CN108131145B - Construction method for ultra-large-span tunnel excavation support - Google Patents
Construction method for ultra-large-span tunnel excavation support Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 71
- 238000009412 basement excavation Methods 0.000 title claims abstract description 59
- 239000002689 soil Substances 0.000 claims abstract description 28
- 239000004567 concrete Substances 0.000 claims description 73
- 238000005507 spraying Methods 0.000 claims description 62
- 229910000831 Steel Inorganic materials 0.000 claims description 38
- 239000010959 steel Substances 0.000 claims description 38
- 230000003014 reinforcing effect Effects 0.000 claims description 27
- 238000005553 drilling Methods 0.000 claims description 6
- 239000011378 shotcrete Substances 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 26
- 238000006243 chemical reaction Methods 0.000 abstract description 4
- 238000004873 anchoring Methods 0.000 abstract description 3
- 239000011435 rock Substances 0.000 description 9
- 238000010586 diagram Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000008520 organization Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000005422 blasting Methods 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D20/00—Setting anchoring-bolts
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Abstract
The invention relates to a construction method for an ultra-large span tunnel excavation support, which adopts a method of top tunnel advance, layered excavation, core reservation and key anchoring, divides an ultra-large section tunnel into eleven parts for excavation according to the principle of basically uniform horizontal and vertical directions, and firstly excavates a top layer middle tunnel; then, excavating all parts on two sides from top to bottom, left and right alternately and in layers, and performing primary support after each part is excavated; and finally, gradually excavating the core soil and the inverted arch in layers to form a closed and ring-shaped supporting system. The invention has the advantages of simple construction method, less process conversion, safe and reliable construction, high mechanization degree and capability of organizing safe and rapid construction.
Description
Technical Field
The invention relates to the technical field of tunnel construction, in particular to a construction method of an ultra-large span tunnel excavation support, and specifically relates to a construction method of a tunnel excavation support of an underground station with a span of more than 25 m.
Background
The super-large span tunnel (usually span is greater than 25m) is because the excavation section is big, and the shape is flat, and the general section of country rock overall stability is poor, has increased tunnel construction deformation and stable control's the degree of difficulty, and careless a little will appear accidents such as collapse. The key to successful tunnel construction is how to select a correct excavation supporting method, ensure the safety of the construction process and control the deformation of surrounding rocks.
For the ultra-large span tunnel, construction methods such as a CD method, a CRD method, a double-side-wall pit guiding method, a multi-pit guiding method and the like are mostly adopted at home and abroad for construction, and a large section is divided into a plurality of small sections for construction by arranging a plurality of guide pits and a plurality of transverse and vertical temporary supports. The method has the advantages of small pilot tunnel section, incapability of adopting large-scale mechanical construction, more working procedures, more cross, slow construction progress, more temporary supports, large deformation of surrounding rocks during temporary support dismantling and high safety risk.
Disclosure of Invention
Based on the above, the invention aims to provide a construction method for the excavation and support of the ultra-large span tunnel, which has the advantages of simple construction method, less process conversion, safe and reliable construction, high mechanization degree and capability of organizing safe and rapid construction.
The purpose of the invention is realized by the following technical scheme: the construction method for excavation and support of the ultra-large-span tunnel divides the tunnel into eleven parts for construction along a section, wherein the eleven parts comprise a top layer left side hole, a top layer middle hole, a top layer right side hole, a middle step left side hole, middle step middle core soil, a middle step right side hole, a lower step left side hole, lower step middle core soil, a lower step right side hole, a left side inverted arch and a right side inverted arch from top to bottom from left, and the eleven parts are constructed according to the following steps:
s1: excavating a top-layer middle tunnel and performing primary support;
s2: excavating a top left-side hole and performing primary support;
s3: excavating a top layer right side hole and performing primary support;
s4: excavating a left hole of the middle step and performing primary support;
s5: excavating a middle step right hole and performing primary support;
s6: excavating a left side hole of a lower step and performing primary support;
s7: excavating a right hole of the lower step and performing primary support;
s8: excavating core soil in the middle of the middle step;
s9: excavating core soil in the middle of the lower step;
s10: excavating and primary supporting a left inverted arch;
s11: and (5) excavating and primary supporting the inverted arch on the right side.
The method comprises the steps of adopting top tunnel advancing, layered excavation, core reservation and key anchoring methods for the underground station tunnel with the span of more than 25m, dividing the tunnel with the oversized cross section into eleven parts for excavation according to the principle that the transverse direction and the vertical direction are basically uniform, and excavating a top middle tunnel; then, excavating all parts on two sides from top to bottom, left and right alternately and in layers, and performing primary support after each part is excavated; and finally, gradually excavating the core soil and the inverted arch in layers to form a closed and ring-shaped supporting system. Compared with the prior art, the construction method is simple, and the process conversion is less; temporary supports are not arranged in the middle, the construction space is large, large-scale construction machinery organization parallel line production can be adopted in each step, the construction efficiency is high, and the construction progress is fast; and need not to demolish interim support, construction safe and reliable.
Further, the preliminary bracing comprises a steel frame installation, concrete spraying, prestressed anchor rods and prestressed anchor cables. By adopting the pre-stressed anchor rod and pre-stressed anchor cable supporting system, the self-bearing capacity of the surrounding rock can be fully exerted, the deformation of the surrounding rock is reduced, and the construction safety is ensured.
Further, the step S1 includes the following steps:
s11: excavating a top middle hole;
s12: after the top layer middle tunnel is excavated, primarily spraying concrete to the arch part of the top layer middle tunnel, mounting an arch part steel frame and a profile steel inclined strut, spraying secondary concrete to the arch part of the top layer middle tunnel, and spraying temporary closed concrete to the side wall of the top layer middle tunnel;
s13: after 20m of top layer middle tunnel excavation, constructing a top layer middle tunnel arch prestressed anchor rod and a prestressed anchor cable, hanging a reinforcing mesh, and spraying third-time concrete to the top layer middle tunnel arch;
s14: after the construction of the arch prestressed anchor rods and prestressed anchor cables of the middle tunnel of the top layer is finished, dismantling the arch section steel inclined struts;
the step S2 includes the steps of:
s21: after the construction of the prestressed anchor rods and prestressed anchor cables at the arch part of the top-layer middle tunnel is finished, excavating a top-layer left tunnel, and lagging behind the top-layer middle tunnel by 30-35 m;
s22: after the left hole of the top layer is dug, primarily spraying concrete to the arch part of the left hole of the top layer, mounting an arch part steel frame, drilling a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s23: after 20m of top left tunnel excavation, constructing arch prestressed anchor rods and prestressed anchor cables of the top left tunnel, hanging a reinforcing mesh, and spraying third-time concrete;
the step S3 includes the steps of:
s31: after the construction of the prestressed anchor rods and the prestressed anchor cables at the arch part of the top left side cave is finished, excavating the top right side cave, and lagging behind the top left side cave by 30-35 m;
s32: after the right hole of the top layer is dug, primarily spraying concrete to the arch part of the right hole of the top layer, mounting an arch part steel frame, drilling a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s33: and (3) after the top right side tunnel is excavated for 20m, constructing the prestressed anchor rods and the prestressed anchor cables at the arch part of the top right side tunnel, hanging a reinforcing mesh, and spraying third-time concrete.
Further, the step S4 includes the following steps:
s41: excavating a left hole of a middle step after the construction of the arch prestressed anchor rod and the prestressed anchor cable of the right hole of the top layer is finished;
s42: after the excavation of the middle step left side hole is finished, primarily spraying concrete to the middle step left side hole arch wall, installing an arch wall steel frame, setting a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s43: after 20m of excavation is carried out on the left side cave of the middle step, construction of a prestressed anchor rod and a prestressed anchor cable of the arch wall of the left side cave of the middle step is started, a reinforcing mesh is hung, and third-time concrete is sprayed;
the step S5 includes the steps of:
s51: excavating a middle step right hole after construction of the prestressed anchor rods and the prestressed anchor cables of the arch wall of the middle step left hole is finished;
s52: after the excavation of the middle step right side hole is finished, primarily spraying concrete to the middle step right side hole arch wall, installing an arch wall steel frame, setting a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s53: and (3) after 20m of excavation is carried out on the right side hole of the middle step, constructing the prestressed anchor rods and the prestressed anchor cables of the arch wall of the right side hole of the middle step, hanging a reinforcing mesh, and spraying third-time concrete.
Further, the step S6 includes the following steps:
s61: excavating a left side hole of a lower step after construction of the prestressed anchor rods and the prestressed anchor cables of the arch wall of the middle step right side hole is finished;
s62: after the excavation of the left hole of the lower step is finished, primarily spraying concrete to the side wall of the left hole of the lower step, mounting a side wall steel frame, hanging a reinforcing mesh, and spraying secondary concrete;
the step S7 includes the steps of:
s71: lagging the left hole of the lower step by 20m, and excavating the right hole of the lower step;
s72: and after the excavation of the right hole of the lower step is finished, primarily spraying concrete to the side wall of the right hole of the lower step, mounting a side wall steel frame, hanging a reinforcing mesh, and spraying secondary concrete.
Further, in the step S8, retarding the lower step right hole by 20m, and excavating the middle core soil of the middle step; in the step S9, the central core soil of the middle step is lagged by 20m, and the central core soil of the lower step is excavated.
Further, the step S10 includes the following steps:
s101: lagging the core soil at the middle part of the lower step by 20m, and excavating a left inverted arch;
s102: after the left inverted arch is excavated, primarily spraying concrete to the left inverted arch, mounting a steel frame, hanging a reinforcing mesh, and spraying concrete for the second time;
the step S11 includes the steps of:
s111: 3m of the left inverted arch is lagged, and the right inverted arch is excavated;
s112: and after the excavation of the right inverted arch is finished, primarily spraying concrete to the right inverted arch, mounting a steel frame, hanging a reinforcing mesh, and spraying concrete for the second time.
For a better understanding and practice, the invention is described in detail below with reference to the accompanying drawings.
Drawings
Fig. 1 is a schematic view of a construction sequence of a construction method of an ultra-large span tunnel excavation support according to an embodiment.
FIG. 2 is a schematic diagram of an embodiment of a top layer after excavation.
Figure 3 is a schematic diagram of an embodiment after top layer excavation.
Fig. 4 is a schematic core soil reservation diagram according to an embodiment.
Detailed Description
Referring to fig. 1 to 4, the embodiment provides a construction method for excavation and support of a super-large span tunnel, wherein surrounding rocks of the super-large span tunnel are V-grade strongly weathered granite, and an excavation section is 19.7m high and 32.7m wide. According to the principle that the tunnel is basically uniform in the horizontal and vertical directions, the large-section tunnel is divided into eleven parts for construction, and the eleven parts comprise a top layer left hole B, a top layer middle hole A, a top layer right hole C, a middle step left hole D, middle step middle core soil H, a middle step right hole E, a lower step left hole F, lower step middle core soil I, a lower step right hole G, a left inverted arch J and a right inverted arch K from left to right from top to bottom. Firstly, excavating a top layer middle tunnel A, then excavating each part at two sides from top to bottom, left and right alternately and layer by layer, applying a prestressed anchor rod and a prestressed anchor cable on an arch part and a side wall for anchoring after each part is excavated, and finally excavating core soil and an inverted arch step by layer to form a closed ring-shaped supporting system. The method specifically comprises the following steps:
the method comprises the following steps: excavation and preliminary bracing of top layer middle tunnel A include the following process:
firstly, excavating a top layer middle hole A, wherein the height of an excavated section is 6.5m, the width of the excavated section is 8m, and weak blasting excavation is carried out after measurement and lofting, wherein the footage is 1m in each cycle;
secondly, after the top layer middle tunnel A is excavated, primarily spraying C30 concrete with the thickness of 5cm to the arch part of the top layer middle tunnel, installing an arch part grid steel frame and a profile steel inclined strut 2, connecting the top end of the profile steel inclined strut 2 with the steel frame, supporting the bottom end of the profile steel inclined strut 2 on surrounding rocks at two sides, spraying C30 concrete 1 with the thickness of 18cm for the second time to the arch part, and spraying C30 concrete 3 with the thickness of 5cm to the side wall for temporary sealing;
thirdly, after the top layer middle hole A is excavated for 20m, the arch part begins to be constructedA prestressed anchor rod 5 and a prestressed anchor cable 4, wherein the length of the prestressed anchor rod 5 is 11m, the longitudinal distance of the ring is 1.2m, the length of the prestressed anchor cable 4 is 25m,15.2, the design tension is 1000kN, and the longitudinal distance of the rings is 2.4 m; after the prestressed anchor rod 5 and the prestressed anchor cable 4 are constructed, the arch part is hungSpraying C30 concrete with the thickness of 12cm for the third time to the arch part by using a reinforcing mesh with the thickness of 6mm @20cm by 20cm to cover the end of the anchor rod and the anchor head of the anchor cable;
fourthly, the arch section steel inclined strut 2 is dismantled.
Step two: excavation and preliminary bracing of top layer left side hole B include the following process:
firstly, excavating a top left side cave B after construction of an arch prestressed anchor rod 5 and a prestressed anchor cable 4 of a top middle cave A is finished;
secondly, after the top left hole B is excavated, the top left hole arch wall part is subjected to primary concrete spraying, a lengthening steel frame is installed, and 4 holes with the length of 5m are arranged42, locking the anchor rod 7, and spraying the second-time concrete 6;
thirdly, after 20m of excavation is carried out on the left side cave B of the top layer, construction of a prestressed anchor rod 9 and a prestressed anchor cable 8 of the arch wall part of the left side cave of the top layer is started, a reinforcing mesh is hung, and third-time concrete is sprayed.
Step three: excavation and preliminary bracing of top layer right side hole C include the following process:
firstly, excavating a top left hole C after construction of a top left hole B arch wall pre-stressed anchor rod 9 and a pre-stressed anchor cable 8 is finished;
secondly, after the top layer right hole C is excavated, primarily spraying concrete to the arch wall part of the top layer right hole, installing a lengthening steel frame, arranging a locking anchor rod 11, and spraying secondary concrete 10;
thirdly, after the top right side cave C is excavated for 20m, the arch prestressed anchor rods 13 and the prestressed anchor cables 12 of the top right side cave begin to be constructed, the reinforcing mesh is hung, and the third-time concrete is sprayed.
Step four: excavation and preliminary bracing of middle step left side hole D include the following process:
firstly, excavating a middle step left hole D after the construction of a top layer right hole C arch prestressed anchor rod 13 and a prestressed anchor cable 12 is finished;
secondly, after the excavation of the middle step left side hole D is finished, primarily spraying concrete to the arch wall of the middle step left side hole, installing an arch wall steel frame, drilling a lock leg anchor pipe 15, and spraying secondary concrete 14;
thirdly, after 20m of excavation is carried out on the middle step left side cave D, construction of a middle step left side cave arch wall prestressed anchor rod 17 and a prestressed anchor cable 16 is started, a reinforcing mesh is hung, and third-time concrete is sprayed.
Step five: excavation and preliminary bracing of middle step right side hole E include the following process:
firstly, excavating a middle step right hole E after construction of an arch wall prestressed anchor rod 17 and a prestressed anchor cable 16 of the middle step left hole D is finished;
secondly, after the middle step right hole E is excavated, primarily spraying concrete to the arch wall of the middle step right hole, mounting an arch wall steel frame, drilling a lock leg anchor pipe 19, and spraying secondary concrete 18;
thirdly, after 20m of the middle step right side cave E is excavated, constructing a middle step right side cave arch wall prestressed anchor rod 21 and a prestressed anchor cable 20, hanging a reinforcing mesh, and spraying third-time concrete.
Step six: excavation and preliminary bracing of lower step left side hole F include the following process:
firstly, excavating a lower step left hole F after the construction of a prestressed anchor rod 21 and a prestressed anchor cable 20 of an arch wall of a middle step right hole E is finished;
secondly, after the left hole F of the lower step is excavated, the concrete is primarily sprayed on the side wall of the left hole of the lower step, the side wall steel frame is installed, the reinforcing mesh is hung, and the concrete 22 is sprayed.
Step seven: excavation and preliminary bracing of lower step right side hole G include following process:
firstly, lagging a left hole 20m of a lower step, and excavating a right hole G of the lower step;
secondly, after the excavation of the lower step right hole G is finished, primary concrete spraying is carried out on the side wall of the lower step right hole, a side wall steel frame is installed, a reinforcing mesh is hung, and concrete 23 is sprayed.
Step eight: well step middle part core soil H excavates, includes: and (5) lagging the G part 20m of the right hole of the lower step, and excavating the core soil H in the middle of the middle step.
Step nine: lower step middle part core soil I excavation includes: and (5) lagging the central core soil H part of the middle step by 20m, and excavating the central core soil I of the lower step.
Step ten: excavation and preliminary bracing of left side invert J includes the following process:
firstly, lagging the central soil I part 20m in the middle of the lower step, and excavating a left inverted arch J;
secondly, after the left-side inverted arch J is excavated, the concrete is primarily sprayed on the left-side inverted arch, a steel frame is installed, a reinforcing mesh is hung, and the concrete is sprayed 24.
Step eleven: excavation and preliminary bracing of right side inverted arch K include the following process:
firstly, delaying the J part 3m of the left inverted arch, and excavating a right inverted arch K;
secondly, after the excavation of the right inverted arch K is finished, primary concrete spraying is carried out on the right inverted arch, a steel frame is installed, a reinforcing mesh is hung, and concrete 25 is sprayed.
And after the eleven steps are completed, sealing the primary support into a ring, and finishing the excavation support of the ultra-large span tunnel.
Compared with the prior art, the invention has the advantages of simple construction method, less process conversion, safe and reliable construction, high mechanization degree and capability of organizing safe and rapid construction:
1) the arch wall adopts a prestressed anchor rod and prestressed anchor cable supporting system, so that the self-bearing capacity of the surrounding rock can be fully exerted, the deformation of the surrounding rock is reduced, and the construction safety is ensured;
2) temporary supports are not arranged in the middle, the construction space is large, large-scale construction machinery organization parallel line production can be adopted in each step, the construction efficiency is high, and the construction progress is fast;
3) need not to demolish interim support, construction safe and reliable.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (5)
1. A construction method for excavation and support of a super-large span tunnel is characterized by comprising the following steps: dividing the tunnel into eleven parts for construction along the section, wherein the eleven parts comprise a top layer left hole, a top layer middle hole, a top layer right hole, a middle step left hole, middle step middle core soil, a middle step right hole, a lower step left hole, lower step middle core soil, a lower step right hole, a left inverted arch and a right inverted arch from left to right from top to bottom, and the eleven parts are constructed according to the following steps:
s1: excavating a top-layer middle tunnel and performing primary support;
s2: excavating a top left-side hole and performing primary support;
s3: excavating a top layer right side hole and performing primary support;
s4: excavating a left hole of the middle step and performing primary support;
s5: excavating a middle step right hole and performing primary support;
s6: excavating a left side hole of a lower step and performing primary support;
s7: excavating a right hole of the lower step and performing primary support;
s8: excavating core soil in the middle of the middle step;
s9: excavating core soil in the middle of the lower step;
s10: excavating and primary supporting a left inverted arch;
s11: excavating and primary supporting a right inverted arch;
wherein the step S1 includes the steps of:
s11: excavating a top middle hole;
s12: after the top layer middle tunnel is excavated, primarily spraying concrete to the arch part of the top layer middle tunnel, mounting an arch part steel frame and a profile steel inclined strut, spraying secondary concrete to the arch part of the top layer middle tunnel, and spraying temporary closed concrete to the side wall of the top layer middle tunnel;
s13: after 20m of top layer middle tunnel excavation, constructing a top layer middle tunnel arch prestressed anchor rod and a prestressed anchor cable, hanging a reinforcing mesh, and spraying third-time concrete to the top layer middle tunnel arch;
s14: after the construction of the arch prestressed anchor rods and prestressed anchor cables of the middle tunnel of the top layer is finished, dismantling the arch section steel inclined struts;
the step S2 includes the steps of:
s21: after the construction of the prestressed anchor rods and prestressed anchor cables at the arch part of the top-layer middle tunnel is finished, excavating a top-layer left tunnel, and lagging behind the top-layer middle tunnel by 30-35 m;
s22: after the left hole of the top layer is dug, primarily spraying concrete to the arch part of the left hole of the top layer, mounting an arch part steel frame, drilling a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s23: after 20m of top left tunnel excavation, constructing arch prestressed anchor rods and prestressed anchor cables of the top left tunnel, hanging a reinforcing mesh, and spraying third-time concrete;
the step S3 includes the steps of:
s31: after the construction of the prestressed anchor rods and the prestressed anchor cables at the arch part of the top left side cave is finished, excavating the top right side cave, and lagging behind the top left side cave by 30-35 m;
s32: after the right hole of the top layer is dug, primarily spraying concrete to the arch part of the right hole of the top layer, mounting an arch part steel frame, drilling a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s33: after 20m of top right tunnel excavation, starting construction of a prestressed anchor rod and a prestressed anchor cable at the arch part of the top right tunnel, hanging a reinforcing mesh, and spraying third-time concrete;
the primary support comprises a steel frame, sprayed concrete, a prestressed anchor rod and a prestressed anchor cable.
2. The construction method for the ultra-large span tunnel excavation support according to claim 1, characterized in that:
the step S4 includes the steps of:
s41: excavating a left hole of a middle step after the construction of the arch prestressed anchor rod and the prestressed anchor cable of the right hole of the top layer is finished;
s42: after the excavation of the middle step left side hole is finished, primarily spraying concrete to the middle step left side hole arch wall, installing an arch wall steel frame, setting a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s43: after 20m of excavation is carried out on the left side cave of the middle step, construction of a prestressed anchor rod and a prestressed anchor cable of the arch wall of the left side cave of the middle step is started, a reinforcing mesh is hung, and third-time concrete is sprayed;
the step S5 includes the steps of:
s51: excavating a middle step right hole after construction of the prestressed anchor rods and the prestressed anchor cables of the arch wall of the middle step left hole is finished;
s52: after the excavation of the middle step right side hole is finished, primarily spraying concrete to the middle step right side hole arch wall, installing an arch wall steel frame, setting a locking anchor rod or an anchor pipe, and spraying secondary concrete;
s53: and (3) after 20m of excavation is carried out on the right side hole of the middle step, constructing the prestressed anchor rods and the prestressed anchor cables of the arch wall of the right side hole of the middle step, hanging a reinforcing mesh, and spraying third-time concrete.
3. The construction method for the ultra-large span tunnel excavation support according to claim 2, characterized in that:
the step S6 includes the steps of:
s61: excavating a left side hole of a lower step after construction of the prestressed anchor rods and the prestressed anchor cables of the arch wall of the middle step right side hole is finished;
s62: after the excavation of the left hole of the lower step is finished, primarily spraying concrete to the side wall of the left hole of the lower step, mounting a side wall steel frame, hanging a reinforcing mesh, and spraying secondary concrete;
the step S7 includes the steps of:
s71: lagging the left hole of the lower step by 20m, and excavating the right hole of the lower step;
s72: and after the excavation of the right hole of the lower step is finished, primarily spraying concrete to the side wall of the right hole of the lower step, mounting a side wall steel frame, hanging a reinforcing mesh, and spraying secondary concrete.
4. The construction method for the ultra-large span tunnel excavation support according to claim 3, characterized in that: in the step S8, lagging the right hole of the lower step by 20m, and excavating the core soil in the middle of the middle step; in the step S9, the central core soil of the middle step is lagged by 20m, and the central core soil of the lower step is excavated.
5. The construction method for the ultra-large span tunnel excavation support according to claim 4, characterized in that:
the step S10 includes the steps of:
s101: lagging the core soil at the middle part of the lower step by 20m, and excavating a left inverted arch;
s102: after the left inverted arch is excavated, primarily spraying concrete to the left inverted arch, mounting a steel frame, hanging a reinforcing mesh, and spraying concrete for the second time;
the step S11 includes the steps of:
s111: 3m of the left inverted arch is lagged, and the right inverted arch is excavated;
s112: and after the excavation of the right inverted arch is finished, primarily spraying concrete to the right inverted arch, mounting a steel frame, hanging a reinforcing mesh, and spraying concrete for the second time.
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CN108843340B (en) * | 2018-06-15 | 2023-09-26 | 中铁工程设计咨询集团有限公司 | Support structure in shape of character of ultra-large span tunnel and excavation construction method thereof |
CN109113749A (en) * | 2018-08-20 | 2019-01-01 | 中铁建大桥工程局集团第五工程有限公司 | Four line large section railway tunnel construction method of weak surrounding rock |
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CN110424989B (en) * | 2019-08-09 | 2024-02-09 | 中铁第六勘察设计院集团有限公司 | Primary support structure of ultra-large span underground engineering in hard rock area and construction method thereof |
CN112963155B (en) * | 2021-03-05 | 2023-05-23 | 北京城建设计发展集团股份有限公司 | Lute excavation construction method for arch part of large-section tunnel of soil-rock composite stratum |
CN113605901A (en) * | 2021-07-20 | 2021-11-05 | 西南交通大学 | Strong anchor middle pilot tunnel construction method based on extra-large section tunnel construction |
CN114086993A (en) * | 2021-11-30 | 2022-02-25 | 中铁第四勘察设计院集团有限公司 | Supporting system and excavation method for oversized section tunnel |
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CN102220868B (en) * | 2011-05-23 | 2013-06-19 | 重庆中环建设有限公司 | Urban shallow buried large-section tunnel five-step excavating method |
CN102562074A (en) * | 2012-02-03 | 2012-07-11 | 中铁四局集团第二工程有限公司 | Construction method for composite stratum with hard top and soft bottom of large-section tunnel |
CN102720504A (en) * | 2012-06-13 | 2012-10-10 | 北京市公路桥梁建设集团有限公司 | Double-side-wall-pilot-hole subsection bench cut method construction method |
CN103628889A (en) * | 2013-11-28 | 2014-03-12 | 中铁十三局集团有限公司 | Quick sealing method for excavating phyllite stratum tunnel |
CN104500076B (en) * | 2014-11-26 | 2017-11-24 | 中国电建集团成都勘测设计研究院有限公司 | Large section, Long span collapse and cave-in granular media tunnel driving method |
CN104653187B (en) * | 2014-12-11 | 2017-06-06 | 中铁十九局集团有限公司 | Method for excavating geological large-section tunnel with water-rich sand layer |
CN205532615U (en) * | 2016-04-12 | 2016-08-31 | 中建四局第五建筑工程有限公司 | Super large section tunnel excavates structure |
CN106761778B (en) * | 2017-01-24 | 2018-08-07 | 山东大学 | A kind of underground digging in subway station construction technology suitable for upper-soft lower-hard ground |
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