Supporting system for asymmetric large deformation control of layered soft rock tunnel and construction method of supporting system

Abstract

The invention discloses a layered soft rock tunnel asymmetric large deformation control support system and a construction method thereof. The layered soft rock tunnel asymmetric large deformation control support system comprises a sprayed concrete primary support, a polyethylene plate buffer layer, a sprayed concrete reinforcing layer and a reinforced concrete secondary lining which are sequentially arranged in the radial direction of a tunnel from outside to inside. The polyethylene plate buffer layer comprises a plurality of polyethylene plates, one sides of the polyethylene plates are symmetrically arranged on the surface of the sprayed concrete primary support, the sprayed concrete reinforcing layer is provided with steel bar grids and sprayed concrete, the steel bar grids are arranged on the other sides of the polyethylene plates, and the sprayed concrete is arranged on the exposed surface of the polyethylene plate buffer layer. And the reinforced concrete secondary lining is molded reinforced concrete. The method is simple in design and convenient to construct, mechanical operation is easy, the problem of stress concentration caused by asymmetric large deformation is effectively counteracted, and the overall stability and durability of the tunnel are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnels and underground engineering, in particular to a support system for controlling asymmetric large deformation of a layered soft rock tunnel and a construction method thereof. Background Art

[0002] During the construction and subsequent operation and maintenance of layered soft rock tunnels, they often encounter severe challenges of asymmetric large deformation of the surrounding rock. This asymmetric large deformation is mainly due to the complexity of the geological structure, the inclination of the rock layer, and the influence of factors such as groundwater, which causes uneven displacement and deformation of the rocks around the tunnel, resulting in uneven force on the lining structure, and may also cause its deformation to exceed the design limit, thereby causing cracking, peeling, and even overall damage to the lining, seriously threatening the tunnel's function and structural safety.

[0003] Especially under geological conditions where soft rock is obviously stratified and rock mass strength is generally low, the rheological effect and asymmetric stress distribution of the surrounding rock will further aggravate the asymmetry of tunnel deformation, seriously threatening the safety and stability of the project. In order to deal with this problem, the existing asymmetric support system usually uses support materials with different stiffness or strength to locally strengthen the tunnel. For example, in areas with more severe deformation, higher strength support materials may be used or the thickness of the support layer may be increased to provide additional support. Although such methods can control deformation to a certain extent and alleviate the problem of uneven force on the lining structure. However, the support design is complex and requires comprehensive consideration of multiple factors such as geological conditions, deformation mode, performance of support materials, and construction feasibility. Secondly, the construction process is cumbersome and requires high-precision measurement and positioning technology, as well as a professional construction team to ensure the accurate installation of the support structure. This not only increases the construction cost, but may also prolong the construction period. However, even if a good support effect is achieved in the early stage of construction, in the long-term operation process, due to the continuous deformation of the surrounding rock and the redistribution of stress, failure may occur due to local stress concentration, thereby threatening the long-term stability and safety of the tunnel. Therefore, it is urgent to develop a support system for the asymmetric large deformation problem in layered soft rock tunnels to provide a more solid guarantee for the safe construction and long-term operation of layered soft rock tunnels. Summary of the invention

[0004] The purpose of the present invention is to provide a support system for a layered soft rock tunnel with asymmetric large deformation control and a construction method thereof, so as to solve the problem in the prior art that asymmetric stress concentration easily leads to support failure.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The support system for asymmetric large deformation control of layered soft rock tunnels includes shotcrete initial support, polyethylene board buffer layer, shotcrete reinforcement layer and reinforced concrete secondary lining arranged in sequence from outside to inside along the tunnel radial direction; The polyethylene board buffer layer includes a plurality of polyethylene boards, one side of which is symmetrically arranged on the surface of the initial support of the shotcrete, the shotcrete reinforcement layer is provided with a steel grid and shotcrete, the steel grid is arranged on the other side of the polyethylene board, the shotcrete is arranged on the exposed surface of the polyethylene board buffer layer, and the reinforced concrete secondary lining is cast-in-place reinforced concrete.

[0006] Furthermore, the shotcrete initial support includes a steel arch frame and shotcrete, the steel arch frame is erected at the tunnel face, the shotcrete is sprayed on the surrounding rock surface of the tunnel face, and the shotcrete wraps the steel arch frame.

[0007] Furthermore, a nickel-based chemical plating layer is provided on both side surfaces of the polyethylene plate, and an anti-oxidation protective coating is provided on the surface of the nickel-based chemical plating layer.

[0008] Furthermore, the material of the anti-oxidation protective coating is epoxy resin.

[0009] Furthermore, the polyethylene sheet is adhered to the surface of the initial support of the shotcrete by means of a binder.

[0010] Furthermore, the binder is polyurethane glue.

[0011] Furthermore, the steel bar grid includes a plurality of transverse steel bars and longitudinal steel bars, the transverse steel bars and the longitudinal steel bars are arranged in a staggered manner, and the plurality of transverse steel bars and longitudinal steel bars are distributed at intervals.

[0012] Furthermore, the transverse steel bars and the longitudinal steel bars are fixedly connected by spot welding.

[0013] A construction method of the support system for asymmetric large deformation control of a layered soft rock tunnel, comprising: After tunnel excavation, a steel arch is erected at the face and shotcrete is placed to form the initial support of shotcrete; Cut the polyethylene sheet to a suitable size and perform anti-corrosion treatment on both sides of the polyethylene sheet; The anti-corrosion treated polyethylene sheet is symmetrically pasted on the surface of the initial support of the shotcrete to form a polyethylene sheet buffer layer; A steel bar grid is arranged on the exposed side of the polyethylene sheet buffer layer, and then secondary shotcrete is sprayed to form a shotcrete reinforcement layer; A reinforced concrete secondary lining is cast inside the shotcrete reinforcement layer.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a support system for asymmetric large deformation control of a layered soft rock tunnel, wherein shotcrete initial support, polyethylene sheet buffer layer, shotcrete reinforcement layer and reinforced concrete secondary lining are sequentially arranged from outside to inside along the radial direction of the tunnel. The polyethylene sheet buffer layer includes a plurality of polyethylene sheets, one side of the polyethylene sheet is symmetrically arranged on the surface of the shotcrete initial support, and through the symmetrical support structure design and the reasonable application of the polyethylene sheet buffer layer, the asymmetric stress distribution of the surrounding rock can be effectively balanced, the local stress concentration can be reduced, the overall stability of the tunnel can be improved, and the long-term rheological characteristics of the surrounding rock can be particularly adapted. The shotcrete reinforcement layer is provided with a steel mesh and shotcrete, the steel mesh is arranged on the other side of the polyethylene sheet, the shotcrete is arranged on the exposed surface of the polyethylene sheet buffer layer, and is secondarily covered and fixed by the reinforced concrete secondary lining, the staggered transverse steel bars and the longitudinal steel bars, and after being fixed by the shotcrete reinforcement layer, become part of the overall support with the steel mesh, which helps to bear the external surrounding rock pressure, significantly enhances the overall bearing capacity of the support system, and further blocks the erosion of the reinforced concrete secondary lining by underground acid / alkali ions. The process is simple, the construction efficiency is high, and no complex equipment and multiple adjustments are required, which reduces the construction difficulty and engineering cost. The present invention aims at the characteristics of asymmetric large deformation of layered soft rock tunnels. By symmetrically arranging a polyethylene plate buffer layer with certain elasticity and deformation capacity in the tunnel, using efficient buffer layer materials, and performing anti-corrosion treatment on it, combined with reasonable installation and fixing methods, the overall symmetrical design is scientific and reasonable, the structural stiffness is uniform, and it is easy to mechanize and operate. It can absorb and disperse the deformation energy of the surrounding rock, balance the asymmetric stress distribution, avoid stress concentration and local failure problems that may be caused by asymmetric support, and improve the adaptability of the tunnel support structure. At the same time, by covering and fixing with reinforced sprayed concrete, the construction process can be significantly simplified, and the overall stability and durability of the tunnel can be improved. It is suitable for a variety of surrounding rock grades and complex geological conditions, especially showing excellent adaptability under layered soft rock or asymmetric large deformation conditions. The present invention combines construction simplicity, long-term support reliability and engineering economy, and has broad engineering application value and promotion prospects.

[0015] Furthermore, the polyethylene board buffer layer uses polyethylene sheets that have been treated with anti-corrosion. Through multiple processes such as chemical nickel plating, anti-oxidation coating and UV protection, it effectively prevents instability problems caused by sheet corrosion during tunnel service, significantly enhances the durability of the material, and can effectively resist moisture, chemical corrosion and microbial erosion, extending the service life of the buffer layer, thereby reducing maintenance costs throughout the life cycle.

[0016] Furthermore, the polyethylene board buffer layer is installed through symmetrical bonding, which is simple to construct. The bonding agent can fill the tiny bumps on the initial support surface, achieve efficient bonding between the buffer layer and the shotcrete, and enhance the tightness and stability of the overall structure. At the same time, the bonding layer provides uniform adhesion to avoid the buffer layer from falling off or loosening due to local uneven force, thereby ensuring the long-term stability of the support structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is a schematic diagram of the support system structure for asymmetric large deformation control of layered soft rock tunnels according to the present invention.

[0019] Figure 2 This is a schematic diagram of the buffer layer reinforcement layout of the present invention.

[0020] Among them: 1- shotcrete initial support, 2- polyethylene board buffer layer, 3- shotcrete reinforcement layer, 4- reinforced concrete secondary lining, 5- transverse reinforcement, 6- longitudinal reinforcement. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0027] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings: See also Figure 1 The present invention provides a support system for asymmetric large deformation control of a layered soft rock tunnel, comprising a shotcrete initial support 1, a polyethylene board buffer layer 2, a shotcrete reinforcement layer 3 and a reinforced concrete secondary lining 4 arranged in sequence from outside to inside along the tunnel radial direction.

[0031] The shotcrete initial support 1 includes a steel arch frame and shotcrete. The steel arch frame is erected at the tunnel face. The shotcrete is sprayed on the surrounding rock surface of the tunnel face and wraps the steel arch frame. Traditional buffer materials are easily degraded by humid environment, chemical corrosion or microbial erosion, resulting in buffer failure. Therefore, the polyethylene plate buffer layer 2 uses a number of polyethylene plates. The thickness of the polyethylene plate buffer layer 2 is 20~30mm. The polyethylene plate is cut to a suitable size (1m×1m). A uniform nickel-based chemical plating layer is applied on both sides of the polyethylene plate to improve its corrosion resistance. A layer of anti-oxidation protective coating made of epoxy resin is applied on the surface of the nickel-based chemical plating layer to further isolate oxygen and corrosive media, effectively preventing the instability caused by polyethylene plate corrosion during the service of the tunnel. At the same time, the durability of the polyethylene plate buffer layer 2 is improved, thereby reducing the maintenance cost during the entire life cycle.

[0032] The polyethylene sheet buffer layer 2 is pasted on the shotcrete initial support 1 by means of a bonding agent. By symmetrically arranging the polyethylene sheet buffer layer 2 with certain elasticity and deformation ability in the tunnel, the surrounding rock pressure can be effectively dispersed, the asymmetric stress distribution can be balanced, and the adaptability of the tunnel support structure can be improved. The material of the bonding agent is polyurethane glue, which can fill the tiny bumps on the surface of the shotcrete initial support 1, realize the efficient bonding between the polyethylene sheet buffer layer 2 and the shotcrete initial support 1, and enhance the tightness and stability of the overall structure. At the same time, the bonding layer provides uniform adhesion, avoiding the polyethylene sheet buffer layer 2 from falling off or loosening due to local uneven force, and ensuring the long-term stability of the support structure.

[0033] After bonding with adhesive, a steel grid (Φ6mm) is arranged on the exposed side of the polyethylene board buffer layer 2 to further fix the polyethylene board. The transverse steel bars 5 and the longitudinal steel bars 6 are arranged in a staggered manner. The steel grid is first arranged between the polyethylene board buffer layer 2 and the shotcrete lining of the shotcrete initial support 1. There are two transverse steel bars 5 and longitudinal steel bars 6 on each polyethylene board, which are installed at a distance of 0.3m from both sides of the polyethylene board. The steel bar spacing is 0.4m. The transverse steel bars 5 and the longitudinal steel bars 6 are fixed by spot welding. The steel grid is used to further fix the polyethylene board to prevent the adhesive from not being firmly bonded and causing the polyethylene board to fall off. After the horizontal and vertical steel bars are laid out, the horizontal steel bars 5, the longitudinal steel bars 6 and the polyethylene board buffer layer 2 are sprayed with concrete for the second time. The steel grid serves as the reinforcement of the sprayed concrete reinforcement layer 3, so that the steel bars and the polyethylene board buffer layer 2 are tightly combined to form the sprayed concrete reinforcement layer 3, which is fixed as a whole. This can significantly simplify the construction process, reduce costs, and improve the overall stiffness and durability of the support system. At the same time, it further blocks the erosion of the underground acid / alkali ions on the reinforced concrete secondary lining 4. The reinforced concrete secondary lining 4 is cast-in-place reinforced concrete and is arranged on the inner side of the sprayed concrete reinforcement layer 3.

[0034] The construction method of the support system for asymmetric large deformation control of a layered soft rock tunnel of the present invention comprises the following steps: Step 1: After tunnel excavation, a steel arch frame is promptly erected at the tunnel face, and concrete is sprayed to form initial sprayed concrete support 1; Step 2: Cut the polyethylene sheet into a suitable size (1m×1m), apply a uniform nickel-based chemical plating layer on both sides of the polyethylene sheet to improve its corrosion resistance, and apply an anti-oxidation protective coating made of epoxy resin on the surface of the nickel-based chemical plating layer to further isolate oxygen and corrosive media; Step 3: symmetrically pre-bond the anti-corrosion treated polyethylene sheet to the surface of the shotcrete initial support 1 by means of a binder (polyurethane glue) to form a polyethylene sheet buffer layer 2; Step 4: Arrange a steel grid (Φ6 mm) on the exposed side of the polyethylene board buffer layer to further fix the polyethylene board. The steel grid is arranged in a staggered manner with transverse steel bars 5 and longitudinal steel bars 6. Arrange the steel grid between the polyethylene board buffer layer 2 and the shotcrete lining. Each polyethylene board has two transverse steel bars 5 and longitudinal steel bars 6, which are installed at a distance of 0.3m from both sides of the polyethylene board. The steel bar spacing is 0.4m. Fix the transverse steel bars 5 and longitudinal steel bars 6 by spot welding, and then spray concrete for the second time to form a shotcrete reinforcement layer 3. Fix the steel grid as a whole so that the steel grid is tightly combined with the polyethylene board buffer layer 2, while improving the overall stiffness and durability of the support system. Step 5: Cast a reinforced concrete secondary lining 4 inside the shotcrete reinforcement layer 3.

[0035] Through the above construction method of the present invention, a support structure system of shotcrete initial support 1, polyethylene plate buffer layer 2, shotcrete reinforcement layer 3 and reinforced concrete secondary lining 4 is set up, and a symmetrical support structure of polyethylene plate buffer layer 2 is proposed to control asymmetric large deformation, evenly distribute lining stiffness, effectively offset the stress concentration problem caused by asymmetric large deformation, improve the overall stability and durability of the tunnel, and perform anti-corrosion treatment on the buffer material polyethylene plate, effectively preventing the instability problem caused by polyethylene plate corrosion during the service of the tunnel, and at the same time improving the durability of the polyethylene plate buffer layer 2, thereby reducing the maintenance cost during the whole life cycle. At the same time, the construction process is optimized, and the method of adhesive installation and steel shotcrete covering and fixing is adopted, which can significantly simplify the construction process, reduce costs, and improve the overall stability and durability of the support system.

[0036] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A support system for asymmetric large deformation control of layered soft rock tunnels, characterized by: It comprises a shotcrete primary support (1), a polyethylene board buffer layer (2), a shotcrete reinforcement layer (3) and a reinforced concrete secondary lining (4) which are arranged in sequence from the outside to the inside along the radial direction of the tunnel; The polyethylene sheet buffer layer (2) comprises a plurality of polyethylene sheets, one side of which is symmetrically arranged on the surface of the shotcrete primary support (1), the shotcrete reinforcement layer (3) is provided with a steel mesh and shotcrete, the steel mesh is arranged on the other side of the polyethylene sheet, the shotcrete is arranged on the exposed surface of the polyethylene sheet buffer layer (2), and the reinforced concrete secondary lining (4) is cast-in-place reinforced concrete.

2. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 1 is characterized in that: The shotcrete initial support (1) comprises a steel arch frame and shotcrete, wherein the steel arch frame is erected at the tunnel face, and the shotcrete is sprayed on the surrounding rock surface of the tunnel face, and the shotcrete wraps the steel arch frame.

3. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 1 is characterized in that: A nickel-based chemical plating layer is arranged on both sides of the polyethylene plate, and an anti-oxidation protective coating is arranged on the surface of the nickel-based chemical plating layer.

4. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 3 is characterized in that: The material of the anti-oxidation protective coating is epoxy resin.

5. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 1 is characterized in that: The polyethylene sheet is adhered to the surface of the shotcrete initial support (1) by means of a binder.

6. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 5 is characterized in that: The adhesive is polyurethane adhesive.

7. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 1 is characterized in that: The steel bar grid comprises a plurality of transverse steel bars (5) and longitudinal steel bars (6), wherein the transverse steel bars (5) and the longitudinal steel bars (6) are arranged in a staggered manner, and the plurality of transverse steel bars (5) and longitudinal steel bars (6) are distributed at intervals.

8. The support system for asymmetric large deformation control of layered soft rock tunnel according to claim 7 is characterized in that: The transverse steel bars (5) and the longitudinal steel bars (6) are fixedly connected by spot welding.

9. A construction method for a layered soft rock tunnel support system with asymmetric large deformation control according to any one of claims 1 to 8, characterized in that: include: After tunnel excavation, a steel arch is erected at the tunnel face and shotcrete is placed to form shotcrete initial support (1); Cut the polyethylene sheet to a suitable size and perform anti-corrosion treatment on both sides of the polyethylene sheet; The anti-corrosion treated polyethylene sheet is symmetrically adhered to the surface of the shotcrete initial support (1) to form a polyethylene sheet buffer layer (2); Arranging a steel mesh on the exposed side of the polyethylene sheet buffer layer (2), and then performing secondary shotcrete spraying to form a shotcrete reinforcement layer (3); A reinforced concrete secondary lining (4) is cast inside the shotcrete reinforcement layer (3).

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