Soft rock roadway large deformation control method

Abstract

The invention provides a soft rock roadway large deformation control method, and relates to the technical field of soft rock roadway supporting, and the method comprises the following steps: carrying out a crustal stress test, obtaining a crustal stress distribution rule of a roadway area, and analyzing the relationship between roadway arrangement and a crustal stress field, and the influence of crustal stress on roadway surrounding rock stress distribution; based on a ground stress test result, an anchor net cable, sprayed concrete, U-shaped shed and inverted arch active support system is constructed; according to the method, a series of stress tests and other studies are carried out, a series of relations between crustal stress distribution rules and a coal rock mass structure are obtained, an original passive supporting mode of anchor net and shed erecting is adjusted into active supporting of anchor net cable, concrete spraying, U-shaped shed and inverted arch, efficient cooperative control among different supporting measures is achieved, and the supporting effect is good. The supporting system and the supporting characteristic curve are adapted and matched with the deformation activity state of the surrounding rock, the self-bearing capacity of the surrounding rock and the supporting capacity of the supporting system are exerted to the maximum extent, and the purpose of maintaining the stability of a roadway is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of soft rock tunnel support, and in particular to a large deformation control method for a soft rock tunnel. Background Art

[0002] Jurassic weakly cemented mudstone is a special type of soft rock that is widely found. Due to the special diagenetic conditions, it forms a rock mass with unique physical and mechanical properties such as low strength, poor cementation, easy weathering, cementation, low uniaxial compressive and tensile strength. When excavating tunnels in underground projects such as coal mines, surrounding rock instability is prone to occur, and tunnel maintenance is difficult, which is an urgent problem to be solved in coal mine safety production. Its characteristics are that the original rock strength is low and the mudstone is easy to become mud. It is a rock with low strength in the natural waterless state or dry conditions. Once it encounters water, the rock will become muddy, disintegrate, and expand, causing the surrounding rock to lose its bearing layer. In the process of underground coal mining, the tunnel is severely deformed, easy to become unstable, and the tunnel stability cannot be maintained for a long time, which brings serious challenges to the safe production of the mine. Therefore, the present invention proposes a large deformation control method for soft rock tunnels to solve the problems existing in the prior art. Summary of the invention

[0003] In view of the above problems, the present invention proposes a large deformation control method for soft rock tunnels, which adjusts the original passive support mode of "anchor net + frame shed" to "anchor net cable + sprayed concrete + U-shaped shed + anti-bottom arch" active support, thereby realizing efficient coordinated control between different support measures to ensure that the support system and the support characteristic curve are adapted and matched to the deformation activity state of the surrounding rock, thereby maximizing the self-bearing capacity of the surrounding rock and the supporting capacity of the support system.

[0004] To achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a large deformation control method for soft rock tunnel, comprising the following steps: S1: Conduct geostress testing to obtain the geostress distribution law in the tunnel area, analyze the relationship between tunnel layout and geostress field, and the influence of geostress on the stress distribution of tunnel surrounding rocks; S2: Based on the ground stress test results, an active support system of "anchor net cable + shotcrete + U-shaped shed + anti-bottom arch" is constructed; S3: Construct the circular tunnel according to the designed section. After the tunnel is excavated, use anchor nets to actively support the entire section immediately; S4: spray concrete on the top and side of the tunnel to form a protective layer; S5: Install U-shaped sheds on the entire section to form a circular structure as a whole; S6: pouring the semicircle at the bottom of the tunnel to form the tunnel floor; S7: Continuously monitor and evaluate the support effect and summarize the support report.

[0005] A further improvement is that: S1 comprises the following steps: Based on the research of controlling large deformation of soft rock tunnels, the crack evolution angle of large deformation of soft rock tunnels is collected; The large deformation mechanism of soft rock tunnels is obtained according to the crack evolution angle by using laboratory tests, theoretical analysis, numerical simulation and field tests; According to the large deformation mechanism, the geostress test is carried out to obtain the geostress distribution law in the tunnel area; Taking the common "anchor net + scaffolding" passive support method as the research direction, the relationship between tunnel layout and ground stress field, as well as the influence of ground stress on the stress distribution of tunnel surrounding rock are analyzed; The above passive support method is used to suppress the rheological mechanism of the roadway and is subdivided into individual support measures.

[0006] A further improvement is that: S2 comprises the following steps: Use the ground stress testing instrument to test the ground stress of the rocks around the tunnel; Record and analyze the test results, input the test results and S1 analysis results into 3DEC software and FLAC3D software for tunnel simulation; Input anchor net cable + shotcrete + anti-bottom arch + U-shaped shed in the form of unit measures to carry out support simulation, and then combine multiple unit measures to construct an active support system of anchor net cable + shotcrete + anti-bottom arch + U-shaped shed; Simulate the active support system and adjust the parameters until the support standards are met to obtain the solution.

[0007] Further improvements include: recording and analyzing the test results, including the magnitude, direction and distribution of ground stress, as well as the direction and magnitude of the principal stress of the rock around the tunnel and whether there are high stress areas.

[0008] A further improvement is that: S3 comprises the following steps: The anchor cable is a steel strand anchor cable, and the anchor rod is a left-handed high-strength threaded steel anchor rod without longitudinal ribs; Construct the circular tunnel according to the designed section. After the tunnel is excavated, lay the steel mesh in time and arrange the anchor rods evenly around the tunnel to form a permanent support net. Finally, arrange the anchor cables evenly around the tunnel to reinforce the support of the deep rock mass.

[0009] A further improvement is that: said S4 comprises the following steps: Choose high-durability concrete materials; A combination of wet spraying and damp spraying is used to spray concrete on the top and side walls of the tunnel to form a protective layer; The thickness of the protective layer is controlled to be 150-200mm.

[0010] A further improvement is that: S5 comprises the following steps: Install the U-shaped shed in full section, make the shed legs contact closely with the bottom plate, make the shed roof contact firmly with the top plate, and form a circular structure as a whole; Reinforcement components are arranged at the connection between the legs of the U-shaped shed and the bottom plate, and at the connection between the shed roof and the top plate.

[0011] A further improvement is that: S6 comprises the following steps: Thoroughly clean the bottom of the tunnel to remove debris; According to the shape and size of the semicircle at the bottom of the tunnel, a formwork is set to resist the side pressure of pouring; Pour concrete into the formwork, and vibrate during the pouring process to eliminate bubbles; The concrete is cured to form the tunnel floor.

[0012] A further improvement is that: said S7 comprises the following steps: Continuously monitor and evaluate the support effect to verify whether the combined support system can achieve the effect of controlling surrounding rock deformation; Record the support characteristic curve of the support system and the surrounding rock deformation activity state curve, and summarize the support report.

[0013] The beneficial effects of the present invention are: 1. The present invention obtains a series of relationships between ground stress and coal rock structure, such as the ground stress distribution law, by carrying out a series of stress tests and other studies, and adjusts the original passive support mode of "anchor net + frame shed" to the active support of "anchor net cable + shotcrete + U-shaped shed + anti-bottom arch", so as to realize efficient coordinated control between different support measures, so as to ensure that the support system and the support characteristic curve are adapted and matched to the deformation activity state of the surrounding rock, maximize the self-bearing capacity of the surrounding rock and the supporting capacity of the support system, and achieve the purpose of controlling the deformation of the surrounding rock and maintaining the stability of the tunnel.

[0014] 2. The present invention is applied to the support and management of soft rock tunnels, which can reduce the disrepair rate of tunnels, reduce the labor required for repairs, and reduce the safety risks of repeated temporary repair operations. At the same time, it can ensure mine ventilation, transportation, etc., and significantly improve safety benefits. It can be promoted to similar soft rock mines to effectively solve the problem of soft rock mine support. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of the present invention; Figure 2 It is a cross-sectional support diagram of the present invention. DETAILED DESCRIPTION

[0016] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0017] Embodiment 1 according to Figure 1 , 2 As shown, this embodiment proposes a large deformation control method for soft rock tunnels, comprising the following steps: S1: Conduct geostress testing to obtain the geostress distribution law in the tunnel area, analyze the relationship between tunnel layout and geostress field, and the influence of geostress on the stress distribution of tunnel surrounding rocks; S2: Based on the ground stress test results, construct an active support system of anchor net cable + shotcrete + U-shaped shed + anti-bottom arch; S3: Construct the circular tunnel according to the designed section. After the tunnel is excavated, use anchor nets to actively support the entire section immediately; S4: spray concrete on the top and side of the tunnel to form a protective layer; S5: Install U-shaped sheds on the entire section to form a circular structure as a whole; S6: pouring the semicircle at the bottom of the tunnel to form the tunnel floor; S7: Continuously monitor and evaluate the support effect and summarize the support report.

[0018] The present invention adopts the research methods of laboratory test, theoretical analysis, numerical simulation and field test, takes the effective control of large deformation of soft rock tunnel as the research goal, and studies the large deformation mechanism of deep soft rock tunnel from the perspective of crack evolution. In-depth analysis of the rheological mechanism of the tunnel is carried out to achieve efficient coordinated control between different support measures; ensure that the support system and the support characteristic curve are adapted and matched with the surrounding rock deformation activity state, and verify the joint support system based on anchor spraying; maximize the self-bearing capacity of the surrounding rock and the supporting capacity of the support system to achieve the purpose of controlling the deformation of the surrounding rock and maintaining the stability of the tunnel. In summary, the proposed soft rock control technology "anchor net cable + sprayed concrete + U-shaped shed + anti-bottom arch"; the main process is to construct a circular tunnel according to the designed section, first use the anchor net cable to carry out timely and active support of the entire section, then spray concrete on the top and side of the tunnel, and then install a U-shaped shed on the entire section (forming a circle as a whole), and do a good job of pouring the semicircle at the bottom of the tunnel to form the tunnel floor.

[0019] Embodiment 2 according to Figure 1 , 2 As shown, this embodiment proposes a large deformation control method for soft rock tunnels, comprising the following steps: Conduct geostress tests to obtain the geostress distribution law in the tunnel area, analyze the relationship between tunnel layout and geostress field, and the influence of geostress on the stress distribution of tunnel surrounding rock; specifically include the following steps: based on the control of large deformation of soft rock tunnels, collect the crack evolution angle of large deformation of soft rock tunnels; use laboratory tests, theoretical analysis, numerical simulation and field tests to obtain the large deformation mechanism of soft rock tunnels according to the crack evolution angle; conduct geostress tests according to the large deformation mechanism to obtain the geostress distribution law in the tunnel area; take the general "anchor net + scaffolding" passive support method as the research direction, analyze the relationship between tunnel layout and geostress field, and the influence of geostress on the stress distribution of tunnel surrounding rock; obtain the rheological mechanism of the above passive support method to inhibit tunnel flow, and subdivide it into individual support measures. Through conducting geostress tests, rock mechanical properties evaluation and support technology research, and constructing geostress test boreholes, we can obtain the geostress distribution law, the relationship between tunnel layout and geostress field, the influence of geostress on the stress distribution of tunnel surrounding rock, and the relationship between geostress and coal rock structure. The original passive support method of "anchor net + shed" was gradually adjusted to active support of "anchor net cable + shotcrete + anti-bottom arch + U-shaped shed". Through continuous exploration and improvement in the actual production process, combined with the research methods of laboratory tests, theoretical analysis, numerical simulation and field tests, with the effective control of large deformation of soft rock tunnels as the research goal, the large deformation mechanism of deep soft rock tunnels was studied from the perspective of crack evolution, and the relevant control technology was deeply analyzed to inhibit the rheological mechanism of the tunnel, so as to achieve efficient coordinated control between different support measures.

[0020] Based on the ground stress test results, an anchor net cable + shotcrete + U-shaped shed + anti-bottom arch active support system is constructed; specifically, the following steps are included: Use ground stress test instruments to test the ground stress of rocks around the tunnel; Record and analyze the test results, including the size, direction and distribution of ground stress, as well as the direction and size of the principal stress of the rocks around the tunnel, and whether there is a high stress area; Input the test results and the analysis results of S1 into 3DEC software and FLAC3D software for tunnel simulation; Input anchor net cable + shotcrete + anti-bottom arch + U-shaped shed in the form of unit measures for support simulation, and then combine multiple unit measures to construct an anchor net cable + shotcrete + anti-bottom arch + U-shaped shed active support system; Simulate the support of the active support system, adjust the parameters until it meets the support standards, and obtain a plan. Use ground stress test instruments (such as stress relief method, hydraulic fracturing method, etc.) to test the ground stress of rocks around the tunnel. Record and analyze the test results, including the size, direction and distribution of ground stress. According to the test results, determine the direction and size of the principal stress of the rocks around the tunnel, and whether there is a high stress area. Analyze the impact of ground stress on tunnel stability and provide a basis for the design of support system.

[0021] The circular tunnel is constructed according to the designed section. After the tunnel is excavated, the anchor net cable is immediately used for active support of the entire section. The specific steps include: the anchor cable selects the steel strand anchor cable, and the anchor rod selects the left-handed high-strength threaded steel anchor rod without longitudinal ribs; the circular tunnel is constructed according to the designed section. After the tunnel is excavated, the steel mesh is laid in time, and the anchor rods are evenly arranged around the tunnel to form a permanent support net; finally, the anchor cables are evenly arranged around the tunnel to reinforce the deep rock mass. According to the rock mechanical properties and ground stress test results, the appropriate anchor rod type and specification are selected. The anchor rods are evenly arranged around the tunnel to form an effective support net. The spacing between the anchor rods is designed according to the rock mechanical properties and support requirements. Metal mesh is laid between the anchor rods to enhance the integrity and stability of the support. The metal mesh is made of corrosion-resistant and high-strength materials. Anchor cables are set at key parts of the tunnel (such as the top plate, two sides, etc.) to improve the bearing capacity of the support.

[0022] The top and side of the tunnel are sprayed with concrete to form a protective layer. The specific steps include: selecting high-durability concrete materials; using a combination of wet spraying and damp spraying to spray concrete on the top and side of the tunnel to form a protective layer; controlling the thickness of the protective layer to be 150-200mm. Select high-strength and durable concrete materials. Use wet spraying or damp spraying to ensure the bonding between concrete and rock. Design the thickness of the sprayed concrete according to the support requirements and the mechanical properties of the rock.

[0023] The U-shaped shed is installed on the whole section to form a circular structure as a whole; the specific steps include: installing the U-shaped shed on the whole section, making the shed legs closely contact with the bottom plate, and making the shed roof firmly contact with the top plate, so as to form a circular structure as a whole; reinforcing components are set at the connection between the legs and the bottom plate of the U-shaped shed, and at the connection between the shed roof and the top plate. According to the cross-sectional dimensions and support requirements of the tunnel, select the appropriate specifications and models of the U-shaped shed. The installation of the U-shaped shed is carried out strictly in accordance with the design requirements to ensure that the shed legs are in close contact with the bottom plate, and the shed roof is in firm contact with the top plate. Reinforcing components are set at the key parts of the U-shaped shed (such as the connection between the shed legs and the bottom plate, the connection between the shed roof and the top plate, etc.) to improve the bearing capacity of the support.

[0024] The semicircle at the bottom of the tunnel is poured to form the tunnel floor; the specific steps include: thoroughly cleaning the bottom of the tunnel to remove debris; setting a template to resist the side pressure of pouring according to the shape and size of the semicircle at the bottom of the tunnel; pouring concrete into the template, and vibrating during the pouring process to eliminate bubbles; curing the concrete to form the tunnel floor. According to the deformation of the tunnel floor and the results of the ground stress test, a reasonable anti-bottom arch shape and size are designed. Laying the bottom, leveling and compacting, applying anchor rods and grouting anchor rods, laying metal mesh and spraying concrete, after the construction is completed, the support effect of the anti-bottom arch is monitored to ensure the stability of the tunnel floor.

[0025] The support effect is continuously monitored and evaluated, and a support report is summarized, which specifically includes the following steps: continuously monitor and evaluate the support effect to verify whether the combined support system can achieve the effect of controlling surrounding rock deformation; record the support characteristic curve of the support system and the surrounding rock deformation activity state curve, and summarize the support report.

[0026] The large deformation control method for soft rock tunnels is carried out through a series of stress tests and other studies to obtain a series of relationships between ground stress and coal rock structure, such as the ground stress distribution law. The original passive support mode of "anchor net + frame shed" is adjusted to the active support of "anchor net cable + shotcrete + U-shaped shed + anti-bottom arch", and efficient coordinated control between different support measures is achieved to ensure that the support system and the support characteristic curve are adapted and matched to the deformation activity state of the surrounding rock, maximize the self-bearing capacity of the surrounding rock and the supporting capacity of the support system, and achieve the purpose of controlling the deformation of the surrounding rock and maintaining the stability of the tunnel. The present invention is applied to the support and management of soft rock tunnels, reduces the disrepair rate of tunnels, reduces the labor required for repairs, reduces the safety risks of repeated repair temporary operations, and at the same time ensures mine ventilation, transportation, etc., with significantly improved safety benefits. It can be promoted to the same type of soft rock mines to effectively solve the support problems of soft rock mines.

[0027] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for controlling large deformation of soft rock tunnels, characterized by: The following steps are involved: S1: Conduct geostress testing to obtain the geostress distribution law in the tunnel area, analyze the relationship between tunnel layout and geostress field, and the influence of geostress on the stress distribution of tunnel surrounding rocks; S2: Based on the ground stress test results, an active support system of "anchor net cable + shotcrete + U-shaped shed + anti-bottom arch" is constructed; S3: Construct the circular tunnel according to the designed section. After the tunnel is excavated, use anchor nets to actively support the entire section immediately; S4: spray concrete on the top and side of the tunnel to form a protective layer; S5: Install U-shaped sheds on the entire section to form a circular structure as a whole; S6: pouring the semicircle at the bottom of the tunnel to form the tunnel floor; S7: Continuously monitor and evaluate the support effect and summarize the support report.

2. A method for controlling large deformation of soft rock tunnel according to claim 1, characterized in that: The S1 comprises the following steps: Based on the research of controlling large deformation of soft rock tunnels, the crack evolution angle of large deformation of soft rock tunnels is collected; The large deformation mechanism of soft rock tunnels is obtained according to the crack evolution angle by using laboratory tests, theoretical analysis, numerical simulation and field tests; According to the large deformation mechanism, the geostress test is carried out to obtain the geostress distribution law in the tunnel area; Taking the common "anchor net + scaffolding" passive support method as the research direction, the relationship between tunnel layout and ground stress field, as well as the influence of ground stress on the stress distribution of tunnel surrounding rock are analyzed; The above passive support method is used to suppress the rheological mechanism of the roadway and is subdivided into individual support measures.

3. A method for controlling large deformation of soft rock tunnel according to claim 2, characterized in that: The S2 comprises the following steps: Use the ground stress testing instrument to test the ground stress of the rocks around the tunnel; Record and analyze the test results, input the test results and S1 analysis results into 3DEC software and FLAC3D software for tunnel simulation; Input anchor net cable + shotcrete + anti-bottom arch + U-shaped shed in the form of unit measures to carry out support simulation, and then combine multiple unit measures to construct the "anchor net cable + shotcrete + U-shaped shed + anti-bottom arch" active support system; Simulate the active support system and adjust the parameters until the support standards are met to obtain the solution.

4. A method for controlling large deformation of soft rock tunnel according to claim 3, characterized in that: Record and analyze the test results, including the magnitude, direction and distribution of ground stress, as well as the direction and magnitude of the principal stress of the rock around the tunnel and whether there are high stress areas.

5. A method for controlling large deformation of soft rock tunnel according to claim 4, characterized in that: The S3 comprises the following steps: The anchor cable is a steel strand anchor cable, and the anchor rod is a left-handed high-strength threaded steel anchor rod without longitudinal ribs; Construct the circular tunnel according to the designed section. After the tunnel is excavated, lay the steel mesh in time and arrange the anchor rods evenly around the tunnel to form a permanent support net. Finally, arrange the anchor cables evenly around the tunnel to reinforce the support of the deep rock mass.

6. A method for controlling large deformation of soft rock tunnel according to claim 5, characterized in that: The S4 comprises the following steps: Choose high-durability concrete materials; A combination of wet spraying and damp spraying is used to spray concrete on the top and side walls of the tunnel to form a protective layer; The thickness of the protective layer is controlled to be 150-200mm.

7. A method for controlling large deformation of soft rock tunnels according to claim 6, characterized in that: The S5 comprises the following steps: Install the U-shaped shed in full section, make the shed legs contact closely with the bottom plate, make the shed roof contact firmly with the top plate, and form a circular structure as a whole; Reinforcement components are arranged at the connection between the legs of the U-shaped shed and the bottom plate, and at the connection between the shed roof and the top plate.

8. A method for controlling large deformation of soft rock tunnels according to claim 7, characterized in that: The S6 comprises the following steps: Thoroughly clean the bottom of the tunnel to remove debris; According to the shape and size of the semicircle at the bottom of the tunnel, a formwork is set to resist the side pressure of pouring; Pour concrete into the formwork, and vibrate during the pouring process to eliminate bubbles; The concrete is cured to form the tunnel floor.

9. A method for controlling large deformation of soft rock tunnels according to claim 8, characterized in that: The S7 comprises the following steps: Continuously monitor and evaluate the support effect to verify whether the combined support system can achieve the effect of controlling surrounding rock deformation; Record the support characteristic curve of the support system and the surrounding rock deformation activity state curve, and summarize the support report.

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