A construction method for large-section tunnel excavation support structure

Abstract

The invention discloses a construction method for a large-section tunnel excavation support structure, which is to excavate from both ends to the middle, the composite lining sections at both ends are excavated by the CD method, the footage is cyclical, the whole section is divided into 4 parts, and the excavation is carried out in sequence; the middle single-layer lining section is excavated by the step method, the footage is cyclical, the whole section is divided into 3 parts, and the excavation is carried out in sequence. The invention has the following beneficial effects: the method of the invention is adopted, the construction speed is fast, a lot of manpower is saved, and the production cost is reduced; the construction arrangement is more reasonable, the construction progress is accelerated, the construction period and unnecessary manpower costs are saved, and it is ensured that the task can be successfully completed within the specified shorter construction period.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a construction method for a large-section tunnel excavation support structure. Background Art

[0002] The Guizhou Road Station-Xizhen Station section (hereinafter referred to as the Guixi Section) is about 546.9 meters long. Guizhou Road Station is located on the southwest side of the intersection of Guizhou Road and Tuandao 2nd Road. After leaving Guizhou Road Station, the line is laid northward along Taixi 5th Road, passing under a large number of buildings and connecting to Xizhen Station at the intersection of Feixian Road and Yuncheng North Road. According to operational needs, a double storage line is set up in front of Xizhen Station to form a four-line large-section tunnel.

[0003] According to the geological characteristics, there are 4 types of sections in the four-line large sections of the Guixi section: ZA, ZB, ZC, and ZD. The ZA and ZB sections are composite lining structures, while the ZC and ZD sections are single-pass lining structures. The ZA section is IV2-level surrounding rock and adopts composite lining; the ZB section is IV1-level surrounding rock, with a wide excavation section and composite lining; the ZC section is II-level surrounding rock and adopts single-layer lining; the ZD section is II-level surrounding rock and adopts single-layer lining.

[0004] This application proposes a new excavation and support construction method for the above-mentioned large-section tunnel, so as to provide experience for the excavation of large-section tunnels with the same geology. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a construction method for a large-section tunnel excavation support structure, which overcomes the defects of the prior art.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0007] A method for constructing a large-section tunnel excavation support structure, wherein the construction is to excavate from both ends toward the middle, the composite lining sections at both ends are excavated by the CD method, with cyclic advance, and the entire section is divided into four parts, which are excavated in sequence; the single-layer lining section in the middle is excavated by the step method, with cyclic advance, and the entire section is divided into three parts, which are excavated in sequence.

[0008] Preferably, in the above technical solution, the composite lining section excavation comprises the following steps:

[0009] (1) Excavation of the upper bench of the pilot tunnel: a double row of small guide tubes are installed along the arch of the dark excavation section, with t = 3.5 mm, L = 4.0 m, and annular spacing of @ 400 mm; the pilot tunnel is excavated first, with an excavation depth of 1 grid spacing. The excavated earth and stone are temporarily piled in the tunnel of the lower pilot tunnel excavated by the TBM as a working platform, and steel grids and temporary middle partitions are erected, and anchor rods and mesh spraying support are installed;

[0010] (2) Excavate the lower steps of the pilot tunnel first: advance one grid spacing per excavation cycle; after the excavation is completed, promptly erect the grid and temporary support, and install anchor rods and mesh spraying support;

[0011] (3) Excavation of the upper step of the rear pilot tunnel: After the upper step of the first pilot tunnel is excavated and the conditions for the excavation of the rear pilot tunnel are met, the rear pilot tunnel is excavated; the earth and stone after excavation are temporarily piled up in the tunnel of the lower pilot tunnel TBM excavation, which serves as a working platform, and grids, anchors, and mesh spraying support are set up in time;

[0012] (4) Excavation of the lower step of the rear pilot tunnel: advance by 2 grid spacings in each excavation cycle; after the excavation is completed, the grids are erected, anchors are driven, and mesh support is provided in a timely manner.

[0013] Preferably, in the above technical solution, excavation of a single-layer lining section includes the following steps:

[0014] (1) Excavation of the upper steps of the pilot tunnel: Excavation of the upper steps of the right line is carried out first according to the actual conditions on site; after the excavation is completed, spraying of single-layer lining concrete support is carried out;

[0015] (2) Excavation of the upper steps of the rear pilot tunnel: excavation of the left line is carried out in a timely manner after the conditions are met; after the excavation is completed, a single layer of lining concrete is sprayed;

[0016] (3) Excavation of the lower bench rock pillar: The lower bench is excavated by the two-bench method, with a cycle advance of 3m. The middle rock pillar is excavated by vertical drilling;

[0017] (4) Excavation of the remaining part of the lower step: The remaining rock pillars of the lower step were excavated using vertical drilling, with an excavation depth of 3m; the side walls on both sides were manually drilled using air guns, with a cycle depth of 3m.

[0018] Preferably, in the above technical scheme, the construction method also includes pipeline layout and slag discharge in the tunnel. The pipeline layout in the tunnel is to arrange ventilation pipes in the arch of the TBM standard tunnel, set a pedestrian passage on the left, and arrange Fengshui pipes on the right. The tunnel arch is filled with 0.5m high and 3m wide slag, which is used as a slag discharge channel after filling.

[0019] Preferably, in the above technical scheme, the construction method also includes construction platform operation: when the right-line cross channel is excavated, the excavated earth and stone are transported to the right-line horse head gate of Xizhen Station, and a loader and an excavator are used to raise and level a working platform to facilitate the step-up excavation construction, and the slag pad height is 3m; the upper half section at the horse head gate is excavated to the top in two times, and a grid spray anchor support is erected; the earth and stone excavated from the first expansion is used to continue to raise the working platform to facilitate the second expansion construction; the work platform columns and longitudinal beams are made of 18 I-beams, and the side wings are made of Ф89 steel pipes and Ф76 telescopic steel pipes, and mechanically assisted towing and traction wire ropes are used for movement.

[0020] Preferably, in the above technical solution, the construction method further comprises, before constructing the large cross-section section, tunneling through the TBM and excavating the rest of the cross-section using the drilling and blasting method.

[0021] A construction platform for a large-section tunnel excavation support structure comprises a working platform, a work platform is arranged above the working platform, a protection platform is arranged on the periphery of the work platform, a protection net is installed on the periphery of the protection platform, the protection net is tied and fixed to the guardrail platform, one side of the work platform is connected to the surrounding rock of the tunnel face, and two ladders are arranged on the work platform.

[0022] Preferably, in the above technical solution, the work platform is composed of columns, longitudinal beams and side wings welded together, the columns and longitudinal beams are made of 18 I-beams, and the side wings are made of Ф89 steel pipes and Ф76 telescopic steel pipes.

[0023] Preferably, in the above technical solution, the working platform is used for step-up excavation construction, and is formed by raising and leveling the earth excavated from the adjacent line tunnels using a loader and an excavator.

[0024] Preferably, in the above technical solution, the two ladders are respectively arranged on both sides of the working platform.

[0025] The above technical solution of the present invention has the following beneficial effects:

[0026] (1) The method of the present invention has a fast construction speed, saves a lot of manpower, and reduces production costs.

[0027] (2) The construction arrangement is more reasonable, which speeds up the construction progress, saves construction time and unnecessary manpower costs, and ensures that the task can be successfully completed within the prescribed shorter construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a schematic diagram of a construction scaffold for a large-section tunnel excavation support structure.

[0029] Figure 2 It is another schematic diagram of a construction platform for a large-section tunnel excavation support structure according to the present invention. DETAILED DESCRIPTION

[0030] The specific implementation modes of the present invention are described in detail below to facilitate a further understanding of the present invention, but are not intended to limit the present invention.

[0031] Example 1 Excavation Organization Plan

[0032] like Figure 1 , Figure 2As shown, based on the geological conditions of the four-line large section in the Guixi section, the ground environment, the tunnel section structure, the support method, and the slag discharge capacity of the lifting equipment at Guizhou Road Station and Xizhen Station, it is planned to excavate from both ends to the middle, working face 1: excavation from Guizhou Road Station to Xizhen Station, working face 2: excavation from Xizhen Station to Guizhou Road Station. This plan has fewer process conversions, fast process follow-up, and is easy to organize subsequent construction. The excavation section changes less, the slag discharge is more uniform, and the construction period is basically controllable.

[0033] Sections ZA and ZB are composite lining sections with Class IV surrounding rock, and are excavated using the CD method. Sections ZC and ZD are single-layer lining sections with Class II surrounding rock, and are excavated using the left and right pilot tunnel step method and the step method.

[0034] (1) Working face 1 of Guizhou Road Station: The work face is gradually raised from the left and right lines of the standard tunnel end of the TBM section to the top of the large section. The designed grid spacing is 0.5m, the height is raised by 0.25m each time, the height angle is 27°, the horizontal side wall position has an outward expansion angle of 25°, the middle partition wall position has an outward expansion angle of 13°, and the height to the top requires 12m. The temporary support of the raised section is the same as the permanent support structure.

[0035] (2) The right line shall be constructed first. After the right line is raised to the top, the excavation shall continue forward. After the left line is ready for excavation, the left line shall be excavated. The distance between the left and right line faces shall not be less than 15m.

[0036] (3) The left and right lines are constructed by normal blasting. After the left line is raised to the top of the arch, the left and right lines are constructed forward normally. The reverse excavation is carried out by blasting during the intervals, which does not occupy the overall construction period.

[0037] (4) The left and right lines of the standard tunnel end of the TBM section are gradually raised to the top of the large section. The grid spacing is 0.5m, the height is raised by 0.25m each time, the height angle is 27°, the horizontal side wall position has an outward expansion angle of 25°, the middle partition wall position has an outward expansion angle of 13°, and the height to the top requires 12m. The temporary support of the raised section is the same as the permanent support structure.

[0038] The excavation steps for ZA and ZB composite lining sections are as follows:

[0039] (1) Excavation of the upper bench of the pilot tunnel: a double row of small guide tubes are installed along the arch of the dark excavation section, with t = 3.5 mm, L = 4.0 m, and annular spacing of @ 400 mm; the pilot tunnel is excavated first, with an excavation depth of 1 grid spacing. The excavated earth and stone are temporarily piled in the tunnel of the lower pilot tunnel excavated by the TBM as a working platform, and steel grids and temporary middle partitions are erected, and anchor rods and mesh spraying support are installed;

[0040] (2) Excavate the lower steps of the pilot tunnel first: advance one grid spacing per excavation cycle; after the excavation is completed, promptly erect the grid and temporary support, and install anchor rods and mesh spraying support;

[0041] (3) Excavation of the upper step of the rear pilot tunnel: After the upper step of the first pilot tunnel is excavated and the conditions for the excavation of the rear pilot tunnel are met, the rear pilot tunnel is excavated; the earth and stone after excavation are temporarily piled up in the tunnel of the lower pilot tunnel TBM excavation, which serves as a working platform, and grids, anchors, and mesh spraying support are set up in time;

[0042] (4) Excavation of the lower step of the rear pilot tunnel: advance by 2 grid spacings in each excavation cycle; after the excavation is completed, the grids are erected, anchors are driven, and mesh support is provided in a timely manner.

[0043] The excavation steps for ZC and ZD single-layer lining sections are as follows:

[0044] (1) Excavation of the upper steps of the pilot tunnel: Excavation of the upper steps of the right line is carried out first according to the actual conditions on site; after the excavation is completed, spraying of single-layer lining concrete support is carried out;

[0045] (2) Excavation of the upper steps of the rear pilot tunnel: excavation of the left line is carried out in a timely manner after the conditions are met; after the excavation is completed, a single layer of lining concrete is sprayed;

[0046] (3) Excavation of the lower bench rock pillar: The lower bench is excavated by the two-bench method, with a cycle advance of 3m. The middle rock pillar is excavated by vertical drilling;

[0047] (4) Excavation of the remaining part of the lower step: The remaining rock pillars of the lower step were excavated using vertical drilling, with an excavation depth of 3m; the side walls on both sides were manually drilled using air guns, with a cycle depth of 3m.

[0048] Example 2: Indoor and outdoor layout plan

[0049] (1) Cave layout

[0050] A ventilation pipe is arranged on the arch of the TBM standard tunnel, a pedestrian passage is set on the left, and a wind and water pipe is arranged on the right. The tunnel arch is filled with 0.5m high and 3m wide slag, which is used as a mucking channel after filling.

[0051] (2) Construction ventilation design standards

[0052] Dust concentration: Dust containing more than 10% free silicon dioxide per m3 of air is 2 mg; when the free silicon dioxide content is less than 10%, the mineral and animal and plant dust that does not contain harmful substances is 10 mg; the water-mixed dust containing less than 10% free silicon dioxide is 6 mg.

[0053] Carbon monoxide (CO) concentration: The carbon monoxide (CO) concentration in the air shall not exceed 0.0024% (24ppm by volume) and shall not exceed 30mg / m3 by weight. 30 minutes after the construction workers enter the cave, the concentration should drop below 30mg / m3.

[0054] Temperature inside the tunnel: The most suitable temperature for working in the tunnel is 15-20℃, and the temperature of the excavation working face should not exceed 28℃.

[0055] Noise standards: my country's "Noise Hygiene Standards for Industrial Enterprises" (1970) stipulates that the noise hygiene standards for newly built enterprises are: the noise level should not exceed 85 decibels during an 8-hour working period; if the noise level reaches 88 decibels, the working period can only be within 4 hours to protect hearing. Relevant construction specifications stipulate that the noise level should not exceed 90 decibels.

[0056] (3) Off-site layout

[0057] In order to ensure the quality, safety and construction period of the construction, reduce costs and carry out civilized construction, we have arranged the site plan reasonably according to the environmental conditions and characteristics of the project. The facilities and equipment on the construction site are arranged according to the specific construction site, and the site layout is reasonably adjusted as the construction progresses.

[0058] The construction area is divided according to the scope of construction, and the first consideration is the fixed and inconvenient facilities to ensure that each machine and equipment has enough operating surface during construction and does not interfere with each other. A 25T lifting derrick is installed at the boundary between the open and dark excavation of Guizhou Road Station, which is responsible for the slag feeding and hoisting construction of the small mileage operation surface. The derrick is fully enclosed to avoid construction noise disturbing the public; the slag storage yard is arranged above the arch of the dark excavation section and is enclosed by a 3m high steel plate. The slag yard has a plane area of ​​130㎡ and a slag storage capacity of about 260m3; the air compressor is arranged above the top plate of the open excavation section, and the transformer is arranged on the north side of the derrick. The rest of the sand and gravel silos, cement warehouses, mixing stations and other facilities have been completed when Guizhou Road Station was excavated.

[0059] Embodiment 3 Mucking scheme

[0060] 1. Transportation plan

[0061] like Figure 1 , Figure 2 As shown, the TBMs on the left and right lines are currently excavating and discharging slag. It is expected that the right line will be excavated and reach the track well on March 15, and the left line will be completed on April 20. It is tentatively planned that the right line will be excavated first, and the left line will be constructed after the conditions are met. Therefore, the right line will first be excavated and expanded in half a section toward Xizhen Station, and a 4m rock column will be reserved on the left to ensure the safety of the left line TBM battery vehicle transportation.

[0062] (1) Each tunnel face in the tunnel is equipped with a 60 excavator for transporting and loading the slag. The transport vehicle is a dump truck. Considering the distance and time of slag transportation, each tunnel face is equipped with two dump trucks to transport slag. During the peak period of slag discharge for each lifting equipment, four trucks are transporting slag to meet the lifting needs.

[0063] (2) The route for transporting slag in the tunnel: the slag from the left line of Guizhou Road Station is transported to the right line through the passage inside the station and then poured into the slag bucket. The slag from Xizhen Station is lifted to the ground through the No. 1 ventilation shaft.

[0064] Example 4 Construction scaffolding scheme

[0065] 1. Bench operation

[0066] When the right-line cross channel is excavated, the excavated earth and stone are transported to the right-line horse head gate of Xizhen Station, and a loader and excavator are used to raise and level a working platform to facilitate the step-up excavation construction. The slag pad height is 3m. The upper half section of the horse head gate is excavated twice to the top, and grid spray anchor support is set up. The earth and stone excavated from the first expansion is used to continue to raise the working platform to facilitate the second expansion construction. The columns and longitudinal beams of the workbench are made of 18 I-beams, and the side wings are made of Ф89 steel pipes and Ф76 telescopic steel pipes. Mechanically assisted traction wire ropes are used for movement.

[0067] 2. Working principle and process

[0068] (1) Working principle

[0069] The loader bucket is used to lift the platform and move it into position. After the construction platform reaches the face, it is fine-tuned to make the work platform connect with the surrounding rock of the face. Workers can quickly prepare for excavation and start rock drilling by using lighting and wind and water pipes.

[0070] (2) Workflow

[0071] The loader is in place, the hopper lifts the stand, the support is moved, the stand is in place, measurements are made, the driller is in place, and drilling operations begin.

[0072] 3. Safety measures

[0073] Production of work platform protection platform: Use 20 diameter threaded steel bars to weld the guardrail frame. When welding the guardrail frame, leave a gap for people to pass through. The welding joints must ensure the welding quality. After the frame welding is completed, install the green protection net, and the protection net and the guardrail are tied firmly. There are 2 ladders on the upper and lower sides of the work platform, one on each side of the platform.

[0074] 4. Protection plan for underpasses

[0075] Plan 1: Before the four-line large-section blasting construction, the residents of several houses will be relocated, and the blasting construction will be carried out after the relocation. After the blasting is completed, a house appraisal unit will be asked to appraise the house again. If the house is damaged during the blasting construction, the house will be repaired; if the blasting does not cause damage to the house, the residents will move back without repair.

[0076] Option 2: Before the four-line large-section blasting construction, residents of several houses will be relocated. After the relocation is completed, the houses will be reinforced and the residents will be moved back after the blasting is completed.

[0077] Plan three: Before the four-line large-section blasting construction, the houses will be reinforced according to the appraisal report, and the residents do not need to relocate. The blasting construction will be carried out after the house reinforcement is completed.

[0078] A construction platform for a large-section tunnel excavation support structure comprises a working platform, wherein a work platform 2 is arranged above the working platform 1, a protective platform is arranged on the periphery of the work platform 2, a protective net is installed on the periphery of the protective platform, the protective net is tied and fixed to the guardrail platform, one side of the work platform 2 is connected to the surrounding rock of the tunnel face, and two ladders are arranged on the work platform.

[0079] Furthermore, the workbench 2 is welded together by columns, longitudinal beams and side wings. The columns and longitudinal beams are made of 18 I-beams, and the side wings are made of Ф89 steel pipes and Ф76 telescopic steel pipes.

[0080] Furthermore, the working platform is used for step-up excavation construction, and is formed by raising and leveling the earth excavated from the adjacent line tunnels using loaders and excavators.

[0081] Furthermore, the two ladders are respectively arranged on both sides of the working platform.

[0082] The construction method and construction structure of the present invention have the following advantages:

[0083] (2) The method of the present invention has a fast construction speed, saves a lot of manpower and reduces production costs.

[0084] (2) The construction arrangement is more reasonable, which speeds up the construction progress, saves construction time and unnecessary manpower costs, and ensures that the task can be successfully completed within the prescribed shorter construction period.

[0085] Although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various choices and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention is limited by the claims and their equivalents.

Claims

1. A method for constructing a large-section tunnel excavation support structure, characterized in that: The construction method is to excavate from both ends to the middle, the composite lining sections at both ends are excavated by CD method, the advance is cyclic, the whole section is divided into 4 parts, and the excavation is carried out in sequence; the single-layer lining section in the middle is excavated by step method, the advance is cyclic, the whole section is divided into 3 parts, and the excavation is carried out in sequence; The composite lining section excavation comprises the following steps: (1) Excavation of the upper bench of the pilot tunnel: a double row of small guide tubes are installed along the arch of the dark excavation section, with t = 3.5 mm, L = 4.0 m, and annular spacing of @ 400 mm; the pilot tunnel is excavated first, with an excavation depth of 1 grid spacing. The excavated earth and stone are temporarily piled in the tunnel of the lower pilot tunnel excavated by the TBM as a working platform, and steel grids and temporary middle partitions are erected, and anchor rods and mesh spraying support are installed; (2) Excavate the lower steps of the pilot tunnel first: advance one grid spacing per excavation cycle; after the excavation is completed, promptly erect the grid and temporary support, and install anchor rods and mesh spraying support; (3) Excavation of the upper step of the rear pilot tunnel: After the upper step of the first pilot tunnel is excavated and the conditions for the excavation of the rear pilot tunnel are met, the rear pilot tunnel is excavated; the earth and stone after excavation are temporarily piled up in the tunnel of the lower pilot tunnel TBM excavation, which serves as a working platform, and grids, anchors, and mesh spraying support are set up in time; (4) Excavation of the lower step of the rear pilot tunnel: advance by 2 grid spacings in each excavation cycle; erect grids, install anchors, and use mesh spraying support in a timely manner after excavation is completed; A work platform is arranged above the work platform, a protection platform is arranged on the periphery of the work platform, a protection net is installed on the periphery of the protection platform, the protection net is tied and fixed to the guardrail platform, one side of the work platform is connected to the surrounding rock of the face, and two ladders are arranged on the work platform.

2. The large-section tunnel excavation support structure construction method according to claim 1 is characterized in that: The excavation of a single-layer lining section includes the following steps: (1) Excavation of the upper steps of the pilot tunnel: Excavation of the upper steps of the right line is carried out first according to the actual conditions on site; after the excavation is completed, spraying of single-layer lining concrete support is carried out; (2) Excavation of the upper steps of the rear pilot tunnel: excavation of the left line is carried out in a timely manner after the conditions are met; after the excavation is completed, a single layer of lining concrete is sprayed; (3) Excavation of the lower bench rock pillar: The lower bench is excavated by the two-bench method, with a cycle advance of 3m. The middle rock pillar is excavated by vertical drilling; (4) Excavation of the remaining part of the lower step: The remaining rock pillars of the lower step were excavated using vertical drilling, with an excavation depth of 3m; the side walls on both sides were manually drilled using air guns, with a cycle depth of 3m.

3. The large-section tunnel excavation support structure construction method according to claim 2 is characterized in that: The construction method also includes pipeline layout and slag discharge in the tunnel. The pipeline layout in the tunnel is to arrange ventilation pipes in the arch of the TBM standard tunnel, set up a pedestrian passage on the left, and arrange air and water pipes on the right. The tunnel arch is filled with 0.5m high and 3m wide slag, which is used as a slag discharge channel after filling.

4. The large-section tunnel excavation support structure construction method according to claim 3 is characterized in that: The construction method also includes construction platform operation: when the right-line cross channel is excavated, the excavated earth and stone are transported to the right-line horse head gate of Xizhen Station, and a loader and an excavator are used to raise and level a working platform to facilitate the step-up excavation construction, with a slag pad height of 3m; the upper half section at the horse head gate is excavated to the top in two steps, and a grid spray anchor support is set up; the earth and stone excavated for the first time is used to continue to raise the working platform to facilitate the second excavation construction; the working platform columns and longitudinal beams are made of 18 I-beams, and the side wings are made of Ф89 steel pipes and Ф76 telescopic steel pipes, and mechanically assisted towing wire ropes are used for movement.

5. The large-section tunnel excavation support structure construction method according to claim 1, characterized in that: The construction method also includes excavating the remaining part of the section by drilling and blasting before the TBM is driven through the section with the large cross section.

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