CN110761811A - Layered soft rock tunnel asymmetric supporting structure and construction method - Google Patents
Layered soft rock tunnel asymmetric supporting structure and construction method Download PDFInfo
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- 239000011435 rock Substances 0.000 title claims abstract description 241
- 238000010276 construction Methods 0.000 title claims abstract description 16
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 95
- 239000010959 steel Substances 0.000 claims abstract description 95
- 239000004570 mortar (masonry) Substances 0.000 claims abstract description 37
- 239000004567 concrete Substances 0.000 claims abstract description 21
- 238000005507 spraying Methods 0.000 claims abstract description 20
- 238000000034 method Methods 0.000 claims abstract description 10
- 239000002689 soil Substances 0.000 claims abstract description 8
- 238000009412 basement excavation Methods 0.000 claims description 27
- 238000004873 anchoring Methods 0.000 claims description 11
- 230000003014 reinforcing effect Effects 0.000 claims description 10
- 238000009434 installation Methods 0.000 claims description 6
- 238000013461 design Methods 0.000 claims description 5
- 239000004744 fabric Substances 0.000 claims description 3
- 230000002787 reinforcement Effects 0.000 claims description 2
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- 238000011217 control strategy Methods 0.000 description 2
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- 239000011378 shotcrete Substances 0.000 description 2
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- 238000010586 diagram Methods 0.000 description 1
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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
- E21D11/14—Lining predominantly with metal
- E21D11/18—Arch members ; Network made of arch members ; Ring elements; Polygon elements; Polygon elements inside arches
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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
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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
- E21D11/14—Lining predominantly with metal
- E21D11/15—Plate linings; Laggings, i.e. linings designed for holding back formation material or for transmitting the load to main supporting members
- E21D11/152—Laggings made of grids or nettings
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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
- E21D20/02—Setting anchoring-bolts with provisions for grouting
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Abstract
The invention discloses an asymmetric supporting structure of a layered soft rock tunnel and a construction method, and the asymmetric supporting structure comprises a pipe shed support perpendicular to the bedding surface direction of a layered soft rock layer, a pipe shed support not perpendicular to the bedding surface direction of the layered soft rock layer, a steel arch frame, a mortar anchor rod perpendicular to the bedding surface direction of the layered soft rock layer, a mortar anchor rod not perpendicular to the bedding surface direction of the layered soft rock layer, a pressure type anchor rope, an upper step foot locking anchor rod, a lower step foot locking anchor rod, an inverted arch primary support, primary concrete spraying and secondary lining. According to the invention, the asymmetric supporting structure is adopted, and the supporting structure is reinforced in the direction perpendicular to the bedding surface and easy to crush and damage aiming at the layered soft rock strata with different bedding surface dip angles, so that the stress state of the tunnel supporting structure can be effectively improved, the construction method is still based on the traditional upper and lower step reserved core soil method, no additional workload is required, and the time and the economic cost are maximally saved while the tunnel supporting requirement is met.
Description
Technical Field
The invention relates to the technical field of underground engineering, in particular to an asymmetric supporting structure of a layered soft rock tunnel and a construction method.
Background
In the west Tibetan area of China, weak surrounding rock strata mainly comprising phyllite, slate, shale and sandstone are widely distributed, and the strata have obvious sedimentary characteristics and show anisotropic mechanical characteristics, wherein the carbonaceous phyllite is the most obvious. When the tunnel passes through the layered soft rock stratum, the deformation characteristic of the surrounding rock and the mechanical property of the supporting structure have obvious asymmetric characteristics. And if the axial direction of the tunnel is not vertical or parallel to the main stress field, the shear stress generated by the initial ground stress field at the periphery of the tunnel structure can aggravate the asymmetric deformation characteristic, and the safety performance of the supporting structure is influenced. Due to the fact that the weak surrounding rock is low in strength and poor in self-supporting capacity, the tunnel supporting structure can bear large load, and the tunnel can be damaged by extrusion. The deformation characteristics and failure modes are closely related to the angle of the bedding plane. For a horizontal layered surrounding rock tunnel, the damage of a supporting structure is mainly concentrated on an arch crown and an arch bottom, and collapse and bottom heave disasters are easy to happen; for the inclined layered surrounding rock tunnel, an obvious asymmetric deformation mechanism is provided, the surrounding rock along the normal direction of the bedding surface is subjected to bending inner bulging deformation towards the inner side hollow surface, and asymmetric cracking disasters are easy to occur at the positions of a left arch shoulder and a right arch foot of a tunnel supporting structure; for a steep-dip layered surrounding rock tunnel, the deformation of the surrounding rock is concentrated at the positions of the side walls at the left and right sides, and the occurrence of concrete cracking and peeling disasters is more easily caused by stress concentration. Many engineering practices show that the influence of the layered soft rock on the deformation of the surrounding rock and the mechanical behavior of the supporting structure is mainly reflected on the bedding angle and the bedding thickness. Therefore, for the tunnel penetrating through the layered soft rock stratum, a reasonable supporting mode and a construction method are adopted, and the method has important significance for the safety guarantee of the tunnel structure.
In the aspect of the supporting technology of the layered soft rock, a great deal of research is carried out by a plurality of scholars at home and abroad. The support measures of the tunnel in the inclined layered mudstone are researched by the Zjun Confucian and Chou leathers through field monitoring, model tests and theoretical analysis, and the result shows that the long anchor pipe vertical to the rock stratum surface is arranged at the arch waist of the tunnel in an encrypted manner, so that the bias load can be effectively transferred, and the self-bearing capacity of the surrounding rock is fully utilized. According to the Xiabinwei, the stress distribution of surrounding rocks of a cavern, a conventional anchor rod and a lengthened anchor rod model is researched through a physical model experiment, the mechanical effect of the anchor rods with different lengths for reinforcing the lower-layer-shaped surrounding rocks is analyzed, and the result shows that the surrounding rocks reinforced by the anchor rods form a compressive stress field, so that the internal stress state of the surrounding rocks is effectively improved. Aiming at the asymmetric deformation and damage phenomena shown after excavation and support of deep inclined rock layer roadway surrounding rocks, such as Sunxinging and Zhangfeng, numerical simulation and engineering application research are carried out on a deformation and damage mechanism and a coupling control strategy of the deep inclined rock layer roadway surrounding rocks. An asymmetric coupling control strategy is provided, and the key parts which are subjected to differential deformation damage are reinforced and supported by anchor cables, bottom angle anchor rods and the like, so that the aim of controlling the asymmetric deformation of the roadway is fulfilled. Nevertheless, in most of the tunnels passing through the layered soft rock in China, the adopted supporting technology is still insufficient:
1. most of the current lining support parameters are designed uniformly, in a layered soft rock stratum, a lining structure can bear asymmetric load, a lining structure can bear larger surrounding rock load in the direction vertical to a bedding surface, and the support structure at the position is easy to damage;
2. at present, the method for designing the tunnel supporting structure at home and abroad still mainly adopts an engineering analogy experience design method, but from the perspective of safety and economy, the design method is not reasonable;
3. in a layered soft rock stratum, surrounding rocks are easy to deform greatly, but the existing supporting system still takes the hard resistance of a supporting structure as the main choice for the problem, so that the supporting parameters are increased, and the construction cost is greatly increased.
Disclosure of Invention
The invention aims to solve the defects in the prior art and provide the safe and effective layered soft rock tunnel asymmetric supporting structure and the construction method which are simple and efficient in construction, economic and reasonable and can solve the problem that the tunnel is subjected to asymmetric load in a layered stratum.
In order to achieve the purpose, the invention is implemented according to the following technical scheme:
an asymmetric supporting structure of a layered soft rock tunnel comprises a pipe shed advance support arranged in surrounding rocks of the layered soft rock tunnel, wherein the pipe shed advance support comprises a pipe shed support perpendicular to the bedding plane direction of the layered soft rock and a pipe shed support not perpendicular to the bedding plane direction of the layered soft rock, which are composed of steel pipes, the length of the steel pipes adopted by the pipe shed support perpendicular to the bedding plane direction of the layered soft rock is larger than that of the steel pipes adopted by the pipe shed support not perpendicular to the bedding plane direction of the layered soft rock, a steel arch is arranged below a surrounding rock wall of the layered soft rock tunnel, a mortar anchor rod perpendicular to the bedding plane direction of the layered soft rock and used for anchoring the steel arch and a mortar anchor rod not perpendicular to the bedding plane direction of the layered soft rock are arranged along a surrounding rock drill of the layered soft rock tunnel, the length of the mortar anchor rod perpendicular to the bedding plane direction of the layered soft rock is larger than that of the mortar anchor rod not perpendicular to the bedding plane direction of the layered soft rock, the method is characterized in that pressure type anchor cables for anchoring a steel arch frame are further arranged in the direction perpendicular to the bedding surface of the layered soft rock tunnel surrounding rock, upper step locking anchor rods are arranged at two side arch feet of the steel arch frame in an upper step annular excavation portion of the tunnel along the layered soft rock tunnel surrounding rock, lower step locking anchor rods are arranged at two side arch feet of the steel arch frame in a lower step annular excavation portion of the tunnel along the layered soft rock tunnel surrounding rock, an inverted arch initial support is arranged in an inverted arch excavation portion of the tunnel, initial-stage concrete spraying is arranged between the steel arch frame and the layered soft rock tunnel surrounding rock, and a secondary lining is arranged at the lower wall of the initial-stage concrete spraying.
The steel arch comprises a steel arch vertical to the layered soft rock layer surface direction and a steel arch not vertical to the layered soft rock layer surface direction, the steel arch vertical to the layered soft rock layer surface direction adopts 20b type I steel, and the steel arch not vertical to the layered soft rock layer surface direction adopts 20a type I steel.
The secondary lining comprises a secondary lining vertical to the bedding surface direction of the layered soft rock layer and a secondary lining not vertical to the bedding surface direction of the layered soft rock layer, and the thickness of the secondary lining vertical to the bedding surface direction is 5-10cm compared with the thickness of the secondary lining not vertical to the bedding surface direction of the layered soft rock layer.
And a waterproof layer is arranged between the initial concrete spraying and the secondary lining.
The waterproof layer is waterproof cloth.
A construction method of an asymmetric supporting structure of a layered soft rock tunnel comprises the following steps:
1) constructing pipe shed advance supports in the surrounding rocks of the layered soft rock tunnel, wherein the pipe shed advance supports comprise pipe shed supports perpendicular to the bedding plane direction of the layered soft rock and pipe shed supports not perpendicular to the bedding plane direction of the layered soft rock, and grouting and reinforcing the surrounding rocks in front of the tunnel face;
2) firstly, excavating an upper step annular excavation part, reserving a core soil part, immediately paving a reinforcing mesh after excavation, installing a steel arch frame perpendicular to the bedding surface direction of the layered soft rock layer and a steel arch frame not perpendicular to the bedding surface direction of the layered soft rock layer, then installing a mortar anchor rod perpendicular to the bedding surface direction of the layered soft rock layer and a mortar anchor rod not perpendicular to the bedding surface direction of the layered soft rock layer, installing upper step locking anchor rods along the surrounding rocks of the layered soft rock tunnel at two side arch feet of the steel arch frame positioned in the upper step annular excavation part of the tunnel, arranging pressure type anchor cables for anchoring the steel arch frame along the surrounding rocks of the layered soft rock tunnel in the direction perpendicular to the bedding surface direction, spraying initial spraying concrete between the steel arch frame and the surrounding rocks of the layered soft rock tunnel after installation, and closing the tunnel face in time to complete the initial support of the upper step;
3) excavating core soil and a lower step, immediately paving a reinforcing mesh and installing a steel arch frame perpendicular to the bedding surface direction of the layered soft rock and a steel arch frame not perpendicular to the bedding surface direction of the layered soft rock after the excavation is finished, then installing a mortar anchor rod perpendicular to the bedding surface direction of the layered soft rock and a mortar anchor rod not perpendicular to the bedding surface direction of the layered soft rock, installing a lower step locking anchor rod along the surrounding rocks of the layered soft rock tunnel at the arch feet at two sides of the steel arch frame positioned in the lower step annular excavation part of the tunnel, further arranging a pressure type anchor rope for anchoring the steel arch frame along the surrounding rocks of the layered soft rock tunnel in the direction perpendicular to the bedding surface direction, spraying initial-stage spraying concrete between the steel arch frame and the surrounding rocks of the layered soft rock tunnel after the installation is finished, and closing the tunnel face in time to finish the initial stage support of the lower step;
4) excavating an inverted arch, and immediately setting an inverted arch primary support after excavation;
5) after the primary support of the upper step, the primary support of the lower step and the primary support of the inverted arch are arranged, a waterproof layer is laid along the lower wall of the primary concrete spraying, an internal reinforcement cage of the secondary lining is installed according to the design drawing, and finally the secondary lining is poured by utilizing a template trolley;
6) and continuing to excavate the next circulating tunnel until the next circulating tunnel passes through the layered soft rock section.
Compared with the prior art, the asymmetric supporting structure is adopted, the supporting structure is reinforced in the direction perpendicular to the bedding surface and easy to crush and damage aiming at the layered soft rock stratum with different bedding surface inclination angles, the stress state of the tunnel supporting structure can be effectively improved, the construction method is still based on the traditional upper and lower step reserved core soil method, no additional workload is caused, the tunnel supporting requirement is met, and the time and the economic cost are saved to the maximum extent.
Drawings
Fig. 1 is a schematic diagram of an asymmetric supporting structure of a layered soft rock tunnel in the invention.
Fig. 2 is a schematic view of the construction method of the asymmetric supporting technology of the present invention.
Fig. 3 is a schematic view of the pressure anchor cable of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments. The specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
As shown in fig. 1, the asymmetric supporting structure of the layered soft rock tunnel of the embodiment comprises a pipe shed advance support arranged in the surrounding rock of the layered soft rock tunnel, wherein the pipe shed advance support comprises a pipe shed support 1 perpendicular to the physical surface direction of the layered soft rock layer and a pipe shed support 5 not perpendicular to the physical surface direction of the layered soft rock layer, the length of the steel pipe used for the pipe shed support 1 perpendicular to the physical surface direction of the layered soft rock layer is greater than the length of the steel pipe used for the pipe shed support 5 not perpendicular to the physical surface direction of the layered soft rock layer, specifically, the length of the steel pipe used for the pipe shed support 1 perpendicular to the physical surface direction of the layered soft rock layer is 30m, the length of the steel pipe used for the pipe shed support 5 not perpendicular to the physical surface direction of the layered soft rock layer is 25m, a steel arch is arranged below the surrounding rock wall of the layered soft rock tunnel, the steel arch comprises a steel arch 2 perpendicular to the physical surface direction of the layered soft rock layer and a steel arch 6 not perpendicular to the physical surface direction of the layered soft rock layer, the steel arch centering 2 vertical to the layered soft rock bedding surface direction adopts H-shaped steel 20b, the steel arch centering 6 not vertical to the layered soft rock bedding surface direction adopts H-shaped steel 20a, and the circumferential distance between the steel arch centering 2 vertical to the layered soft rock bedding surface direction and the steel arch centering 6 not vertical to the layered soft rock bedding surface direction is 0.6 m; a mortar anchor rod 3 perpendicular to the bedding surface direction of the layered soft rock and a mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock are arranged along the surrounding rock drill of the layered soft rock tunnel for anchoring a steel arch frame, the length of the mortar anchor rod 3 perpendicular to the bedding surface direction of the layered soft rock is greater than that of the mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock, specifically, the mortar anchor rod 3 perpendicular to the bedding surface direction is 4.5m long, the mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock is 3.5m long, and the circumferential distance between the mortar anchor rod 3 perpendicular to the bedding surface direction of the layered soft rock and the mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock is 1.5 m; the pressure type anchor rope 12 for anchoring the steel arch is further arranged in the direction perpendicular to the bedding surface along the layered soft rock tunnel surrounding rock, upper step locking anchor rods 10 are installed at two side arch feet of the steel arch in the upper step annular excavation portion of the tunnel along the layered soft rock tunnel surrounding rock, lower step locking anchor rods 11 are installed at two side arch feet of the steel arch in the lower step annular excavation portion of the tunnel along the layered soft rock tunnel surrounding rock, an inverted arch initial support 13 is arranged in the inverted arch excavation portion of the tunnel, initial spraying concrete 9 is arranged between the steel arch and the layered soft rock tunnel surrounding rock, and a secondary lining is arranged on the lower wall of the initial spraying concrete 9.
The secondary lining comprises a secondary lining 4 perpendicular to the bedding plane direction of the layered soft rock and a secondary lining 8 not perpendicular to the bedding plane direction of the layered soft rock, and the thickness of the secondary lining 4 perpendicular to the bedding plane direction is 5-10cm larger than that of the secondary lining 8 not perpendicular to the bedding plane direction of the layered soft rock.
In the actual construction process, a waterproof layer 14 is arranged between the initial concrete spraying 9 and the secondary lining, and in this embodiment, the waterproof layer 14 may be made of waterproof cloth, or of course, other waterproof materials may be used.
Referring to fig. 2, the embodiment further provides a construction method of the asymmetric supporting structure of the layered soft rock tunnel, which includes the following specific steps:
1) constructing a pipe shed advance support in the surrounding rock of the layered soft rock tunnel, wherein the pipe shed advance support comprises a pipe shed support 1 vertical to the bedding surface direction of the layered soft rock and a pipe shed support 5 not vertical to the bedding surface direction of the layered soft rock, the length of a steel conduit adopted by the pipe shed support 1 vertical to the bedding surface direction of the layered soft rock is 30m, the length of a steel conduit adopted by the pipe shed support 5 not vertical to the bedding surface direction of the layered soft rock is 25m, and grouting and reinforcing the surrounding rock in front of the tunnel face;
2) firstly excavating an upper step annular excavation part I, reserving a core soil II part, immediately paving a reinforcing mesh after excavation, installing a steel arch frame 2 vertical to the layered soft rock layer surface direction and a steel arch frame 6 not vertical to the layered soft rock layer surface direction, adopting I20 b type I steel for the steel arch frame 2 vertical to the layered soft rock layer surface direction, adopting 20a type I steel for the steel arch frame 6 not vertical to the layered soft rock layer surface direction, setting the annular distance between the steel arch frame 2 vertical to the layered soft rock layer surface direction and the steel arch frame 6 not vertical to the layered soft rock layer surface direction to be 0.6m, then installing a mortar anchor rod 3 vertical to the layered soft rock layer surface direction and a mortar anchor rod 7 not vertical to the layered soft rock layer surface direction, setting the mortar anchor rod 3 vertical to the layered soft rock layer surface direction to be 4.5m, setting the mortar anchor rod 7 vertical to the layered soft rock layer surface direction to be 3.5m, setting the mortar anchor rod 3 vertical to the layered soft rock layer surface direction and the layered soft rock layer surface direction not vertical to be 4.5m 7, the circumferential distance between the upper step and the lower step is 1.5m, and upper step locking anchor rods 10 are arranged at arch springing positions on two sides of a steel arch frame positioned in an upper step annular excavation part of the tunnel along layered soft rock tunnel surrounding rocks; for the stratified rock mass, the supporting structure of the tunnel in the direction vertical to the bedding surface needs to bear larger non-uniform pressure, so a pressure type anchor rope 12 with the length of 6.8m for anchoring a steel arch is also arranged along the surrounding rock of the stratified soft rock tunnel in the direction vertical to the bedding surface, the structure of the pressure type anchor rope 12 is shown in figure 3, one end of the pressure type anchor rope is fixed in the deep rock mass, and prestress is applied to the pressure type anchor rope, so that the spalling can be prevented in the unloading process of the stratified rock mass; after the installation is finished, spraying initial-stage sprayed concrete 9 between the steel arch frame and the layered soft rock tunnel surrounding rock and closing the tunnel face in time, wherein the initial-stage sprayed concrete 9 is C20 concrete and has the thickness of 20 cm; at the moment, the primary support of the upper step is completed;
3) excavating a core soil II and a lower step III, immediately paving a reinforcing mesh and installing a steel arch frame 2 perpendicular to the layered soft rock layer surface direction and a steel arch frame 6 not perpendicular to the layered soft rock layer surface direction after excavating, wherein the steel arch frame 2 perpendicular to the layered soft rock layer surface direction adopts H-shaped steel of H20 b type, the steel arch frame 6 not perpendicular to the layered soft rock layer surface direction adopts H-shaped steel of 20a type, and the circumferential distance between the steel arch frame 2 perpendicular to the layered soft rock layer surface direction and the steel arch frame 6 not perpendicular to the layered soft rock layer surface direction is 0.6 m; then installing a mortar anchor rod 3 perpendicular to the bedding surface direction of the layered soft rock and a mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock, wherein the length of the mortar anchor rod 3 perpendicular to the bedding surface direction is 4.5m, the length of the mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock is 3.5m, and the circumferential distance between the mortar anchor rod 3 perpendicular to the bedding surface direction of the layered soft rock and the mortar anchor rod 7 not perpendicular to the bedding surface direction of the layered soft rock is 1.5 m; lower step locking anchor rods 11 are arranged at arch feet on two sides of a steel arch frame positioned in a lower step annular excavation part of the tunnel along layered soft rock tunnel surrounding rocks, pressure type anchor cables 12 for anchoring the steel arch frame are also arranged along the layered soft rock tunnel surrounding rocks in the direction vertical to the bedding surface, initial spraying concrete 9 is sprayed between the steel arch frame and the layered soft rock tunnel surrounding rocks after the installation is finished, the tunnel surface is closed in time, the initial spraying concrete 9 also adopts C20 concrete, and the thickness is also 20 cm; at the moment, the primary support of the lower step is completed;
4) excavating an inverted arch IV, and immediately setting an inverted arch primary support 13 after excavation;
5) after the primary support of the upper step, the primary support of the lower step and the primary support 13 of the inverted arch are arranged, a waterproof layer 14 is laid along the lower wall of the primary concrete-spraying 9, then an internal reinforcing steel bar framework of a secondary lining is installed according to a design drawing, and finally, a template trolley is used for secondary lining pouring, wherein the thickness of the secondary lining 4 perpendicular to the bedding surface direction is 5-10cm larger than that of the secondary lining 8 not perpendicular to the bedding surface direction of the layered soft rock;
6) and continuing to excavate the next circulating tunnel until the next circulating tunnel passes through the layered soft rock section.
The technical solution of the present invention is not limited to the limitations of the above specific embodiments, and all technical modifications made according to the technical solution of the present invention fall within the protection scope of the present invention.
Claims (6)
1. The utility model provides an asymmetric supporting construction in stratiform soft rock tunnel, is including setting up the pipe shed advance support in stratiform soft rock tunnel country rock, its characterized in that: the pipe shed advance support comprises a pipe shed support (1) which is composed of steel guide pipes and is vertical to the bedding surface direction of the layered soft rock layer and a pipe shed support (5) which is not vertical to the bedding surface direction of the layered soft rock layer, the length of the steel guide pipes adopted by the pipe shed support (1) which is vertical to the bedding surface direction of the layered soft rock layer is greater than the length of the steel guide pipes adopted by the pipe shed support (5) which is not vertical to the bedding surface direction of the layered soft rock layer, a steel arch is arranged below the surrounding rock wall of the layered soft rock tunnel, a mortar anchor rod (3) which is vertical to the bedding surface direction of the layered soft rock layer and is used for anchoring the steel arch and a mortar anchor rod (7) which is not vertical to the bedding surface direction of the layered soft rock layer are arranged along the surrounding rock of the layered soft rock tunnel, the length of the mortar anchor rod (3) which is vertical to the bedding surface direction of the layered soft rock layer is greater than the mortar anchor rod (7) which is not vertical to the bedding surface direction of the layered soft rock layer, and a pressure type anchor rope (12, install upper step lock foot stock (10) along stratiform soft rock tunnel country rock at the both sides hunch foot department of the steel bow member that is located the upper step annular excavation portion in tunnel, install lower step lock foot stock (11) along stratiform soft rock tunnel country rock at the both sides hunch foot department of the steel bow member that is located the lower step annular excavation portion in tunnel, set up inverted arch preliminary bracing (13) in the inverted arch excavation portion that is located the tunnel, be equipped with initial stage between steel bow member and the stratiform soft rock tunnel country rock and spout concrete (9), initial stage spouts concrete (9) lower wall and sets up secondary lining.
2. The layered soft rock tunnel asymmetric supporting structure according to claim 1, characterized in that: the steel arch comprises a steel arch (2) perpendicular to the layered soft rock layer surface direction and a steel arch (6) not perpendicular to the layered soft rock layer surface direction, wherein the steel arch (2) perpendicular to the layered soft rock layer surface direction is made of H20 b type I steel, and the steel arch (6) not perpendicular to the layered soft rock layer surface direction is made of H20 a type I steel.
3. The layered soft rock tunnel asymmetric supporting structure according to claim 1, characterized in that: the secondary lining comprises a secondary lining (4) perpendicular to the bedding surface direction of the layered soft rock layer and a secondary lining (8) not perpendicular to the bedding surface direction of the layered soft rock layer, and the thickness of the secondary lining (4) perpendicular to the bedding surface direction is 5-10cm greater than that of the secondary lining (8) not perpendicular to the bedding surface direction of the layered soft rock layer.
4. The layered soft rock tunnel asymmetric supporting structure according to claim 1, characterized in that: and a waterproof layer (14) is arranged between the initial concrete spraying (9) and the secondary lining.
5. The layered soft rock tunnel asymmetric supporting structure according to claim 1, characterized in that: the waterproof layer (14) is waterproof cloth.
6. A construction method of the layered soft rock tunnel asymmetric supporting structure as claimed in any one of claims 1 to 5, characterized in that: the method comprises the following steps:
1) constructing pipe shed advance supports in the surrounding rocks of the layered soft rock tunnel, wherein the pipe shed advance supports comprise a pipe shed support (1) vertical to the bedding surface direction of the layered soft rock and a pipe shed support (5) not vertical to the bedding surface direction of the layered soft rock, and grouting and reinforcing the surrounding rocks in front of the tunnel face;
2) firstly, excavating an upper step annular excavation part (I), reserving a core soil (II), immediately laying a reinforcing mesh after excavation, installing a steel arch frame (2) vertical to the layered soft rock layer surface direction and a steel arch frame (6) not vertical to the layered soft rock layer surface direction, then installing a mortar anchor rod (3) vertical to the layered soft rock layer surface direction and a mortar anchor rod (7) not vertical to the layered soft rock layer surface direction, an upper step locking anchor rod (10) is arranged at arch feet on two sides of a steel arch frame positioned in an upper step annular excavation part of the tunnel along layered soft rock tunnel surrounding rocks, a pressure type anchor rope (12) for anchoring the steel arch frame is also arranged along the layered soft rock tunnel surrounding rocks in the direction vertical to the bedding surface, and after the installation is finished, initial spraying concrete (9) is sprayed between the steel arch frame and the layered soft rock tunnel surrounding rocks and the tunnel face is closed in time, so that the initial support of the upper step is finished;
3) excavating core soil (II) and a lower step (III), immediately laying a reinforcing mesh and installing a steel arch (2) vertical to the bedding surface direction of the layered soft rock and a steel arch (6) not vertical to the bedding surface direction of the layered soft rock after the excavation is finished, then installing a mortar anchor rod (3) vertical to the bedding surface direction of the layered soft rock and a mortar anchor rod (7) not vertical to the bedding surface direction of the layered soft rock, lower step locking anchor rods (11) are arranged at arch feet on two sides of a steel arch frame positioned in a lower step annular excavation part of the tunnel along layered soft rock tunnel surrounding rocks, pressure type anchor cables (12) for anchoring the steel arch frame are also arranged along the layered soft rock tunnel surrounding rocks in the direction vertical to the bedding surface, and after the installation is finished, initial stage spraying concrete (9) is sprayed between the steel arch frame and the layered soft rock tunnel surrounding rocks and the tunnel face is closed in time to finish the primary support of the lower step;
4) excavating an inverted arch (IV), and immediately arranging an inverted arch primary support (13) after excavation;
5) after the primary support of the upper step, the primary support of the lower step and the primary support (13) of the inverted arch are arranged, a waterproof layer (14) is laid along the lower wall of the primary concrete spraying (9), then a secondary lining internal reinforcement framework is installed according to a design drawing, and finally a template trolley is used for casting the secondary lining;
6) and continuing to excavate the next circulating tunnel until the next circulating tunnel passes through the layered soft rock section.
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| CN112963187A (en) * | 2021-03-18 | 2021-06-15 | 东北大学 | Tunnel large-deformation targeted supporting method controlled by structural stress and bedding |
| CN113137235A (en) * | 2021-04-30 | 2021-07-20 | 中铁十六局集团第二工程有限公司 | Construction method of high-ground-stress soft rock extrusion large-deformation tunnel |
| CN113588190A (en) * | 2021-10-08 | 2021-11-02 | 四川藏区高速公路有限责任公司 | Vibration response test device for blasting construction to adjacent existing tunnel |
| CN114483128A (en) * | 2022-01-19 | 2022-05-13 | 中铁第一勘察设计院集团有限公司 | Support system for high-ground-stress joint soft rock tunnel and construction method |
| CN114483132A (en) * | 2022-01-17 | 2022-05-13 | 四川绵九高速公路有限责任公司 | Directional reinforcing method for weak face bedding trend and tunnel excavation direction under condition of parallel or small-angle intersection |
| CN114991823A (en) * | 2022-07-12 | 2022-09-02 | 成都理工大学 | Asymmetric large-deformation double-layer primary support structure for extremely-high ground stress soft rock tunnel |
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| CN113137235A (en) * | 2021-04-30 | 2021-07-20 | 中铁十六局集团第二工程有限公司 | Construction method of high-ground-stress soft rock extrusion large-deformation tunnel |
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| CN114483132A (en) * | 2022-01-17 | 2022-05-13 | 四川绵九高速公路有限责任公司 | Directional reinforcing method for weak face bedding trend and tunnel excavation direction under condition of parallel or small-angle intersection |
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