Underground space rapid construction method for overcrossing existing operating subway tunnel

Abstract

The invention belongs to the field of building construction, and particularly relates to an underground space rapid construction method for overcrossing an existing operating subway tunnel, which comprises the following steps: step 1, removing 1.5 m-thick topsoil on the surface of an excavated area before excavation; secondly, the foundation pit of the excavated area is divided into nine small blocks; thirdly, nine small blocks in the second step are dug through a warehouse jumping method; fourthly, after each small block is dug to the preset depth, a gravel cushion layer, an EPS plate and a gluing formwork are sequentially laid from bottom to top; fifthly, bottom plate steel bars bound in advance are hoisted to the bottom of the foundation pit at the positions where the bottom plate steel bars are laid in the third step, and then concrete containing a reinforcing agent is poured to the bottom plate steel bars; sixthly, waterproof construction is conducted on the foundation pit through an acrylate spraying film, the waterproof effect is guaranteed, and the problems that in an existing construction mode, the speed is low, the requirement of an overpass underground space project cannot be met, and the time limitation of a subway department cannot be met are solved.

Description

Technical Field

[0001] This application belongs to the field of building construction, specifically a rapid construction method for underground spaces that cross existing operational subway tunnels. Background Technology

[0002] Constructing underground spaces that cross existing operational subway tunnels is a common problem in urban development. Ensuring the safety of operational tunnels while constructing underground spaces is a key technical challenge.

[0003] The typical construction sequence for underground spaces is earthwork excavation → foundation layer pouring → formwork erection → waterproof membrane application → rebar tying → foundation slab pouring → sidewall and roof slab pouring, etc. Following this sequence, one construction section takes approximately two days. To prevent the unloading of soil above the subway from affecting its uplift, the maintenance department of existing operating subways generally requires approximately eight hours from excavation to foundation slab pouring (subway closure time is from 10:30 PM to 6:30 AM the following morning), minimizing the exposure time of the foundation pit and reducing the adverse effects of excavation above existing subway tunnels. Two days clearly does not meet the subway department's requirements; therefore, a rapid construction method needs to be developed that satisfies both the requirements of the underground space project itself and the subway department's time constraints. Summary of the Invention

[0004] The purpose of this application is to address the shortcomings of existing technologies by replacing concrete foundations with a sand and gravel subbase, EPS boards, and plywood formwork to achieve rapid construction, and by using acrylate spray film for internal waterproofing. This approach not only meets waterproofing requirements but also saves time for construction, solving the problems of slow construction speed, inability to meet the requirements of projects spanning underground spaces, and inability to meet the time constraints of subway departments.

[0005] The above-mentioned technical objective of this application is achieved through the following technical solution: A rapid construction method for underground spaces that cross existing operational subway tunnels includes the following steps: Step 1: Before excavation, remove the top 1.5m thick layer of loose soil from the surface of the area to be excavated; The second step is to divide the excavation area into nine smaller sections; The third step is to use the skip-cut method to excavate the nine small blocks from the second step; Step 4: After digging each small block to the preset depth, lay the sand and gravel cushion layer, EPS board, and plywood template from bottom to top. Step 5: Hoist the pre-tied bottom slab reinforcement bars to the bottom of the foundation pit at the location laid in Step 3, and then pour concrete containing reinforcing agent for the bottom slab reinforcement bars. Step 6: Apply an acrylic spray film to the foundation pit for waterproofing to ensure the waterproofing effect.

[0006] Preferably, the fifth step also includes pre-embedding a waterstop at the transverse construction joint of the bottom slab formed at the bottom of the foundation pit.

[0007] Preferably, after the waterstop is pre-embedded in step five, the quick-opening formwork is installed, and Hy-Rib metal steel mesh is used to separate the transverse construction joints of the base plate, and then concrete containing an early-strength agent is poured.

[0008] Preferably, the sixth step is performed after the concrete has reached the design strength.

[0009] Preferably, before implementing the first step, prepare the materials, machinery, personnel, and base plate for construction, pre-tie the reinforcing bars, and have the concrete pump truck arrive in advance.

[0010] Preferably, the construction time of the third step is within 3 hours, the construction time of the fourth step is within half an hour, the total time for the fifth step, from the pre-embedded waterstop to the transverse construction joint of the base plate separated by Hy-Rib metal steel mesh, is within 3 hours, and the sixth step is within 1.5 hours.

[0011] Preferably, the bottom slab reinforcement is hoisted at a pre-reserved mechanical connection joint with a segmented joint.

[0012] The beneficial effects of this application are: 1. To change the traditional subbase construction process, while meeting the specifications, we propose to use a sand and gravel subbase, EPS board, and plywood formwork to replace the concrete subbase, thereby achieving rapid construction.

[0013] 2. Under the premise of time constraints, conventional external waterproofing membrane construction is limited. Timely application of new acrylic spray film for internal waterproofing construction can meet the waterproofing requirements while saving time for construction. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the use of the skip-barrel method in this application; Figure 2 This is a schematic diagram of the foundation pit in this application; Figure 3 This is a schematic diagram showing the foundation pit after the sand and gravel cushion layer, EPS board, and plywood formwork have been laid in the present application. Figure 4 This is a schematic diagram showing the installation of bottom slab reinforcement in the foundation pit of this application; Figure 5 This is a diagram showing the relationship between the stone cushion layer, EPS board, and plywood in this application. Figure 6This is a diagram showing the relationship between the Quick-Open template and the Hy-Rib metal steel mesh in this application.

[0015] Among them, 1. foundation pit; 2. small blocks; 3. sand and gravel cushion layer; 4. EPS board; 5. plywood formwork; 6. bottom slab reinforcement; 7. quick-opening formwork; 8. Hy-Rib metal steel mesh; 9. subway. Detailed Implementation

[0016] like Figure 1-6 As shown, a rapid construction method for underground spaces that cross existing operational subway tunnels includes the following steps: Step 1: Before excavation, remove the top 1.5m thick layer of loose soil from the surface of the area to be excavated; The second step is to divide the excavation area into nine smaller sections. Step 3: Use the skip-cut method to dig out the nine small blocks 2 from step 2; Step 4: After digging each small block 2 to the preset depth, lay the sand and gravel cushion layer 3, EPS board 4, and plywood template 5 from bottom to top. Fifth step: hoist the pre-tied bottom slab steel bars 6 to the bottom of the foundation pit 1 at the position laid in the third step, and then pour concrete containing reinforcing agent for the bottom slab steel bars 6. Step 6: Apply an acrylic spray film to the foundation pit 1 for waterproofing to ensure the waterproofing effect.

[0017] In this embodiment, before excavation, approximately 1.5m of loose soil is removed from the surface. When excavation begins at 10:30 PM, each foundation pit 1 is excavated to the bottom. At the bottom of the pit, a sand and gravel cushion layer 3, EPS board 4, and plywood formwork 5 are laid in sequence. After the laying is completed, the pre-tied bottom slab reinforcement 6 is hoisted to the bottom of the pit. Then, a waterstop is pre-embedded at the transverse construction joint of the bottom slab, and a quick-release formwork 7 is installed. The transverse construction joint of the bottom slab is separated by Hy-Rib metal steel mesh 8. Then, early-strength concrete is poured. All the above important nodes must be completed within 8 hours. After the concrete strength reaches the design requirements, the underground structure waterproofing (acrylate spray waterproofing layer) is then carried out.

[0018] As a preferred method, the fifth step also includes pre-embedding a waterstop at the transverse construction joint of the bottom slab formed at the bottom of the foundation pit 1. This serves a waterproofing function.

[0019] As a preferred method, after pre-embedding the waterstop in step five, install the quick-opening template 7, and at the same time, use Hy-Rib metal steel mesh 8 to separate the transverse construction joints of the base plate, and then pour concrete containing an early-strength agent.

[0020] As a preferred approach, the sixth step is performed after the concrete has reached the design strength.

[0021] As a preferred approach, before implementing the first step, prepare the materials, machinery, personnel, and foundation slab for construction, pre-tie the reinforcing bars, and ensure that the concrete pump truck arrives in advance.

[0022] As a preferred method, the construction time of the third step is within 3 hours, the construction time of the fourth step is within half an hour; the total time for the fifth step, from the pre-embedded waterstop to the transverse construction joint of the base plate separated by Hy-Rib metal steel mesh 8, is within 3 hours; and the sixth step is within 1.5 hours.

[0023] As a preferred method, the bottom plate reinforcement 6 is hoisted at a pre-reserved mechanical connection joint with a segmented joint.

[0024] Taking the construction of a new underground space directly above an operating subway line as an example, the underground space intersects subway line 9 at approximately a 75-degree angle. The net distance between the top surface of the subway tunnel and the bottom slab of the underground structure is approximately 9 meters. The foundation pit 1 within the subway special protection zone is divided into 9 small sections, and the skip-excavation method is used for section excavation, excavating sequentially according to the numbers 1-9. Figure 1 As shown.

[0025] Before excavation, all preparations must be in place, such as the availability of materials, machinery, and personnel, the pre-tying of the bottom slab reinforcement bars, and the early arrival of the concrete pump truck. The main construction procedures are as follows: 1) Before excavation, remove the topsoil, which is about 1.5m thick. This will allow for minor changes to the load above Metro Line 9 and buy time for subsequent excavation.

[0026] 2) After receiving the excavation order, the remaining earthwork was excavated in an orderly and efficient manner. The earthwork excavation took place from 22:30 to 1:30, lasting 3 hours.

[0027] 3) After the earthwork excavation, the sand and gravel cushion layer 3, EPS board 4, and plywood formwork 5 were laid. The time was from 1:30 to 2:00, lasting 0.5 hours.

[0028] 4) After the pit bottom cushion layer is prepared, the hoisting of the bottom slab reinforcement 6 will begin. Mechanical connection joints for the reinforcement will be reserved at the joint with the next section. The construction joint will be separated by Hy-Rib metal mesh 8 and pre-embedded with a waterstop. The time is from 2:00 to 5:00, lasting 3.0 hours.

[0029] 5) After all installation is complete, begin pouring the foundation slab concrete. To ensure the concrete reaches the design strength as soon as possible, an appropriate amount of early-strength agent can be added. This process takes 1.5 hours, from 5:00 AM to 6:30 AM. This concludes the key milestone.

[0030] Once the concrete strength reaches the design requirements, waterproofing (acrylate spray waterproofing layer) will be applied to the underground space to ensure the waterproofing effect of the underground structure.

[0031] The method described in this application is mainly used in open-cut underground engineering projects that cross over operating subway tunnels, where there are high requirements for the environmental protection level around the foundation pit, short exposure time of the foundation pit, and limited construction time.

Claims

1. A rapid construction method for underground spaces that cross over existing operational subway tunnels, characterized in that, Includes the following steps: Step 1: Before excavation, remove the top 1.5m thick layer of loose soil from the surface of the area to be excavated; The second step is to divide the excavation area (1) into nine small blocks (2); Step 3: Use the skip-room method to dig out the nine small blocks from step 2 (2); Step 4: After digging each small block (2) to the preset depth, lay the sand and gravel cushion layer (3), EPS board (4), and plywood template (5) from bottom to top. Fifth step: hoist the pre-tied bottom plate steel bars (6) to the bottom of the foundation pit (1) at the position laid in the third step, and then pour concrete containing reinforcing agent for the bottom plate steel bars (6); Step 6: Apply an acrylic spray film to the foundation pit (1) for waterproofing to ensure the waterproofing effect.

2. The rapid construction method for underground space crossing an existing operating subway tunnel according to claim 1, characterized in that: The fifth step also includes pre-embedding a waterstop at the transverse construction joint of the bottom plate formed at the bottom of the foundation pit (1).

3. The rapid construction method for underground space crossing an existing operating subway tunnel according to claim 2, characterized in that: After the waterstop is pre-embedded in the fifth step, the quick-opening template (7) is installed. At the same time, Hy-Rib metal steel mesh (8) is used to separate the horizontal construction joints of the base plate, and then concrete containing early strength agent is poured.

4. The rapid construction method for underground space crossing an existing operating subway tunnel according to claim 1, characterized in that: The sixth step is carried out after the concrete has reached the design strength.

5. A rapid construction method for underground space crossing an existing operating subway tunnel as described in claim 1, characterized in that: Before implementing the first step, prepare the materials, machinery, personnel, and foundation slab for construction, pre-tie the reinforcing bars, and ensure the concrete pump truck arrives in advance.

6. A rapid construction method for underground space crossing an existing operating subway tunnel according to claim 3, characterized in that: The construction time for the third step is within 3 hours, the construction time for the fourth step is within half an hour; the total time for the fifth step, from the pre-embedded waterstop to the transverse construction joint of the base plate separated by Hy-Rib metal steel mesh (8), is within 3 hours; the sixth step is within 1.5 hours.

7. A rapid construction method for underground space crossing an existing operating subway tunnel according to claim 3, characterized in that: The bottom plate reinforcement (6) is hoisted at a pre-reserved mechanical connection joint with a segmented joint.

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