Steel caisson composite structure for large-diameter pipe jacking working pit and caisson construction method

Abstract

This invention discloses a steel caisson composite structure and construction method for large-diameter pipeline jacking pits, suitable for groundwater-rich conditions. The structure includes a precast steel cylinder and multiple circumferential stiffening ribs arranged within the precast steel cylinder along its depth. A first reinforcement measure is provided around the side of the precast steel cylinder that connects to the jacking pipe, and a second reinforcement measure is provided on the side facing away from the jacking pipe. Inside, near the lower end, from bottom to top, are a full-span soil reinforcement measure, a concrete cushion layer, a reinforced concrete base slab, and an anti-buoyancy bracket. A third reinforcement measure is provided around the precast steel cylinder, surrounding the first and second reinforcement measures. During caisson construction, the precast steel cylinder is first rocked, then downward pressure is applied to sink it into the soil. Circumferential stiffening ribs are then installed inside the precast steel cylinder during the excavation stage. This invention solves the anti-buoyancy problem during construction, effectively prevents the sudden surge of pressurized water, and ensures the safety of pipe jacking operations.

Description

Technical Field

[0001] This invention relates to the field of caisson construction technology, and in particular to a steel caisson composite structure and caisson construction method for large-diameter pipe jacking pits. Background Technology

[0002] Currently, in densely populated and commercial areas like Shanghai, the main method used in trenchless construction of municipal underground pipelines is pipe jacking.

[0003] However, traditional pipe jacking requires working pits on the construction site, which occupies a large area, has a significant environmental impact, takes a long time, and is costly.

[0004] Therefore, how to adapt the construction of caissons connected to pipe jacking to various constraints such as tight schedules, complex surrounding environments, and small construction sites, and achieve the goals of safe and reliable, controllable schedule, functional compliance, economic rationality, and convenient construction of large-diameter deep excavation under complex geological conditions, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the present invention provides a steel caisson composite structure and caisson construction method for large-diameter pipe jacking working pits. The purpose is to meet the requirements of bearing the water and soil pressure on the outside and the overload of the construction at the well edge, while also having the function of blocking groundwater seepage, solving the anti-buoyancy problem in the construction process, effectively preventing the sudden surge of pressurized water, and ensuring the safety of pipe jacking operations in and out of the tunnel.

[0006] To achieve the above objectives, the present invention discloses a steel caisson composite structure for a large-diameter pipe jacking working pit, for use in groundwater-rich conditions, comprising a precast steel cylinder and multiple circumferential stiffening ribs arranged in the precast steel cylinder along the depth direction of the precast steel cylinder;

[0007] The precast steel cylinder has a first reinforcement measure on the side wall that connects to the jacking pipe, and a second reinforcement measure on the side facing away from the jacking pipe. Inside, near the bottom, from bottom to top, there are a full-soil reinforcement measure, a concrete cushion layer, a reinforced concrete base slab, and an anti-buoyancy bracket.

[0008] Outside the first and second reinforcement measures, a third reinforcement measure is provided that surrounds the precast steel cylinder.

[0009] Preferably, the sidewall at the junction of the precast steel cylinder and the jacking pipe is provided with a plurality of vertical stiffening ribs extending along the depth direction of the precast steel cylinder around the axis.

[0010] Preferably, the precast steel cylinder is provided with a drainage well.

[0011] Preferably, the diameter of the jacking pipe is between φ300 mm and φ2400 mm.

[0012] Preferably, the first reinforcement measure, the second reinforcement measure, and the third reinforcement measure are all all-around high-pressure jet grouting piles.

[0013] This invention also provides a caisson construction method, employing the steel caisson composite structure described above for large-diameter pipe jacking pits, comprising the following steps:

[0014] Step 1: The precast steel cylinder is sunk into the soil by first shaking it and then applying downward pressure.

[0015] Step 2: After the precast steel cylinder has sunk into place, during the earthwork excavation stage, all circumferential stiffening ribs are installed layer by layer along the depth inside the precast steel cylinder.

[0016] The beneficial effects of this invention are:

[0017] This invention can adapt to constraints such as tight schedules, complex surrounding environments, and limited construction sites, and achieves the goals of safe and reliable large-diameter pipe jacking pits under complex geological conditions, controllable construction period, functional requirements, economic rationality, and convenient implementation.

[0018] This invention facilitates the sinking construction of steel caissons, adapts to the stress requirements of large-diameter, deep excavation, and facilitates soil removal and installation of jacking equipment during pipe jacking, thereby accelerating the construction speed.

[0019] This invention makes full use of its own anti-buoyancy conditions, effectively reducing the thickness of the underwater sealing of traditional steel caissons, further reducing the requirements for over-excavation, reducing the difficulty of underwater pouring of sealing concrete, and ensuring the construction quality of underwater sealing concrete.

[0020] This invention occupies a small area, has minimal impact on the surrounding environment during implementation, can be flexibly deployed in complex environments, and possesses both strong practicality and wide applicability.

[0021] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0022] Figure 1 A plan view of an embodiment of the present invention is shown.

[0023] Figure 2 A schematic diagram of a longitudinal cross-sectional structure is shown in one embodiment of the present invention. Detailed Implementation

[0024] Example: Figure 1 and Figure 2 As shown, a steel caisson composite structure for a large-diameter pipe jacking working pit is used in groundwater-rich conditions. It includes a precast steel cylinder Y1 and multiple circumferential stiffening ribs Y2 set in the precast steel cylinder Y1 along the depth direction of the precast steel cylinder Y1.

[0025] The precast steel cylinder Y1 is provided with a first reinforcement measure Y3 on the side wall that is connected to the jacking pipe D1, and a second reinforcement measure Y4 on the side facing away from the jacking pipe D1. The interior is provided with a full-soil reinforcement measure Y6, a concrete cushion layer Y8, a reinforced concrete base plate Y9 and an anti-buoyancy bracket Y7 in sequence from bottom to top near the bottom.

[0026] Outside the first reinforcement measure Y3 and the second reinforcement measure Y4, there is a third reinforcement measure Y5 that surrounds the precast steel cylinder Y1.

[0027] This invention achieves the functions of bearing the water and soil pressure on the outside, overloading of well construction, and blocking groundwater seepage through the combined action of precast steel cylinder Y1 and multiple circumferential stiffening ribs Y2. It can be flexibly arranged in complex sites without the need for on-site concrete pouring and curing. Compared with the currently commonly used retaining schemes, it can save a lot of construction time, so the construction process is faster and more efficient.

[0028] The first reinforcement measure Y3, the second reinforcement measure Y4, and the third reinforcement measure Y5 are applicable to various complex geological and hydrological conditions and effectively address the problem of confined water inrush.

[0029] In some embodiments, the sidewall at the junction of the precast steel cylinder Y1 and the jacking pipe D1 is provided with a plurality of vertical stiffening ribs Y11 extending along the depth direction of the precast steel cylinder Y1 around the axis.

[0030] In some embodiments, a drainage well Y10 is provided inside the precast steel cylinder Y1.

[0031] In some embodiments, the diameter of the jacking pipe D1 is from φ300 mm to φ2400 mm.

[0032] In practical applications, this invention is suitable for pipe jacking construction with diameters from φ300 to φ2400 (D1), with more reliable jacking accuracy, and can meet the jacking requirements of most pipelines.

[0033] In some embodiments, the first reinforcement measure Y3, the second reinforcement measure Y4, and the third reinforcement measure Y5 are all omnidirectional high-pressure jet grouting piles.

[0034] This invention also provides a caisson construction method, employing the steel caisson composite structure described above for large-diameter pipe jacking pits, comprising the following steps:

[0035] Step 1: First, shake the precast steel cylinder Y1 and then apply downward pressure to sink the precast steel cylinder Y1 into the soil;

[0036] Step 2: After the precast steel cylinder Y1 has sunk into place, during the earthwork excavation stage, all circumferential stiffening ribs Y2 are installed layer by layer along the depth inside the precast steel cylinder Y1.

[0037] When constructing a caisson using a steel caisson composite structure for large-diameter pipe jacking pits, the precast steel cylinder Y1 needs to be repeatedly rotated circumferentially during the sinking process to cut the soil and create conditions for the caisson to sink. As the caisson depth increases, a greater circumferential torsional force is required to cut the soil. Therefore, the precast steel cylinder Y1 needs sufficient strength and stiffness, especially circumferential stiffness, particularly for large-diameter and deep steel caissons. Simply relying on the thickness of the caisson sidewalls is insufficient to meet these requirements, and increasing the wall thickness not only increases the difficulty of welding and hoisting the steel caisson but also significantly increases investment. This invention solves the strength problem of the precast steel cylinder Y1 by setting circumferential stiffening ribs Y2 and vertical stiffening ribs Y11, achieving a low steel consumption while meeting greater circumferential shear resistance and stability. It can also meet different sinking depths, planar dimensions, and usage requirements, greatly reducing project costs and construction difficulty, and has strong practicality.

[0038] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A steel caisson composite structure for pipe jacking pits of large-diameter pipelines, used in groundwater-rich environments; characterized in that, It includes a precast steel cylinder (Y1) and multiple circumferential stiffening ribs (Y2) arranged in the precast steel cylinder (Y1) along the depth direction of the precast steel cylinder (Y1); The precast steel cylinder (Y1) is provided with a first reinforcement measure (Y3) on the side wall that is connected to the jacking pipe (D1), and a second reinforcement measure (Y4) on the side facing away from the jacking pipe (D1). Inside, near the lower end, from bottom to top, there are a full-soil reinforcement measure (Y6), a concrete cushion layer (Y8), a reinforced concrete base slab (Y9), and an anti-buoyancy corbel (Y7). Outside the first reinforcement measure (Y3) and the second reinforcement measure (Y4), a third reinforcement measure (Y5) is provided, which surrounds the precast steel cylinder (Y1).

2. The steel caisson composite structure for large-diameter pipe jacking working pits according to claim 1, characterized in that, The sidewall at the junction of the precast steel cylinder (Y1) and the jacking pipe (D1) is provided with a number of vertical stiffening ribs (Y11) extending along the depth direction of the precast steel cylinder (Y1) around the axis.

3. The steel caisson composite structure for large-diameter pipe jacking working pits according to claim 1, characterized in that, The precast steel cylinder (Y1) is equipped with a drainage well (Y10).

4. The steel caisson composite structure for large-diameter pipe jacking working pits according to claim 1, characterized in that, The diameter of the jacking pipe (D1) is from φ300 mm to φ2400 mm.

5. The steel caisson composite structure for large-diameter pipe jacking working pits according to claim 1, characterized in that, The first reinforcement measure (Y3), the second reinforcement measure (Y4), and the third reinforcement measure (Y5) are all all-round high-pressure jet grouting piles.

6. A caisson construction method, characterized in that, The steel caisson composite structure for large-diameter pipe jacking working pits as described in any one of claims 1 to 5 includes the following steps: Step 1: The precast steel cylinder (Y1) is first shaken and then downward pressure is applied to sink the precast steel cylinder (Y1) into the soil. Step 2: After the precast steel cylinder (Y1) has sunk into place, during the earthwork excavation stage, all circumferential stiffening ribs (Y2) are installed layer by layer along the depth inside the precast steel cylinder (Y1).

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