Construction method for underground excavation tunnel to pass through operating subway station in close range

Abstract

The invention relates to a tunnel construction reinforcement measure, and particularly discloses a construction method for a subsurface tunnel to pass through an operating subway station in a close range, which comprises the following steps: when a to-be-excavated tunnel is excavated to a position which is a certain distance away from an existing line station, temporarily closing a tunnel face to construct a grout stop wall, reinforcing a soil body in a front range by adopting deep hole grouting, and controlling the grouting pressure; the influence on the existing line is reduced as much as possible; and after grouting is completed, the grout stopping wall is broken, primary supporting structure excavation and supporting are conducted, the grout stopping wall is constructed again when excavation is conducted for the first time to the boundary of the station, the grout stopping wall is constructed again every time a certain distance is excavated in a subsequent cavity, the soil layer in a certain range in front is reinforced, and circulation is conducted till the tunnel face passes through the existing line station. By means of the construction mode of circular grouting reinforcement, temporary inverted arch supporting and upper and lower pilot tunnel excavation, the problem that collapse is prone to occurring in tunnel excavation under existing lines is solved, and meanwhile the construction period is effectively shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of construction of mined tunnels, and more particularly to a construction method for a mined tunnel closely passing under an operating subway station. Background Art

[0002] During the construction of the subway, it is usually necessary to excavate a tunnel passing through an existing operating subway. The vertical distance between the existing line and the tunnel to be excavated is generally only a few meters, making the construction of the tunnel to be excavated extremely difficult. During the tunnel excavation process, without timely and effective reinforcement measures, problems such as collapse and settlement are likely to occur during the construction, affecting the operation of the existing subway line; while the implementation of ordinary reinforcement measures seriously affects the construction period. For example, when using the CRD four - pilot - hole construction method for a rectangular tunnel section, although the tunnel can be divided into multiple pilot holes to increase the structural strength and the ability to resist risks, its construction period is relatively long. Each pilot hole needs to be excavated in a certain order, and the construction risk of removing the temporary support is relatively large. Summary of the Invention

[0003] Aiming at the problem of the serious contradiction between the reinforcement measures and the construction period in the existing construction methods, the present invention provides a construction method for a mined tunnel closely passing under an operating subway station, which can ensure the reinforcement strength and realize the tunnel excavation without affecting the operation of the existing subway, effectively reducing the construction period.

[0004] The present invention is realized through the following technical solutions:

[0005] A construction method for a mined tunnel closely passing under an operating subway station includes the following steps:

[0006] 1) When the tunnel in the construction section to be constructed is excavated to the position of the first distance outside the side - pile strip foundation of the existing operating subway station, temporarily seal the working face to construct a grout - stopping wall, and adopt deep - hole grouting to reinforce the soil mass in the range of the second distance in front of the working face, where the second distance is greater than the first distance; after the grouting is completed, break through the grout - stopping wall in the upper - half section to carry out the excavation and support of the primary support structure until the outside of the side - pile strip foundation of the existing operating subway station.

[0007] 2) Construct the first - cycle grout - stopping wall at the position close to the outside of the side - pile strip foundation, and adopt deep - hole grouting to reinforce the soil mass in the range of the third distance in front of the first - cycle grout - stopping wall; after the grouting is completed, break through the grout - stopping wall in the upper - half section to carry out the excavation and support of the primary support structure, and excavate and support to the depth of the fourth distance. When supporting, include constructing a temporary inverted arch at the bottom of the upper - half section, where the fourth distance is less than the third distance.

[0008] 3) Construct the Nth cycle grouting wall close to the tunnel face of the upper section, and use deep hole grouting to reinforce the soil in the third distance range in front of the Nth cycle grouting wall; after the grouting is completed, remove the upper section grouting wall to carry out the excavation and support of the primary support structure, and excavate and support the depth of the fourth distance, including constructing a temporary invert at the bottom of the upper section;

[0009] 4) Repeat the construction method in step 3), excavate and support until it exceeds the outer side of the side pile strip foundation on the other side of the existing operating subway station, and then stop the cycle, thus completing the construction of the crossing section of the upper section;

[0010] 5) Compensatory grouting is performed again from the temporary invert of the upper section to the lower section; after the grouting is completed, the lower section is excavated to complete the crossing section construction of the lower section.

[0011] Optionally, in step 3), when the upper section is excavated and supported and there is a fifth distance offset depth from the lower section, compensatory grouting is performed on the lower section again.

[0012] Optionally, the fifth distance is 15m.

[0013] Optionally, in step 3), radial compensatory grouting is performed on the grouting blind area using a small conduit.

[0014] Optionally, the first distance is 12 m, the second distance is 9 m, the third distance is 12 m, and the fourth distance is 9 m or 10 m.

[0015] Optionally, in step 3), between different cycles, the fourth distance adopts the same or different numerical ranges.

[0016] A construction method for a dark-excavated tunnel passing under an operating subway station at a close distance comprises the following steps:

[0017] 1) Standard grouting: 12m / section grouting range to the bottom of the side pile strip foundation;

[0018] 2) After grouting is completed, the upper half section grouting wall is removed to carry out the initial support structure excavation and support until the outside of the side pile strip foundation; the first cycle grouting wall 1 is closely attached to the outside of the side pile strip foundation, overlapping the standard grouting area of 12m / section by 3m, and the grouting hole is grouting in the grouting area 1; the first cycle grouting length is 12m, and the grouting is carried out to the bottom of the existing station middle guide tunnel strip foundation;

[0019] 3) After grouting is completed, the grouting wall of the upper section is removed to carry out excavation and support of the primary support structure; the second cycle of grouting is 12m long, and grouting is carried out to the side of the existing station side pile strip foundation; and radial compensation grouting is carried out with a small guide tube in the blind area of grouting; the lower section is staggered 15m from the upper section, and compensation grouting is carried out again, and excavation is carried out after grouting is completed;

[0020] 4) The upper half section is excavated to a position 2 m away from the mid-span of the side span of the existing station to set up a grout stop wall 3. The grouting range of the third cycle overlaps with the grouting area 2 by 2 m. The grouting depth of the third cycle is 12 m. Small ducts are used for radial compensatory grouting in the grouting blind area. For the lower half section, it is staggered from the upper half section by 15 m, and compensatory grouting is carried out again. After the grouting is completed, excavation is followed up.

[0021] 5) After the upper half section completes the excavation and crossing, the upper half section is changed to standard grouting and excavated forward. The area below the existing line is compensated for grouting again from the temporary inverted arch of the upper half section to the lower half section. After the grouting is completed, the lower half section excavates the crossing section.

[0022] The technical solution of the present invention has at least the following beneficial effects:

[0023] The construction method for a mined tunnel to closely pass under an operating subway station of the present invention, through grouting reinforcement, excavation and support in the length direction of the tunnel to be excavated, relies on the temporary inverted arch to complete the closed-loop support of the upper half section during support, improving the support strength. During the excavation of the upper half section, grouting reinforcement is continuously carried out on the lower half section, thereby further improving the strength of the soil mass in the excavated formation and avoiding collapse or settlement. After the upper half section completes the excavation and crossing, the lower half section is then excavated. The entire process is completed by relying on the upper and lower pilot tunnels. Compared with the four-pilot-tunnel CRD construction method of the prior art, the construction period is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the tunnel construction structure in step 1) of Embodiment 1 of the present invention;

[0025] Figure 2 It is a schematic diagram of the tunnel construction structure in step 2) of Embodiment 1 of the present invention;

[0026] Figure 3 It is a schematic diagram of the tunnel construction structure in step 3) of Embodiment 1 of the present invention;

[0027] Figure 4 It is a schematic diagram of the tunnel construction structure in step 4) of Embodiment 1 of the present invention;

[0028] Figure 5 It is a schematic diagram of the tunnel construction structure in step 5) of Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Embodiment 1:

[0030] A construction method for a mined tunnel to closely pass under an operating subway station includes the following steps:

[0031] 1) Refer to Figure 1 , the grouting range of 12 m per section of standard grouting reaches below the side pile strip foundation; control the grouting pressure to minimize the impact on the existing line;

[0032] 2) Refer to Figure 2 , after grouting is completed, break through the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure until the outside of the side pile strip foundation; the first cycle grout stop wall 1 is closely attached to the outside of the side pile strip foundation, overlapping with the standard grouting 12m / section area by 3m, and grouting is carried out in the grouting hole grouting area 1; the first cycle grouting length is 12m, and grouting is carried out until below the existing station middle pilot tunnel strip foundation;

[0033] 3) Refer to Figure 3 , after grouting is completed, break through the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure; the second cycle grouting length is 12m, and grouting is carried out until the side of the existing station side pile strip foundation; and small duct radial compensation grouting is carried out for the grouting blind area; in the lower half section, stagger 15m from the upper half section, and carry out compensation grouting again. After the grouting is completed, follow up with the excavation;

[0034] 4) Refer to Figure 4 , when the upper half section is excavated to a position 3 grout stop walls are set up at the mid-span of the side span of the existing station, and the third cycle grouting range overlaps with the grouting area 2 by 2m; the third cycle grouting depth is 12m; and small duct radial compensation grouting is carried out for the grouting blind area; in the lower half section, stagger 15m from the upper half section, and carry out compensation grouting again. After the grouting is completed, follow up with the excavation;

[0035] 5) Refer to Figure 5 , after the upper half section is excavated and passed through, the upper half section is changed to standard grouting and excavated forward; the area below the existing line is compensated grouted again from the temporary inverted arch in the upper half section to the lower half section; after the grouting is completed, the lower half section is excavated through the section.

[0036] The construction method for the mined tunnel to closely pass under the operating subway station of the present invention, through the grouting reinforcement of the entire section in the length direction of the tunnel to be excavated, the excavation and support of the upper half section, and relying on the temporary inverted arch to complete the closed-loop support of the upper half section during support, improving the support strength. During the excavation of the upper half section, continue to grout and reinforce the lower half section. Through such a construction method, the structural strength of the soil body below the existing line or the existing line station is significantly improved, avoiding tunnel collapse or settlement during excavation, and at the same time minimizing the impact on the existing line as much as possible. After the upper half section is excavated and passed through, the lower half section is then excavated. The entire process is completed by relying on the upper and lower pilot tunnels. While ensuring that the structural strength meets the construction requirements, the construction period is significantly improved compared with the four-pilot tunnel CRD construction method of the prior art.

[0037] Example 2:

[0038] A construction method for the mined tunnel to closely pass under the operating subway station, comprising the following steps:

[0039] 1) When the tunnel in the construction section is excavated to the position of the first distance outside the side pile strip foundation of the existing operating subway station, in this embodiment, the first distance is 9m. Of course, it can also be appropriately adjusted according to the site conditions. For the area more than 9m outside the side pile strip foundation of the existing operating subway station, the construction can be carried out according to the conventional tunnel excavation construction method, such as construction steps like arch crown grouting reinforcement, tunnel excavation and support, and secondary lining. The arch crown grouting is continuously carried out until the outside of the side pile strip foundation of the existing operating subway station.

[0040] Temporarily seal the heading face to construct a grout stopping wall, and adopt deep-hole grouting to reinforce the soil mass in the range of the second distance in front of the heading face, control the grouting pressure, and try to minimize the impact on the existing line. The second distance is greater than the first distance. In this embodiment, the second distance is 12m. In this way, the grouting range can extend beyond the side of the side pile strip foundation of the existing operating subway station. Specifically, in the numerical range of this embodiment, it can extend 3m in length. During the subsequent excavation process, the structural strength of the tunnel under the side pile strip foundation of the existing operating subway station can be ensured. After the grouting is completed, break the grout stopping wall in the upper half section to carry out the excavation and support of the primary support structure until the outside of the side pile strip foundation of the existing operating subway station. In this embodiment, the excavation length is 9m, and 3m is reserved without excavation, just reaching the outside edge of the side pile strip foundation of the existing operating subway station.

[0041] 2) Construct the first cycle grout stopping wall at the position close to the outside of the side pile strip foundation, and adopt deep-hole grouting to reinforce the soil mass in the range of the third distance in front of the first cycle grout stopping wall. The range of the third distance is 12m in this embodiment; after the grouting is completed, break the grout stopping wall in the upper half section to carry out the excavation and support of the primary support structure, and excavate and support to the depth of the fourth distance. The fourth distance is 9m in this embodiment. When supporting, a temporary inverted arch is constructed at the bottom of the upper half section. The fourth distance is less than the third distance. The grouting range is the third distance of 12m, and the excavation depth is the fourth distance of 9m, ensuring that there is always an overlapping range of 3m for grouting to avoid the collapse of the heading face after excavation.

[0042] 3) Construct the Nth cycle grout stopping wall at the position of the heading face close to the upper half section, and adopt deep-hole grouting to reinforce the soil mass in the range of the third distance in front of the Nth cycle grout stopping wall; after the grouting is completed, break the grout stopping wall in the upper half section to carry out the excavation and support of the primary support structure, and excavate and support to the depth of the fourth distance. When supporting, a temporary inverted arch is constructed at the bottom of the upper half section. In this step, the construction can be carried out in cycles according to the third distance of 12m for grouting range and the fourth distance of 9m for excavation depth. Of course, between different cycles, the fourth distance can adopt the same or different numerical ranges. For example, the excavation depth can be 9m each time, always maintaining an overlapping range of 3m; of course, the fourth distance can also be appropriately adjusted according to the construction position. For example, during the last excavation, the excavation depth can be 10m.

[0043] During the grouting process, due to the concave cavity structure between the side span and the side pile strip foundation of the existing line, there is a grouting blind area, so small-tube radial compensation grouting is carried out in the grouting blind area.

[0044] When the upper section is excavated and supported and there is a fifth distance offset depth from the lower section, compensatory grouting is performed on the lower section again. That is to say, the distance between the heading face of the upper section and the heading face of the lower section must be judged in each cycle. If it exceeds the fifth distance, which is 15m in this embodiment, compensatory grouting is required for the lower section to further improve the structural strength of the soil in the lower section.

[0045] 4) Follow the construction method of step 3) in a cycle, excavate and support until it exceeds the outside of the side pile strip foundation on the other side of the existing operating subway station, then stop the cycle, and the construction of the crossing section of the upper section is completed.

[0046] 5) Compensatory grouting is performed again from the temporary invert of the upper section to the lower section; after the grouting is completed, the lower section is excavated to complete the crossing section construction of the lower section.

[0047] The construction method of the dark-excavated tunnel under the operating subway station at a close distance of the present invention is to reinforce the entire section in the length direction of the tunnel to be excavated by grouting, excavate and support the upper section, and rely on a temporary invert to complete the closed-loop support of the upper section during support to improve the support strength. During the excavation of the upper section, the lower section is continuously reinforced by grouting. Through such a construction method, the structural strength of the soil under the existing line or the existing line station is significantly improved, and tunnel collapse or settlement is avoided during the excavation process, while the existing line is affected as little as possible. After the excavation of the upper section is completed, the lower section is excavated and constructed. The entire process is completed by relying on the upper and lower guide holes. Under the condition of ensuring that the structural strength meets the construction requirements, the construction period is significantly improved compared with the four-guide hole CRD construction method of the prior art.

Claims

1. A construction method for a mined tunnel to pass under an operating subway station at a short distance, characterized in that, It includes the following steps: 1) When the tunnel in the construction section is excavated to the position at the first distance outside the strip foundation of the side pile of the existing operating subway station, temporarily seal the heading face to construct a grout stop wall, and adopt deep-hole grouting to reinforce the soil mass in the range of the second distance in front of the heading face, where the second distance is greater than the first distance; after the grouting is completed, break the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure until the outside of the strip foundation of the side pile of the existing operating subway station; 2) Construct the first-cycle grout stop wall at the position close to the outside of the strip foundation of the side pile, and adopt deep-hole grouting to reinforce the soil mass in the range of the third distance in front of the first-cycle grout stop wall; after the grouting is completed, break the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure, and excavate and support to the depth of the fourth distance. When supporting, it includes constructing a temporary invert at the bottom of the upper half section, and the fourth distance is less than the third distance; 3) Construct the Nth-cycle grout stop wall at the position close to the heading face of the upper half section, and adopt deep-hole grouting to reinforce the soil mass in the range of the third distance in front of the Nth-cycle grout stop wall; after the grouting is completed, break the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure, and excavate and support to the depth of the fourth distance. When supporting, it includes constructing a temporary invert at the bottom of the upper half section; 4) Cycle and construct according to the construction method in step 3). When the excavation and support reach beyond the outside of the strip foundation of the side pile on the other side of the existing operating subway station, stop the cycle. Thus, the construction of the crossing section in the upper half section is completed; 5) Re-compensate grouting from the temporary invert in the upper half section to the lower half section; after the grouting is completed, excavate the lower half section to complete the construction of the crossing section in the lower half section.

2. The construction method for a mined tunnel to pass under an operating subway station at a short distance according to claim 1, characterized in that, In step 3), when there is a staggered depth of the fifth distance between the upper half section after excavation and support and the lower half section, re-compensate grouting is carried out on the lower half section.

3. The construction method for the mined tunnel to pass under the operating subway station at a short distance according to claim 2, characterized in that The fifth distance is 15m.

4. The construction method for the mined tunnel to pass under the operating subway station at a short distance according to claim 1, characterized in that, In step 3), small pipe radial compensation grouting is carried out for the grouting blind area.

5. The construction method for the mined tunnel to pass under an operating subway station at a close distance according to claim 1, characterized in that, The first distance is 12m, the second distance is 9m, the third distance is 12m, and the fourth distance is 9m or 10m.

6. The construction method for the mined tunnel to pass under the operating subway station at a short distance according to claim 1, characterized in that, In step 3), between different cycles, the fourth distance adopts the same or different numerical ranges.

7. A construction method for a mined tunnel to pass under an operating subway station at a short distance, characterized in that, It includes the following steps: 1) Standard grouting: The grouting range is 12m per section to the lower part of the strip foundation of the side pile; 2) After the grouting is completed, break the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure until the outside of the strip foundation of the side pile; The first-cycle grout stop wall 1 is closely attached to the outside of the strip foundation of the side pile, overlapping with the standard grouting area of 12m per section by 3m, and the grouting holes are used for grouting in grouting area 1; The first-cycle grouting length is 12m, and the grouting reaches below the middle guide hole strip foundation of the existing station; 3) After the grouting is completed, break the grout stop wall in the upper half section to carry out the excavation and support of the primary support structure; The second-cycle grouting length is 12m, and the grouting reaches the side of the strip foundation of the existing station's side pile; And small pipe radial compensation grouting is carried out for the grouting blind area; In the lower half section, it is staggered by 15m from the upper half section, and re-compensate grouting is carried out. After the grouting is completed, follow-up excavation is carried out; 4) When the upper half section is excavated to the position at the mid-span of the side span of the existing station, construct a grout stop wall 3. The third-cycle grouting range overlaps with grouting area 2 by 2m; The third-cycle grouting depth is 12m; And small pipe radial compensation grouting is carried out for the grouting blind area; In the lower half section, it is staggered by 15m from the upper half section, and re-compensate grouting is carried out. After the grouting is completed, follow-up excavation is carried out; 5) After the upper half section excavation is completed and the crossing is passed through, the upper half section is changed to standard grouting for forward excavation; the area below the existing line is compensated for grouting again from the temporary inverted arch of the upper half section to the lower half section; after the grouting is completed, the lower half section excavation is completed for the crossing section.

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