Soft soil foundation pit inclined supporting system based on PCC piles

Abstract

The utility model discloses a soft soil foundation pit slant supporting system based on PCC piles. The soft soil foundation pit slant supporting system comprises a bottom plate and a plurality of PCC piles, the base plate is provided with a top surface and a bottom surface, the top end of the first end supporting structure is higher than the top surface of the base plate, and the top end of the second end supporting structure is lower than the bottom surface of the base plate; the first cemented soil reinforcing body is located on the side, close to the second end supporting structure, of the first end supporting structure and used for reinforcing soft soil on the inner side of the first end supporting structure; the second cement soil reinforcing body is located outside the second end supporting structure, and the second cement soil reinforcing body is located below the bottom face of the bottom plate and used for reinforcing soft soil around the second end supporting structure; and one end of the inclined supporting structure is connected with the top end of the first end supporting structure.

Description

Technical Field

[0001] The utility model relates to the technical field of geotechnical engineering, in particular to a soft soil foundation pit oblique support system based on PCC piles. Background Art

[0002] At present, the domestic foundation pit support system mainly includes horizontal support, inclined support and inclined support piles. There are also inclined supports directly set in rock and soil with good soil properties. Commonly used support materials are reinforced concrete, steel pipes, steel sections and steel lattice structures. The setting of horizontal supports makes subsequent excavation and underground structure construction inconvenient. When the foundation pit plane is large, the support cost is high and the construction period is greatly increased. At the same time, some projects only require unilateral support, and horizontal supports cannot be set. The inclined support is supported on the bottom plate of the underground structure completed in advance. It is necessary to leave triangular soil and the bottom plate post-casting strip first, which will affect the safety of the underground structure. It cannot be set at the edge of the foundation pit of the main building and the subsequent triangular soil excavation is very difficult. There are problems such as secondary excavation and secondary pouring, which greatly delays the construction period.

[0003] The oblique support directly set in the rock and soil with good soil quality solves some of the difficulties in setting up horizontal support and excavating earthwork in the later stage. It can achieve secondary excavation and one-time pouring, making full use of the strength of the rock and soil and being relatively economical. However, when the bottom of the foundation pit is a soft foundation with poor soil quality, the force is mainly concentrated on the end rock and soil, which often cannot provide sufficient support and cause the foundation pit to become unstable. The oblique support piles use the combined effect of the upper steel concrete oblique support and the lower prefabricated piles and cement soil to form oblique support piles with the support point located in the foundation soil at the bottom of the foundation. The oblique support piles are cross-constructed with the retaining piles, which can achieve one-time excavation and one-time pouring. They have been successfully applied in many silt sand and clay foundation projects, but due to the insufficient support force of deep soft soil foundation pits, they are rarely used in deep soft soil foundation pits. At the same time, the ends of the conventional oblique support piles need to be buried deep in the foundation pit for support. The piles are too long, and the square piles are usually 400mm long at the ends, with a cross-sectional area of ​​only 0.16 square meters. Therefore, the corresponding end resistance is small, and conventional oblique support piles in deep soft foundation projects often cannot provide sufficient bearing capacity. The length of the oblique support piles in some projects has exceeded 40m, and the slenderness ratio of the oblique support piles exceeds 100. When the supporting force is large, the overly long oblique support piles are very likely to cause instability and cause engineering accidents, which will also greatly increase the cost of the oblique support system and the difficulty of related construction, which runs counter to the principle of "safety, economy and convenient construction" advocated in foundation pit projects.

[0004] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to a person skilled in the art. Utility Model Content

[0005] The utility model aims to provide a soft soil foundation pit oblique support system based on PCC piles which can provide sufficient bearing capacity.

[0006] To achieve the above-mentioned purpose, the utility model provides an oblique support system for a soft soil foundation pit based on PCC piles, characterized in that it includes: a base plate; a first end support structure, and a second end support structure, the first end support structure and the second end support structure are respectively perpendicular to the base plate, wherein the top of the first end support structure is higher than the top surface of the base plate, and the top of the second end support structure is lower than the bottom surface of the base plate; a first cement soil reinforcement body, the first cement soil reinforcement body is located on a side of the first end support structure close to the second end support structure, and is used to reinforce the soft soil inside the first end support structure; a second cement soil reinforcement body, the second cement soil reinforcement body is located outside the second end support structure, and the second cement soil reinforcement body is located below the bottom surface of the base plate, and is used to reinforce the soft soil around the second end support structure; an oblique support structure, one end of the oblique support structure is connected to the top of the first end support structure, and the other end is connected to the top of the second end support structure.

[0007] In one or more embodiments, the first end support structure includes a supporting pile and a capping beam, wherein the capping beam is located on top of the supporting pile.

[0008] In one or more embodiments, the second end support structure includes at least one PCC pile and a reinforced concrete pier, wherein the reinforced concrete pier is located on top of the PCC pile.

[0009] In one or more embodiments, a first embedded steel plate is provided on the side of the top beam close to the second end support structure, a second embedded steel plate is provided on the side of the steel concrete pier close to the first end support structure, and the oblique support structure connects the first embedded steel plate and the second embedded steel plate.

[0010] In one or more embodiments, there are a plurality of PCC piles, and the tops of the plurality of PCC piles are respectively connected to the bottom of the reinforced concrete pier.

[0011] In one or more embodiments, the number of the PCC pile is one.

[0012] In one or more embodiments, the PCC pile has an outer diameter greater than or equal to 900 mm and a wall thickness greater than or equal to 100 mm.

[0013] In one or more embodiments, the oblique support structure is a steel pipe oblique support, a steel lattice oblique support, a steel section oblique support or a steel concrete oblique support.

[0014] In one or more embodiments, the first cement soil reinforcement body and the second cement soil reinforcement body are axially stirred single-axis, double-axis, three-axis, multi-axis cement soil piles, rotary jet cement soil piles or grouting cement soil reinforcement bodies.

[0015] The utility model provides a diagonal support system for soft soil foundation pits based on PCC piles. By reinforcing the bottom soft soil with cement soil, the resistance is increased. In addition, large-diameter thin-walled barrel piles (PCC piles) and steel concrete piers are arranged at the bottom of the diagonal support. The cement soil and large-diameter thin-walled barrel piles provide horizontal resistance and vertical resistance for the diagonal support, respectively, and jointly support the diagonal support structure to provide sufficient bearing capacity for the diagonal support. Due to the large-diameter thin-walled barrel piles connected to the bottom of the diagonal support, the bottom of the diagonal support structure does not need to be buried too deep underground, which reduces the length of the diagonal support structure and prevents the instability of the diagonal support piles that are too long from causing engineering accidents. In addition, by providing a small number of large-diameter thin-walled barrel piles to provide support, it is more economical and more reliable to bear the force, and an effective fulcrum is provided for the soft soil area, making the diagonal support structure more suitable for deep soft soil foundation pits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a soft soil foundation pit oblique support system based on PCC piles provided in an embodiment of the utility model.

[0017] Figure 2 It is a detailed structural schematic diagram of a soft soil foundation pit oblique support system based on PCC piles provided in an embodiment of the utility model.

[0018] Figure 3 It is a top view of a second end support structure of a single PCC pile provided in an embodiment of the utility model.

[0019] Figure 4 It is a top view of the second end support structure of a plurality of PCC piles in the first arrangement manner provided in an embodiment of the present invention.

[0020] Figure 5 It is a top view of the second end support structure of multiple PCC piles in the second arrangement provided in an embodiment of the present invention.

[0021] Figure 6 It is a top view of the second end support structure of multiple PCC piles in the third arrangement manner provided in an embodiment of the present utility model.

[0022] Figure 7 It is a top view of the second end support structure of a plurality of PCC piles in a fourth arrangement manner provided in an embodiment of the present invention.

[0023] Figure 8It is a top view of the second end support structure of multiple PCC piles in the fifth arrangement provided in an embodiment of the present invention.

[0024] Description of main reference numerals:

[0025] 1-base plate, 2-first end support structure, 21-support piles, 22-top beam, 23-first embedded steel plate, 3-second end support structure, 31-PCC piles, 32-steel concrete piers, 33-second embedded steel plate, 4-first cement soil reinforcement body, 5-second cement soil reinforcement body, 6-oblique support structure, 7-first water stop plate, 8-second water stop plate. DETAILED DESCRIPTION

[0026] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0027] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0028] Embodiment 1:

[0029] A PCC pile-based oblique support system for soft soil foundation pits, such as Figures 1 to 8 As shown, it includes: a base plate 1; a first end support structure 2, and a second end support structure 3, wherein the first end support structure 2 and the second end support structure 3 are respectively perpendicular to the base plate 1, wherein the top end of the first end support structure 2 is higher than the top surface of the base plate 1, and the top end of the second end support structure 3 is lower than the bottom surface of the base plate 1; a first cement soil reinforcement body 4, which is arranged on a side of the first end support structure 2 close to the second end support structure 3, and is used to reinforce the soft soil inside the first end support structure 2; a second cement soil reinforcement body 5, which is located outside the second end support structure 3, and the second cement soil reinforcement body 5 is located below the bottom surface of the base plate 1, and is used to reinforce the soft soil around the second end support structure 3; an oblique support structure 6, one end of which is connected to the top end of the first end support structure 2, and the other end is connected to the top end of the second end support structure 3.

[0030] Specifically, the first cement reinforcement body and the second cement reinforcement body reinforce the soft soil at the bottom of the foundation pit to increase resistance. The second end support structure 3 arranged at the bottom of the base plate 1 and the second cement reinforcement body implanted in the second end structure provide horizontal resistance and vertical resistance for the diagonal brace respectively, and jointly support the diagonal support structure 6 to provide sufficient bearing capacity for the diagonal brace. Since the second end support structure 3 is arranged at the bottom, the bottom of the diagonal support structure 6 does not need to be buried too deep underground, so the length of the diagonal support structure 6 is much shorter than that of conventional diagonal support piles, which reduces the length of the diagonal support structure 6 and prevents engineering accidents caused by instability due to excessively long diagonal support piles. Since the bottom does not need to be buried too deep underground, the convenience of installing the diagonal support structure 6 is also better than that of conventional diagonal support piles, and secondary excavation and one-time pouring can be achieved without affecting the safety of the underground structure. As a preferred embodiment, a first water stop 7 is provided at the place where the oblique support structure 6 is connected to the base plate 1. A shear wall is provided on the side of the first end support structure 2 close to the second end support structure 3, and a second water stop 8 is provided at the connection between the shear wall and the oblique support structure 6. The top surface of the first cement reinforcement body is higher than the top of the base plate 1, and the bottom surface of the first cement reinforcement body is lower than the bottom surface of the base plate 1. A pit edge reserved triangular soil is provided between the first cement reinforcement body and the second cement reinforcement body. The apex of the pit edge reserved triangular soil is flush with the top surface of the first cement reinforcement body, and the bottom surface of the pit edge reserved triangular soil is flush with the bottom surface of the base plate 1.

[0031] As an optional implementation, the first end support structure 2 includes a supporting pile 21 and a top pressure beam 22 , and the top pressure beam 22 is located on the top of the supporting pile 21 .

[0032] Specifically, the oblique supporting structure 6 is connected to the top pressing beam 22 , and the top pressing beam 22 provides a reaction force for the oblique supporting structure 6 .

[0033] As an optional implementation, the second end support structure 3 includes at least one PCC pile 31 and a reinforced concrete buttress 32 , wherein the reinforced concrete buttress 32 is located on the top of the PCC pile 31 .

[0034] Specifically, the second end support structure 3 includes a PCC pile 31. Compared with bored cast-in-place piles, when the amount of concrete used in large-diameter cast-in-place thin-walled barrel piles is similar to that of solid bored cast-in-place piles, the former has a larger moment of inertia of section. Since the large-diameter cast-in-place thin-walled barrel piles are far away from the central axis, the annular cross-sectional characteristics of the large-diameter cast-in-place thin-walled barrel piles enable the horizontal resistance and vertical bearing capacity of the material to be fully utilized, thereby avoiding the inability of the foundation soil of the bottom plate 1 to provide sufficient support. The steel diagonal brace uses the steel concrete pier 32 as a strong resistance fulcrum to provide reliable diagonal support for the support piles 21. Using PCC piles 31 to provide support is more economical and more reliable.

[0035] As an optional embodiment, a first embedded steel plate 23 is provided on the side of the top pressure beam 22 close to the second end support structure 3, a second embedded steel plate 33 is provided on the side of the steel concrete pier 32 close to the first end support structure 2, and the oblique support structure 6 connects the first embedded steel plate 23 and the second embedded steel plate 33.

[0036] Specifically, the first embedded steel plate 23 is embedded in the top beam 22 , and the second embedded steel plate 33 is embedded in the reinforced concrete pier 32 .

[0037] As an optional implementation, there are multiple PCC piles 31 , and the tops of the multiple PCC piles 31 are respectively connected to the bottom of the reinforced concrete pier 32 .

[0038] Specifically, the reinforced concrete pier 32 can connect a single or multiple large-diameter cast-in-place thin-walled cylindrical piles into one, and the multiple PCC piles can be arranged in a vertical column, a horizontal row, a rectangular or a triangular arrangement.

[0039] As an optional implementation, there is one PCC pile 31 .

[0040] As an optional implementation, the outer diameter of the PCC pile 31 is greater than or equal to 900 mm, and the wall thickness is greater than or equal to 100 mm.

[0041] Specifically, the large-diameter cast-in-place thin-wall cylindrical piles use reinforced concrete as the cast-in-place thin wall.

[0042] As an optional implementation, the oblique support structure 6 is a steel pipe oblique support, a steel lattice oblique support, a steel section oblique support or a steel concrete oblique support.

[0043] Specifically, the oblique supporting structure may also be other types of oblique braces, as long as they are made of steel or reinforced concrete.

[0044] As an optional implementation, the first cement soil reinforcement body and the second cement soil reinforcement body are axially stirred single-axis, double-axis, three-axis, multi-axis cement soil piles, rotary jet cement soil piles or grouting cement soil reinforcement bodies.

[0045] Specifically, the first cement soil reinforcement body and the second cement soil reinforcement body may also be other types of cement soil reinforcement bodies.

[0046] By adopting the above technical scheme, the utility model provides a PCC pile-based oblique support system for soft soil foundation pits. By reinforcing the bottom soft soil with cement soil, the resistance is increased. In addition, large-diameter thin-walled barrel piles (PCC piles) and steel concrete piers are set at the bottom of the oblique support. The cement soil and large-diameter thin-walled barrel piles provide horizontal resistance and vertical resistance for the oblique support, respectively, and jointly support the oblique support structure to provide sufficient bearing capacity for the oblique support. Due to the large-diameter thin-walled barrel piles connected to the bottom of the oblique support, the bottom of the oblique support structure does not need to be buried deep underground to provide sufficient end resistance, which reduces the length of the oblique support structure and prevents the oblique support piles from becoming unstable due to excessive length, thereby preventing engineering accidents. In addition, by setting a small number of large-diameter thin-walled barrel piles to provide support, it is more economical and more reliable to bear force, and provides effective fulcrums for soft soil areas, making the oblique support structure more suitable for deep soft soil foundation pits.

[0047] Embodiment 2:

[0048] The specific construction steps of using this soft soil foundation pit oblique support system based on PCC piles are as follows:

[0049] S1: After laying out according to the drawing, the cement soil reinforcement body, the large-diameter cast-in-place thin-walled cylindrical piles and the supporting piles are sequentially implanted;

[0050] S2: After the above-mentioned supporting piles reach the designed strength, the capping beam and the upper embedded steel plate are constructed according to the drawings;

[0051] S3: According to the drawings and soil conditions, a basin-type excavation method is used to excavate the first time to the edge of the pit to reserve triangular soil, and the steel concrete pier and the lower embedded steel plate are constructed;

[0052] S4: After the capping beam and reinforced concrete buttress reach the design strength, the steel diagonal brace is installed and firmly welded or connected with the upper and lower embedded steel plates by high-strength bolts, and a certain prestress is applied to the steel diagonal brace to control the deformation of the foundation pit as appropriate;

[0053] S5: excavating the reserved triangular soil for the second time and pouring the foundation slab at one time;

[0054] S6: After the above-mentioned base plate is cast and reaches the design strength, the steel diagonal braces may not be removed and recovered first, depending on the deformation of the foundation pit. When constructing the shear wall, water stop plates can be set and cast together. After the structure is completed and reaches the design strength and the basement is backfilled, the steel diagonal braces can be subsequently removed and recovered to avoid deformation caused by removing the support.

[0055] The foregoing description of specific exemplary embodiments of the utility model is for the purpose of illustration and illustration. These descriptions are not intended to limit the utility model to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the utility model and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the utility model and various different options and changes. The scope of the utility model is intended to be defined by the claims and their equivalents.

Claims

1. A PCC pile-based soft soil foundation pit oblique support system, characterized in that: include: Base plate; A first end support structure and a second end support structure, wherein the first end support structure and the second end support structure are respectively perpendicular to the bottom plate, wherein the top end of the first end support structure is higher than the top surface of the bottom plate, and the top end of the second end support structure is lower than the bottom surface of the bottom plate; a first cement-soil reinforcement body, the first cement-soil reinforcement body being located on a side of the first end support structure close to the second end support structure and being used to reinforce the soft soil inside the first end support structure; A second cement soil reinforcement body, the second cement soil reinforcement body is located outside the second end support structure, the second cement soil reinforcement body is located below the bottom surface of the bottom plate, and is used to reinforce the soft soil around the second end support structure; An oblique support structure, one end of which is connected to the top of the first end support structure, and the other end of which is connected to the top of the second end support structure.

2. The PCC pile-based soft soil foundation pit oblique support system according to claim 1, characterized in that: The first end support structure includes a supporting pile and a top beam, and the top beam is located on the top of the supporting pile.

3. The PCC pile-based soft soil foundation pit oblique support system according to claim 2, characterized in that: The second end support structure includes at least one PCC pile and a reinforced concrete pier, wherein the reinforced concrete pier is located on the top of the PCC pile.

4. The PCC pile-based soft soil foundation pit oblique support system according to claim 3, characterized in that: A first embedded steel plate is provided on the side of the top beam close to the second end support structure, a second embedded steel plate is provided on the side of the reinforced concrete pier close to the first end support structure, and the oblique support structure connects the first embedded steel plate and the second embedded steel plate.

5. The PCC pile-based soft soil foundation pit oblique support system according to claim 3, characterized in that: There are a plurality of PCC piles, and the tops of the plurality of PCC piles are respectively connected to the bottom of the reinforced concrete pier.

6. The PCC pile-based soft soil foundation pit oblique support system according to claim 1, characterized in that: There is one PCC pile.

7. The PCC pile-based soft soil foundation pit oblique support system according to claim 3, characterized in that: The outer diameter of the PCC pile is greater than or equal to 900 mm, and the wall thickness is greater than or equal to 100 mm.

8. The PCC pile-based soft soil foundation pit oblique support system according to claim 1, characterized in that: The oblique support structure is a steel pipe oblique support, a steel lattice oblique support, a section steel oblique support or a steel concrete oblique support.

9. The PCC pile-based soft soil foundation pit oblique support system according to claim 1, characterized in that: The first cement soil reinforcement body and the second cement soil reinforcement body are axially stirred single-axis, double-axis, three-axis, multi-axis cement soil piles, rotary jet cement soil piles or grouting cement soil reinforcement bodies.

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