Foundation pit engineering steel truss support and concrete support combined system servo system and construction technology

Abstract

The invention discloses a foundation pit engineering steel truss support and concrete support combined system servo system and a construction technology, and relates to the technical field of deep foundation pit engineering.The foundation pit engineering steel truss support and concrete support combined system servo system comprises an enclosure structure, the enclosure structure is buried around a foundation pit, the outer side face of the enclosure structure abuts against a soil body of the foundation pit, and an initial support is installed between the opposite faces of the top of the enclosure structure; the inner side faces of the enclosure structures abut against the foundation pit combined supporting system. The foundation pit combined supporting system comprises a steel truss supporting system and a concrete supporting system, the concrete supporting system is installed in the middle of a foundation pit, the two ends of the concrete supporting system are fixedly connected with the steel truss supporting system, and the steel truss supporting system abuts against the inner side face of the enclosure structure through steel enclosing purlins. And a prestress loading unit is arranged between the opposite surfaces of the steel truss supporting system and the steel enclosing purlin. According to the foundation pit engineering steel truss support and concrete support combined system servo system and the construction technology, construction is convenient, the construction period is short, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of deep foundation pit engineering, and in particular to a servo system and a construction process for a combined system of steel truss support and concrete support for foundation pit engineering. Background Art

[0002] In deep foundation pit projects in soft soil areas, plate support structures combined with horizontal internal supports are often used to control the deformation of the retaining structure during the foundation pit excavation stage and protect the safety of the foundation pit and the surrounding environment. In order to improve the ability to actively control the deformation of the foundation pit, steel support servo systems and concrete support servo systems have been increasingly used in foundation pit projects in recent years. The main problems of existing support servo systems are:

[0003] 1. Steel support servo system. This support servo system adopts the method of one support corresponding to one jack loading device, which is mostly used for the bracing arrangement of narrow strip foundation pits. When used in large-area foundation pits, the steel support span is large, the stability of the support will decrease rapidly, and it is easy to become unstable and damaged, which will endanger the safety of the foundation pit project. In addition, the steel support servo system is mostly used in support systems without purlins or with one steel purlin. The horizontal spacing of the steel supports is relatively dense, which affects the speed of earth excavation;

[0004] 2. Concrete support servo system. This support servo system uses a jack loading device between the concrete purlin and the retaining pile / wall. The support arrangement is relatively flexible and can be used for large-scale foundation pit projects. However, since the concrete support adopts a cast-in-place structure, after the foundation pit is excavated to the support bottom elevation, the concrete support construction and maintenance time is long. During this process, the horizontal deformation of the foundation pit retaining pile continues to develop, thus reducing the ability of the concrete support servo system to control the horizontal deformation of the foundation pit retaining pile.

[0005] In summary, the existing steel support servo system and concrete support servo system cannot simultaneously adapt to the requirements of large-scale foundation pit engineering and rapid formation of support construction.

[0006] How to develop a servo system and construction process for a combination system of steel truss support and concrete support for foundation pit engineering so as to reduce support construction time and save construction period while being applicable to large-area foundation pit engineering has become a technical problem that needs to be solved urgently by technical personnel in this field. Summary of the invention

[0007] The purpose of the present invention is to provide a servo system and construction process for a combined system of steel truss support and concrete support for foundation pit engineering, so as to solve the problems listed in the background technology.

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

[0009] The present invention discloses a servo system for a combination of steel truss support and concrete support for a foundation pit project, comprising a retaining structure, wherein the retaining structure is buried around the foundation pit, the outer side surface of the retaining structure abuts against the soil of the foundation pit, an initial support is installed between the top opposite surfaces of the retaining structure, and the inner side surface of the retaining structure abuts against the foundation pit combined support system;

[0010] The foundation pit combined support system includes a steel truss support system and a concrete support system. The concrete support system is installed in the middle of the foundation pit. Both ends of the concrete support system are respectively fixedly connected to the steel truss support system. The steel truss support system is abutted against the inner side surface of the enclosure structure through a steel purlin, and a prestressed loading unit is installed between the opposite surfaces of the steel truss support system and the steel purlin.

[0011] Preferably, the concrete support system comprises a support column, the upper end of the support column is fixedly connected to the lower surface of the initial support, and the lower end of the support column is located in the soil of the foundation pit;

[0012] A supporting crossbeam is fixedly mounted on the side wall of the supporting column.

[0013] Preferably, the steel truss support system includes a steel truss, and the steel truss includes a steel truss body, and the steel truss body is fixedly connected to the end of the supporting beam through a connecting node.

[0014] Preferably, the connection node comprises a limit steel, which is horizontally fixedly mounted on the side wall of the steel truss body by high-strength bolts, and the limit steel abuts against the upper and lower surfaces of the supporting beam respectively;

[0015] It also includes a limiting steel plate, which is vertically fixed on the side wall of the steel truss body by the high-strength bolts, and the limiting steel plate is respectively in contact with the left and right surfaces of the supporting beam;

[0016] A beam-penetrating sleeve is installed at the end of the supporting crossbeam; the limiting steel plate is fixedly connected to the supporting crossbeam by tension bolts passing through the beam-penetrating sleeve.

[0017] Preferably, the prestressed loading unit comprises a steel purlin and a steel bracket, the steel bracket is fixedly mounted on the side wall of the enclosure structure, and the lower surface of the steel purlin abuts against the upper surface of the steel bracket.

[0018] Preferably, the free end of the steel truss body is overlapped on the steel bracket.

[0019] Preferably, it further comprises a jack, one end of the jack abuts against the side wall of the steel purlin, and the other end of the jack abuts against the side wall of the steel truss body.

[0020] Preferably, after the jacking operation is completed, a force-retaining box is installed between the steel purlin and the side wall of the steel truss body.

[0021] Preferably, it further comprises a hanger, the upper end of which is connected to the side wall of the enclosure structure, and the other end of which is fixedly connected to the steel truss body.

[0022] A construction process of a servo system for a combination system of steel truss support and concrete support for foundation pit engineering, comprising the following steps:

[0023] Step 1: Drive in the retaining structure and supporting columns, excavate the first layer of earthwork, and construct the initial support;

[0024] Step 2: The foundation pit is excavated in a basin-like manner, the soil in the middle part of the foundation pit is excavated to the next support bottom elevation, and the support beam in the middle part is constructed;

[0025] Step 3: Excavate the soil in the remaining soil area around the foundation pit to the next support bottom elevation, construct a steel bracket on the side wall of the retaining structure, place a steel purlin and a jack on the steel bracket, and fix it with a hanging rod;

[0026] Step 4: Fix and install the steel truss at the end of the supporting beam;

[0027] Step 5: The fixed end of the jack is in contact with the steel purlin, and the working end of the jack is in contact with the steel truss. The jack is used to apply prestress between the steel purlin and the steel truss to control the horizontal deformation of the enclosure structure.

[0028] Step 6: After the prestressing is completed, install the force box between the steel purlin and the steel truss, and move the jack to the next working surface;

[0029] Step 7: Repeat steps 2 and 6, constructing the steel truss support system and the concrete support system downwards.

[0030] Compared with the prior art, the beneficial technical effects of the present invention are:

[0031] The present invention discloses a servo system of a combined system of steel truss supports and concrete supports for foundation pit engineering. The system adopts a basin-type excavation method for foundation pit engineering to first form a concrete support in the middle part, then excavate the surrounding soil of the foundation pit, and quickly install the steel truss supports and steel surrounding purlins. The system applies prestress to the surrounding structure by means of a jack, and can effectively reduce the horizontal deformation of the surrounding structure during the excavation stage of the foundation pit in environmentally sensitive soft soil areas, thereby protecting the safety of the surrounding environment. Since the rigidity of the steel truss support system around the foundation pit is greatly improved compared with conventional surrounding purlins, the spacing between concrete support columns in the middle area of ​​the foundation pit can be further enlarged, the arrangement form is more flexible, and the construction space is large. The present invention also has the advantages of convenient construction, fast construction period, low cost, etc., and has a prospect of wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] Figure 1 It is a top view schematic diagram of a servo system of a steel truss support and concrete support combination system for foundation pit engineering of the present invention;

[0034] Figure 2 It is a side view of the connection node between the steel truss support and the poured concrete support of the present invention;

[0035] Figure 3 A top view of a connection node between a steel truss support and a poured concrete support according to the present invention;

[0036] Figure 4 This is a schematic diagram of the initial support construction of the present invention;

[0037] Figure 5 This is a schematic diagram of basin-type excavation and concrete support construction in the middle part of the foundation pit in the present invention;

[0038] Figure 6 It is a schematic diagram of excavation of the soil-retaining area around the foundation pit, construction of steel truss supports and construction of prestressing of the prestressed loading unit in the present invention.

[0039] Explanation of the reference numerals in the accompanying drawings: 1. Enclosure structure; 2. Steel purlin; 3. Steel truss; 31. Position-limiting steel; 32. Steel truss body; 33. High-strength bolts; 34. Position-limiting steel plates; 35. Beam sleeves; 36. Tension bolts; 4. Support beams; 5. Jacks; 6. Force boxes; 7. Initial support; 8. Support columns; 9. Steel brackets; 10. Suspension rods. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by 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 used to limit the present invention.

[0041] like Figure 1-6 As shown, a servo system of a combined steel truss support and concrete support system for a foundation pit project includes a retaining structure 1, the retaining structure 1 is buried around the foundation pit, the outer side of the retaining structure 1 abuts against the soil of the foundation pit, an initial support 7 is installed between the top opposite surfaces of the retaining structure 1, and the inner side of the retaining structure 1 abuts against the foundation pit combined support system;

[0042] The foundation pit combined support system includes a steel truss support system and a concrete support system. The concrete support system is installed in the middle of the foundation pit. Both ends of the concrete support system are fixedly connected to the steel truss support system. The steel truss support system is abutted against the inner side surface of the enclosure structure 1 through the steel enclosure purlin 2, and a prestressed loading unit is installed between the opposite surfaces of the steel truss support system and the steel enclosure purlin 2.

[0043] By setting up a concrete support system in the middle of the foundation pit, setting up a steel truss support system around the foundation pit, and setting up a prestressed loading unit between the steel truss support system and the steel perimeter purlin, in conjunction with the basin-type excavation construction method of the foundation pit, the concrete support system is first installed in the middle area of ​​the foundation pit, and then the steel truss support system is formed around the foundation pit. According to the principle of the time and space effect of the foundation pit in the soft soil area, the speed of support formation is accelerated, and combined with the application of prestress to the steel truss support system, the horizontal deformation of the retaining structure during the foundation pit excavation stage is reduced to protect the safety of the surrounding environment;

[0044] Furthermore, the steel truss support system is formed by splicing steel bars, and the steel bars are connected by high-strength bolts;

[0045] The concrete support system can be a cast-in-place structure or a prefabricated structure, and the connection between the concrete support system and the steel truss support system is a steel structure assembly connection;

[0046] At the same time, basin-style excavation and zoning construction are adopted. The concrete support system or structural beam-slab unit in the middle area is constructed first. After reaching the corresponding strength and age, the surrounding areas are constructed symmetrically in sections, and the steel truss support system is quickly formed in sections and prestressed. This can effectively control the deformation of the retaining structure and the protected environmental buildings, and make full use of the rigidity and reliability of the concrete support system.

[0047] Furthermore, the force of the steel perimeter purlin is converted into a steel truss + steel perimeter purlin + concrete support system, which has greater rigidity, more reliable deformation control, and a clearer force transmission system. The concrete support spacing and the number of braces can be flexibly adjusted according to the force per linear meter of the steel perimeter purlin and the support size. The support can avoid the construction of underground structures first, or form a large space without support areas, which is conducive to construction organization and flexible adjustment of construction plans, and accelerates the overall construction progress of the project;

[0048] It can also make full use of the strength and rigidity of concrete supports, fully improve the utilization rate of column piles and engineering piles, and reduce the costs of supports, columns and column piles.

[0049] Specifically, the concrete support system includes a support column 8, the upper end of the support column 8 is fixedly connected to the lower surface of the initial support 7, and the lower end of the support column 8 is located in the soil of the foundation pit;

[0050] The supporting crossbeam 4 is fixedly installed on the side wall of the supporting column 8. By adopting a basin-type excavation method, a prefabricated / cast-in-place concrete support is first formed in the middle part, and soil is left around the excavated foundation pit. Finally, the steel truss support system and steel purlin are quickly installed. This can speed up the formation of the foundation pit support and effectively reduce the horizontal deformation of the retaining structure during the foundation pit excavation stage.

[0051] Specifically, the steel truss support system includes a steel truss 3, and the steel truss 3 includes a steel truss body 32, and the steel truss body 32 is fixedly connected to the end of the supporting beam 4 through a connection node;

[0052] By adjusting the parameters such as the steel section and spacing of the steel truss support system, the bending resistance of the steel truss support system can be adjusted to meet different foundation pit requirements. Since the rigidity of the steel truss support system around the foundation pit is much higher than that of the conventional purlin, the spacing of the concrete support rods in the middle area of ​​the foundation pit can be further increased, the layout is more flexible, the construction space is large, and the foundation pit excavation construction is convenient and the support rods avoid the vertical wall columns and other structural components of the basement.

[0053] Specifically, the connection node includes a limiting steel 31, which is horizontally fixed on the side wall of the steel truss body 32 by high-strength bolts 33, and the limiting steel 31 is respectively abutted against the upper and lower surfaces of the supporting beam 4;

[0054] It also includes a limiting steel plate 34, which is vertically fixed on the side wall of the steel truss body 32 through the high-strength bolts 33, and the limiting steel plate 34 is respectively in contact with the left and right surfaces of the supporting beam 4;

[0055] The end of the support beam 4 is installed with a beam sleeve 35; the limit steel plate 34 is fixedly connected to the support beam 4 by a tension bolt 36 passing through the beam sleeve 35;

[0056] By setting the limiting steel plates 34 on the upper and lower surfaces of the supporting beam 4, setting the limiting steel plates 34 on the left and right sides of the supporting beam 4 on the side of the steel truss body 32 at the connection interface, setting the horizontal beam sleeve 35 inside the supporting beam 4, and setting the tension bolts 36 in the beam sleeve 35 to tightly connect the limiting steel plates 34 on the left and right sides with the supporting beam 4; the limiting steel plates, limiting steel and other steel components at the connection nodes are connected together by high-strength bolts 33;

[0057] The limiting steels 31 located on the upper and lower surfaces of the supporting cross beam 4 can be in the form of ribbed steel plates, steel walkway plates, channel steels, etc.

[0058] Specifically, the prestressed loading unit includes a steel purlin 2 and a steel bracket 9 . The steel bracket 9 is fixedly mounted on the side wall of the enclosure structure 1 . The lower surface of the steel purlin 2 abuts against the upper surface of the steel bracket 9 .

[0059] Specifically, the free end of the steel truss body 32 is overlapped on the steel bracket 9 .

[0060] Specifically, it also includes a jack 5, one end of the jack 5 abuts against the side wall of the steel purlin 2, and the other end of the jack 5 abuts against the side wall of the steel truss body 32. By applying prestress to the steel purlin through the jack, the horizontal deformation of the retaining structure during the foundation pit excavation stage can be effectively reduced.

[0061] Specifically, after the lifting operation of the jack 5 is completed, a force box 6 is installed between the steel purlin 2 and the side wall of the steel truss body 32, and the jack pushes the steel truss body 32 away from the steel purlin 2 along the upper surface of the steel bracket, so that prestress is applied between the steel truss body 32 and the steel purlin 2, and a force box 6 is installed between the steel purlin 2 and the side wall of the steel truss body 32. After the prestress is applied and the force box is installed, the jack can be removed for the next steel truss support system construction, thereby improving the use efficiency of the jack and reducing the number of jacks.

[0062] Specifically, it also includes a hanger 10 , the upper end of which is connected to the side wall of the enclosure structure 1 , and the other end of which is fixedly connected to the steel truss body 32 .

[0063] A construction process of a servo system for a combination system of steel truss support and concrete support for foundation pit engineering, comprising the following steps:

[0064] Step 1: Drive in the retaining structure and supporting columns, excavate the first layer of earthwork, and construct the initial support;

[0065] Step 2: The foundation pit is excavated in a basin-like manner, the soil in the middle part of the foundation pit is excavated to the next support bottom elevation, and the support beam in the middle part is constructed;

[0066] Step 3: Excavate the soil in the remaining soil area around the foundation pit to the next support bottom elevation, construct a steel bracket on the side wall of the retaining structure, place a steel purlin and a jack on the steel bracket, and fix it with a hanging rod;

[0067] Step 4: Fix and install the steel truss at the end of the supporting beam;

[0068] Step 5: The fixed end of the jack is in contact with the steel purlin, and the working end of the jack is in contact with the steel truss. The jack is used to apply prestress between the steel purlin and the steel truss to control the horizontal deformation of the enclosure structure.

[0069] Step 6: After the prestressing is completed, install the force box between the steel purlin and the steel truss, and move the jack to the next working surface;

[0070] Step 7: Repeat steps 2 and 6, constructing the steel truss support system and the concrete support system downwards.

[0071] This process is particularly suitable for the overall excavation of large-scale foundation pits. It can not only speed up the construction progress, reduce the project cost, and reduce the separation of enclosure structures; it can also reduce deformation and environmental impact through the prestressed steel truss support system. It can also be suitable for foundation pits of various shapes, especially those with strange shapes. The steel truss support system uses triangular trusses, which can be combined according to the shape of the foundation pit, and the deformation is controlled by the axial force servo system perpendicular to the foundation pit edge, so that the boundary shape of the inner concrete support system is regular, which is convenient for support arrangement;

[0072] Furthermore, this process can be combined with the center island process, which can not only speed up the construction period, but also effectively utilize the center island structure beams and slabs as a support system, effectively reducing the project cost.

[0073] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0074] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A servo system for a combination of steel truss support and concrete support for a foundation pit project, comprising a retaining structure (1), wherein the retaining structure (1) is buried around the foundation pit, the outer side surface of the retaining structure (1) is in contact with the soil of the foundation pit, and an initial support (7) is installed between the top opposite surfaces of the retaining structure (1), characterized in that: The inner side surfaces of the enclosure structure (1) are in contact with the foundation pit combined support system; The foundation pit combined support system comprises a steel truss support system and a concrete support system. The concrete support system is installed in the middle of the foundation pit. Both ends of the concrete support system are respectively fixedly connected to the steel truss support system. The steel truss support system is abutted against the inner side surface of the enclosure structure (1) through a steel purlin (2), and a prestressed loading unit is installed between the opposite surfaces of the steel truss support system and the steel purlin (2).

2. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 1, characterized in that: The concrete support system comprises a support column (8), the upper end of the support column (8) is fixedly connected to the lower surface of the initial support (7), and the lower end of the support column (8) is located in the soil of the foundation pit; A supporting crossbeam (4) is fixedly mounted on the side wall of the supporting column (8).

3. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 2, characterized in that: The steel truss support system comprises a steel truss (3), wherein the steel truss (3) comprises a steel truss body (32), and the steel truss body (32) is fixedly connected to the end of the supporting crossbeam (4) via a connection node.

4. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 3, characterized in that: The connection node comprises a limiting steel (31), the limiting steel (31) is horizontally fixedly installed on the side wall of the steel truss body (32) by means of high-strength bolts (33), and the limiting steel (31) is respectively in contact with the upper and lower surfaces of the supporting crossbeam (4); It also includes a limiting steel plate (34), which is vertically fixed on the side wall of the steel truss body (32) through the high-strength bolts (33), and the limiting steel plate (34) is respectively in contact with the left and right surfaces of the supporting crossbeam (4); A beam-penetrating sleeve (35) is installed at the end of the supporting crossbeam (4); the limiting steel plate (34) is fixedly connected to the supporting crossbeam (4) by means of tension bolts (36) that penetrate the beam-penetrating sleeve (35).

5. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 4, characterized in that: The prestressed loading unit comprises a steel purlin (2) and a steel bracket (9); the steel bracket (9) is fixedly mounted on the side wall of the enclosure structure (1); the lower surface of the steel purlin (2) abuts against the upper surface of the steel bracket (9).

6. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 5, characterized in that: The free end of the steel truss body (32) is overlapped on the steel bracket (9).

7. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 6, characterized in that: It also includes a jack (5), one end of the jack (5) abuts against the side wall of the steel purlin (2), and the other end of the jack (5) abuts against the side wall of the steel truss body (32).

8. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 7, characterized in that: After the lifting operation of the jack (5) is completed, a force-retaining box (6) is installed between the steel purlin (2) and the side wall of the steel truss body (32).

9. A servo system for a combination of steel truss support and concrete support for foundation pit engineering according to claim 8, characterized in that: It also includes a hanger bar (10), the upper end of which is connected to the side wall of the enclosure structure (1), and the other end of which is fixedly connected to the steel truss body (32).

10. A construction process of a servo system for a combination of steel truss support and concrete support for foundation pit engineering, which is completed according to a servo system for a combination of steel truss support and concrete support for foundation pit engineering according to any one of claims 1 to 9, and is characterized in that: The steps include: Step 1: Drive in the retaining structure and supporting columns, excavate the first layer of earthwork, and construct the initial support; Step 2: The foundation pit is excavated in a basin-like manner, the soil in the middle part of the foundation pit is excavated to the next support bottom elevation, and the support beam in the middle part is constructed; Step 3: Excavate the soil in the remaining soil area around the foundation pit to the next support bottom elevation, construct a steel bracket on the side wall of the retaining structure, place a steel purlin and a jack on the steel bracket, and fix it with a hanging rod; Step 4: Fix and install the steel truss at the end of the supporting beam; Step 5: The fixed end of the jack is in contact with the steel purlin, and the working end of the jack is in contact with the steel truss. The jack is used to apply prestress between the steel purlin and the steel truss to control the horizontal deformation of the enclosure structure. Step 6: After the prestressing is completed, install the force box between the steel purlin and the steel truss, and move the jack to the next working surface; Step 7: Repeat steps 2 and 6, constructing the steel truss support system and the concrete support system downwards.

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