excavated soil layer 2, in the crown beam 3 A number of vertically arranged square rib columns 4 are cast in sections at the reserved positions; wherein, after each section of square rib column 4 is cast, a transversely placed waist beam 5 is arranged on the section of square rib column 4 and close to the inner side of the foundation pit, and each waist beam 5 is provided with a number of waist beam anchor holes 6, and an anchor cable or anchor rod 7 is inserted into each waist beam anchor hole 6, and the anchor cable or anchor rod 7 is constructed, and the anchor cable or anchor rod 7 and the waist beam 5 are fastened to the square rib column 4 by using an anchor (number omitted in the figure).

[0023] In the embodiment of the present invention, in order to ensure the stability of the structure during the initial construction, a number of crown beam anchor holes 8 are also provided on the crown beam 3; an anchor cable or anchor rod 7 is inserted into each of the crown beam anchor holes 8, and the anchor cable or anchor rod 7 is constructed and fastened with the anchor. It can be understood that the process of constructing the anchor cable or anchor rod 7 in the soil body on the side of the foundation pit is to drill a hole into the soil body on the side of the foundation pit, put the anchor cable or anchor rod 7 into the hole after the hole is formed, and perform grouting according to the design requirements. After the strength of the grouting body reaches the design requirements, the anchor cable or anchor rod 7 is fastened at the position of the waist beam anchor hole 6 or the crown beam anchor hole 8 using the anchor.

[0024] In the embodiment of the present invention, considering factors such as optimal stability and support strength of the structure, specifically, a square rib column 4 is closely attached to a steel pipe pile 1 , and two steel pipe piles 1 are arranged between two adjacent square rib columns 4 .

[0025] In the embodiment of the present invention, considering that the square rib column 4 is a lateral force-bearing member, in order to ensure the force integrity of the entire square rib column 4, specifically, a groove 4-1 for embedding the steel pipe pile 1 is provided on the side of the square rib column 4; longitudinal force-bearing bars 4-2 are evenly arranged along the straight edge of the square rib column 4, and each longitudinal force-bearing bar 4-2 is fixed by an annular stirrup 4-3, and the two ends of the annular stirrup 4-3 are located at the two opposite sides of the groove 4-1 and are respectively connected to the extended oblique segment stirrup 4-4, and the ends of the two oblique segment stirrups 4-4 are fixed on a longitudinal force-bearing bar 4-2 at the edge in the direction opposite to the groove 4-1, and the two oblique segment stirrups 4-4 intersect with the middle part of a straight stirrup 4-5 near the position of the groove 4-1, and the straight stirrup 4-5 and the two oblique segments are respectively fastened with a longitudinal force-bearing bar 4-2 at each intersection point, and the two ends of the straight stirrup 4-5 are respectively fixed on the longitudinal force-bearing bars 4-2 at the two opposite straight edges of the square rib column 4. The reinforcement layout and structural design of the square rib column 4 can concentrate the stress position of the square rib column 4 on the side of the groove 4-1 of the square rib column 4, which can greatly enhance the stress strength of the square rib column 4 and increase the overall stability of the supporting structure.

[0026] In an embodiment of the present invention, after each steel pipe pile 1 is driven into the soil layer 2 along the edge of the foundation pit to be excavated, self-compacting concrete is poured into the steel pipe pile 1 and a crown beam 3 is poured on the top of each steel pipe pile 1 to form an integral structure. On this basis, the foundation pit is excavated, and after each soil layer 2 of a set depth is excavated, support construction is completed, including the construction of the square rib column 4 of the corresponding length of the soil layer 2, the construction of the waist beam 5 and the anchor cable or anchor rod 7. The process is repeated until the square rib column 4 completes the construction from the crown beam 3 to the designed depth of the bottom of the foundation pit and the construction of the waist beam 5 and the anchor cable or anchor rod 7, thereby achieving the purpose of foundation pit support reinforcement.

[0027] In order to facilitate accurate understanding of the support structure of the present invention, the construction method of the composite steel pipe pile 1 foundation pit support structure disclosed in the embodiment of the present invention is described.

[0028] The construction method of the composite steel pipe pile foundation pit support structure of the present invention comprises the following steps:

[0029] (1) A plurality of steel pipe piles 1 arranged vertically and linearly are driven into the soil layer 2 according to the design requirements, and self-compacting concrete is poured into the pipes. The steel pipe piles 1 are close to the excavation edge of the foundation pit;

[0030] (2) constructing a crown beam 3 on the top of the steel pipe pile 1, connecting the top of the steel pipe pile 1 with the steel bars inside the crown beam 3 to form an integral skeleton, and providing a reserved position for the crown beam 3 on the side of the steel pipe pile 1 close to the inside of the foundation pit;

[0031] (3) A plurality of crown beam anchor holes 8 are evenly distributed on the crown beam 3; an anchor cable or anchor rod 7 is inserted into each of the crown beam anchor holes 8, and the anchor cable or anchor rod 7 is constructed and fastened with an anchor;

[0032] (4) A foundation pit is excavated within the support range surrounded by the steel pipe piles 1. After each layer of soil is excavated from top to bottom, the square rib columns 4 are cast in sections at the reserved positions of the crown beams 3 in a continuous manner. After each layer of soil is excavated, a waist beam 5 and an anchor cable or anchor rod 7 are constructed at the casting section of the square rib columns 4 corresponding to the soil layer 2. The waist beam 5 is transversely arranged and evenly distributed with a plurality of waist beam anchor holes 6. An anchor cable or anchor rod 7 is inserted into each waist beam anchor hole 6. The anchor cable or anchor rod 7 is constructed, and the anchor cable or anchor rod 7 and the waist beam 5 are fastened to the square rib columns 4 using anchors.

[0033] The present invention can effectively improve the lateral force resistance performance of the foundation pit support structure in this way, ensure the normal service life of the foundation pit, be safe and reduce the project cost, simplify the process, have simple technology, occupy a small construction area, and be easy to apply and promote.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite steel pipe pile foundation pit support structure, characterized in that: The structure includes a plurality of steel pipe piles arranged vertically and linearly, the bottom of the steel pipe piles is driven into the soil layer, self-compacting concrete is poured in the pipe, and a crown beam is poured on the top of each steel pipe pile to form an integral structure, and a reserved position is provided on the cast crown beam on the side of the steel pipe pile close to the inside of the foundation pit; in the process of excavating the foundation pit layer by layer within the support range surrounded by each steel pipe pile, corresponding to each newly excavated soil layer, a plurality of vertically arranged square rib columns are cast in sections at the reserved position of the crown beam; wherein, after the casting of each section of square rib column is completed, a horizontally placed waist beam is arranged on the section of square rib column and close to the inside of the foundation pit, each waist beam is provided with a plurality of waist beam anchor holes, an anchor cable or anchor rod is inserted into each waist beam anchor hole, the anchor cable or anchor rod is constructed, and the anchor cable or anchor rod and the waist beam are fastened to the square rib column by an anchor device; A groove for embedding steel pipe piles is provided on the side of the square rib column; longitudinal stress-bearing bars are evenly arranged along the straight edge of the square rib column, and each longitudinal stress-bearing bar is fixed by an annular stirrup, and the two ends of the annular stirrup are located at the two opposite sides of the groove and are respectively connected to the extended oblique segment stirrups, and the ends of the two oblique segment stirrups are fixed on a longitudinal stress-bearing bar at the edge opposite to the groove, and the two oblique segment stirrups intersect with the middle part of a straight stirrup close to the groove position, and the straight stirrup and the two oblique segment stirrups are respectively fastened with a longitudinal stress-bearing bar at each intersection point, and the two ends of the straight stirrup are respectively fixed on the longitudinal stress-bearing bars at the two opposite straight edges of the square rib column.

2. The composite steel pipe pile foundation pit support structure according to claim 1, characterized in that: The crown beam is also provided with a plurality of crown beam anchor holes; an anchor cable or anchor rod is inserted into each of the crown beam anchor holes, and the anchor cable or anchor rod is constructed and fastened with an anchor device.

3. The composite steel pipe pile foundation pit support structure according to claim 1, characterized in that: A square rib column is closely attached to a steel pipe pile, and two steel pipe piles are arranged between two adjacent square rib columns.

4. The composite steel pipe pile foundation pit support structure according to claim 3, characterized in that: The distance between two adjacent steel pipe piles is not greater than 500 mm, and the depth at which the bottom of the square rib column is embedded in the soil layer at the bottom of the foundation pit is not less than 500 mm.

5. The construction method of the composite steel pipe pile foundation pit support structure according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: (1) A number of steel pipe piles arranged vertically and linearly are driven into the soil layer according to the design requirements, and self-compacting concrete is poured into the pipes. The steel pipe piles are close to the excavation edge of the foundation pit; (2) constructing a cap beam on the top of the steel pipe pile, connecting the top of the steel pipe pile with the steel bars inside the cap beam to form an integral skeleton, and providing a reserved position for the cap beam on the side of the steel pipe pile close to the inside of the foundation pit; (3) A plurality of crown beam anchor holes are evenly distributed on the crown beam; an anchor cable or anchor rod is inserted into each of the crown beam anchor holes, and the anchor cable or anchor rod is constructed and fastened with an anchor tool; (4) A foundation pit is excavated within the support range surrounded by the steel pipe piles. After each layer of soil is excavated from top to bottom, square rib columns are cast in sections at the reserved position of the crown beam in a continuous manner. After each layer of soil is excavated, a waist beam and an anchor cable or anchor rod are constructed at the casting section of the square rib column corresponding to the soil layer. The waist beam is transversely arranged and evenly distributed with a plurality of waist beam anchor holes. An anchor cable or anchor rod is inserted into each waist beam anchor hole, and the anchor cable or anchor rod is constructed. The anchor cable or anchor rod and the waist beam are fastened to the square rib column using an anchor.

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