Method for reconstructing cross-hole tunnel adapted to elevation adjustment of main line tunnel

Abstract

The technical problem to be solved by the present application is to provide a transverse tunnel reconstruction method suitable for the elevation adjustment of a main tunnel, so as to solve the problem that the transverse tunnel form still needs to be used to play the drainage and transportation functions after the adjustment of the main tunnel line position, and to avoid the problem that the constructed transverse tunnel becomes a "waste project". The method comprises the following steps: adjusting the main tunnel line position in the form of avoiding crossing or crossing as short as possible according to the distribution characteristics of the adverse geology; determining the position of the intersection point of the transverse tunnel and the main tunnel after the adjustment of the line position, and then determining the elevation H of the transverse tunnel bottom at the intersection point; according to the elevation H of the transverse tunnel bottom at the intersection point of the main tunnel and the transverse tunnel after the adjustment, judging whether the elevation H is in the following range, and then selecting a reconstruction technical scheme: if H is in the limit lowering range H0-H1, a transverse tunnel lowering slope small slope reconstruction technical scheme is selected; if H is in the reasonable range H1-H2, a transverse tunnel slope adaptability reconstruction technical scheme is selected; and if H is in the limit lifting range H2-H3, a transverse tunnel spiral large slope reconstruction technical scheme is selected.

Description

Technical Field

[0001] This invention belongs to the field of tunnel and underground engineering technology, and relates to a method for modifying cross tunnels after the elevation of the main tunnel has been adjusted. Background Technology

[0002] In the southwest region, long tunnels account for a relatively high proportion. Due to the engineering difficulty and construction period, it is necessary to construct large-scale auxiliary tunnels, such as cross passages, inclined shafts, and pilot tunnels. Among them, cross passages are designed as tunnels with a longitudinal slope of not less than 3‰ downhill towards the outside of the tunnel to facilitate drainage and construction transportation during the tunnel construction and operation periods.

[0003] For long tunnels, the limited accuracy of the survey during the design phase makes the unpredictability of tunnels traversing complex geological conditions even more prominent, posing a significant obstacle to normal tunnel construction. In most cases, a method of "excavating while revising the design" is adopted. However, when encountering extremely complex geological conditions, continuing to construct the tunnel according to the original design would increase engineering investment significantly to address adverse geological conditions, and could also lead to uncontrollable construction schedules and impact on railway operational safety. Therefore, after comprehensive analysis and comparison, within the acceptable range for the line, the railway alignment will be changed to avoid or minimize the passage through adverse geological conditions. Simultaneously, after changing the main tunnel alignment of a long tunnel, if the already constructed auxiliary tunnels are still constructed in a straight line to the changed main tunnel alignment, the tunnel slope may be reversed. Cross passages originally designed for drainage may become "abandoned projects." Specifically, during the main tunnel construction and operation, a large amount of groundwater cannot be discharged to the outside of the tunnel in sections through the tunnels. Considering tunnel construction and operational safety, it is necessary to reselect the location of the cross passages. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for the reconstruction of cross tunnels after the elevation adjustment of the main tunnel, so as to solve the problem that the cross tunnels still need to be used to perform drainage and transportation functions after the main tunnel alignment is adjusted, and to avoid the cross tunnels that have been constructed becoming "abandoned projects".

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] This invention relates to a method for modifying cross passages after the elevation of a main tunnel has been adjusted, and includes the following steps:

[0007] Step 1: Adjust the alignment of the main tunnel based on the characteristics of adverse geological conditions, in order to avoid crossing or to cross the tunnel in the shortest possible distance;

[0008] Step 2: Determine the location of the intersection of the transverse tunnel and the main tunnel after adjusting the alignment, and then determine the elevation H of the bottom of the transverse tunnel at the intersection.

[0009] Step 3: Based on the adjusted elevation H of the bottom of the transverse tunnel at the intersection of the main tunnel and the transverse tunnel, determine which range it falls within, and then select a targeted modification technical solution:

[0010] ① If H is within the extreme reduction range of H0 to H1, then the cross tunnel slope reduction type small slope modification technology scheme shall be selected. H0 is the bottom elevation of the pit from the cross tunnel entrance with an extreme slope of 3‰ to the intersection point, which is the lower limit of the extreme reduction range. H1 is the bottom elevation of the pit from the current working face of the cross tunnel with an extreme slope of 3‰ to the intersection point, which is the upper limit of the extreme reduction range and the lower limit of the reasonable range.

[0011] ② If H is within the reasonable range of H1 to H2, then the cross tunnel slope adaptation modification technology scheme shall be selected. H2 is the bottom elevation of the pit from the current working face of the cross tunnel with a maximum slope of 5% to the intersection point, which is the upper limit of the reasonable range and the lower limit of the maximum elevation range.

[0012] ③ If H is within the extreme elevation range H2~H3, then the transverse tunnel spiral type large slope modification technology scheme shall be selected. H3 is the bottom elevation of the pit from the current working face of the transverse tunnel with an extreme slope of 5% to the intersection point, which is the upper limit of the extreme elevation range.

[0013] ④ If none of H falls within the above range, the adjusted main tunnel alignment will inevitably cause the constructed cross tunnels to become "abandoned projects," so the main tunnel alignment will be adjusted and optimized.

[0014] The method for determining H0, H1, H2, and H3 is as follows: H0 = h0 + (L0 + L1) × 3‰, H1 = h1 + (L1) × 3‰, H2 = h1 + (L1) × 5%, H3 = h1 + (L1') × 5%, where L1' should not be greater than twice L1 and should not be greater than 1000m;

[0015] In the formula: h0 is the bottom elevation of the pit at the entrance of the constructed cross tunnel, h1 is the bottom elevation of the pit at the working face of the constructed cross tunnel, L0 is the length of the constructed cross tunnel section, L1 is the straight-line distance from the working face of the constructed cross tunnel to the intersection of the adjusted main tunnel and the cross tunnel, and L1' is the detour distance from the working face of the constructed cross tunnel to the intersection of the adjusted main tunnel and the cross tunnel.

[0016] The proposed cross-tunnel slope reduction technology is divided into two schemes based on the appropriate distance Lg from the retreating cross-tunnel face: if Lg does not exceed 300m, the bottom of the pit is modified and a drainage culvert is installed; if Lg exceeds 300m but is not greater than L0, a bypass drainage cross-tunnel is opened at the appropriate distance Lg from the retreating cross-tunnel face, with a minimum drainage slope of 3‰ connecting to the main tunnel; the unconstructed cross-tunnel is designed with a 3‰ slope, and the location of its intersection with the bottom of the constructed cross-tunnel is taken as Lg.

[0017] The proposed cross-tunnel slope adaptation technology involves adjusting the elevation of the intersection point between the cross-tunnel and the main tunnel according to the elevation of the main tunnel, so that the slopes of the unconstructed cross-tunnel section can be smoothly connected to those of the constructed cross-tunnel section.

[0018] The proposed transverse tunnel spiral-type steep slope modification technology involves increasing the length of the transverse tunnel at the working face of the existing transverse tunnel by spiraling around it, with a slope of 5%, to match the elevation increase of the main line.

[0019] The beneficial effects of this invention are mainly reflected in the following aspects:

[0020] First, three technical solutions were proposed for different main tunnel alignment ranges: small-slope modification of cross tunnels, slope-adaptive modification of cross tunnels, and large-slope modification of cross tunnels with spiraling paths. These solutions solved the problem that cross tunnels could not perform their drainage and transportation functions after the main tunnel alignment was adjusted, thus ensuring the safety of railway tunnel construction and operation.

[0021] Second, it reduced the impact of rerouting the main tunnel on project investment and avoided turning the constructed cross tunnels into "abandoned projects", which is in line with the "dual carbon" target. Attached Figure Description

[0022] This instruction manual includes the following eight figures:

[0023] Figure 1 This is a flowchart of the method for modifying cross tunnels after the elevation adjustment of the main tunnel, which is adapted to the present invention.

[0024] Figure 2 This is a longitudinal section diagram of the bypass drainage tunnel in the transverse tunnel slope reduction type small slope modification technology;

[0025] Figure 3 This is a plan view of the bypass drainage transverse tunnel, which is part of the transverse tunnel slope reduction type small slope modification technology.

[0026] Figure 4 This is a longitudinal section diagram of the drainage culvert buried at the bottom of the pit in the transverse tunnel slope reduction type small slope modification technology.

[0027] Figure 5 This is a plan view of the drainage culvert buried at the bottom of the pit in the transverse tunnel slope reduction type small slope modification technology;

[0028] Figure 6 This is a longitudinal section diagram of the transverse tunnel slope adaptive modification technology;

[0029] Figure 7 This is a longitudinal section diagram of the transverse tunnel spiral-type steep slope modification technology;

[0030] Figure 8 This is a plan view of the horizontal tunnel spiral-shaped steep slope modification technology. Detailed Implementation

[0031] The invention will be further described below with reference to the accompanying drawings.

[0032] Reference Figure 1 This invention relates to a method for modifying cross passages after the elevation of a main tunnel has been adjusted, and includes the following steps:

[0033] Step 1: Adjust the alignment of the main tunnel based on the characteristics of adverse geological features, in order to avoid crossing or to cross the tunnel in the shortest possible distance;

[0034] Step 2: Determine the location of the intersection of the transverse tunnel and the main tunnel after adjusting the alignment, and then determine the elevation H of the bottom of the transverse tunnel at the intersection.

[0035] Step 3: Based on the adjusted elevation H of the bottom of the transverse tunnel at the intersection of the main tunnel and the transverse tunnel, determine which range it falls within, and then select a targeted modification technical solution:

[0036] ① If H is within the extreme reduction range of H0 to H1, then the cross tunnel slope reduction type small slope modification technology scheme shall be selected. H0 is the bottom elevation of the pit from the cross tunnel entrance with an extreme slope of 3‰ to the intersection point, which is the lower limit of the extreme reduction range. H1 is the bottom elevation of the pit from the current working face of the cross tunnel with an extreme slope of 3‰ to the intersection point, which is the upper limit of the extreme reduction range and the lower limit of the reasonable range.

[0037] ② If H is within the reasonable range of H1 to H2, then the cross tunnel slope adaptation modification technology scheme shall be selected. H2 is the bottom elevation of the pit from the current working face of the cross tunnel with a maximum slope of 5% to the intersection point, which is the upper limit of the reasonable range and the lower limit of the maximum elevation range.

[0038] ③ If H is within the extreme elevation range H2~H3, then the transverse tunnel spiral type large slope modification technology scheme shall be selected. H3 is the bottom elevation of the pit from the current working face of the transverse tunnel with an extreme slope of 5% to the intersection point, which is the upper limit of the extreme elevation range.

[0039] ④ If none of H falls within the above range, the adjusted main tunnel alignment will inevitably cause the constructed cross tunnels to become "abandoned projects," so the main tunnel alignment will be adjusted and optimized.

[0040] The method for determining H0, H1, H2, and H3 is as follows: H0 = h0 + (L0 + L1) × 3‰, H1 = h1 + (L1) × 3‰, H2 = h1 + (L1) × 5%, H3 = h1 + (L1') × 5%, where L1' should not be greater than twice L1 and should not be greater than 1000m;

[0041] In the formula: h0 is the bottom elevation of the pit at the entrance of the constructed cross tunnel, h1 is the bottom elevation of the pit at the working face of the constructed cross tunnel, L0 is the length of the constructed cross tunnel section, L1 is the straight-line distance from the working face of the constructed cross tunnel to the intersection of the adjusted main tunnel and the cross tunnel, and L1' is the detour distance from the working face of the constructed cross tunnel to the intersection of the adjusted main tunnel and the cross tunnel.

[0042] Reference Figures 2-5 The proposed transverse tunnel slope reduction technology is divided into two schemes based on the appropriate distance Lg from the tunnel face: if Lg does not exceed 300m, the bottom of the pit is modified and a drainage culvert is installed, such as... Figure 2 and Figure 3 If Lg exceeds 300m but is not greater than L0, a bypass drainage tunnel should be constructed at a suitable distance Lg from the tunnel face, connecting to the main tunnel with a minimum drainage slope of 3‰. Figure 4 and Figure 5 The unconstructed section of the cross tunnel is designed with a slope of 3‰. The location of its intersection with the bottom of the constructed section of the cross tunnel is taken as Lg.

[0043] Reference Figure 6 The aforementioned cross-tunnel slope adaptive modification technology solution involves adjusting the elevation of the intersection point between the cross-tunnel and the main tunnel according to the elevation of the main tunnel, so that the slopes of the unconstructed cross-tunnel section and the constructed cross-tunnel section can be smoothly connected.

[0044] Reference Figure 7 and Figure 8 The proposed transverse tunnel spiral-type steep slope modification technology involves increasing the length of the transverse tunnel at the working face of the existing transverse tunnel by spiraling around it, with a slope of 5%, to match the elevation of the main line. Example

[0045] The Chengdu-Kunming Railway Line Emei-Miyi section expansion project involves approximately 5.6 kilometers of the Jiermu Tunnel exit section and approximately 5.3 kilometers of the Xinbaishiyan Tunnel entrance section, which traverse Upper Sinian dolomite strata. Construction revealed that this section of dolomite strata has undergone dissolution and sandification under the influence of regional fault structures and groundwater, forming irregular and unfavorable geological formations such as sand-bricks and gravel, posing significant construction challenges and safety risks. Furthermore, the steep slopes at both ends of the Jiermu and Xinbaishiyan tunnels, influenced by unloading fissures, present a high risk of rockfalls and potential safety hazards during operation. Considering the current construction status, it is necessary to make local adjustments to the horizontal and vertical profiles of the tunnels to reduce engineering risks. At this time, 821 meters of the No. 2 cross passage and 50 meters of the No. 3 cross passage of the Jiermu Tunnel have been completed.

[0046] To avoid rendering the already constructed cross passages unusable, the method of this invention was used in the design of alignment adjustments and tunnels. Specifically, the elevation at the intersection of the No. 2 cross passage and the main tunnel of the Jiermu Tunnel was lowered by 5.911m compared to the original design. To utilize the existing constructed section of the No. 2 cross passage of the Jiermu Tunnel, an adjustment scheme using a small-slope modification technique for the cross passage was adopted, involving a bypass drainage cross passage. Figure 2 , Figure 3 The elevation at the intersection of the No. 3 cross passage and the main tunnel of the Jiermu Tunnel was lowered by 5.749m compared to the original design. To utilize the existing constructed section of the No. 3 cross passage of the Jiermu Tunnel, an adjustment was made using a small-slope modification technique involving the installation of drainage culverts. Figure 4 , Figure 5 The method of this invention reduces engineering scrapping caused by the rerouting of the main tunnel, saving approximately 17.42 million yuan in physical engineering investment.

[0047] This invention proposes three technical solutions for different main tunnel alignments: gentle slope modification of cross passages, slope-adaptive modification of cross passages, and spiral modification of cross passages with large slopes. These solutions address the problem of cross passages failing to fulfill their drainage and transportation functions after main tunnel alignment adjustments, ensuring the safety of railway tunnel construction and operation. Simultaneously, they reduce the impact of main tunnel alignment changes on project investment and prevent already constructed cross passages from becoming "abandoned projects," thus aligning with "dual carbon" targets.

[0048] The above description is merely an illustration of some principles of the present invention for the transformation of cross tunnels after the elevation adjustment of the main tunnel. It is not intended to limit the present invention to the specific structures and applicable scope shown and described. Therefore, all possible modifications and equivalents that may be used fall within the scope of the patent application of this invention.

Claims

1. A method for modifying cross passages after the elevation adjustment of the main tunnel, comprising the following steps: Step 1: Adjust the alignment of the main tunnel based on the characteristics of adverse geological conditions, in order to avoid crossing or to cross the tunnel in the shortest possible distance; Step 2: Determine the location of the intersection of the transverse tunnel and the main tunnel after adjusting the alignment, and then determine the elevation H of the bottom of the transverse tunnel at the intersection. Step 3: Based on the adjusted elevation H of the bottom of the transverse tunnel at the intersection of the main tunnel and the transverse tunnel, determine which range it falls within, and then select a targeted modification technical solution: ① If H is within the extreme reduction range of H0 to H1, then the cross tunnel slope reduction type small slope modification technology scheme shall be selected. H0 is the bottom elevation of the pit from the cross tunnel entrance with an extreme slope of 3‰ to the intersection point, which is the lower limit of the extreme reduction range. H1 is the bottom elevation of the pit from the current working face of the cross tunnel with an extreme slope of 3‰ to the intersection point, which is the upper limit of the extreme reduction range and the lower limit of the reasonable range. ② If H is within the reasonable range of H1 to H2, then the cross tunnel slope adaptation modification technology scheme shall be selected. H2 is the bottom elevation of the pit from the current working face of the cross tunnel with a maximum slope of 5% to the intersection point, which is the upper limit of the reasonable range and the lower limit of the maximum elevation range. ③ If H is within the extreme elevation range H2~H3, then the transverse tunnel spiral type large slope modification technology scheme shall be selected. H3 is the bottom elevation of the pit from the current working face of the transverse tunnel with an extreme slope of 5% to the intersection point, which is the upper limit of the extreme elevation range. ④ If none of H falls within the above range, the adjusted main tunnel alignment will inevitably cause the constructed cross tunnels to become "abandoned projects," so the main tunnel alignment will be adjusted and optimized. The method for determining H0, H1, H2, and H3 is as follows: H0 = h0 + (L0 + L1) × 3‰, H1 = h1 + (L1) × 3‰, H2 = h1 + (L1) × 5%, H3 = h1 + (L1') × 5%, where L1' should not be greater than twice L1 and should not be greater than 1000m; In the formula: h0 is the bottom elevation of the pit at the entrance of the constructed cross tunnel, h1 is the bottom elevation of the pit at the working face of the constructed cross tunnel, L0 is the length of the constructed cross tunnel section, L1 is the straight-line distance from the working face of the constructed cross tunnel to the intersection of the adjusted main tunnel and the cross tunnel, and L1' is the detour distance from the working face of the constructed cross tunnel to the intersection of the adjusted main tunnel and the cross tunnel.

2. The method for modifying cross tunnels after elevation adjustment of the main tunnel as described in claim 1, characterized in that: The proposed cross-tunnel slope reduction technology is divided into two schemes based on the appropriate distance Lg from the retreating cross-tunnel face: if Lg does not exceed 300m, the bottom of the pit is modified and a drainage culvert is installed; if Lg exceeds 300m but is not greater than L0, a bypass drainage cross-tunnel is opened at the appropriate distance Lg from the retreating cross-tunnel face, with a minimum drainage slope of 3‰ connecting to the main tunnel; the unconstructed cross-tunnel is designed with a 3‰ slope, and the location of its intersection with the bottom of the constructed cross-tunnel is taken as Lg.

3. The method for modifying a cross tunnel after adjusting the elevation of a main tunnel, as described in claim 1, is characterized in that: The proposed cross-tunnel slope adaptation technology involves adjusting the elevation of the intersection point between the cross-tunnel and the main tunnel according to the elevation of the main tunnel, so that the slopes of the unconstructed cross-tunnel section can be smoothly connected to those of the constructed cross-tunnel section.

4. The method for modifying cross tunnels after elevation adjustment of the main tunnel as described in claim 1, characterized in that: The proposed transverse tunnel spiral-type steep slope modification technology involves increasing the length of the transverse tunnel at the working face of the existing transverse tunnel by spiraling around it, with a slope of 5%, to match the elevation increase of the main line.

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