Soft rock roadway supporting method and supporting device

Abstract

This invention relates to the field of roadway support technology, and discloses a method and device for supporting soft rock roadways. The method includes a shield support step, a temporary support step, and a permanent support step. The shield support step includes: erecting arch support modules in the roadway, so that the arch support modules are in contact with the arch of the roadway; installing forward beams, connecting the forward beams to both the arch of the roadway and the arch support modules; the temporary support step includes: laying a steel mesh, so that the steel mesh is in contact with the surrounding rock surface of the roadway; connecting the steel mesh to the arch support modules; the permanent support step includes: connecting a flexible mold bag to the arch support modules; injecting concrete into the flexible mold bag, which solidifies to form a shell structure; wherein, in the temporary support step, the forward beams are removed for reuse. Through this phased support process, the stability and safety of soft rock roadways are significantly improved, while the forward beams are recycled, reducing construction costs.

Description

Technical Field

[0001] This invention relates to the field of tunnel support technology, and more specifically to a method and device for supporting soft rock tunnels. Background Technology

[0002] Soft rock is characterized by low strength, easy expansion upon contact with water, and easy weathering, making the support of tunnels excavated in soft rock extremely challenging. Traditional techniques for supporting soft rock tunnels mainly employ methods such as bolt support, scaffold support, and concrete support. However, bolt support, which relies on an anchoring system to "stitch" loose surrounding rock into a whole, is prone to anchor point failure under high ground pressure and strong expansion conditions, with anchoring force rapidly diminishing and making it difficult to maintain long-term rock stability. Scaffold support uses U-shaped steel to form collapsible supports, utilizing their collapsible nature to adapt to surrounding rock deformation. However, the supports themselves have limited rigidity and lack effective bonding with the surrounding rock, resulting in insufficient overall load-bearing capacity and susceptibility to twisting failure due to localized stress concentration. While shotcrete support can seal the rock surface to prevent weathering and water exposure, the shotcrete layer thickness is limited, making it highly susceptible to cracking and spalling under conditions of large surrounding rock deformation.

[0003] Currently, existing technologies also employ combined support methods such as "anchor mesh shotcrete" and "anchor cable + steel frame + shotcrete". However, most of these combined methods are still simple superpositions of "one-time tunneling" or "simultaneous construction", which are difficult to adapt to the dynamic deformation requirements of soft rock.

[0004] Therefore, there is an urgent need for a soft rock tunnel support method that can work in stages, realize the recycling of support materials, and has high stability and adaptability. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one of the above-mentioned technical problems in the prior art and to provide a soft rock roadway support method and support device. This soft rock roadway support method effectively solves the problems of soft rock roadway support failure, high cost, and low efficiency through phased and progressive support.

[0006] To achieve the above objectives, the present invention provides a method for supporting soft rock tunnels, comprising the following steps: The shielding and support step is carried out in the section of the roadway at a first preset distance from the working face. The shielding and support step includes: The arch support module is installed in the tunnel so that it fits against the arch of the tunnel. Install the forward probe beam, and connect the forward probe beam to the arch roof and the arch support module of the roadway respectively; The temporary support step is carried out in the section of the roadway at a second predetermined distance from the working face. The temporary support step includes: Lay a steel mesh so that it fits against the surrounding rock surface of the tunnel; Connect the steel mesh to the arch support module; and The permanent support step is carried out in the section of the roadway at a third predetermined distance from the working face. The permanent support step includes: Connect the flexible molded bag to the arch support module; Concrete is injected into the flexible mold bag, and the concrete solidifies to form a shell structure. In the temporary support step, after connecting the steel mesh to the arch support module, the front probe beam is removed for reuse.

[0007] The soft rock tunnel support method provided by this invention includes a first preset distance section for shield support. This involves erecting arch support modules and fitting them against the tunnel arch, while simultaneously installing forward beams to connect the tunnel arch and the arch support modules, forming a stable cantilever shield structure. This provides a safe working space for the tunneling machine operators and allows for moderate deformation of the surrounding rock in the early stages of excavation to release expansion energy, preventing rigid support from directly bearing peak pressure and causing early failure. As the tunnel advances, a second preset distance section undergoes temporary support. This involves laying a steel mesh and ensuring it is tightly fitted to the surrounding rock surface. The steel mesh is then connected to the arch support modules to form a flexible constraint layer, effectively controlling the early deformation rate of the surrounding rock and preventing localized rockfalls and spalling. After connecting the steel mesh to the arch support modules, the forward beams are removed and reused in the next tunneling cycle, reducing material consumption and engineering costs. As the tunnel is further excavated, permanent support is implemented in the third pre-set distance section. This involves connecting flexible formwork bags to arch support modules and injecting concrete into them. After the concrete solidifies, a high-strength shell structure is formed. This shell structure works synergistically with the arch support modules. The shell structure primarily bears the pressure of the surrounding rock, while the arch support modules provide bending and shear resistance. Together, they effectively control the deformation of the surrounding rock. Furthermore, the flexible formwork bag, acting as a molding die for the concrete, remains on the surface of the shell structure after the concrete solidifies, forming a continuous physical waterproof isolation layer. This effectively prevents external moisture from contacting the soft rock, fundamentally inhibiting the vicious cycle of soft rock swelling upon contact with water. It also prevents groundwater in the surrounding rock from seeping into the support structure, significantly improving the impermeability and long-term stability of the support system.

[0008] Therefore, the soft rock tunnel support method provided by this invention achieves precise matching between the timing of support and the spatiotemporal deformation patterns of the surrounding rock by respectively deploying shield support, temporary support, and permanent support in the first, second, and third preset distance sections of the tunnel at different distances from the working face. Through the three-stage, zoned, time-based, and graded application of support—"shield support—temporary support—permanent support"—it comprehensively solves common problems in existing technologies such as inappropriate support timing, material waste, insufficient waterproofing, and low construction efficiency. This support method significantly improves the stability and safety of soft rock tunnels, reduces support costs, and simultaneously enables the recycling of key materials such as forward beams. It has outstanding advantages such as high construction efficiency, good support effect, and excellent economy. This invention is applicable to support engineering of various types of soft rock tunnels, especially suitable for tunnel construction environments with complex geological conditions, poor surrounding rock stability, and significant water swelling and large deformation.

[0009] In some embodiments, during the shielding and support step, a gravel cushion layer is laid at the bottom of the tunnel before the arch support module is erected.

[0010] In some embodiments, during the shielding and support step, before installing the forward beam, a forward beam mounting hole is drilled in the arch of the roadway, and the angle between the extension direction of the forward beam mounting hole and the extension direction of the roadway is 3-8°.

[0011] In some implementations, the shielding and support step is performed every fourth preset distance of tunnel excavation.

[0012] In some embodiments, during the shielding and support step, multiple forward-probing beams are installed, and the distance between two adjacent forward-probing beams is a fourth preset distance.

[0013] In some embodiments, during the temporary support step, prior to laying the steel mesh, a reinforcement step is performed on the fractured areas of the surrounding rock face of the roadway, the reinforcement step including: Clear loose bunkers; The area was sealed with sprayed concrete.

[0014] In some embodiments, prior to the permanent support step, a leveling step is performed on the surrounding rock surface of the roadway, the leveling step including: The protruding rock mass is removed and / or concrete is sprayed into the recessed area to make the flatness error of the surrounding rock surface of the tunnel within ±5mm.

[0015] In some embodiments, during the permanent support step, the flexible mold bag is connected to the arch support module in a high-to-low direction; The flexible mold bag is provided with multiple grouting holes. In the step of injecting concrete into the flexible mold bag, concrete is injected into each of the grouting holes in a direction from low to high.

[0016] In some embodiments, the arch support module includes an arch frame for supporting the surrounding rock face of the tunnel and a leg assembly connected to the bottom of the arch frame. The leg assembly includes a leg body connected to the bottom of the arch frame, a leg nut disposed inside the leg body, a leg thread portion threaded to the leg nut, and a leg base connected to the bottom of the leg thread portion.

[0017] In some embodiments, the arch support module further includes a hook disposed on the arcuate portion of the arch top frame, a first lifting ring connected to the hook, and a second lifting ring nested and connected to the first lifting ring, wherein the diameter of the second lifting ring is larger than the diameter of the first lifting ring, and the front probing beam is connected to the second lifting ring.

[0018] In some embodiments, the forward beam includes a beam tip, a beam body, and a tail hook connected in sequence. The beam tip is connected to the arch of the tunnel, the beam body is connected to the arch support module, and the tail hook is connected to the steel mesh.

[0019] In addition, the present invention also provides a soft rock roadway support device, which is used in the above-mentioned soft rock roadway support method, the soft rock roadway support device comprising: An arch support module and a forward-probing beam are provided. The arch support module is used to support the surrounding rock face of the roadway during the shielding and support step. The forward-probing beam is connected to the arch support module and the arch top of the roadway, respectively. Reinforcing mesh, which is used to lay on the surrounding rock face of the roadway during the temporary support step and is connected to the arch support module; and, A flexible formwork bag is used to connect to the arch support module during the permanent support step and to inject concrete.

[0020] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the cross-sectional structure of permanent support formed by the soft rock tunnel support method provided by the present invention; Figure 2 This is a structural schematic diagram of the arch support module provided by the present invention; Figure 3 yes Figure 2 An enlarged schematic diagram of part A in the middle; Figure 4 yes Figure 2 Enlarged schematic diagram of part B in the middle; Figure 5This is a schematic diagram of the structure for forming a shield support using the soft rock tunnel support method provided by the present invention; Figure 6 This is a schematic diagram of the forward-probing beam provided by the present invention.

[0022] Explanation of reference numerals in the attached figures 10-Outrigger assembly; 101-Outrigger base; 102-Outrigger threaded part; 103-Outrigger nut; 104-Outrigger body; 20-Arch frame; 201-Second lifting ring; 202-Hook; 30-Front extension beam; 301-Beam tip; 302-Beam body; 303-Tail hook; 40-Reinforcing mesh; 50-Flexible mold bag; 60-Shell structure; 70-Gravel cushion layer. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] In this invention, unless otherwise stated, the terms "upper," "lower," "left," "right," "inner," "outer," "top," "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0026] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] This invention addresses the challenges of soft rock tunnels, which are prone to low strength, water-induced expansion, and weathering. Traditional support methods often suffer from support structure failure and large deformation of the surrounding rock. Furthermore, existing technologies using single or simple combined support systems are ill-suited to the dynamic deformation requirements of soft rock, and suffer from low material recovery rates and poor construction efficiency. This invention provides a support method for soft rock tunnels, combining... Figures 1-6 As shown, one embodiment of the soft rock tunnel support method according to the present invention includes the following steps: The shielding and support procedure involves providing shielding and support in the section of the roadway at a first predetermined distance from the working face. This shielding and support procedure includes: The arch support module is installed in the tunnel so that it fits against the arch of the tunnel. Install the forward probe beam 30, and connect the forward probe beam 30 to the arch roof and arch support module of the roadway respectively; The temporary support procedure involves implementing temporary support in the section of the roadway at a second predetermined distance from the working face. This temporary support procedure includes: Lay steel mesh 40 to make it fit against the surrounding rock surface of the tunnel; Connect the steel mesh 40 to the arch support module; and The permanent support step is carried out in the section of the roadway at the third preset distance from the working face. The permanent support step includes: Connect the flexible molded bag 50 to the arch support module; Concrete is injected into the flexible mold bag 50, and after the concrete solidifies, a shell structure 60 is formed. In the temporary support step, after the steel mesh 40 is connected to the arch support module, the front beam 30 is removed for reuse.

[0029] Through the above technical solution, a shield support step is carried out in the first preset distance section. This involves erecting an arch support module and fitting it against the tunnel arch, while simultaneously installing a forward-probing beam 30 to connect the tunnel arch and the arch support module, forming a stable cantilever shield structure. This provides a safe working space for the tunneling machine operators and allows the surrounding rock to deform moderately in the early stages of excavation to release expansion energy, preventing the rigid support from directly bearing peak pressure and failing early. As the tunnel advances, a temporary support step is carried out in the second preset distance section. This involves laying a steel mesh 40 and fitting it tightly against the surrounding rock surface, then connecting the steel mesh 40 to the arch support module to form a flexible constraint layer. This effectively controls the early deformation rate of the surrounding rock, preventing local rockfalls and spalling. After connecting the steel mesh 40 to the arch support module, the forward-probing beam 30 is removed and reused in the next tunneling cycle, reducing material consumption and engineering costs. As the tunnel is further excavated, permanent support is implemented in the third pre-set distance section. This involves connecting the flexible mold bag 50 to the arch support module and injecting concrete into it. After the concrete solidifies, a high-strength shell structure 60 is formed. This shell structure 60 works synergistically with the arch support module. The shell structure 60 primarily bears the pressure of the surrounding rock, while the arch support module provides bending and shear resistance. Together, they effectively control the deformation of the surrounding rock. Furthermore, the flexible mold bag 50, acting as a molding die for the concrete, remains on the surface of the shell structure 60 after the concrete solidifies, forming a continuous physical waterproof barrier layer. This effectively prevents external moisture from contacting the soft rock, fundamentally inhibiting the vicious cycle of soft rock swelling upon contact with water. It also prevents groundwater in the surrounding rock from seeping into the support structure, significantly improving the impermeability and long-term stability of the support system.

[0030] Therefore, the soft rock tunnel support method provided by this invention achieves precise matching between the timing of support and the spatiotemporal deformation patterns of the surrounding rock by respectively deploying shield support, temporary support, and permanent support in the first, second, and third preset distance sections of the tunnel at different distances from the working face. Through the three-stage, zoned, time-based, and graded application of support—"shield support—temporary support—permanent support"—it comprehensively solves common problems in existing technologies such as inappropriate support timing, material waste, insufficient waterproofing, and low construction efficiency. This support method significantly improves the stability and safety of soft rock tunnels, reduces support costs, and simultaneously achieves the recycling of key materials such as the forward beam 30. It has outstanding advantages such as high construction efficiency, good support effect, and excellent economy. This invention is applicable to support engineering of various types of soft rock tunnels, especially suitable for tunnel construction environments with complex geological conditions, poor surrounding rock stability, and significant water expansion and large deformation.

[0031] In some implementations, during the shield support step, before erecting the arch support modules, a crushed stone cushion layer 70 is laid at the bottom of the roadway. The crushed stone cushion layer 70 effectively distributes the upper load, improves the foundation bearing capacity, and provides a stable support platform for subsequent support structures. The crushed stone cushion layer 70 should be made of crushed stone with uniform particle size and meeting strength standards. During laying, it is essential to ensure uniform thickness and compaction that meets construction requirements.

[0032] In some embodiments, during the shielding and support step, before installing the forward beam 30, mounting holes for the forward beam are drilled in the arch of the roadway, with the angle between the extension direction of the mounting holes and the extension direction of the roadway being 3-8°. For example, the angle between the extension direction of the mounting holes and the extension direction of the roadway is 5°, ensuring that the installed forward beam 30 is located outside the roadway's outline and that there is an appropriate gap between the forward beam 30 and the surrounding rock surface of the roadway, thereby fully utilizing the support function of the forward beam 30.

[0033] In some embodiments, a hydraulic drilling rig is used to construct the probing beam mounting hole in the tunnel arch. In some embodiments, the probing beam 30 is inserted 1.2m into the probing beam mounting hole.

[0034] In some implementations, a shielding and support step is performed every fourth preset distance of tunnel excavation to ensure that the tunnel excavation work is carried out in a cyclical manner of "excavating one end and supporting one section," thus ensuring the continuity and stability of the tunnel support system. In some implementations, the tail end of the newly installed forward beam 30 is connected to the steel mesh 40 installed in the temporary support step, achieving an effective connection between the old and new support structures and further maintaining the continuity and integrity of the support system.

[0035] In some implementations, during the shielding and support step, multiple forward-probing beams 30 are installed, with the distance between two adjacent forward-probing beams 30 being a fourth preset distance. This ensures both the strength of the shielding and support and forms an effective cantilever beam structure, providing reliable safety protection for tunneling machine operators and effectively preventing accidents such as roof collapse.

[0036] In some implementations, during the temporary support step, before laying the steel mesh 40, a reinforcement step is performed on the fractured area of ​​the surrounding rock face of the roadway. The reinforcement step includes: Clear loose bunkers; The area was sealed with sprayed concrete.

[0037] In some implementations, C20 concrete is used.

[0038] In some implementations, a leveling step is performed on the surrounding rock surface of the roadway before the permanent support step, thereby ensuring that the flexible mold bag 50 can fit tightly against the surrounding rock surface of the roadway and avoid voids. The leveling step includes: The protruding rock mass is removed and / or concrete is sprayed into the depressed area to make the flatness error of the surrounding rock surface of the tunnel within ±5mm.

[0039] In some implementations, after the leveling step and before the permanent support step, high-pressure air ducts are used to remove dust from the surrounding rock surface of the roadway, creating favorable construction conditions for permanent support.

[0040] In some embodiments, during the permanent support step, the flexible formwork bag 50 is connected to the arch support module in a high-to-low direction. That is, the flexible formwork bag 50 is first connected to the top of the arch support module, and then the flexible formwork bag 50 is connected to the arch support module on both sides in a high-to-low direction. Furthermore, the flexible formwork bag 50 is provided with multiple grouting holes. During the concrete injection step into the flexible formwork bag 50, concrete is injected into each grouting hole in a low-to-high direction, thereby ensuring that the concrete fills the flexible formwork bag 50 and forms a uniform shell structure 60 after the concrete solidifies.

[0041] In some implementations, during the permanent support step, concrete, specifically C30-C40 concrete, is injected into the flexible mold bag 50.

[0042] In some implementations, see Figure 1 , Figure 2 and Figure 4 As shown, the arch support module includes an arch top frame 20 and a leg assembly 10. The arch top frame 20 is used to support the surrounding rock face of the tunnel. The leg assembly 10 is connected to the bottom of the arch top frame 20. The leg assembly 10 includes a leg body 104, a leg nut 103, a leg threaded part 102, and a leg base 101. The leg body 104 is connected to the bottom of the arch top frame 20. The leg nut 103 is located inside the leg body 104. The leg threaded part 102 is threadedly connected to the leg nut 103. The leg base 101 is connected to the bottom of the leg threaded part 102. The outrigger base 101 is used for the outrigger body 104 and the outrigger threaded part 102. The outrigger nut 103 is located inside the outrigger body 104 and is threadedly connected to the outrigger threaded part 102. Therefore, by rotating the outrigger body 104, the outrigger body 104 can be moved axially, thereby adjusting the height of the outrigger assembly 10 and ensuring that the arch frame 20 connected to the outrigger assembly 10 can provide effective support for the roadway.

[0043] In some implementations, refer to Figure 2 and Figure 3As shown, the arch support module also includes a hook 202 mounted on the arc-shaped portion of the arch top frame 20, a first lifting ring connected to the hook 202, and a second lifting ring 201 nested with the first lifting ring. The diameter of the second lifting ring 201 is larger than that of the first lifting ring. The forward beam 30 is connected to the second lifting ring 201. The nested connection between the first and second lifting rings 201 allows relative rotation between them. Since the forward beam 30 is connected to the second lifting ring 201, the relative rotation of the second lifting ring 201 enables adaptive adjustment of the installation angle of the forward beam 30, effectively reducing the accuracy requirements for drilling positioning and making construction more convenient and efficient. The connection between the second lifting ring 201 and the forward beam 30 allows the forward beam 30 to pass through the second lifting ring 201, enabling its recycling and reducing material costs. The first lifting ring has a smaller diameter, while the second lifting ring 201 has a larger diameter. This makes it easier for the first lifting ring to be hung on the hook 202 and for the front extension beam 30 to pass through the second lifting ring 201. It also makes it easier for the operator to distinguish between the first and second lifting rings 201 and prevent installation errors.

[0044] In some implementations, see Figure 5 and Figure 6 As shown, the forward-probing beam 30 includes a beam tip 301, a beam body 302, and a tail hook 303 connected in sequence. The beam tip 301 is connected to the arch of the tunnel, the beam body 302 is connected to the arch support module, and the tail hook 303 is connected to the steel mesh 40. In some embodiments, see [reference needed]. Figure 6 As shown, the front end of the beam tip 301 has a 30° wedge angle, which facilitates the insertion of the beam tip 301 into the rock mass of the tunnel. In some embodiments, an anti-slip pad is provided inside the hook opening of the tail hook 303 and it is suspended on the steel mesh 40 to prevent the forward beam 30 from sliding backward. In some embodiments, the beam body 302 passes through the second lifting ring 201.

[0045] The specific construction process of the soft rock tunnel support method provided by this invention is described in detail below: (1) Cover and support steps: The first preset distance from the tunnel face is used for shielding and support procedures, which can be 0-2m. First, a 150mm thick crushed stone cushion layer is laid at the bottom of the tunnel to provide a stable support platform for the subsequent support structure. At 0.5 meters from the tunnel face, the first arch support module is erected, ensuring the outrigger base 101 is securely installed on the crushed stone cushion layer 70, guaranteeing the stability of the arch support module. A hydraulic drilling rig is used to construct the pre-expansion beam installation hole in the tunnel roof, with a drilling depth of up to 1.5m. The pre-expansion beam installation hole maintains a 5° elevation angle with the tunnel direction. The pre-expansion beam 30 is inserted 1.2m into the pre-expansion beam installation hole, with the beam body 302 of the pre-expansion beam 30 passing through the second lifting ring 201. (See also...) Figure 5As shown, multiple forward-probing beams 30 are installed on an arched frame 20. The distance between two adjacent forward-probing beams 30 is a fourth preset distance, for example, the fourth preset distance is 0.8m. Shielding and support are provided every time the tunnel advances the fourth preset distance, for example, every time the tunnel advances 0.8m.

[0046] (2) Temporary support steps: Temporary support is implemented at a second predetermined distance from the tunnel face, which can be 2-5 meters. For example, when the tunneling depth exceeds 2 meters, steel mesh 40 is installed. The steel mesh 40 is laid from top to bottom, starting from the centerline of the tunnel's arch and then symmetrically extending towards both sides. In the temporary support step, multiple pieces of steel mesh 40 are typically laid to conform to the surrounding rock surface within the second predetermined distance. The steel mesh 40 is connected by double-strand binding with #16 steel wire, with the distance between two adjacent binding points not exceeding 200mm to ensure reliable connections between the steel mesh 40. Additionally, each binding point is wrapped with at least three turns to prevent loosening during construction.

[0047] The steel mesh 40 is fixedly connected to the arch support module using #8 iron wire. When connecting, ensure that the steel mesh 40 is tightly attached to the surrounding rock surface. When connecting the steel mesh 40 to the arch support module, ensure at least 4 fixing points per meter to ensure the stability of the overall support.

[0048] For areas with fractured surrounding rock, reinforcement steps are taken. In the reinforcement steps, the loose rock mass is first cleared, and then C20 concrete is sprayed to seal it. The concrete is made of P.O42.5 cement, medium and coarse sand and 5-10mm crushed stone, with the water-cement ratio controlled between 0.45 and 0.5. The spraying pressure is maintained at 0.4-0.6MPa and the spraying distance is controlled at 0.8-1.2 meters to ensure the density and bond strength of the concrete.

[0049] In addition, the surrounding rock surface should be cleaned before laying the reinforcing mesh 40, and the overlap length between two reinforcing meshes 40 should not be less than 100mm. During the reinforcement step, the surrounding rock surface should be moistened before spraying concrete. After the reinforcing mesh 40 is laid, the front probe beam 30 can be pulled out within the second preset distance section for recycling.

[0050] (3) Permanent support steps: Permanent support is implemented at a third pre-set distance from the tunnel face, which can be 5-10 meters. Before construction, the surrounding rock surface of the tunnel is leveled. Protruding rock masses can be removed to a flat surface using tools such as pneumatic picks. For locally depressed areas, shotcrete is used for filling. This leveling process ensures the flatness error of the surrounding rock surface is controlled within ±5mm. After leveling, high-pressure air ducts are used to remove dust from the surrounding rock surface, creating favorable conditions for subsequent construction.

[0051] First, the flexible formwork bag 50 is suspended. The suspension of the flexible formwork bag 50 is carried out from top to bottom. The flexible formwork bag 50 is connected to the hook 202 on the arch frame 20. First, the flexible formwork bag 50 is connected to the top hook 202 of the arch frame 20, and then the flexible formwork bags 50 are suspended to both sides in sequence. During the suspension process, ensure that the bag body of the flexible formwork bag 50 is in close contact with the surrounding rock surface to avoid air pockets. The flexible formwork bag 50 has multiple grouting holes. Concrete is injected through the grouting pipe starting from the lowest grouting hole. The concrete can be C30-C40 concrete; for example, C35 concrete is used, and 5% UEA expansion agent is injected to form micro-expansion concrete with an expansion rate of 0.02-0.04% and a slump maintained at 180±20mm. This prevents the shell from separating from the flexible formwork bag and the arch support, ensuring that the three work closely together. At the same time, the pores generated by the expansion reaction significantly improve the density and impermeability of the shell structure 60, forming a double waterproof barrier together with the flexible formwork bag 50 to inhibit the expansion of soft rock when exposed to water. Furthermore, during the concrete injection process, the grouting pressure is maintained at 0.3-0.5MPa, and the grouting speed is kept uniform to avoid pressure fluctuations and prevent local incomplete filling or overpressure.

[0052] After injecting concrete into the flexible mold bag 50, seal the grouting hole with a rubber stopper. Before sealing, clean the opening of the grouting hole and carry out the curing step. During the curing step, maintain the ambient temperature at 5-30℃ and the relative humidity at no less than 80%. After the curing step is completed, inspect the formed shell structure 60 before proceeding to the next construction step.

[0053] In addition, the present invention also provides a soft rock tunnel support device for the above-mentioned soft rock tunnel support method, see [link to relevant documentation]. Figures 1-6 As shown, the soft rock tunnel support device includes: an arch support module, a forward beam 30, a steel mesh 40, and a flexible mold bag 50. The arch support module is used to support the surrounding rock surface of the tunnel during the shield support step. The forward beam 30 is connected to the arch support module and the arch top of the tunnel respectively. The steel mesh 40 is used to be laid on the surrounding rock surface of the tunnel during the temporary support step and is connected to the arch support module. The flexible mold bag 50 is used to be connected to the arch support module during the permanent support step and is used to inject concrete.

[0054] The soft rock tunnel support device provided by the present invention is described in detail below.

[0055] See Figure 4As shown, the outrigger assembly 10 includes an outrigger base 101, an outrigger threaded portion 102, an outrigger nut 103, and an outrigger body 104. The outrigger base 101 is made of a 300mm×300mm×20mm steel plate. The bottom of the outrigger threaded portion 102 is welded to the outrigger base 101. The outrigger threaded portion 102 has an M60×5mm trapezoidal thread with a length of 800mm. The outrigger nut 103 is fixed in the inner cavity of the outrigger body 104. The outrigger body 104 is made of a 200mm×200mm×10mm square steel tube. A steel rod is welded to the front end of the outrigger body 104, which can be inserted into the mounting hole at the bottom of the arch frame 20. The outrigger threaded portion 102 and the outrigger nut 103 are connected by a threaded engagement, thereby adjusting the height of the outrigger assembly 10 by rotating the outrigger body 104. The height adjustment range is 200-800mm.

[0056] See Figures 1-3 As shown, the arch frame 20 is made of seamless steel pipe with a diameter of φ108mm×5mm. The arch frame 20 has an arc-shaped part and straight parts on both sides. The radius of curvature of the arc-shaped part is the same as the radius of curvature of the arch of the tunnel. The length of the straight parts can be 600-1200m. The bottom of the straight parts has mounting holes for mounting the outriggers 104. Multiple hooks 202 are welded to the arc-shaped part of the arch frame 20. The distance between two adjacent hooks 202 is 500mm to suspend the front extension beam 30 or the flexible mold bag 50. The front extension beam 30 passes through the second lifting ring 201, which is nested with the first lifting ring. The first lifting ring is hung on the hook 202. The diameter of the first lifting ring is 18mm, and the diameter of the second lifting ring 201 is 30mm.

[0057] See Figure 6 As shown, the front extension beam 30 is made of round steel and includes a beam tip 301, a beam body 302, and a tail hook 303. The surface of the front extension beam 30 is galvanized to prevent rust, and the tensile strength of the front extension beam is not less than 400 MPa.

[0058] The steel mesh 40 is made of φ6.5mm Q235 steel bars welded together, with a mesh size of 100mm×100mm and a reinforced border around the mesh.

[0059] The flexible mold bag 50 is made of 1.2mm thick PVC coated fabric with a tensile strength ≥30kN / m. The flexible mold bag 50 is equipped with multiple grouting holes and venting holes, which are alternately arranged with a spacing of 1m between them. The grouting pressure bearing capacity is ≥0.5MPa.

[0060] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for supporting soft rock tunnels, characterized in that, Includes the following steps: The shielding and support step is carried out in the section of the roadway at a first preset distance from the working face. The shielding and support step includes: The arch support module is installed in the tunnel so that it fits against the arch of the tunnel. Install the forward probe beam (30) so that the forward probe beam (30) is connected to the arch of the roadway and the arch support module respectively; The temporary support step is carried out in the section of the roadway at a second predetermined distance from the working face. The temporary support step includes: Lay a steel mesh (40) so that the steel mesh (40) fits against the surrounding rock surface of the roadway; Connect the steel mesh (40) to the arch support module; and, The permanent support step is carried out in the section of the roadway at a third predetermined distance from the working face. The permanent support step includes: Connect the flexible molded bag (50) to the arch support module; Concrete is injected into the flexible mold bag (50), and the concrete solidifies to form a shell structure (60). In the temporary support step, after the steel mesh (40) is connected to the arch support module, the front probe beam (30) is removed for reuse.

2. The soft rock tunnel support method according to claim 1, characterized in that, In the shielding and support step, before erecting the arch support module, a gravel cushion layer (70) is laid at the bottom of the tunnel.

3. The soft rock tunnel support method according to claim 1, characterized in that, In the shielding and support step, before installing the forward probe beam (30), a forward probe beam mounting hole is drilled in the arch of the roadway, and the angle between the extension direction of the forward probe beam mounting hole and the extension direction of the roadway is 3-8°.

4. The soft rock tunnel support method according to claim 1, characterized in that, The shielding and support step is performed every fourth preset distance of tunnel excavation; and / or, in the shielding and support step, a plurality of the forward probe beams (30) are installed, and the distance between two adjacent forward probe beams (30) is the fourth preset distance.

5. The soft rock tunnel support method according to claim 1, characterized in that, In the temporary support step, before laying the steel mesh (40), a reinforcement step is performed on the fractured area of ​​the surrounding rock face of the roadway, the reinforcement step including: Clear loose bunkers; The area was sealed with sprayed concrete.

6. The soft rock tunnel support method according to claim 1, characterized in that, Before performing the permanent support step, the surrounding rock surface of the roadway is leveled. The leveling step includes: The protruding rock mass is removed and / or concrete is sprayed into the recessed area to make the flatness error of the surrounding rock surface of the tunnel within ±5mm.

7. The soft rock tunnel support method according to claim 1, characterized in that, In the permanent support step, the flexible mold bag (50) is connected to the arch support module in a high-to-low direction; The flexible mold bag (50) is provided with multiple grouting holes. In the step of injecting concrete into the flexible mold bag (50), concrete is injected into each of the grouting holes in a direction from low to high.

8. The soft rock tunnel support method according to any one of claims 1-7, characterized in that, The arch support module includes an arch frame (20) for supporting the surrounding rock face of the roadway and a leg assembly (10) connected to the bottom of the arch frame (20). The leg assembly (10) includes a leg body (104) connected to the bottom of the arch frame (20), a leg nut (103) disposed inside the leg body (104), a leg threaded part (102) threadedly connected to the leg nut (103), and a leg base (101) connected to the bottom of the leg threaded part (102).

9. The soft rock tunnel support method according to claim 8, characterized in that, The arch support module also includes a hook (202) disposed on the arc-shaped part of the arch top frame (20), a first lifting ring connected to the hook (202), and a second lifting ring (201) nested and connected to the first lifting ring. The diameter of the second lifting ring (201) is larger than the diameter of the first lifting ring, and the front probe beam (30) is connected to the second lifting ring (201).

10. A support device for soft rock roadways, characterized in that, The soft rock roadway support method according to any one of claims 1-9, wherein the soft rock roadway support device comprises: The arch support module and the forward probe beam (30) are used to support the surrounding rock surface of the roadway during the shielding and support step. The forward probe beam (30) is connected to the arch support module and the arch top of the roadway respectively. Reinforcing mesh (40), said reinforcing mesh (40) being laid on the surrounding rock face of the roadway during the temporary support step and connected to the arch support module; and, Flexible mold bag (50), which is used to connect with the arch support module in the permanent support step and to inject concrete.

Images