Structure of soft soil layer backfill pressure steel pipe underpassing road

Abstract

The utility model relates to the technical field of water conservancy and hydropower engineering, concretely is a kind of soft soil layer backfill pressure steel pipe underpass road structure.The purpose is to provide a kind of soft soil layer backfill pressure steel pipe underpass road structure, the structure should be able to guarantee the long-term stable operation of pressure steel pipe and the normal use of road.The technical scheme is a kind of soft soil layer backfill pressure steel pipe underpass road structure, including concrete cushion, the enclosure structure being arranged in the both sides of concrete cushion, the layered backfill structure being filled between concrete cushion and enclosure structure top, the pressure steel pipe being buried in layered backfill structure and the road structure being arranged in layered backfill structure top and being connected the both sides enclosure structure.

Description

Technical Field

[0001] This utility model relates to the field of water conservancy and hydropower engineering technology, specifically a structure for a pressure steel pipe to pass under a road in soft soil backfill. Background Technology

[0002] The construction structure for pressure steel pipes passing under roads refers to an engineering structure directly laid beneath the road surface to protect the pressure steel pipes (transporting water, oil, gas, etc.), typically paired with foundation protection or support components. Traditional construction structures for pressure steel pipes passing under roads usually take the following two forms: One method is direct backfilling without a dedicated retaining structure: the area around the pressure steel pipe is backfilled with plain soil or a single type of sand and gravel without any retaining or waterproofing structure. This method cannot limit the lateral deformation of the soft soil layer surrounding the pressure steel pipe, and during construction and operation, the soft soil is prone to lateral compression, causing the pressure steel pipe to shift and deform. In addition, the poor permeability and difficulty in controlling the compaction degree of a single backfill material can easily lead to groundwater accumulation, exacerbating the compression of the soft soil near the pressure steel pipe and ultimately causing road settlement.

[0003] Another approach is a simple retaining structure combined with extensive backfilling: some projects use a simple retaining structure consisting of sandbags and small sheet piles around the pressure steel pipe. However, this type of structure lacks sufficient rigidity and water-stopping performance, and cannot effectively resist the lateral pressure of the soft soil layer, easily leading to deformation and leakage of the retaining structure. Furthermore, the backfill layer is often made of a single material, lacking a layered design, resulting in uneven load distribution and stress concentration at the top of the pressure steel pipe, causing damage. It also fails to meet the road's load-bearing requirements for the stability of the backfill layer.

[0004] Traditional construction structures generally fail to provide sufficiently stable support and good waterproofing and seepage resistance, thus failing to effectively guarantee the long-term stable operation of pressure steel pipes shallowly buried in soft soil layers and the normal use of roads. How to design a structure for backfilled pressure steel pipes passing under roads in soft soil layers (especially in shallow burial conditions) has become an urgent problem to be solved by those skilled in the art. Utility Model Content

[0005] The purpose of this utility model is to overcome the deficiencies in the above-mentioned background technology and provide a structure for backfilling a pressure steel pipe under a road in soft soil layer. This structure should be able to ensure the long-term stable operation of the pressure steel pipe and the normal use of the road.

[0006] The technical solution of this utility model is: A structure for a road under a pressure steel pipe backfilled in soft soil includes a concrete cushion layer, retaining structures on both sides of the concrete cushion layer, a layered backfill structure filling the space between the concrete cushion layer and the retaining structures, a pressure steel pipe buried in the layered backfill structure, and a road structure set on top of the layered backfill structure and connecting the retaining structures on both sides.

[0007] The pressure steel pipe is connected to the concrete cushion layer by anchor bars; one end of the anchor bar is welded to the outer wall of the steel pipe and the other end is embedded in the concrete cushion layer.

[0008] The retaining structure is embedded in the soft soil layer below the concrete cushion layer; the retaining structure is a diaphragm wall.

[0009] The layered backfill structure includes, from bottom to top, a sand and gravel layer, a lime-soil layer, and a crushed stone layer.

[0010] The pressure steel pipe is buried in the sand and gravel layer and the lime-soil layer.

[0011] The outer wall of the pressure steel pipe is provided with an anti-corrosion coating.

[0012] The beneficial effects of this utility model are: This utility model is applicable to the construction scenario of pressure steel pipes buried shallowly in soft soil layers passing under roads. It specifically solves the engineering problems caused by the characteristics of soft soil under shallow burial conditions, effectively reduces the risk of road settlement and steel pipe deformation, extends the service life of pressure steel pipes, and takes into account the safety, economy and traffic convenience of the project.

[0013] This utility model addresses the challenges of embedding pressure steel pipes in soft soil layers through the coordinated design of a retaining structure, a layered backfill structure, a concrete cushion layer, and a road structure. The retaining structure is positioned on both sides of the pressure steel pipe to prevent soil erosion and water seepage, maintaining a certain gap to avoid stress concentration. The layered backfill structure consists of three layers, which respectively distribute the load, prevent water seepage, and accommodate deformation. The concrete cushion layer is placed below the pressure steel pipe and secured with anchor bars, distributing the load and fixing the pipe. The road structure can directly support traffic without requiring the construction of temporary roads, significantly reducing traffic interruption time while also constraining backfill deformation and improving overall stability. Attached Figure Description

[0014] Figure 1 This is a cross-sectional structural diagram of the present invention.

[0015] Figure label: 1. Pressure steel pipe; 2. Concrete cushion layer; 3. Retaining structure; 4. Sand and gravel layer; 5. Lime-soil layer; 6. Crushed stone layer; 7. Anchor bar; 8. Road structure. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0017] like Figure 1 As shown, a structure for a road under a pressure steel pipe backfilled in soft soil includes a pressure steel pipe 1, a concrete cushion layer 2, a retaining structure 3, and a road structure 8.

[0018] The pressure steel pipe is made of high-strength, corrosion-resistant steel, and the appropriate wall thickness is selected according to the pressure and pipe diameter required for actual construction.

[0019] The outer wall of the pressure steel pipe is provided with an anti-corrosion coating, such as a 3mm thick epoxy coal tar coating, to resist the erosion of groundwater and corrosive media.

[0020] The concrete cushion layer is located at the bottom layer (below the pressure steel pipe). The concrete cushion layer is made of C30 concrete with a thickness of 30~50cm and is used to disperse the pressure of the overall structure and enhance the bearing capacity of the foundation.

[0021] The pressure steel pipe is fixed to the concrete pad layer by anchor bars 7. The anchor bars are ribbed steel bars, spaced apart along the length of the pressure steel pipe (the spacing and other parameters of the anchor bars can be changed according to actual construction needs). One end of the anchor bar is embedded in the concrete pad layer to a depth of not less than 20d, where d is the diameter of the anchor bar. The other end is welded to the outer wall of the pressure steel pipe using a double-sided fillet weld process, with a weld height ≥0.5d. This enhances the overall connection between the pressure steel pipe and the concrete pad layer and restricts the relative displacement of the pressure steel pipe.

[0022] As a preferred option, the anchor bars are HRB400E with a diameter of 20mm, a spacing of 100cm, an implantation depth of 40cm in the concrete pad, and a weld height of 10mm when welded to the pressure steel pipe.

[0023] The retaining structure is set on both sides of the concrete cushion layer and arranged along both sides of the road, with the pressure steel pipe arranged between the retaining structures on both sides. The retaining structure is a diaphragm wall made of C30 reinforced concrete (other equivalent retaining structures such as cast-in-place piles and sheet piles can also be selected according to engineering geological conditions, foundation pit depth, and other requirements). The bottom of the retaining structure is embedded in the soft soil layer below the concrete cushion layer to ensure the effect of waterproofing and seepage prevention.

[0024] The retaining structure maintains a certain distance from the pressure steel pipe, forming a closed retaining wall to limit lateral deformation of the soft soil layer and meet the core requirements for the stiffness and water-stopping performance of the retaining structure under shallow-buried conditions. The thickness and embedment depth of the retaining structure need to be calculated and adjusted in conjunction with the depth of the foundation pit and the physical and mechanical parameters of the soft soil to ensure that the retaining and water-stopping requirements of the project are met.

[0025] Preferably, the thickness of the enclosure structure is 120cm, the bottom of the enclosure structure is embedded at least 10m below the concrete cushion layer, and the distance between the enclosure structure and the pressure steel pipe is 1.5m.

[0026] The layered backfill structure includes, from bottom to top, a sand and gravel layer 4, a lime-soil layer 5, and a crushed stone layer 6.

[0027] The sand and gravel layer consists of graded sand and gravel with a particle size of 5-15mm and a compaction degree of ≥95%. It covers part of the pressure steel pipe to disperse the load on the pressure steel pipe and remove a small amount of groundwater.

[0028] The lime-soil layer comprises lime and plain soil (cohesive soil) in a volume ratio of 3:7 or 2:8, with a compaction degree ≥93% and a moisture content controlled within the range of optimum moisture content ±2%, forming a rigid transition layer to block groundwater.

[0029] The crushed stone layer consists of open-graded crushed stone of 20-40mm with a compaction degree of ≥94%, and is used to bear the load transmitted by the road structure and adapt to settlement differences.

[0030] The pressure steel pipe is buried in the sand and gravel layer and the lime-soil layer. The pressure steel pipe is at least 0.5m away from the crushed stone layer and at least 3.0m away from the road structure, so as to leave enough space for load transfer and protection of the pressure steel pipe.

[0031] The road structure is located on top of the layered backfill structure and connects to the retaining structures on both sides. It is integrally cast with C30 reinforced concrete, with a thickness of 50cm and a width consistent with the spacing of the retaining structures. The road structure can be used directly as a temporary or permanent road, while also serving as a constraint structure for the layered backfill structure, improving overall stability.

[0032] The working principle of this utility model is as follows: When vehicle loads or other superstructure loads are applied to the road, the pressure is first transferred through the road structure 8 to the layered backfill structure. The open-graded crushed stone layer 6, with its good gradation and internal friction characteristics, evenly distributes the load to the lime-soil layer 5. The lime-soil layer further transfers the load to the sand and gravel layer 4. The graded sand and gravel in the sand and gravel layer, together with the concrete cushion layer 2, evenly distributes the load into the soft soil foundation. Anchor bars 7 enhance the connection between the pressure steel pipe and the concrete cushion layer, effectively limiting the displacement of the pressure steel pipe. The retaining structure 3 is set on both sides of the pressure steel pipe to resist the lateral pressure in the soft soil layer and to provide waterproofing and seepage prevention.

[0033] The accompanying drawings illustrate preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

Claims

1. A structure for a pressure steel pipe passing under a road in soft soil backfill, characterized in that: It includes a concrete cushion layer (2), a retaining structure (3) set on both sides of the concrete cushion layer, a layered backfill structure filling the space between the concrete cushion layer and the retaining structure, a pressure steel pipe (1) buried in the layered backfill structure, and a road structure (8) set on top of the layered backfill structure and connecting the retaining structures on both sides.

2. The structure for a pressure steel pipe under a road with backfill in soft soil layer according to claim 1, characterized in that: The pressure steel pipe is connected to the concrete cushion layer by anchor bars (7); one end of the anchor bar is welded to the outer wall of the steel pipe and the other end is implanted into the concrete cushion layer.

3. The structure for a pressure steel pipe passing under a road in soft soil layer backfill as described in claim 2, characterized in that: The retaining structure is embedded in the soft soil layer below the concrete cushion layer; the retaining structure is a diaphragm wall.

4. The structure for a pressure steel pipe under a road with backfill in soft soil layer according to claim 3, characterized in that: The layered backfill structure includes, from bottom to top, a sand and gravel layer (4), a lime-soil layer (5), and a crushed stone layer (6).

5. The structure for a pressure steel pipe under a road with backfill in soft soil layer according to claim 4, characterized in that: The pressure steel pipe is buried in the sand and gravel layer and the lime-soil layer.

6. The structure for a pressure steel pipe under a road with backfill in soft soil layer according to claim 5, characterized in that: The outer wall of the pressure steel pipe is provided with an anti-corrosion coating.

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