Rapid support structure and method for foundation pit in narrow space working shaft

Abstract

The present invention provides a quick support structure and method for a foundation pit in a narrow space working shaft, and relates to the technical field of foundation pit support. The structure includes a casing, a purlin, a corner brace and a first lattice column. The casing includes four support plates connected in sequence. A first lattice column is arranged at the end corner inside the casing. The first lattice column is arranged vertically, and the bottom of the first lattice column extends into the bottom of the foundation pit. The purlin is a rectangular structure, the side of the purlin is connected to the inner surface of the support plate, and a corner brace is arranged at the end corner of the purlin. The two ends of the corner brace are respectively connected to the purlins of two adjacent support plates. The casing can be made first and then the foundation pit is excavated, and the casing is fixed quickly and simply, which greatly reduces the time used for foundation pit support, thereby improving construction efficiency and greatly reducing the road occupation time and the impact on traffic. The structure is provided with a purlin and a corner brace to support the casing, ensure the stability of the casing, and thus provide a good support effect.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit support, and in particular to a quick support structure and method for a foundation pit of a working well in a narrow space. Background Art

[0002] In municipal engineering, the excavation depth of a large pipeline working pit is generally about 6m, and steel sheet piles are generally used for foundation pit support before excavation. Steel sheet pile support saves time and effort, and the cost is relatively low, but in special circumstances, such as poor soil conditions at the site, no construction sites around the site, old pipelines around the site are easily affected by vibration, and municipal traffic roads cannot be occupied for a long time, it is difficult to use steel sheet piles for support.

[0003] For example, in the construction of a double well chamber structure, one is a wet well for mud drainage with a diameter of 1.2m, and the other is a dry well for mud drainage with a diameter of 1.4m. The wall thickness is 0.24m, the net distance between the two wells is not less than 1.0m, the minimum distance between the well chamber and the main pipeline is 2.0m, and the well chamber is parallel to the main pipeline. Considering the well chamber foundation size and the need to ensure at least a 0.5m wide working surface, the minimum excavation size of the well chamber foundation pit length and width are considered to be 6m. In this project, since the pipeline project is located on the non-motorized vehicle lane of the existing municipal road, the total width of the road is 15m, and it is a north-south transportation hub in the city that cannot be closed. In order to minimize the impact on road traffic, it is necessary to select construction equipment with a small construction working surface, and try to minimize the working surface and road occupation construction time of the pipeline well construction. Under the condition of avoiding deformation of pipes and road uplift in municipal roads caused by soil-squeezing pile construction, the vertical settlement and horizontal displacement of roads are reduced to the minimum. The existing bored pile process will occupy more construction work surfaces, the steel sheet pile process has serious soil squeezing problems and high construction noise, and the high-pressure grouting curtain wall method does not meet the actual requirements of the site due to its low strength and long construction and maintenance period. Therefore, a new narrow space working well foundation pit support structure is needed for foundation pit support. Summary of the invention

[0004] In view of this, the purpose of the present invention is to propose a rapid support structure and method for a foundation pit in a narrow space working shaft to solve the above-mentioned problems.

[0005] Based on the above purpose, the present invention provides a rapid support structure for a foundation pit in a narrow space working shaft, comprising: a casing, a purlin, a corner brace and a lattice column; the casing comprises four support plates connected in sequence, a first lattice column is arranged at the end corner inside the casing, the first lattice column is arranged vertically, and the bottom of the first lattice column extends into the bottom of the foundation pit; the purlin is a rectangular structure, the side of the purlin is connected to the inner surface of the support plate, and the end corner of the purlin is provided with a corner brace, and the two ends of the corner brace are respectively connected to the purlin of two adjacent support plates.

[0006] Furthermore, the device also includes a second lattice column, which is arranged at the connection position of the angle brace and the surrounding purlin, and the second lattice column is vertically arranged, and the bottom of the second lattice column extends into the bottom of the foundation pit.

[0007] Furthermore, the support plate is a rectangular steel plate to ensure the stability of the support.

[0008] The rapid support method for the foundation pit of a narrow space working well is carried out according to the following steps:

[0009] S1. Make a casing, and weld the surrounding purlins and corner braces inside the casing;

[0010] S2. Hoist the casing into the foundation pit and fix it;

[0011] S3, installing first lattice columns at the four end corners of the casing respectively, and driving the first lattice columns to the bottom of the foundation pit;

[0012] S4. Install the second lattice column at the end corner of the angle support, and inject the second lattice column into the bottom of the foundation pit to complete the support of the foundation pit.

[0013] Compared with the prior art, the beneficial effect of the present invention is that the casing is manufactured before the foundation pit support is performed, and the casing is placed in the foundation pit as an integral structure, and then the casing is fixed by the first lattice column and the second lattice column, and the casing is installed in the foundation pit to achieve the support function of the foundation pit. The casing can be manufactured before the foundation pit is excavated, and the casing is fixed quickly and simply, which greatly reduces the time used for foundation pit support, thereby improving construction efficiency and greatly reducing the road occupation time and the impact on traffic. The device is provided with a surrounding purlin and a corner brace to support the casing, ensure the stability of the casing, and thus provide a good support function. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A top view of a quick support structure for a foundation pit in a narrow space provided by an embodiment of the present invention;

[0015] Figure 2 A partial schematic diagram of a rapid support structure for a foundation pit in a narrow space provided by an embodiment of the present invention;

[0016] Figure 3 A cross-sectional view of a rapid support structure for a foundation pit in a narrow space provided by an embodiment of the present invention;

[0017] Figure 4 A three-dimensional schematic diagram of a rapid support structure for a foundation pit in a narrow space working shaft provided by an embodiment of the present invention.

[0018] Description of the accompanying drawings The following are marked in the figure: 1. casing; 2. surrounding purlin; 3. angle brace; 4. first lattice column; 5. second lattice column. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0020] like Figure 1 As shown, the invention proposes a fast supporting structure for a foundation pit in a narrow space, which is composed of a casing 1, a purlin 2, a corner brace 3, a first lattice column 4 and a second lattice column 5. The casing 1 is composed of four supporting plates connected in sequence, and the supporting plates are rectangular steel plates. The four supporting plates are connected at the ends and welded together to form a casing 1 with a rectangular structure. First lattice columns 4 are arranged at the end corners inside the casing 1. The first lattice columns 4 are arranged vertically, and two first lattice columns 4 are arranged at each end corner, such as Figure 2 As shown, two first lattice columns 4 are perpendicular to each other and are respectively close to the support plates. The bottom of the first lattice column 4 extends into the bottom of the foundation pit. The purlin 2 is a rectangular structure. The side of the purlin 2 is connected to the inner surface of the support plate. An angle brace 3 is provided at the end corner of the purlin 2. The two ends of the angle brace 3 are respectively connected to the purlin 2 of two adjacent support plates, which plays a supporting role for the casing 1. Figure 3 As shown, the second lattice column 5 is arranged at the connection position between the angle support 3 and the surrounding purlin 2, the second lattice column 5 is arranged vertically, and the bottom of the second lattice column 5 extends into the bottom of the foundation pit.

[0021] The rapid support method for the foundation pit of a narrow space working well is carried out according to the following steps:

[0022] S1. According to the size of the pipeline working shaft on the design drawing and the working surface conditions, determine the size of the casing 1 and make the casing 1. Select four rectangular steel plates with a thickness of 20 mm, and use full welding to connect the ends of the four steel plates in sequence to form a rectangular casing 1. Use No. 20a I-beams to make purlins 2, weld purlins 2 to the inner wall of casing 1, and evenly distribute several purlins 2 at equal intervals. The four end corners of purlin 2 are respectively welded with angle braces 3 with a length of 1m, and the two ends of angle braces 3 are respectively welded to the purlins 2 of two adjacent steel plates. The angle braces 3 play a supporting role to make casing 1 more stable.

[0023] According to the center coordinates of the pipeline working pit in the design drawings, use GPS instruments to measure and locate, and mark the working pit position with spray paint. Determine the center line of the pipeline and the lower and upper lines of the excavation position through the working pit position. Use a breaker to break the pavement structure within the excavation line, and use an excavator to excavate the first 1.5m roadbed structure layer, with a slope coefficient of 1:0.1. The abandoned soil is stored in a centralized manner for use when the roadbed is restored. Use an excavator to continue to slope downwards with a slope coefficient of 1:0.2, and excavate 1.5m downwards. Then use a long-arm excavator to continue to slope with a slope coefficient of 1:0.2, and excavate downwards until 200mm above the base. The excavation size of the foundation pit should be about 200mm wider than each side of the steel casing 1.

[0024] S2. Use a crane to hoist the casing 1 into the foundation pit. Considering the weight and hoisting distance, the maximum prefabricated component weighs about 7t, the foundation pit depth is 6m, and the center of the component is 3m away from the foundation pit edge. Use a 50t crane, stand 5m away from the pit edge, and have an operating radius of 10.5m. Since it is hoisted into the foundation pit, the hoisting height can be ignored.

[0025] S3, such as Figure 4 As shown, first lattice columns 4 are respectively installed at the four end corners of the casing 1, and the first lattice columns 4 are driven into the bottom of the foundation pit using a hydraulic vibration hammer, with an embedding depth of 1.5 m.

[0026] S4. Install the second lattice column 5 at the end corner of the angle brace 3, and use a hydraulic vibration hammer to drive the second lattice column 5 into the bottom of the foundation pit with an embedding depth of 1.5m to complete the support of the foundation pit.

[0027] Carry out the bottom plate construction: manually remove the 200mm reserved soil above the base, and do not remove the soil within the working surface range, and then carry out the cushion layer concrete construction. Carry out the construction according to the design requirements, and use C25 commercial concrete to cast the cushion layer. During construction, pay attention to the thickness of the cushion layer not less than 40mm.

[0028] Then, the mud discharge valve, pipe connection and well chamber masonry construction are carried out according to the design requirements and construction specifications. After the well chamber masonry is completed, the well chamber cover is covered and the support structure is lifted out by a crane.

[0029] The foundation pit is backfilled in layers, compacted with hydraulic vibration rammer, and then the road structure layer restoration construction is carried out.

[0030] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for rapid support of foundation pit in narrow space working well, characterized in that: Use the fast support structure of the foundation pit in a narrow space for support. The narrow space working shaft foundation pit rapid support structure comprises: a casing, a purlin, a corner brace and a first lattice column; the casing comprises four supporting plates connected in sequence, a first lattice column is arranged at the end corner inside the casing, the first lattice column is arranged vertically, and the bottom of the first lattice column extends into the pit bottom of the foundation pit; the purlin is a rectangular structure, the side of the purlin is connected to the inner surface of the supporting plate, and a corner brace is arranged at the end corner of the purlin, and the two ends of the corner brace are respectively connected to the purlins of two adjacent supporting plates; It also includes a second lattice column, which is arranged at the connection position of the angle brace and the surrounding purlin, and the second lattice column is arranged vertically, and the bottom of the second lattice column extends into the bottom of the foundation pit; The support plate is a rectangular steel plate; The support is carried out in the following steps: S1. Make a casing, and weld the surrounding purlins and corner braces inside the casing; S2. Hoist the casing into the foundation pit and fix it; S3, installing first lattice columns at the four end corners of the casing respectively, and driving the first lattice columns to the bottom of the foundation pit; S4. Install the second lattice column at the end corner of the angle support, and inject the second lattice column into the bottom of the foundation pit to complete the support of the foundation pit.

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