Construction method for breaking existing underground passage by adopting vertical shaft excavation

Abstract

The invention discloses a construction method for breaking an existing underground passage through vertical shaft excavation. The construction method comprises the following steps that a decoration layer of the existing underground passage is dismantled; constructing a blocking waterproof structure at one end of the existing underground passage; backfilling construction is conducted on the existing underground passage; constructing a blocking waterproof structure at the other end of the existing underground passage; underground passages are excavated in the vertical shafts, underground diaphragm walls are constructed, and under-column piles are constructed; constructing a cover plate structure above the underground passage; and the existing underground passage is completely broken under the protection of the cover plate. The interior of the existing underground passage is firstly backfilled with cohesive soil, and then the vertical shaft is adopted to excavate the fixed-point breaking passage structure, so that the construction difficulty and risk are reduced, the disturbance of the breaking passage structure to the stratum is reduced, and the influence on normal traffic on the ground is avoided. According to the method, breaking of the existing underground passage and construction of main structures such as a newly-built underground diaphragm wall and a newly-built under-column pile are conducted at the same time, the time requirement for breaking of the existing passage is weakened, the construction period progress is accelerated, and smooth development of construction of a newly-built subway station is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of underground structure engineering, and in particular relates to a construction method for breaking an existing underground passage by excavating a vertical shaft. Background Art

[0002] Infrastructure construction has achieved vigorous development, urban rail transit lines are crisscrossed, underground land space has been reduced accordingly, construction conditions are complex and changeable, and some engineering difficulties have sprung up like mushrooms after rain. For example, at the intersection of multiple subway lines, the construction of new subway stations will inevitably conflict with some small ancillary facilities of existing subway stations.

[0003] The choice of construction method to eliminate the conflict between the existing underground structure and the new subway station will directly affect the construction progress of the new station and whether the ground traffic can be smooth. Unsmooth construction may even affect the surface subsidence and may even lead to surface collapse.

[0004] At present, the construction technology for demolishing underground passages is generally to demolish the conflict location directly, and then completely demolish the underground passage after the new main structure is built. Although the construction technology is relatively mature, there may be certain risks of excessive surface subsidence during actual implementation. Summary of the invention

[0005] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a construction method for breaking an existing underground passage by using a vertical shaft excavation.

[0006] The technical solution of the present invention is: a construction method for breaking an existing underground passage by using a vertical shaft excavation, comprising the following steps: A. Remove the decoration layer of the existing underground passage; B. Construct a blocking and waterproofing structure at one end of the existing underground passage; C. Backfill the existing underground passage; D. Construct the sealing and waterproofing structure at the other end of the existing underground passage; E. Excavation of underground passages in vertical shafts, construction of ground-connected walls and piles under columns; F. Construction of the cover structure above the underground passage; G. Completely demolish the existing underground passage under the protection of the cover.

[0007] Furthermore, the existing underground passage is located between the cover plate and the middle plate of the new subway station. The existing underground passage conflicts with the new subway station and needs to be abolished.

[0008] Furthermore, the newly constructed ground-anchored walls and column piles of the new metro station vertically penetrate the existing underground passage.

[0009] Furthermore, step A removes the decoration layer of the existing underground passage, and the specific process is as follows: First, the existing underground passage was enclosed using PVC fencing; Then, the decoration layer in the existing underground passage was removed.

[0010] Furthermore, step B constructs a blocking and waterproofing structure at one end of the existing underground passage, and the specific process is as follows: First, a blocking wall is constructed at one end of the existing underground passage; Then, after sealing the wall, the waterproof layer and plain concrete wall were constructed. Finally, the blocking wall adopts reinforced concrete structure and the waterproof layer behind the wall adopts asphalt waterproof membrane.

[0011] Furthermore, step C is to backfill the existing underground passage, and the specific process is as follows: First, the existing underground passage is backfilled in layers with clay soil and compacted; Then, three concrete retaining sills were arranged along the longitudinal direction of the channel during the backfilling process.

[0012] Furthermore, step D constructs the blocking and waterproofing structure at the other end of the existing underground passage, and the specific process is as follows: First, after backfilling is completed, the other end of the existing underground passage is promptly closed; Then, the sealing and waterproofing structure also uses sealing walls, waterproof layers behind walls, and plain concrete walls.

[0013] Furthermore, in step E, the underground passage is excavated in the vertical shaft, and the ground connection wall and column piles are constructed. The specific process is as follows: First, a vertical shaft was excavated from the ground to break the existing underground passage within the scope of the new ground-connected wall; Then, the underground continuous wall is constructed; Finally, the pull-out piles and permanent steel pipe columns are constructed.

[0014] Furthermore, step F is to construct a cover structure above the underground passage, and the specific process is as follows: Based on the underground continuous wall and pull-out piles, the cover slab of the new station is constructed in sequence.

[0015] Furthermore, step G completely breaks down the existing underground passage under the protection of the cover plate. The specific process is as follows: First, after the construction of the cover of the new station is completed, the demolition of the existing underground passage will not affect the surface; Then, the main structure of the new station will be constructed at the same time and the existing underground passage will be completely demolished.

[0016] The beneficial effects of the present invention are as follows: The present invention backfills clay soil inside the existing underground passage first and then uses a vertical shaft to excavate and remove the passage structure at a fixed point, thereby reducing construction difficulty and risk, reducing the disturbance of the passage structure to the stratum, and avoiding the impact on normal ground traffic.

[0017] The present invention demolishes the existing underground passage and constructs new main structures such as ground-connected walls and column piles at the same time, which weakens the time requirement for demolishing the existing passage, speeds up the construction schedule, and ensures the smooth construction of the new subway station. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the conflict section between the existing underground passage and the newly built subway station of the present invention; Figure 2 It is a plan view of the vertical shaft excavation enclosure structure of the present invention; Figure 3 It is a cross-sectional view of the vertical shaft excavation enclosure structure of the present invention; Figure 4 This is a schematic diagram of the completion of the vertical shaft excavation and the construction of a new underground continuous wall and column piles; Figure 5 This is a diagram of a new subway tunnel cover constructed above an existing underground passage by the present invention; Figure 6 This is a schematic diagram of the present invention completely breaking through the existing underground passage. DETAILED DESCRIPTION

[0019] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings and embodiments: like Figures 1 to 6 As shown, a construction method for breaking an existing underground passage by using a vertical shaft excavation comprises the following steps: A. Remove the decoration layer of the existing underground passage; B. Construct a blocking and waterproofing structure at one end of the existing underground passage; C. Backfill the existing underground passage; D. Construct the sealing and waterproofing structure at the other end of the existing underground passage; E. Excavation of underground passages in vertical shafts, construction of ground-connected walls and piles under columns; F. Construction of the cover structure above the underground passage; G. Completely demolish the existing underground passage under the protection of the cover.

[0020] Furthermore, the existing underground passage is located between the cover plate and the middle plate of the new subway station. The existing underground passage conflicts with the new subway station and needs to be abolished.

[0021] Furthermore, the newly constructed ground-anchored walls and column piles of the new metro station vertically penetrate the existing underground passage.

[0022] Furthermore, step A removes the decoration layer of the existing underground passage, and the specific process is as follows: First, the existing underground passage was enclosed using PVC fencing; Then, the decoration layer in the existing underground passage was removed.

[0023] Furthermore, step B constructs a blocking and waterproofing structure at one end of the existing underground passage, and the specific process is as follows: First, a blocking wall is constructed at one end of the existing underground passage; Then, after sealing the wall, the waterproof layer and plain concrete wall were constructed. Finally, the blocking wall adopts reinforced concrete structure and the waterproof layer behind the wall adopts asphalt waterproof membrane.

[0024] Furthermore, step C is to backfill the existing underground passage, and the specific process is as follows: First, the existing underground passage is backfilled in layers with clay soil and compacted; Then, three concrete retaining sills were arranged along the longitudinal direction of the channel during the backfilling process.

[0025] Furthermore, step D constructs the blocking and waterproofing structure at the other end of the existing underground passage, and the specific process is as follows: First, after backfilling is completed, the other end of the existing underground passage is promptly closed; Then, the sealing and waterproofing structure also uses sealing walls, waterproof layers behind walls, and plain concrete walls.

[0026] Furthermore, in step E, the underground passage is excavated in the vertical shaft, and the ground connection wall and column piles are constructed. The specific process is as follows: First, a vertical shaft was excavated from the ground to break the existing underground passage within the scope of the new ground-connected wall; Then, the underground continuous wall is constructed; Finally, the pull-out piles and permanent steel pipe columns are constructed.

[0027] Furthermore, step F is to construct a cover structure above the underground passage, and the specific process is as follows: Based on the underground continuous wall and pull-out piles, the cover slab of the new station is constructed in sequence.

[0028] Furthermore, step G completely breaks down the existing underground passage under the protection of the cover plate. The specific process is as follows: First, after the construction of the cover of the new station is completed, the demolition of the existing underground passage will not affect the surface; Then, the main structure of the new station will be constructed at the same time and the existing underground passage will be completely demolished.

[0029] Specifically, in step E, the underground passage is excavated in the vertical shaft, and the construction site is connected to the wall and the piles under the columns. The plane size of the vertical shaft excavation is 9.2×2.6m (length×width), and the vertical shaft excavation depth is 4.8m.

[0030] Specifically, during the excavation of the shaft, the foundation pit of the shaft retaining structure is supported by Type IV steel sheet piles + four 25a I-beams, among which the four 25a I-beams are arranged along the excavation edge.

[0031] Specifically, before the construction of step E, the range of steel sheet pile driving is determined on the existing hardened road surface, and a breaker hammer is used to break up the road surface within the excavation range of the foundation pit to facilitate the construction of steel sheet piles.

[0032] Specifically, the vault of the existing underground passage is a straight wall section, and the Larsen steel sheet piles of the shaft retaining structure need to be adjusted according to the structural section of the existing underground passage.

[0033] Specifically, during the foundation pit excavation process, steel supports and angle braces are erected in a timely manner, and the supports are set along the excavation edge.

[0034] Specifically, earth excavation can only be carried out after the support is completed. When excavating earth, the principle of vertical stratification and supporting as you dig is followed.

[0035] As an implementation method, the excavation depth of the foundation pit is 4.8m, and the excavation operation is carried out in four layers. The excavation depth of each layer does not exceed 50cm below the corresponding support. The first layer is excavated by an excavator, the second layer is excavated by manual labor and an excavator, and the third and fourth layers are excavated by manual labor and a truck crane.

[0036] Specifically, in order to ensure the overall stability and waterproof effect of the pile bottom of the retaining structure, an inner lining structure is added to the bottom of the shaft pile, and the inner lining structure is reinforced concrete.

[0037] Specifically, step D constructs a blocking and waterproofing structure at the other end of the existing underground passage to prevent backfill soil in the passage from gushing out and affecting other existing underground structures.

[0038] Specifically, Figure 2 and Figure 3 As shown, the plane size of the shaft excavation is 9.2×2.6m (length×width), and the shaft excavation depth is 4.8m. The foundation pit of the shaft retaining structure is supported by type IV steel sheet piles + 4 25a I-beam supports. The type IV steel sheet piles are divided into two types: 6m and 12m.

[0039] More specifically, the 6m Larsen steel sheet piles are used in the long side direction of the shaft, perpendicular to the direction of the underground passage.

[0040] More specifically, the 12m Larsen steel sheet piles are used in the short side direction of the shaft, parallel to the direction of the underground passage. The existing underground passage vault is a straight wall section, and the Larsen steel sheet piles of the shaft enclosure structure are adjusted along the passage structure section.

[0041] Specifically, step E also includes depth control of the steel sheet piles, and the specific process is as follows: First, after the top decoration of the passage is removed and the secondary lining structure is exposed, the surveying personnel will start from the ground and measure the plane position of the ground shaft excavation in the non-paying passage; Then, according to the measured shaft position in the channel, the secondary lining structure contour line is measured and placed at one point every 50cm, and the entire channel contour line and elevation are actually collected as the basis for the control of Larsen steel sheet pile placement; Finally, when constructing the Larsen steel sheet piles for the shaft retaining structure, carry out trial driving more than 5 times, compare and analyze the trial driving data of the Larsen steel sheet piles with the on-site measurement data, and determine the reasonable driving depth.

[0042] Specifically, during the excavation of the foundation pit, steel supports and angle supports are set up in a timely manner, and the supports are set up along the excavation edge. Earth excavation can only be carried out after the support is completed. When excavating earth, the principle of vertical stratification and support as excavation is followed.

[0043] Specifically, the steel supports and angle braces are made of 25a I-beams and connected by welding. Steel corbels are set at the bottom of the steel supports with a spacing of 1.5m. They are made of L75×8mm angle steel, and the brackets are fully welded to the steel sheet piles.

[0044] Specifically, the excavation depth of the foundation pit is 4.8m, and the excavation operation is carried out in four layers. The excavation depth of each layer does not exceed 50cm below the corresponding support. The first layer is excavated by an excavator, the second layer is excavated by manual labor and an excavator, and the third and fourth layers are excavated by manual labor and a truck crane.

[0045] Specifically, Figure 3 As shown, the underground passage is a vaulted straight wall section. The Larsen steel sheet piles of the shaft retaining structure need to be adjusted with the section of the passage structure. The pile bottoms are not in the same plane. At the same time, there is a lot of groundwater at the pile bottom. In order to ensure the overall stability and waterproof effect of the retaining structure pile bottom, a lining structure is added to the shaft pile bottom range. The structure thickness is 200mm, the steel bars are arranged horizontally and vertically with φ10@150mm, and the hooks are arranged in a plum blossom shape with φ10@300×300mm. The lining structure is 2.6m high, and a layer is applied every 50cm as the earthwork is excavated. The concrete uses C30 concrete.

[0046] Specifically, Figure 4 and Figure 5As shown, after the shaft excavation is completed, the passage structure at the corresponding position is demolished, and the ground-anchored wall and column piles of the new subway station are constructed at this position, and the cover slab of the new station is constructed in turn.

[0047] Specifically, Figure 6 As shown, after the construction of the new station cover is completed, the demolition of the underground passage will not affect the surface. At this time, the main body of the new station will be constructed and the existing underground passage will be completely demolished.

[0048] The present invention solves the problem that the demolition of an existing underground tunnel may cause a large disturbance in the surrounding soil, resulting in excessive surface settlement, thereby affecting the construction progress of a new project and normal traffic above the surface.

[0049] The present invention backfills clay soil inside the existing underground passage first and then uses a vertical shaft to excavate and remove the passage structure at a fixed point, thereby reducing construction difficulty and risk, reducing the disturbance of the passage structure to the stratum, and avoiding the impact on normal ground traffic.

[0050] The present invention demolishes the existing underground passage and constructs new main structures such as ground-connected walls and column piles at the same time, which weakens the time requirement for demolishing the existing passage, speeds up the construction schedule, and ensures the smooth construction of the new subway station.

Claims

1. A construction method for breaking an existing underground passage by excavating a vertical shaft, characterized in that: The following steps are involved: A. Remove the decoration layer of the existing underground passage; B. Construct a blocking and waterproofing structure at one end of the existing underground passage; C. Backfill the existing underground passage; D. Construct the sealing and waterproofing structure at the other end of the existing underground passage; E. Excavation of underground passages in vertical shafts, construction of ground-connected walls and piles under columns; F. Construction of the cover structure above the underground passage; G. Completely demolish the existing underground passage under the protection of the cover.

2. A construction method for demolishing an existing underground passage by using a vertical shaft excavation according to claim 1, characterized in that: The existing underground passage is located between the cover plate and the middle plate of the new subway station. The existing underground passage conflicts with the new subway station and needs to be abolished.

3. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1 is characterized in that: The newly built ground-anchored walls and column piles of the new subway station vertically penetrate the existing underground passage.

4. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1 is characterized in that: Step A: Remove the decoration layer of the existing underground passage. The specific process is as follows: First, the existing underground passage was enclosed using PVC fencing; Then, the decoration layer in the existing underground passage was removed.

5. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1 is characterized in that: Step B is to construct the sealing and waterproofing structure at one end of the existing underground passage. The specific process is as follows: First, a blocking wall is constructed at one end of the existing underground passage; Then, after sealing the wall, the waterproof layer and plain concrete wall were constructed. Finally, the blocking wall adopts reinforced concrete structure and the waterproof layer behind the wall adopts asphalt waterproof membrane.

6. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1 is characterized in that: Step C is to backfill the existing underground passage. The specific process is as follows: First, the existing underground passage is backfilled in layers with clay soil and compacted; Then, three concrete retaining sills were arranged along the longitudinal direction of the channel during the backfilling process.

7. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1 is characterized in that: Step D is to construct the blocking and waterproofing structure at the other end of the existing underground passage. The specific process is as follows: First, after backfilling is completed, the other end of the existing underground passage is promptly closed; Then, the sealing and waterproofing structure also uses sealing walls, waterproof layers behind walls, and plain concrete walls.

8. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1 is characterized in that: Step E: excavate the underground passage in the vertical shaft, construct the ground-connected wall and the piles under the columns. The specific process is as follows: First, a vertical shaft was excavated from the ground to break the existing underground passage within the scope of the new ground-connected wall; Then, the underground continuous wall is constructed; Finally, the pull-out piles and permanent steel pipe columns are constructed.

9. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1, characterized in that: Step F constructs the cover structure above the underground passage, and the specific process is as follows: Based on the underground continuous wall and pull-out piles, the cover slab of the new station is constructed in sequence.

10. The construction method of breaking an existing underground passage by using a vertical shaft excavation according to claim 1, characterized in that: Step G completely demolishes the existing underground passage under the protection of the cover plate. The specific process is as follows: First, after the construction of the cover of the new station is completed, the demolition of the existing underground passage will not affect the surface; Then, the main structure of the new station will be constructed at the same time and the existing underground passage will be completely demolished.

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