Construction methods for the foundation pit support of tunnels spanning operating highways

Abstract

This invention discloses a method for constructing a retaining structure for a tunnel foundation pit spanning an operating highway. The method includes the following steps: Step 1: Constructing a full-circle MJS reinforcement body between the existing road surface and the existing roof slab of the operating highway tunnel; Step 2: Constructing bored piles within the completed full-circle MJS reinforcement body using a full-rotation sleeve retaining wall; Step 3: Manually lowering the borehole to rigidly connect the reinforcing cage of the bored piles to the roof slab of the operating highway tunnel; Step 4: Pouring concrete to complete the construction of the bored piles; Step 5: Performing semi-circular MJS reinforcement construction between the completed bored piles, thereby enabling the construction of a retaining structure on top of the roof slab of the operating highway tunnel and the excavation and construction of the new structure. This invention can meet the requirements of constructing a retaining structure, excavating a foundation pit, and constructing a new structure on top of the roof slab of an operating highway tunnel; it does not occupy the working space inside the working shaft, avoids the impact on subsequent pipe jacking and reinforcement construction, and improves construction efficiency.

Description

Technical Field

[0001] This invention relates to a method for constructing retaining walls for tunnel foundation pits that span an operating highway. Background Technology

[0002] Currently, during the implementation of engineering projects, if there is an operating highway tunnel underneath, most projects choose to avoid the structure and conduct detours, which significantly increases costs. However, with the accelerating development of underground space, available sites are becoming increasingly scarce, making detours increasingly unavoidable.

[0003] To address the aforementioned issues, there is an urgent need to design a construction method for the foundation pit of a cross-operating highway tunnel that can combine existing retaining structure construction techniques with minimal impact on the surrounding area. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned shortcomings of existing methods. This invention provides a method for constructing a retaining wall for a tunnel foundation pit that spans an operating highway.

[0005] This invention is achieved through the following technical solution:

[0006] A method for constructing retaining walls for a tunnel foundation pit spanning an operating highway includes the following steps:

[0007] Step 1: Construct a full-circle MJS reinforcement structure between the existing road surface and the top slab of the existing operational highway tunnel;

[0008] Step 2: Construct bored piles within the completed full-circle MJS reinforced body using a full-rotation sleeve retaining wall.

[0009] Step 3: Manually lower the borehole to rigidly connect the reinforcing cage of the bored pile to the roof slab of the operating highway tunnel;

[0010] Step 4: Pour concrete to complete the construction of the bored pile;

[0011] Step 5: Perform semi-circular MJS pile reinforcement construction on the completed bored piles, thereby realizing the construction of the retaining structure on the top of the tunnel roof of the operating highway and excavating the foundation pit and constructing the new structure.

[0012] Furthermore, the diameter of the full-circle MJS reinforcement is 2400mm, and the depth of the full-circle MJS reinforcement is 6200mm-7200mm.

[0013] Furthermore, the center-to-center distance between two adjacent full-circle MJS solids is 1700mm.

[0014] Furthermore, the diameter of the bored pile is 1500mm, and the depth of the bored pile is 6200mm-7200mm.

[0015] Furthermore, the center-to-center distance between two adjacent bored piles is 2250mm.

[0016] Furthermore, the roof slab of the operating highway tunnel is reinforced with rebar, and the depth of the rebar is 620mm.

[0017] Furthermore, the bored pile is welded to the roof of the operating highway tunnel, with a weld length of 280mm and the weld joints are staggered by 50%.

[0018] The beneficial effects of this invention are as follows:

[0019] The construction method for the foundation pit support of tunnels spanning operating highways of the present invention can meet the requirements of constructing the support on the top of the tunnel roof, excavating the foundation pit and constructing the new structure; at the same time, it does not occupy the working space in the working well, avoids the impact on subsequent pipe jacking and reinforcement construction, and improves construction efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the full-circle MJS reinforced body and the bored pile according to an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the bored pile and the roof slab of the operating highway tunnel according to an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] Full-circle MJS solidified 1

[0024] 2 bored piles

[0025] Operating highway tunnel roof 3

[0026] Rebar 31 Detailed Implementation

[0027] The following description of the embodiments is taken with reference to the accompanying drawings, which illustrate specific embodiments in which the invention can be implemented.

[0028] like Figure 1 and Figure 2As shown in the figure, this embodiment discloses a method for constructing a retaining structure for a tunnel foundation pit spanning an operating highway. The method includes the following steps: Step 1: Constructing a full-circle MJS reinforcement body 1 between the existing road surface and the existing roof slab 3 of the operating highway tunnel; Step 2: Constructing bored piles 2 within the completed full-circle MJS reinforcement body 1 using a full-rotation sleeve retaining wall; Step 3: Manually lowering the borehole to rigidly connect the steel cage of the bored piles 2 to the roof slab 3 of the operating highway tunnel; Step 4: Pouring concrete to complete the construction of the bored piles 2; Step 5: Performing semi-circular MJS pile-to-pile reinforcement construction on the completed bored piles 2, thereby realizing the construction of a retaining structure on the top of the roof slab 3 of the operating highway tunnel and excavating the foundation pit and constructing the new structure.

[0029] The present invention discloses a construction method for retaining wall of a tunnel spanning an operating highway. First, a full-circle MJS reinforcement body 1 is constructed to ensure the borehole of the bored piles 2 remains dry during pile formation, thus ensuring the connection quality when rigidly connecting the bored piles 2 to the tunnel roof slab 3. After the bored piles 2 are formed, the hole is manually lowered to rigidly connect the reinforcing cage of the bored piles 2 to the tunnel roof slab 3. Finally, the outer semi-circular MJS piles are reinforced to prevent damage to the MJS reinforcement caused by the previous pile formation, thereby ensuring the overall structural quality. Simultaneously, this method achieves the goal of constructing a retaining structure on top of the operating tunnel roof slab 3 while simultaneously excavating the foundation pit and constructing the new structure; it does not occupy working space within the working shaft, avoiding impact on subsequent pipe jacking and reinforcement construction, and improving construction efficiency.

[0030] The diameter of the full-circle MJS reinforcement 1 is 2400mm, the depth of the full-circle MJS reinforcement 1 is 6200mm-7200mm, and the distance between the centers of two adjacent full-circle MJS reinforcement 1 is 1700mm.

[0031] The diameter of bored pile 2 is 1500mm, the depth of bored pile 2 is 6200mm-7200mm, and the center-to-center distance between two adjacent bored piles 2 is 2250mm. Among these, in... Figure 1 The 1700 marked in the middle represents the center-to-center distance between two adjacent full-circle MJS reinforced bodies 1, and the 2250 represents the center-to-center distance between two adjacent bored piles 2.

[0032] The roof slab 3 of the operating highway tunnel has rebar 31 with a depth of 620mm. When the bored pile 2 is rigidly connected to the roof slab 3 of the operating highway tunnel, the roof slab 3 is reinforced with rebar 31 with a depth of 620mm.

[0033] The bored pile 2 is welded to the roof slab 3 of the operating highway tunnel. The weld length between the bored pile 2 and the roof slab 3 of the operating highway tunnel is 280mm, and the weld joints are staggered by 50%.

[0034] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for constructing retaining walls for a tunnel foundation pit spanning an operating highway, characterized in that, Includes the following steps: Step 1: Construct a full-circle MJS reinforcement structure between the existing road surface and the top slab of the existing operational highway tunnel; Step 2: Construct bored piles within the completed full-circle MJS reinforced body using a full-rotation sleeve retaining wall. Step 3: Manually lower the borehole to rigidly connect the reinforcing cage of the bored pile to the roof slab of the operating highway tunnel; Step 4: Pour concrete to complete the construction of the bored pile; Step 5: Perform semi-circular MJS pile reinforcement construction on the completed bored piles, thereby realizing the construction of the retaining structure on the top of the tunnel roof of the operating highway and excavating the foundation pit and constructing the new structure.

2. The construction method for retaining wall of a tunnel spanning an operating highway according to claim 1, characterized in that, The diameter of the full-circle MJS reinforcement is 2400mm, and the depth of the full-circle MJS reinforcement is 6200mm-7200mm.

3. The construction method for retaining wall of a tunnel spanning an operating highway according to claim 2, characterized in that, The center-to-center distance between two adjacent full-circle MJS reinforced bodies is 1700mm.

4. The construction method for retaining wall of a tunnel spanning an operating highway according to claim 1, characterized in that, The diameter of the bored pile is 1500mm, and the depth of the bored pile is 6200mm-7200mm.

5. The construction method for retaining wall of a tunnel spanning an operating highway according to claim 1, characterized in that, The center-to-center distance between two adjacent bored piles is 2250mm.

6. The construction method for retaining wall of a tunnel spanning an operating highway according to claim 1, characterized in that, The roof slab of the operating highway tunnel is reinforced with rebar, and the depth of the rebar is 620mm.

7. The construction method for retaining wall of a tunnel spanning an operating highway according to claim 1, characterized in that, The bored piles are welded to the roof of the operating highway tunnel, with a weld length of 280mm and the weld joints are staggered by 50%.

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