Subway station first station-then-tunnel-then-station drilling and blasting construction platform layer method
In the construction method of station first, then tunnel and then station, the platform layer area is divided into multiple steps, and excavated separately according to the station return conditions of the left and right lines, and blasting methods such as middle groove pulling and horizontal drilling are used to solve the problems of construction continuity and control difficulty, and effectively manage the construction period and ensure safety.
Patent Information
- Application Number
- CN202510117864.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-24
- Publication Date
- 2025-04-29
AI Technical Summary
In the construction method of station first, then tunnel and then station, after the excavation of the station hall floor is completed, the station time of the left and right lines is inconsistent, resulting in the inability to guarantee the construction continuity, affecting the construction period, and increasing the difficulty of construction control.
By dividing the platform layer area into multiple steps, excavating separately according to the station return conditions of the left and right lines, blasting methods such as pulling grooves in the middle and horizontal drilling are used, segmented excavation of the station line first and then the station line is achieved, avoiding waiting for the station return conditions of the station return conditions of the two lines.
It ensures the continuity of construction, reduces the adverse impact of project postponement on the station construction period, reduces the safety hazards of the initial support structure of the arch station hall floor, and reduces the difficulty of construction control.
Smart Images
Figure CN119900583A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of blasting construction technology for underground subway stations, specifically relating to a method for drilling and blasting construction of the platform layer in subway stations, where the station is built first, then the tunnel is constructed, and then the station is built again. Background Art
[0002] Currently, most existing tunnel-first, station-later construction technologies both domestically and internationally involve tunneling through the tunnel before constructing the subway station using the open-cut method. While this approach is relatively simple in terms of process organization and force system conversion, it also presents practical problems such as significant obstruction of traffic arteries and disruption of vehicle flow. However, research on large-span subway station construction technologies that combine the arch-cover method with a station-first, tunnel-later, and then-station-later approach under shallow-buried tunnel conditions—where the station arch is excavated first, followed by the excavation of the station's substructure after the tunnel boring machine has passed through—is extremely lacking.
[0003] In the existing method of excavating the station first, then the tunnel, and then the station again, after the station concourse level is excavated (most initial support adopts the form of composite initial support) and the shield tunnel passes through the station section, the excavation method for the station platform level is to wait until the left and right line sections meet the conditions for returning the station, and then excavate the platform level sequentially from top to bottom along the longitudinal direction of the station in several construction sections, and promptly implement the initial support.
[0004] However, the existing method of excavating after the station is built, followed by tunneling, and then excavating again still has many shortcomings in actual construction:
[0005] 1. After the station concourse level excavation is completed and the tunnel boring machine passes through the station section, the initial support structure of the arched concourse level is in an unclosed loop state. If it is necessary to wait until both the left and right track sections meet the conditions for station reopening before excavating the platform level, the initial support structure of the arched concourse level will remain in an unclosed loop state for a long time, posing a significant safety hazard to the initial support structure.
[0006] 2. Secondly, in actual construction, since the left and right lines mostly reach the conditions for re-establishing the station at different times, if we wait until both the left and right line sections reach the conditions for re-establishing the station before excavating the platform layer, the continuity of construction cannot be guaranteed, and the construction speed will be greatly reduced, affecting the construction period.
[0007] 3. The existing platform excavation method generates vibration waves during the blasting of the central trench, which will have an adverse effect on the convergence, settlement and deformation of the shield tunnel segments of the left and right lines. During construction, it is necessary to control the deformation values of the shield tunnel segments of the left and right lines at the same time, which increases the difficulty of control in actual construction.
[0008] Therefore, research on the construction method of excavating the platform layer in the drilling and blasting construction method of first station, then tunnel, and then station is urgently needed. Summary of the Invention
[0009] This invention addresses the problems encountered when using the "station first, tunnel second, station third" construction method, such as inconsistent return times for the left and right lines after the completion of the station hall and shield tunnel excavation, which leads to a lack of construction continuity, affects the construction cycle, and makes construction control more difficult.
[0010] This invention provides the following technical solution: a method for constructing a subway station platform layer using a drilling and blasting method, comprising the following steps:
[0011] S1: Excavate the station concourse level and construct initial support;
[0012] S2: The tunnel boring machine passes through the station and temporary segments are installed;
[0013] S3: Based on the segmentation of the initial support grid of the platform level sidewall, the platform level area is divided into upper steps, middle steps, and lower steps; the upper steps are divided into the upper steps inside the first-returned-station line, the upper steps inside the second-returned-station line, the upper steps outside the first-returned-station line, and the upper steps outside the second-returned-station line; the middle steps are divided into the middle area of the middle steps, the middle steps outside the first-returned-station line, and the middle steps outside the second-returned-station line; the lower steps are divided into the middle area of the lower steps, the lower steps outside the first-returned-station line, and the lower steps outside the second-returned-station line.
[0014] S4: After the line that was first returned to the station is returned to the station, the inner side of the line that was first returned to the station is excavated to the upper step.
[0015] S5: Remove the temporary tunnel segments of the existing station line and backfill the tunnel;
[0016] S6: Excavate the upper step outside the station line and construct initial support;
[0017] S7: After the return station is completed, the inner side of the return station line is excavated and a step is built.
[0018] S8: After demolition, temporary tunnel segments were restored and the tunnel was backfilled;
[0019] S9: After excavation, a step is erected on the outer side of the track, and initial support is provided.
[0020] S10: Excavate the middle area of the middle step, the middle step outside the first station return line, the middle step outside the second station return line, the middle area of the lower step, the lower step outside the first station return line, and the lower step outside the second station return line in sequence. After the excavation is completed, the initial support is installed.
[0021] Furthermore, the upper steps on the inner side of the first and second return station lines are excavated by blasting using a central trenching method, while the upper steps on the outer side of the first and second return station lines are excavated by blasting using horizontal drilling.
[0022] Furthermore, the inner upper bench of the first and second resettlement lines is divided into two layers of excavated benches, with the height of both the upper and lower excavated benches being 1750mm. The closest distance between the lower excavated bench of the inner upper bench of the first resettlement line and the temporary segment of the second resettlement line is 3845mm, and the maximum charge per blast hole on the lower excavated bench of the inner upper bench of the first resettlement line is less than 1.5kg.
[0023] Furthermore, in step S1, the station concourse level is excavated horizontally in three sections, with adjacent sections staggered by a distance of 15m or more.
[0024] Furthermore, in step S2, the concrete strength grade of the temporary segments is C30, the segment thickness is 300mm, the width is 1500mm, the temporary segments are assembled in a staggered manner and connected by bent bolts; no tenons or grooves are provided on the contact surfaces of the ring and longitudinal joints of the temporary segments.
[0025] Furthermore, the spacing of the blast holes on the upper excavation step of the inner side of the station line is 1200mm*1200mm, and the charge per blast hole is 1.2kg.
[0026] Furthermore, the spacing of the blast holes on the lower excavation step of the inner side of the station line is 1200mm*1200mm, and the charge per blast hole is 1.3kg.
[0027] Furthermore, the spacing between the blast holes on the upper and lower excavation steps of the inner side of the station track is 1200mm*1200mm, and the charge per blast hole is 1.3kg.
[0028] Furthermore, the spacing between the blast holes in the middle area of the upper step outside the first return station line and the upper step outside the second return station line is 700mm*900mm, and the spacing between the blast holes in the peripheral area of the upper step outside the first return station line and the upper step outside the second return station line is 450mm. The drilling depth of the blast holes is 3.2m, and the charge per blast hole is 1.3kg.
[0029] Furthermore, the middle area of the middle step and the middle area of the lower step are divided into two layers of excavated steps.
[0030] Compared with the prior art, the advantages of the present invention are:
[0031] Once the station concourse level excavation is completed and the tunnel boring machine has passed through the station, the excavation of the station platform level will proceed as follows: for the first line to return to the station, the upper steps on the inner side of the first line will be excavated by blasting through a central trench, while the upper steps on the outer side of the first line will be excavated by blasting through horizontal drilling. This eliminates the need to wait for the second line to return to the station to meet the conditions before excavating the station platform level, and is not constrained by the time of the double-track return. This ensures the continuity of construction and reduces the adverse impact of project delays on the station's schedule.
[0032] Once the left or right track meets the conditions for re-establishing the station, the platform level can be excavated, reducing the time required to complete the excavation of the concourse level. This, in turn, reduces the time required for the arch concourse level support and the platform level support to form a closed ring support structure, better ensuring the safety of the initial support structure of the concourse level and thus reducing safety hazards.
[0033] When excavating the first-returned-station line at the platform level, by controlling the minimum distance from the blast hole to the temporary segments of the subsequent-returned-station line and the maximum charge per hole, it is possible to ensure that the excavation of the upper steps on the inner and outer sides of the first-returned-station line only affects the temporary segments of the first-returned-station line that need to be broken, while the impact on the temporary segments of the subsequent-returned-station line that do not need to be broken is small and under control. This avoids the significant adverse impact on the temporary segments of both the left and right lines when excavating the platform level area using existing excavation methods, which require simultaneous control of the deformation of the temporary segments of both lines to prevent collapse caused by segment damage. Attached Figure Description
[0034] Figure 1 A schematic diagram of the method for constructing the platform layer of a subway station using a "first station, then tunnel, then station" drilling and blasting method;
[0035] Figure 2 A top-down view of the blast hole layout for the upper excavation step on the inner side of the station track.
[0036] Figure 3 Longitudinal section; Layout of blast holes for the upper excavation step on the inner side of the station track.
[0037] Figure 4 A top-down view of the blast hole layout for the lower excavation step of the inner side of the station's upper step.
[0038] Figure 5 Longitudinal section; Layout of blast holes for the lower excavation step of the inner side of the station's upper step.
[0039] Figure 6 A top-down view of the layout of blast holes for the upper excavation step on the inner side of the track of the subsequent station.
[0040] Figure 7Longitudinal section;
[0041] Figure 8 A top-down view of the blast hole layout for the lower excavation step of the inner side of the station track.
[0042] Figure 9 Longitudinal section;
[0043] Figure 10 The diagram shows the layout of blast holes on the outer ramp of the first and second return-to-station lines.
[0044] In the diagram: 1 - Station concourse level; 2 - Upper step; 2.1 - Upper step inside the first station return track; 2.2 - Upper step inside the second station return track; 2.3 - Upper step outside the first station return track; 2.4 - Upper step outside the second station return track; 3 - Middle step; 3.1 - Middle area of the middle step; 3.2 - Middle step outside the first station return track; 3.3 - Middle step outside the second station return track; 4 - Lower step; 4.1 - Middle area of the lower step; 4.2 - Lower step outside the first station return track; 4.3 - Lower step outside the second station return track; 5 - Blast hole. Detailed Implementation
[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0046] like Figure 1 As shown: A method for constructing the platform layer of a subway station by drilling and blasting, including the following steps:
[0047] S1: Excavate the first level of the station concourse and construct initial support;
[0048] S2: The tunnel boring machine passes through the station and temporary segments are installed;
[0049] S3: Based on the segmentation of the initial support grid of the platform level sidewall, the platform level area is divided into upper step 2, middle step 3, and lower step 4; upper step 2 is further divided into upper step 2.1 on the inner side of the first return track, upper step 2.2 on the inner side of the second return track, upper step 2.3 on the outer side of the first return track, and upper step 2.4 on the outer side of the second return track; middle step 3 is divided into the middle area 3.1 of the middle step, middle step 3.2 on the outer side of the first return track, and middle step 3.3 on the outer side of the second return track; lower step 4 is divided into the middle area 4.1 of the lower step, lower step 4.2 on the outer side of the first return track, and lower step 4.3 on the outer side of the second return track.
[0050] S4: After the line that was first returned to the station is returned to the station, excavate the inner side of the upper step of the line that was first returned to the station, 2.1 meters away;
[0051] S5: Remove the temporary tunnel segments of the existing station line and backfill the tunnel;
[0052] S6: Excavate the upper step 2.3 on the outside of the station line and construct initial support;
[0053] S7: After the return station is completed, the inner side of the return station line is excavated with a step of 2.2 meters.
[0054] S8: After demolition, temporary tunnel segments were restored and the tunnel was backfilled;
[0055] S9: After excavation, a 2.4-meter step is added to the outside of the railway line, and initial support is constructed.
[0056] S10: Excavate the middle area 3.1 of the middle step, the middle step 3.2 of the outer side of the first station return line, the middle step 3.3 of the outer side of the second station return line, the middle area 4.1 of the lower step, the lower step 4.2 of the outer side of the first station return line, and the lower step 4.3 of the outer side of the second station return line in sequence. After the excavation is completed, the initial support is applied.
[0057] In this embodiment, the right line is the line that is returned to the station first, and the left line is the line that is returned later. After the station hall level 1 is excavated and the tunnel boring machine passes through the station, for the excavation of the station platform level, the right line's return to the station occurs earlier than the left line. Therefore, the right line's return to the station is carried out first. The upper step 2.1 on the inner side of the line that is returned to the station first is excavated by blasting through a central grooving method, and the upper step 2.3 on the outer side of the line that is returned to the station first is excavated by blasting through horizontal drilling. There is no need to wait for the left line to meet the conditions for returning to the station before excavating the station platform level. It is not constrained by the return time of the left line, thus ensuring the continuity of construction and reducing the adverse impact of project delays on the station's construction period.
[0058] The inner side of the Houhuan Station track, step 2.2, was also excavated by blasting using the central trenching method, while the outer side of the Houhuan Station track, step 2.4, was excavated by blasting using horizontal drilling.
[0059] By adopting the above technical solution, the station platform can be excavated once the left or right line meets the conditions for re-establishment. This reduces the time required to complete the excavation of the concourse level, thereby reducing the time required for the arch concourse level support and the platform level support to form a closed ring support structure. This better ensures the safety of the initial support structure of the concourse level and reduces safety hazards.
[0060] By adopting the above technical solution, when excavating the right track of the platform level for station restoration, by controlling the minimum distance between the blast holes and the temporary segments of the left track and the maximum charge per hole, it is possible to ensure that the excavation of the upper step 2.1 on the inner side of the station restoration line and the upper step 2.3 on the outer side of the station restoration line only affects the temporary segments of the right track that need to be broken, while the impact on the temporary segments of the left track that do not need to be broken is small and under control. This avoids the significant adverse impact on the temporary segments of both the left and right tracks when excavating the platform level area using existing excavation methods, which require simultaneous control of the deformation of the left and right track segments to prevent collapse caused by segment damage.
[0061] The inner upper step 2.1 of the first-return station line and the inner upper step 2.2 of the second-return station line are divided into two layers of excavation steps, with the height of the upper and lower excavation steps both being 1750mm. The closest distance between the lower excavation step of the inner upper step 2.1 of the first-return station line and the temporary segment of the second-return station line is 3845mm. The maximum charge per blast hole on the lower excavation step of the inner upper step 2.1 of the first-return station line is less than 1.5kg.
[0062] like Figure 2 , Figure 3 As shown: The spacing of the blast holes on the upper excavation bench of the inner side of the first-return station line, upper bench 2.1, is 1200mm*1200mm, and the charge per blast hole is 1.2kg. The blasting parameters for the upper excavation bench of the inner side of the first-return station line, upper bench 2.1, are shown in Table 1.
[0063] Table 1: Blasting parameters for the upper excavation bench of the inner side of the first station track, step 2.1
[0064]
[0065] like Figure 4 , Figure 5 As shown: The spacing of the blast holes on the lower excavation bench of the upper bench 2.1 inside the first-return station line is 1200mm*1200mm, and the charge per blast hole is 1.3kg. The blasting parameters for the lower excavation bench of the upper bench 2.1 inside the first-return station line are shown in Table 2.
[0066] Table 2: Blasting parameters for the lower excavation bench of the inner side of the first station track, step 2.1
[0067]
[0068] like Figure 6 , Figure 7As shown: The spacing of the blast holes on the upper and lower excavation benches of the inner side of the relocation station's upper bench 2.2 is 1200mm*1200mm, and the charge per blast hole is 1.3kg. The blasting parameters for the upper excavation bench of the inner side of the relocation station's upper bench 2.2 are shown in Table 3; the blasting parameters for the lower excavation bench of the inner side of the relocation station's upper bench 2.2 are shown in Table 4.
[0069] Table 3: Blasting parameters for the upper excavation bench of the inner side of the Houhuan Station track, 2.2.
[0070]
[0071] Table 4: Blasting parameters for the lower excavation bench of the inner side of the upper bench 2.2 of the Houhuan Station line.
[0072]
[0073] like Figure 8 , Figure 9 As shown: the spacing of the blast holes in the middle area of the upper bench 2.3 on the outer side of the first return station line and the upper bench 2.4 on the outer side of the second return station line is 700mm*900mm; the spacing of the blast holes in the peripheral area of the upper bench 2.3 on the outer side of the first return station line and the upper bench 2.4 on the outer side of the second return station line is 450mm; the drilling depth of all blast holes is 3.2m; and the charge per blast hole is 1.3kg. The blasting parameters for the upper bench 2.3 on the outer side of the first return station line and the upper bench 2.4 on the outer side of the second return station line are shown in Table 5.
[0074] Table 5: Blasting Parameters for the Upper Bench 2.3 on the Outer Side of the First Relocation Line and the Upper Bench 2.4 on the Outer Side of the Second Relocation Line
[0075]
[0076] During the excavation of the middle section 3.1 of the middle bench, the middle bench 3.2 outside the first resettlement line, the middle bench 3.3 outside the second resettlement line, the middle section 4.1 of the lower bench, the lower bench 4.2 outside the first resettlement line, and the lower bench 4.3 outside the second resettlement line, the temporary slabs of the left and right lines had already been broken and backfilled. Therefore, the blasting operation only required excavation according to the conventional blasting construction plan and blasting parameters. The middle section 3.1 of the middle bench and the middle section 4.1 of the lower bench are divided into upper and lower excavation benches.
[0077] Therefore, this invention can ensure the continuity of construction and not affect the construction period when the return times of the left and right lines of the station platform are inconsistent. It also reduces the safety hazards of the initial support structure of the arched station hall when it is not closed into a ring. At the same time, it solves the problem of the difficulty in controlling the shield tunnel segments of the left and right lines during the construction of the platform.
[0078] By adopting the above technical solutions, the safety of the temporary segments on the left line was ensured during the excavation of the right-line return station. Deformation monitoring data showed that the impact of blasting during the excavation of the right-line return station on the temporary segments on the left line was within a controllable range. The maximum settlement of the arch of the temporary segments on the left line was -0.6 mm, and the maximum net clearance convergence was -0.7 mm, both far less than the deformation control value of ±10 mm. Referring to the vibration velocity control requirements for reinforced concrete structures and considering the actual structural conditions, the vibration velocity control value for the segments was set at 5.0 cm / s (as long as no damage occurs). During the on-site blasting construction of the right-line return station excavation, the maximum vibration velocity obtained from the vibration velocity monitoring of the temporary segments on the left line was 4.2 cm / s (only once), and the maximum values of other vibration velocities were all less than 2 cm / s, meeting the safety requirements.
[0079] In step S2, the concrete strength grade of the temporary tunnel segments is C30, the segment thickness is 300mm, and the width is 1500mm. The temporary tunnel segments are assembled using staggered joints and connected by bent bolts; no tenons or grooves are provided on the contact surfaces of the circumferential and longitudinal joints of the temporary tunnel segments. The circumferential main reinforcement of the temporary tunnel segments uses HRB400C12 steel bars, and the internal structural reinforcement uses HPB300A6 steel bars, arranged in a double layer. By adopting the above technical solution, temporary low-density tunnel segments are used for support in the shield tunnel section of the station, achieving the support purpose and ensuring safety while reducing project costs.
[0080] In step S5, after the excavation of the inner side of the upper step 2.1 of the station platform is completed, an excavator is used to mechanically break up the right-line tunnel segments. All mechanical equipment operation is within a 5m range of the middle section. After the segments are broken up, blasted slag is used for backfilling, and the length of the broken, unbackfilled segment must not exceed 5m. After the slag is backfilled inside the segments, an excavator breaker is used to vibrate and compact the slag to improve the density of the backfill layer. By adopting the above technical solution, it is ensured that mechanical operations are all carried out on the slightly weathered granite bearing layer, while avoiding dangerous situations such as collapse caused by large voids inside the slag backfill.
[0081] In step S1, the station concourse level 1 is excavated horizontally in 3 sections, with adjacent sections staggered by a distance of 15m or more.
[0082] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station, characterized in that: The following steps are involved: S1: Excavate the station concourse layer (1) and provide initial support; S2: The shield tunnel passes through the station and temporary segments are installed; S3: The platform area is divided into upper steps (2), middle steps (3) and lower steps (4) based on the segmentation of the primary support grid of the platform side wall; the upper step (2) is divided into the upper step on the inner side of the first return line (2.1), the upper step on the inner side of the second return line (2.2), the upper step on the outer side of the first return line (2.3) and the upper step on the outer side of the second return line (2.4); the middle step (3) is divided into the middle area of the middle step (3.1), the middle step on the outer side of the first return line (3.2) and the middle step on the outer side of the second return line (3.3); the lower step (4) is divided into the middle area of the lower step (4.1), the lower step on the outer side of the first return line (4.2) and the lower step on the outer side of the second return line (4.3); S4: After the first return line is returned to the station, excavate the upper step (2.1) on the inner side of the first return line; S5: Remove the temporary segments of the first return line and backfill the tunnel; S6: Excavate and return the upper step (2.3) on the outer side of the station line first, and apply initial support; S7: After the rear return line is returned to the station, the inner side of the rear return line is excavated and stepped up (2.2); S8: After breaking, return the temporary segments of the line to the station and backfill the tunnel; S9: After excavation, the outer side of the line is returned to the upper step (2.4) and initial support is applied; S10: excavate the middle area of the middle step (3.1), the middle step on the outer side of the first return line (3.2), the middle step on the outer side of the second return line (3.3), the middle area of the lower step (4.1), the lower step on the outer side of the first return line (4.2) and the lower step on the outer side of the second return line (4.3) in sequence, and carry out initial support after the excavation is completed.
2. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 1, characterized in that: The inner upper step (2.1) of the first return line and the inner upper step (2.2) of the second return line are blasted and excavated by the middle groove method, and the outer upper step (2.3) of the first return line and the outer upper step (2.4) of the second return line are blasted and excavated by the horizontal drilling method.
3. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 2, characterized in that: The upper step (2.1) on the inner side of the first return line and the upper step (2.2) on the inner side of the second return line are divided into two layers of excavation steps, and the height of the upper excavation step and the lower excavation step are both 1750mm; the shortest distance between the lower excavation step of the inner side of the first return line (2.1) and the temporary pipe segment of the second return line is 3845mm, and the maximum charge of a single hole of the blasthole on the lower excavation step of the inner side of the first return line (2.1) is less than 1.5kg.
4. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 1 is characterized in that: In step S1, the station hall layer (1) is excavated horizontally into three sections, and the front-to-back offset distance between adjacent sections is greater than or equal to 15m.
5. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 1, characterized in that: In step S2, the concrete strength grade of the temporary segment is C30, the segment thickness is 300 mm, the width is 1500 mm, the temporary segment is assembled in staggered positions and connected by bent bolts; no tongue and groove are provided on the temporary segment ring and longitudinal seam contact surfaces.
6. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 3 is characterized by: The spacing of the blastholes on the upper excavation step of the upper step (2.1) on the inner side of the station line is 1200mm*1200mm, and the charge of a single blasthole is 1.2kg.
7. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 6, characterized in that: The spacing of the blastholes on the lower excavation step of the upper step (2.1) on the inner side of the station line is 1200mm*1200mm, and the charge of a single blasthole is 1.3kg.
8. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station as claimed in claim 7, characterized in that: The spacing between the blast holes on the upper excavation step and the lower excavation step of the upper step (2.2) on the inner side of the rear station line is 1200mm*1200mm, and the single-hole charge of the blast hole is 1.3kg.
9. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station according to claim 8, characterized in that: The spacing between the blast holes in the middle area on the outer upper step (2.3) of the first return station line and the outer upper step (2.4) of the rear return station line is 700mm*900mm, and the spacing between the blast holes in the peripheral area on the outer upper step (2.3) of the first return station line and the outer upper step (2.4) of the rear return station line is 450mm. The drilling depth of the blast holes is 3.2m, and the single-hole charge of the blast holes is 1.3kg.
10. The method for drilling and blasting the platform layer of a subway station by first building the station, then tunneling, and then building the station as claimed in claim 1, characterized in that: The middle area (3.1) of the middle step and the middle area (4.1) of the lower step are divided into upper and lower excavation steps.
Citation Information
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