Low-influence blasting construction method for in-situ reconstruction and extension of small-clear-distance tunnel

Abstract

The invention belongs to the technical field of tunnel engineering, and provides a low-influence blasting construction method for in-situ reconstruction and extension of a small-clear-distance tunnel, which comprises the following construction steps: S1, drilling a plurality of damping holes on a tunnel face along the contour line of an extension tunnel and the contour line of an existing tunnel lining, then digging the plurality of damping holes, and connecting the adjacent damping holes to form a damping groove; s2, the shock absorption groove is filled with an energy absorption shock absorption cushion layer; s3, according to the size of the tunnel face after the shock absorption groove is excavated, shot hole points and explosive loading amount are designed, and slotting holes, peripheral holes and auxiliary holes are drilled in the tunnel face; and S4, damping parts and detonators are sequentially placed in the underholing holes, the peripheral holes and the auxiliary holes correspondingly, and blasting is executed. The situation of surrounding rock expanding excavation is reduced during in-situ reconstruction and extension of the small-clear-distance tunnel, the influence on repeated disturbance of the surrounding rock is reduced, and the overall stability of the tunnel and the safety of the construction process are guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel engineering, and in particular relates to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel. Background Art

[0002] With the acceleration of urbanization, the renewal of infrastructure, and the aging of tunnel facilities during operation, the design standards and traffic capacity of some existing tunnels have become insufficient to meet the growing traffic demand. The tunnel reconstruction and expansion project aims to improve traffic capacity, structural safety and durability, and effectively alleviate urban traffic congestion.

[0003] Small clearance tunnels are a common form of bidirectional highway tunnels. During construction, the rock mass needs to withstand multiple disturbances of drilling, blasting and excavation. The middle rock is subjected to blasting and excavation on both sides, and the surrounding rock pressure on the upper part is relatively large. It is a location that needs to be paid special attention to during the reconstruction and expansion construction. The damage to the repeatedly disturbed surrounding rock by drilling and blasting operations should be avoided.

[0004] The expansion of the tunnel requires the removal of the existing lining. The "demolition before excavation" method has the risk of collapse of the upper rock mass. Therefore, the upper rock mass is usually excavated first and then the lower lining is removed, or the upper rock mass and the lining are blasted together. The existing lining constrains the upper rock mass, requiring a higher amount of explosives during blasting, and the blasting range is difficult to control. Over-excavation is prone to occur, which damages the surrounding rock of the expanded tunnel. Summary of the invention

[0005] The purpose of the present invention is to provide a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel, so as to solve the above-mentioned problems, reduce the situation of surrounding rock excavation during the in-situ reconstruction and expansion of a small-clearance tunnel, reduce the impact of multiple disturbances on the surrounding rock, and ensure the overall stability of the tunnel and the safety of the construction process.

[0006] To achieve the above object, the present invention provides the following solution: a low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel, the construction steps comprising:

[0007] S1. On the tunnel face, drill a number of shock-absorbing holes along the contour line of the expansion tunnel and the contour line of the existing tunnel lining, and then drill a number of shock-absorbing holes to connect adjacent shock-absorbing holes to form shock-absorbing grooves;

[0008] S2, filling the shock absorbing groove with an energy absorbing and shock absorbing cushion layer;

[0009] S3. Design blasthole points and charge amount according to the size of the tunnel face after the shock-absorbing groove is excavated, and drill the groove holes, peripheral holes and auxiliary holes on the tunnel face;

[0010] S4. Place shock absorbers and detonators in the groove holes, peripheral holes and auxiliary holes respectively, and carry out blasting.

[0011] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, in step S1, before drilling the shock-absorbing holes, grouting reinforcement is performed on the surrounding rock mass outside the contour line of the expanded tunnel, and after the grouting reinforcement is completed, soil and rock are backfilled into the existing tunnel.

[0012] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, in step S1, a polymer thixotropic material is used to perform grouting pre-reinforcement on the surrounding rock mass outside the contour line of the expanded tunnel.

[0013] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, in step S1, the depth of the shock-absorbing groove is one footage of tunnel excavation.

[0014] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, in step S2, the energy-absorbing and shock-absorbing cushion layer is made of a porous medium material that has the function of absorbing blasting energy.

[0015] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, the shock-absorbing component includes an energy-absorbing shock-absorbing plug, which is placed at the bottom of the groove eye, the peripheral eye or the auxiliary eye.

[0016] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, in the steps S1 and S2, when drilling shock-absorbing holes, groove holes, peripheral holes or the auxiliary holes, drilling machines with stable operation and small vibration amplitude are selected.

[0017] According to a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel provided by the present invention, in step S1, before drilling the shock-absorbing holes, a temporary steel support is set up at the bottom of the existing tunnel lining.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] 1. The main function of the shock-absorbing groove is to attenuate the stress wave of the face blasting when passing through different media, and to absorb the blasting energy by using the shock-absorbing cushion layer, so as to reduce the disturbance of the face blasting to the surrounding rock of the expanded tunnel; at the same time, the excavation of the shock-absorbing groove separates the existing tunnel lining from the upper rock mass, the outer edge of the contour line of the expanded tunnel and the rock mass to be excavated, thereby removing the peripheral constraints on the rock mass to be excavated, reducing the support in two directions, reducing the strength of the rock mass to be excavated, and reducing the blasting operation, thereby reducing the disturbance to the surrounding rock; due to the shock-absorbing groove In the blasting design, it is only necessary to consider destroying the tunnel face surrounded by the shock-absorbing grooves. Redesigning the blasthole points and the charge according to the size of the tunnel face can significantly reduce the blasthole density and the amount of explosives used, and further reduce the blasting disturbance. The construction of the shock-absorbing grooves also ensures the contour surface of the tunnel expansion and avoids the over-excavation of the surrounding rock. The main function of the shock-absorbing parts is to play a buffering role, so that the blasting mainly acts on the rock mass of the current excavation advance, reducing the damage to the rock mass inside the tunnel face, and preventing the tunnel face from becoming unstable after blasting.

[0020] 2. Overall, the present invention can replace the traditional construction excavation method for small-clearance tunnel expansion, and can effectively avoid the strong disturbance of surrounding rock caused by large-volume direct blasting, reduce the use of explosives, reduce the situation of surrounding rock excavation, reduce the impact of multiple disturbances of surrounding rock, ensure the overall stability of the tunnel and the safety of the construction process, and realize low-impact blasting construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the layout position of the shock absorbing groove and the energy absorbing and shock absorbing cushion layer of the present invention;

[0023] Figure 2 This is a schematic diagram of the energy-absorbing and shock-absorbing cushion layer of the present invention being installed in the shock-absorbing groove;

[0024] Figure 3 It is a schematic diagram of arranging the energy absorbing and shock absorbing plug of the present invention in a blasthole;

[0025] Figure 4 This is a process diagram of the low-impact blasting construction method for tunnel reconstruction and expansion according to the present invention;

[0026] Among them, 1. Existing tunnel lining; 2. Contour line of expanded tunnel; 3. Shock-absorbing groove; 4. Groove eye; 5. Peripheral eye; 6. Auxiliary eye; 7. Detonator; 8. Energy-absorbing shock-absorbing plug; 3a. Contour line of shock-absorbing groove; 3b. Energy-absorbing shock-absorbing cushion layer. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Reference Figure 1-Figure 4 The present invention provides a low-impact blasting construction method for in-situ reconstruction and expansion of a small-clearance tunnel, and the construction steps include:

[0030] S1. On the tunnel face, a number of shock absorbing holes are drilled along the contour line 2 of the expansion tunnel and the contour line 1 of the existing tunnel lining, and a number of shock absorbing holes are excavated to connect adjacent shock absorbing holes to form shock absorbing grooves 3;

[0031] S2, filling the energy absorbing and shock absorbing cushion layer 3b into the shock absorbing groove 3;

[0032] S3, designing blasthole points and charge amount according to the size of the tunnel face after the shock-absorbing groove 3 is excavated, and drilling the groove holes, peripheral holes and auxiliary holes on the tunnel face;

[0033] S4, placing the shock absorbing parts and the detonator 7 in the cut hole 4, the peripheral hole 5 and the auxiliary hole 6 respectively, and performing blasting.

[0034] The main function of the shock-absorbing groove 3 is to attenuate the stress wave of the tunnel face blasting when passing through different media, and to absorb the blasting energy by using the shock-absorbing cushion layer, thereby reducing the disturbance of the tunnel face blasting to the surrounding rock of the expanded tunnel; at the same time, the excavation of the shock-absorbing groove 3 separates the existing tunnel lining 1 from the upper rock mass, the outer edge of the contour line of the expanded tunnel and the rock mass to be excavated, thereby removing the peripheral constraints on the rock mass to be excavated, reducing the support in two directions, reducing the strength of the rock mass to be excavated, and reducing the blasting operation volume, thereby reducing the disturbance to the surrounding rock; due to the shock-absorbing groove 3 In the blasting design, it is only necessary to consider destroying the face surrounded by the shock-absorbing groove 3. Redesigning the blasthole points and the charge amount according to the size of the face can significantly reduce the blasthole density and the amount of explosives used, and further reduce the blasting disturbance; the construction of the shock-absorbing groove 3 also ensures the contour surface of the tunnel excavation, avoiding the over-excavation of the surrounding rock; the main function of the shock-absorbing component is to play a buffering role, so that the blasting mainly acts on the rock mass of the current excavation footage, reducing the damage to the rock mass inside the face, and preventing the face from becoming unstable after blasting. On the whole, the present invention can replace the traditional construction and excavation method for the expansion of small-clearance tunnels, and can effectively avoid the strong disturbance of the surrounding rock caused by direct blasting of large amounts of explosives, reduce the use of explosives, reduce the situation of surrounding rock excavation, reduce the impact of multiple disturbances of the surrounding rock, ensure the overall stability of the tunnel and the safety of the construction process, and achieve low-impact blasting construction.

[0035] As an optional implementation method, during the construction process, drilling equipment is used to drill along the contour line 2 of the expanded tunnel, the boundary between the rock mass to be excavated and the existing tunnel lining 1, and the shock-absorbing holes are densely arranged according to the above contour. Subsequently, the shock-absorbing holes are connected into grooves using a rock planing machine to form a shock-absorbing groove 3.

[0036] As an optional implementation method, for tunnels constructed using the middle partition wall method, while using drilling equipment to drill along the contour line 2 of the expanded tunnel and the boundary between the rock mass to be expanded and the existing tunnel lining 1, shock-absorbing holes are also drilled at the contour line of the rock mass to be expanded and the middle partition wall, and then the shock-absorbing holes are connected into grooves using rock planing equipment to form shock-absorbing grooves 3.

[0037] As an optional implementation, in step S1, before drilling the shock-absorbing holes, grouting reinforcement is performed on the surrounding rock mass outside the contour line 2 of the expanded tunnel, and after the grouting reinforcement is completed, soil and rock are backfilled into the existing tunnel.

[0038] As an optional implementation, in step S1, a polymer thixotropic material is used to perform grouting pre-reinforcement on the surrounding rock mass outside the contour line 2 of the expanded tunnel.

[0039] The main function of grouting reinforcement is to improve the looseness of the stratum and control water, so as to increase the compressive strength and adhesion of the top and sides of the expanded tunnel, achieve the purpose of reinforcement, and improve the anti-disturbance ability of the surrounding rock of the tunnel during the expansion process.

[0040] Backfilling soil and rock into existing tunnels can strengthen the tunnel structure, ensure the safety and stability of the tunnel, prevent ground subsidence and collapse during the renovation and expansion process, and at the same time digest the excavated soil internally to reduce the impact on the environment.

[0041] As an optional implementation, in step S1, the depth of the shock absorbing groove 3 is one footage of tunnel excavation.

[0042] By limiting the depth of the shock-absorbing groove 3, it is ensured that the tunnel face after the shock-absorbing groove is excavated can be fully blasted, and over-excavation can also be avoided.

[0043] The outline width of the shock absorbing groove outline 3a, that is, the width of the shock absorbing groove 3, can be flexibly adjusted according to the surrounding rock conditions and the excavation span.

[0044] As an optional implementation, in step S2, the energy absorbing and shock absorbing cushion layer 3b is made of a porous medium material that has the function of absorbing explosion energy.

[0045] As an optional implementation, different materials can be selected for the energy-absorbing and shock-absorbing cushion layer 3b according to the surrounding rock conditions and the excavation span. Specifically, when the surrounding rock conditions are poor, a polymer thixotropic material is selected, and when the surrounding rock conditions are good, conventional porous medium materials or flowing particles such as coarse sand can be used for filling.

[0046] As an optional implementation, the shock absorbing member includes an energy absorbing and shock absorbing plug 8 , which is placed at the bottom of the cutout eye 4 , the peripheral eye 5 or the auxiliary eye 6 .

[0047] Specifically, taking the cutout hole 4 as an example, the energy absorbing and shock absorbing plug 8 is arranged between the bottom of the cutout hole 4 and the detonator 7, and is used to buffer the rock mass behind the excavation footage, so that the blasting mainly acts on the rock mass at the excavation footage, and prevents the face from becoming unstable after the blasting. The energy absorbing and shock absorbing plug 8 is made of solid material with high energy absorption rate, which is easy to install and construct.

[0048] As an optional implementation, in step S1 and step S2, when drilling the shock-absorbing hole, the groove hole 4, the peripheral hole 5 or the auxiliary hole 6, a drilling machine with stable operation and small vibration amplitude is selected.

[0049] As an optional implementation, in step S1, before drilling the shock-absorbing holes, a temporary steel support is set up at the bottom of the existing tunnel lining 1.

[0050] The main purpose of erecting temporary steel supports is to disperse the pressure and avoid collapse caused by excessive pressure on the tunnel lining. At the same time, it can limit the deformation of the surrounding rock and ensure the stability and safety of the tunnel.

[0051] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do 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 should not be understood as a limitation on the present invention.

[0052] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel, characterized in that: The construction steps include: S1. On the tunnel face, a plurality of shock absorbing holes are drilled along the contour line of the expansion tunnel (2) and the contour line of the existing tunnel lining (1), and a plurality of shock absorbing holes are excavated to connect adjacent shock absorbing holes to form a shock absorbing groove (3); S2, filling the shock absorbing groove (3) with an energy absorbing and shock absorbing cushion layer (3b); S3, designing blasthole points and charge amount according to the size of the tunnel face after the shock absorbing groove (3) is excavated, and drilling the groove holes, peripheral holes and auxiliary holes on the tunnel face; S4, placing the shock absorbing parts and the detonator (7) in the cut hole (4), the peripheral hole (5) and the auxiliary hole (6) respectively, and performing blasting.

2. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 1, characterized in that: In the step S1, before drilling the shock-absorbing hole, grouting reinforcement is performed on the surrounding rock mass outside the contour line (2) of the expanded tunnel, and after the grouting reinforcement is completed, soil and rock are backfilled into the existing tunnel.

3. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 2 is characterized by: In the step S1, a polymer thixotropic material is used to perform grouting pre-reinforcement on the surrounding rock mass outside the contour line (2) of the expanded tunnel.

4. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 1, characterized in that: In the step S1, the depth of the shock absorbing groove (3) is one footage of tunnel excavation.

5. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 1 is characterized by: In the step S2, the energy absorbing and shock absorbing cushion layer (3b) is made of a porous medium material having the function of absorbing explosion energy.

6. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 1, characterized in that: The shock absorbing member comprises an energy absorbing and shock absorbing plug (8), and the energy absorbing and shock absorbing plug (8) is placed at the bottom of the groove eye (4), the peripheral eye (5) or the auxiliary eye (6).

7. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 1, characterized in that: In the step S1 and the step S2, when drilling the shock-absorbing hole, the groove hole (4), the peripheral hole (5) or the auxiliary hole (6), a drilling machine with stable operation and small vibration amplitude is selected.

8. The low-impact blasting construction method for in-situ reconstruction and expansion of a small clearance tunnel according to claim 1, characterized in that: In the step S1, before drilling the shock-absorbing hole, a temporary steel support is set up at the bottom of the existing tunnel lining (1).

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