A tunnel surrounding rock control technology and construction method for soft rock tunnels that are supported before excavation

Abstract

The present invention discloses a tunnel surrounding rock control technology and construction method for supporting a soft rock tunnel before excavation, comprising the following construction steps: S1, designing the spiral radius of an elastic ring support (1) according to the tunnel cross-sectional dimensions, surrounding rock properties, ground stress, elastic-plastic influence zone of the tunnel surrounding rock, and mechanical characteristics of the elastic support, determining the length of the elastic ring support (1) along the preset tunnel strike, whether grouting treatment is required, fixing the anchor length, and arranging the position; S2, performing spiral drilling in a predetermined direction on site using a drilling rig (11) and navigation equipment, and reaching a designated bottom plate; the tunnel surrounding rock control technology and construction method for supporting a soft rock tunnel before excavation of the present invention can be applied not only to soft rock tunnel support, but also to reinforced support of mine tunnels under deep complex geological conditions and high stress environments, as well as reinforced support of deep-sea tunnels and deep underground tunnels, reinforced support of tunnels under surface water bodies, and reinforced support of military underground tunnels.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel support, in particular to a tunnel surrounding rock control technology and a construction method for supporting a soft rock tunnel before excavation. Background Art

[0002] Under soft rock conditions, the stability of deep tunnel support engineering is a prerequisite for safe deep mining of mineral resources. However, due to the high ground stress at depth and the severe impact of construction on the surrounding rock, the tunnels show severe deformation of the surrounding rock during construction, damage to the surrounding rock during construction, roof collapse, floor heaving, and other impact dynamic pressures. This is particularly prominent in tunnels that require certain waterproofing functions. For such tunnels, the traditional technical method and experience are to adopt a high-density, high-rigidity combined support technology solution. However, this method has problems such as high cost, complex support procedures, long construction time, and high labor intensity. Moreover, traditional support methods are based on a construction-first, then support method. During the construction process, the surrounding rock is inevitably subjected to the combined effects of construction and ground stress, which inevitably causes additional deformation and crack development in the surrounding rock. This makes it impossible to achieve the maximum integrity of the tunnel surrounding rock, reduces the rock formation strength, and leads to technical defects such as difficult tunnel support and poor waterproofing.

[0003] In response to this type of tunnel working condition problem and the defects of the current technical solution of combined support and control, based on the analysis of the mechanical mechanism of the destruction and deformation of the surrounding rock of deep tunnels and the mechanical principle of tunnel surrounding rock control, a method with mature technology, simple structure, simple construction operation, low manufacturing cost, and active support in the tunnel surrounding rock is proposed. The purpose is to achieve support and control of the surrounding rock of deep tunnels economically and effectively to meet the needs of deep tunnel construction and deep resource safe mining projects. Summary of the Invention

[0004] To address the deficiencies mentioned in the above-mentioned background technology, the purpose of the present invention is to provide a tunnel surrounding rock control technology and construction method for soft rock tunnels that are supported before excavation. In order to solve the safety problems of deep-ground soft rock tunnels with large surrounding rock stress and the traditional method of first construction and then support, which will lead to the development of surrounding rock cracks, thereby causing increased surrounding rock damage, roof collapse, floor bulging, spalling and other surrounding rock stress instability, the present invention can also meet the safety and waterproofing requirements of tunnels with certain waterproofing needs or the support requirements of deep-sea tunnel surrounding rock. The present invention proposes a tunnel surrounding rock control technology and construction method for soft rock tunnels that are supported before excavation, thereby achieving the coordinated bearing effect of mine pressure on the tunnel surrounding rock, forming a certain range of ground stress stability circle, and at the same time meeting the waterproof and sealing performance of the tunnel engineering surrounding rock.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A tunnel surrounding rock control technology and construction method for supporting a soft rock tunnel before excavation, including the following construction steps:

[0007] S1, based on the cross-sectional dimensions of the tunnel, the properties of the surrounding rock, the magnitude of the ground stress, the elastic-plastic influence zone of the tunnel surrounding rock, and the mechanical characteristics of the elastic support, design the spiral radius of the elastic ring support (1), the length of the elastic ring support (1) along the preset tunnel strike, whether grouting treatment is required, the length of the fixed anchor rod, and the arrangement position;

[0008] S2, using a drilling machine (11) and navigation equipment on site to perform spiral drilling in a predetermined direction and reach a designated bottom plate;

[0009] S3, the tunnel is constructed normally and supported in time, and the tunnel is constructed to the designated floor position, with an appropriate distance reserved to meet the needs of subsequent construction;

[0010] S4, determine the size relationship between the diameter of the guide drill bit and the diameter of the elastic ring bracket. If the elastic ring bracket is larger than the guide drill bit, proceed to step S5. If the elastic ring bracket is smaller than the guide drill bit, skip step S5 and directly proceed to step S6.

[0011] S5, the guide drill bit (17) guided out of the tunnel annular support is replaced with a reaming drill bit (20), the reaming drill bit (20) is connected to the drill rod (6), and the surrounding rock hole is reamed until the reaming drill bit (20) drills out of the tunnel annular support and is installed into the drill hole (12), and the relationship between the diameter of the reaming drill bit (20) and the diameter of the elastic annular support is determined. If the elastic annular support is larger than the reaming drill bit, step S5 is continued. If the elastic annular support is smaller than the reaming drill bit, step S5 is skipped and step S6 is performed;

[0012] S6, push the navigation drill bit (17) or the reaming drill bit (20) out of the base plate, and replace the drill bit with an equal diameter reaming drill bit (20), followed by a single-turn drill bit (18), and connect the single-turn connector (18) to the pull-back drill bit (4) with a D-type shackle (5), and fix the pull-back drill bit (4) and the elastic rod (16) with a wire rope and a wire rope buckle;

[0013] S7, using a drilling machine (11), the elastic support rod (16) is pulled back to a predetermined position in the surrounding rock hole to form an elastic ring bracket (1), the connection between the pull-back drill bit (4) and the elastic ring bracket (1) is disconnected, the sleeve-type annular elastic bracket holder (24) is inserted into the elastic ring bracket (1) of the tunnel annular bracket installation outlet drilling port (13) and the tunnel annular bracket installation inlet drilling port (12), and the annular elastic bracket (1) is punched at the position of the bracket fixing hole (27) of the sleeve-type annular elastic bracket holder, and then Then, a screw is inserted into the bracket fixing hole (27) of the sleeve-type annular elastic bracket fixer, and its position is limited by a bolt, and the annular elastic bracket fixer (24) is fixed together with the annular elastic bracket (1), and the annular elastic bracket outlet grouting sealing cover (22) is installed on the end of the annular elastic bracket (1) for installing the tunnel annular bracket outlet drill hole (13), and the annular elastic bracket inlet drill hole one-way grouting valve (23) is installed on the end of the annular elastic bracket (1) for installing the tunnel annular bracket inlet drill hole (12);

[0014] S8, using a slurry pump to perform grouting and pressure treatment on the hollow elastic support rod (16);

[0015] S9, for the elastic support rod (16) that has been grouted or does not need grouting, insert the fixing anchor rod (14) into the fixing hole (25) of the base of the annular elastic support fixture at the entry (exit) drill hole and fix it, and finally lay the base plate;

[0016] S10: After the annular support 1 is laid in this stage, the next stage of laying is carried out.

[0017] As a preferred solution of the present invention, the elastic support rod (16) is arranged in the surrounding rock of the tunnel, spirally surrounds the tunnel, forms an annular ground stress stabilization ring, and fills and seals the surrounding rock crack structure through grouting to achieve the sealing of the surrounding rock and meet the waterproof requirements of deep-sea tunnels and diving area tunnels.

[0018] As a preferred solution of the present invention, for certain completed tunnels, a ring support (1) can be arranged in the surrounding rock of a certain section of the tunnel that requires special support to reinforce the tunnel surrounding rock.

[0019] As a preferred solution of the present invention, for some tunnels that have been completed but are severely deformed and are not suitable for direct repair, an annular support (1) can be arranged and installed and grouting can be performed to repair the broken surrounding rock and form a ground stress stable zone before the tunnel repair work is carried out.

[0020] As a preferred solution of the present invention, for tunnels with low requirements for surrounding rock waterproofing, relatively high surrounding rock strength, no cracks caused by geological structures, no earth stress, and no need for grouting reinforcement, elastic support rods (16) made of solid materials are directly used, and grouting treatment is omitted to speed up the project progress.

[0021] As a preferred embodiment of the present invention, the sleeve-type annular elastic support fixture (24) matched with the annular elastic support (1) is welded by a steel multi-porous sleeve-type annular elastic support fixture base (26) and a steel pipe with an inner diameter the same as the outer diameter of the annular elastic support (1). When in use, the sleeve-type annular elastic support fixture (24) is inserted into the annular elastic support (1), the annular elastic support (1) is punched at the position of the sleeve-type annular elastic support fixture bracket fixing hole (27), and then a screw is inserted and bolted to fix the annular elastic support fixture (24) and the annular elastic support (1) together, and then the annular support fixing anchor rod (14) is directly inserted into the fixing hole (25) of the sleeve-type annular elastic support fixture base. According to the actual needs of the project, the annular support fixing anchor rod (14) is fixed to the surrounding rock of the tunnel floor from multiple angles.

[0022] The beneficial effects of the present invention are:

[0023] Before the tunnel is excavated, the present invention uses a drill rod to drill an auger in the direction of the tunnel excavation, and uses the elasticity of the drill rod to temporarily support the tunnel surrounding rock. This can reduce damage to the tunnel surrounding rock caused by construction during tunnel excavation and ensure the integrity of the tunnel surrounding rock. After the tunnel construction is completed, the annular elastic rod is pulled back into the auger hole and grouting is performed. The elasticity of the elastic rod can offset part of the surrounding rock pressure, maintaining the integrity of the tunnel surrounding rock. Grouting can fill cracks in the surrounding rock, preventing water seepage in the tunnel, and ultimately forming a stable surrounding rock pressure stress circle, forming a permanent annular support.

[0024] 2. The present invention has a simple structure, simple construction operation, and low manufacturing cost, and can economically and effectively realize the support and control of the surrounding rock of deep underground tunnels, meeting the needs of deep underground tunnel construction and deep underground resource safe mining projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 The present invention is a perspective structural diagram of an elastic support for a soft rock tunnel that is supported before excavation.

[0027] Figure 2 The present invention is a schematic structural cross-sectional view of an elastic support for a soft rock tunnel that is supported before excavation.

[0028] Figure 3 The figure is a schematic side view of the structure of an elastic support for a soft rock tunnel that is supported before excavation according to the present invention.

[0029] Figure 4 The present invention is a schematic top view of the structure of an elastic support for a soft rock tunnel that is supported before excavation.

[0030] Figure 5 The present invention is a structural schematic diagram of a drilling and expanding device for an elastic support in a soft rock tunnel that is supported before excavation.

[0031] Figure 6 The figure is a schematic diagram of the installation of an elastic support for a soft rock tunnel that is supported before excavation according to the present invention.

[0032] Figure 7 This is a schematic diagram of the side grouting holes of an elastic support for a soft rock tunnel that is supported before excavation according to the present invention.

[0033] Figure 8 The present invention is a schematic structural diagram of an installation device for an elastic support for a soft rock tunnel that is supported before excavation.

[0034] Figure 9 The present invention is a schematic diagram of the drill-out side structure of an elastic support for a soft rock tunnel that is supported before excavation.

[0035] Figure 10 The present invention is a schematic structural diagram of the drilling entrance side of an elastic support for a soft rock tunnel that is supported before excavation.

[0036] Figure 11 The present invention is a perspective schematic diagram of a support fixture structure of an elastic support for a soft rock tunnel that is supported before excavation.

[0037] In the picture:

[0038] 1—elastic ring support; 2—traditional ring support for roadway; 3—grouting port for ring support; 4—pullback drill bit; 5—D-type shackle; 6—drill rod; 7—roadway foundation; 8—roadway upper space; 9—tunnel surrounding rock; 10—tunnel cross section; 11—drilling rig; 12—entry port for roadway ring support installation; 13—exit port for roadway ring support installation; 14—anchor bolts for fixing ring support; 15—grouting port for elastic support; 16—elastic support rods. 17—guide drill bit; 18—single-turn drill bit; 19—threaded thread; 20—reaming drill bit; 21—tunnel spraying net; 22—annular elastic bracket drill outlet grouting sealing cover, 23—annular elastic bracket drill inlet one-way grouting valve, 24—sleeve-type annular elastic bracket fixer, 25—anchor rod fixing hole of the ring-type annular elastic bracket fixer, 26—base of the ring-type annular elastic bracket fixer, 27—bracket fixing hole of the ring-type annular elastic bracket fixer. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "around" and the like indicating orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] like Figures 1-11 As shown, a tunnel surrounding rock control technology and construction method for supporting soft rock tunnels before excavation includes the following construction steps:

[0042] S1, based on the cross-sectional dimensions of the tunnel, the properties of the surrounding rock, the magnitude of the ground stress, the elastic-plastic influence zone of the tunnel surrounding rock, and the mechanical characteristics of the elastic support, design the spiral radius of the elastic ring support (1), the length of the elastic ring support (1) along the preset tunnel strike, whether grouting treatment is required, the length of the fixed anchor rod, and the arrangement position;

[0043] S2, using a drilling machine (11) and navigation equipment on site to perform spiral drilling in a predetermined direction and reach a designated bottom plate;

[0044] S3, the tunnel is constructed normally and supported in time, and the tunnel is constructed to the designated floor position, with an appropriate distance reserved to meet the needs of subsequent construction;

[0045] S4, determine the size relationship between the diameter of the guide drill bit and the diameter of the elastic ring bracket. If the elastic ring bracket is larger than the guide drill bit, proceed to step S5. If the elastic ring bracket is smaller than the guide drill bit, skip step S5 and directly proceed to step S6.

[0046] S5, the guide drill bit (17) guided out of the tunnel annular support is replaced with a reaming drill bit (20), the reaming drill bit (20) is connected to the drill rod (6), and the surrounding rock hole is reamed until the reaming drill bit (20) drills out of the tunnel annular support and is installed into the drill hole (12), and the relationship between the diameter of the reaming drill bit (20) and the diameter of the elastic annular support is determined. If the elastic annular support is larger than the reaming drill bit, step S5 is continued. If the elastic annular support is smaller than the reaming drill bit, step S5 is skipped and step S6 is performed;

[0047] S6, push the navigation drill bit (17) or the reaming drill bit (20) out of the base plate, and replace the drill bit with an equal diameter reaming drill bit (20), followed by a single-turn drill bit (18), and connect the single-turn connector (18) to the pull-back drill bit (4) with a D-type shackle (5), and fix the pull-back drill bit (4) and the elastic rod (16) with a wire rope and a wire rope buckle;

[0048] S7, using a drilling machine (11), the elastic support rod (16) is pulled back to a predetermined position in the surrounding rock hole to form an elastic ring bracket (1), the connection between the pull-back drill bit (4) and the elastic ring bracket (1) is disconnected, the sleeve-type annular elastic bracket holder (24) is inserted into the elastic ring bracket (1) of the tunnel annular bracket installation outlet drilling port (13) and the tunnel annular bracket installation inlet drilling port (12), and the annular elastic bracket (1) is punched at the position of the bracket fixing hole (27) of the sleeve-type annular elastic bracket holder, and then Then, a screw is inserted into the bracket fixing hole (27) of the sleeve-type annular elastic bracket fixer, and its position is limited by a bolt, and the annular elastic bracket fixer (24) is fixed together with the annular elastic bracket (1), and the annular elastic bracket outlet grouting sealing cover (22) is installed on the end of the annular elastic bracket (1) for installing the tunnel annular bracket outlet drill hole (13), and the annular elastic bracket inlet drill hole one-way grouting valve (23) is installed on the end of the annular elastic bracket (1) for installing the tunnel annular bracket inlet drill hole (12);

[0049] S8, using a slurry pump to perform grouting and pressure treatment on the hollow elastic support rod (16);

[0050] S9, for the elastic support rod (16) that has been grouted or does not need grouting, insert the fixing anchor rod (14) into the fixing hole (25) of the base of the annular elastic support fixture at the entry (exit) drill hole and fix it, and finally lay the base plate;

[0051] S10: After the annular support 1 is laid in this stage, the next stage of laying is carried out.

[0052] As a preferred solution of the present invention, the elastic support rod (16) is arranged in the surrounding rock of the tunnel, spirally surrounds the tunnel, forms an annular ground stress stabilization ring, and fills and seals the surrounding rock crack structure through grouting to achieve the sealing of the surrounding rock, meeting the waterproofing requirements of deep-sea tunnels, deep underground tunnels and diving area tunnels.

[0053] As a preferred solution of the present invention, for certain completed tunnels, a ring support (1) can be arranged in the surrounding rock of a certain section of the tunnel that requires special support to reinforce the tunnel surrounding rock.

[0054] As a preferred solution of the present invention, for some tunnels that have been completed but are severely deformed and are not suitable for direct repair, an annular support (1) can be arranged and installed and grouting can be performed to repair the broken surrounding rock and form a ground stress stable zone before the tunnel repair work is carried out.

[0055] As a preferred solution of the present invention, for tunnels with low requirements for surrounding rock waterproofing, relatively high surrounding rock strength, no cracks caused by geological structures, no earth stress, and no need for grouting reinforcement, elastic support rods (16) made of solid materials are directly used, and grouting treatment is omitted to speed up the project progress.

[0056] As a preferred embodiment of the present invention, the sleeve-type annular elastic support fixture (24) matched with the annular elastic support (1) is welded by a steel multi-porous sleeve-type annular elastic support fixture base (26) and a steel pipe with an inner diameter the same as the outer diameter of the annular elastic support (1). When in use, the sleeve-type annular elastic support fixture (24) is inserted into the annular elastic support (1), the annular elastic support (1) is punched at the position of the sleeve-type annular elastic support fixture bracket fixing hole (27), and then a screw is inserted and bolted to fix the annular elastic support fixture (24) and the annular elastic support (1) together, and then the annular support fixing anchor rod (14) is directly inserted into the fixing hole (25) of the sleeve-type annular elastic support fixture base. According to the actual needs of the project, the annular support fixing anchor rod (14) is fixed to the surrounding rock of the tunnel floor from multiple angles.

[0057] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these 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 any one or more embodiments or examples.

[0058] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

[0059] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements and simple improvements made to the essential contents of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for constructing surrounding rock of a soft rock tunnel by supporting the tunnel before excavation, characterized in that: The construction steps include: S1. According to the cross-sectional dimensions of the tunnel, the properties of the surrounding rock, the magnitude of the ground stress, the elastic-plastic influence zone of the tunnel surrounding rock, and the mechanical characteristics of the elastic support, the spiral radius of the elastic ring support (1) is designed, the length of the elastic ring support (1) along the predetermined tunnel strike, whether grouting treatment is required, the length of the fixed anchor rod, and the arrangement position; S2, using a drilling machine (11) and navigation equipment on site to perform spiral drilling in a predetermined direction and reach a designated bottom plate; S3. The tunnel is constructed normally and supported in time, and the tunnel is constructed to the designated floor position, with an appropriate distance reserved to meet the needs of subsequent construction; S4. Determine the size relationship between the diameter of the pilot drill bit and the diameter of the elastic ring bracket. If the elastic ring bracket is larger than the pilot drill bit, proceed to step S5. If the elastic ring bracket is smaller than the pilot drill bit, skip step S5 and proceed directly to step S6. S5, replacing the guide drill bit (17) guided out of the tunnel annular support with a reaming drill bit (20), connecting the reaming drill bit (20) to the drill rod (6), and reaming the surrounding rock hole until the reaming drill bit (20) drills out of the tunnel annular support and is installed into the drill hole (12), determining the size relationship between the diameter of the reaming drill bit (20) and the diameter of the elastic annular support, and continuing to step S5 if the elastic annular support is larger than the reaming drill bit, and skipping step S5 and proceeding to step S6 if the elastic annular support is smaller than the reaming drill bit; S6, the pilot drill bit (17) or the reaming drill bit (20) is pushed out of the bottom plate, and the drill bit is replaced with a reaming drill bit (20) of equal diameter, followed by a single-turn connector (18), and the single-turn connector (18) is connected to the pull-back drill bit (4) with a D-type shackle (5), and the pull-back drill bit (4) and the elastic support rod (16) are fixed by a wire rope and a wire rope buckle; S7, using a drilling machine (11) to drag the elastic support rod (16) back to a predetermined position in the surrounding rock hole to form an elastic ring bracket (1), disconnecting the connection between the dragging drill bit (4) and the elastic ring bracket (1), inserting the sleeve-type annular elastic bracket holder (24) into the elastic ring bracket (1) of the tunnel annular bracket installation outlet drilling port (13) and the tunnel annular bracket installation inlet drilling port (12), drilling a hole in the elastic ring bracket (1) at the position of the bracket fixing hole (27) of the sleeve-type annular elastic bracket holder, and then Then, a screw is inserted into the bracket fixing hole (27) of the sleeve-type annular elastic bracket fixer, and its position is limited by a bolt, and the annular elastic bracket fixer (24) is fixed together with the elastic annular bracket (1), and a ring elastic bracket outlet grouting sealing cover (22) is installed on the end of the elastic annular bracket (1) for installing the tunnel annular bracket outlet drill hole (13), and a ring elastic bracket inlet one-way grouting valve (23) is installed on the end of the elastic annular bracket (1) for installing the tunnel annular bracket inlet drill hole (12); S8, using a slurry pump to perform grouting and pressure treatment on the hollow elastic support rod (16); S9, for the elastic support rod (16) that has been grouted or does not need grouting, insert the fixing anchor rod (14) into the fixing hole (25) of the base of the annular elastic support fixture at the drilling entrance or drilling exit, and finally lay the base plate; S10: After the elastic ring support (1) is laid in this stage, the next stage of laying is carried out.

2. The method for constructing surrounding rock of a soft rock tunnel by supporting the tunnel before excavation according to claim 1, characterized in that: The elastic support rod (16) is arranged in the surrounding rock of the tunnel and spirally surrounds the tunnel to form an annular ground stress stabilization ring, and fills and seals the surrounding rock crack structure through grouting to achieve the sealing of the surrounding rock and meet the waterproof requirements of deep-sea tunnels and diving area tunnels.

3. The method for constructing surrounding rock of a soft rock tunnel by supporting the tunnel before excavation according to claim 1, characterized in that: For some completed tunnels, elastic ring supports (1) are arranged in the surrounding rock of a certain section of the tunnel that requires special support to reinforce the surrounding rock of the tunnel.

4. The method for constructing surrounding rock of a soft rock tunnel by supporting the tunnel before excavation according to claim 1, characterized in that: For some tunnels that have been completed but have serious deformation, it is not suitable to repair them directly. Instead, elastic ring supports (1) are arranged and installed, and grouting is performed to repair the broken surrounding rocks and form a ground stress stable zone before repairing the tunnels.

5. The method for constructing surrounding rock of a soft rock tunnel by supporting the tunnel before excavation according to claim 1, characterized in that: For tunnels with low requirements for surrounding rock waterproofing, relatively high surrounding rock strength, no cracks caused by geological structures, no ground stress, and no need for grouting reinforcement, elastic support rods (16) made of solid materials are directly used, and grouting treatment is omitted to speed up the project progress.

6. The method for constructing surrounding rock of a soft rock tunnel by supporting the tunnel before excavation according to claim 1, characterized in that: The sleeve-type annular elastic support fixture (24) matched with the elastic annular support (1) is welded by a steel multi-porous sleeve-type annular elastic support fixture base (26) and a steel pipe with an inner diameter the same as the outer diameter of the elastic annular support (1). When in use, the sleeve-type annular elastic support fixture (24) is inserted into the elastic annular support (1), and the elastic annular support (1) is punched at the position of the sleeve-type annular elastic support fixture bracket fixing hole (27). Then, a screw is inserted and fixed with a bolt to fix the annular elastic support fixture (24) and the elastic annular support (1) together. Then, the annular support fixing anchor rod (14) is directly inserted into the fixing hole (25) of the sleeve-type annular elastic support fixture base. According to actual engineering needs, the annular support fixing anchor rod (14) is fixed to the surrounding rock of the tunnel floor from multiple angles.

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