Controlled blasting demolition charge structure and construction method for reinforced concrete secondary lining in tunnels

Abstract

The present invention provides a controlled explosion dismantling charging structure and construction method for reinforced concrete secondary lining of a tunnel, characterized in that blasting sections are symmetrically arranged at the arch waist and side walls on both sides of the secondary lining, wherein 5 vertical sections are arranged at the arch waist, and the boreholes in each section are parallel and inclined upward; wherein 4 flat sections are arranged at the side walls, and the boreholes in each section are parallel and inclined toward the outside of the tunnel. A 3 cm thick concrete is left at the bottom of the borehole as a protective layer, and a discontinuous interval charging structure is used in the hole. The detonation sequence is to first detonate the arch waist blastholes on both sides, delay for half a second, and then detonate the side wall blastholes on both sides, and delay for 100ms for adjacent blastholes along the longitudinal direction of the tunnel. The principle is that the use of dense blastholes and interval charging structure can easily cause the concrete in the blasting area to fragment, and the concrete fragments are separated from the steel bars to form a weak area; the arch top secondary lining concrete in the non-explosion section overcomes the steel bar support force in the weak area of ​​the arch waist and falls, and drives the arch wall in the non-explosion section to deflect around the weak area of ​​the side wall until the second lining concrete falls to the ground. This method is suitable for the removal of reinforced concrete secondary lining of tunnels.

Description

Technical Field

[0001] The invention belongs to a secondary lining structure dismantling method in the technical field of tunnel construction, and specifically relates to a charging structure and a construction method for controlled blasting dismantling of a reinforced concrete secondary lining of a tunnel. Background Art

[0002] During the construction and operation of the tunnel, due to engineering quality defects or poor geology, the secondary lining concrete may not be able to resist the surrounding rock pressure, resulting in deformation and cracking, or even damage. Commonly used tunnel secondary lining concrete includes two structures: plain concrete and reinforced concrete. When damage occurs and needs to be replaced, it is relatively easy to demolish the plain concrete secondary lining structure because there is no steel skeleton. When removing the reinforced concrete secondary lining, the difficulty of the operation will be greatly increased due to the pulling effect of the steel skeleton in the secondary lining concrete structure. When using traditional weak loosening blasting, the surrounding initial support and surrounding rock are greatly disturbed, which is easy to cause secondary disasters; when using a crushing head for demolition, the efficiency is low and the safety risk is high. Therefore, it is necessary to develop a controlled blasting demolition technology that can reduce the safety risk of demolition operations and reduce the disturbance to the surrounding initial support and surrounding rock, so as to ensure the safe and rapid demolition of the reinforced concrete secondary lining. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a controlled blasting demolition charging structure and a construction method for the demolition of a reinforced concrete secondary lining of a tunnel, which is suitable for the demolition of a reinforced concrete secondary lining of a tunnel.

[0004] The present invention is achieved in this way: a controlled explosion demolition charging structure for a reinforced concrete secondary lining of a tunnel is constructed, characterized in that: demolition sections are divided according to the positions of the construction joints of the secondary lining concrete; arch waist blasting areas are symmetrically arranged at the arch waists on both sides of the secondary lining; 5 vertical sections are arranged in the arch waist blasting areas; the spacing between adjacent sections is 25 cm to 40 cm; the drill holes in the arch waist blasting areas in each section are parallel and inclined upward; the side wall blasting areas are symmetrically arranged at the side walls on both sides of the secondary lining; 4 flat sections are arranged in the side wall blasting areas; the spacing between adjacent sections is 25 cm to 40 cm; the drill holes in the side wall blasting areas in each section are parallel and inclined toward the outside of the tunnel; a discontinuous interval charging structure is used in the drill holes in the arch waist blasting areas to form a first blast hole; the drill holes in the side wall blasting areas also use a discontinuous interval charging structure to form a second blast hole; the detonation direction is, from the temporary The blast holes near the inner side of the secondary lining concrete are detonated layer by layer toward the blast holes outside the secondary lining concrete; the detonation sequence is that the first blast holes on both sides of the arch waist are detonated simultaneously first, and the first blast holes adjacent to each other along the longitudinal direction of the tunnel are detonated in sequence with a delay of 100ms; based on the cross section where the orifices of the first blast hole and the second blast hole are located, after the first blast hole in the same cross section is detonated, the second blast holes on both sides of the side wall are detonated with a delay of half a second; the principle is that the use of dense blast holes and discontinuous interval charging structure can easily make the concrete in the blasting area fragmented, and the concrete fragments are separated from the steel bars and form weak areas in the arch waist and weak areas in the side wall respectively, and the arch top secondary lining concrete in the non-explosion section overcomes the steel bar supporting force in the weak area of ​​the arch waist by its own weight and falls, and drives the arch wall secondary lining concrete in the non-explosion section to deflect around the weak area of ​​the side wall until the second lining concrete falls to the ground; this method is suitable for the removal of reinforced concrete secondary lining of tunnels.

[0005] According to the tunnel reinforced concrete secondary lining controlled blasting demolition charging structure of the present invention, it is characterized in that the angles between the drill holes in the arch waist blasting area and the drill holes in the side wall blasting area and the inner wall surface of the secondary lining concrete are both 30°, the center distance between the drill holes in the adjacent arch waist blasting areas in the same section is 30cm to 40cm, and the center distance between the drill holes in the adjacent side wall blasting areas in the same section is 30cm to 50cm; the diameters of the drill holes in the arch waist blasting area and the drill holes in the side wall blasting area are 42mm, neither of them penetrates the secondary lining concrete, and a 3cm thick secondary lining concrete is left at the bottom of the hole as a protective layer.

[0006] According to the tunnel reinforced concrete secondary lining controlled explosion demolition charging structure of the present invention, it is characterized in that: the discontinuous interval charging structure adopts emulsified strip explosives with a segment length of 10 cm and a diameter of φ32 mm, and the bottom explosives are installed about 10 cm away from the bottom ends of the first blasthole and the second blasthole. The net distance between the second section of explosives and the bottom explosives is 40 to 50 cm, and the net distance between the remaining sections of explosives is 30 to 40 cm. The explosives are connected in series with detonating cords and tied to bamboo strips with waterproof insulating tape for easy installation; the hole mouth is blocked with gun mud with a length of not less than 20 cm.

[0007] A method for controlled blasting and dismantling of secondary reinforced concrete lining in a tunnel, characterized in that it is carried out in the following manner;

[0008] A. Blasting parameter design: design parameters such as drilling profile spacing, drilling hole center distance, and explosive net distance of discontinuous interval charging structure according to the thickness of reinforced concrete secondary lining, concrete strength, and blasting flying stone distance;

[0009] B. Measurement and setting out: Stake out the horizontal section line at a height of 1.0m from the design datum plane of the tunnel invert backfill, and take the horizontal section line as the baseline, and then set out 3 horizontal section lines at the designed interval height above it. The horizontal sections are all parallel to the longitudinal slope of the route; Stake out the vertical section line on the inner wall of the second lining concrete at a height of 3.6m from the design datum plane of the tunnel invert backfill, and take the vertical section line as the baseline, and then set out 4 vertical section lines in the direction of the tunnel centerline according to the designed horizontal distance; Divide the construction joints into sections, and from one end of the second lining concrete to the other end, on each section line, set out the center position of the borehole in the arch waist blasting area and the borehole in the side wall blasting area according to the designed spacing;

[0010] C. Drilling: Use a hydraulic drilling trolley to drill a hole about 5 cm deep vertically along the center of the hole opening in the arch waist blasting area, forming an inclined drilling focus point, and then drill in the direction of the designed inclination angle. The diameter of the hole is 42 mm, and it does not penetrate the second lining concrete. Leave a 3 cm thick second lining concrete at the bottom of the hole as a protective layer;

[0011] D. Installation of shock-absorbing pads on the ground inside the cave: a layer of sand bags is laid on the ground inside the cave as a shock-absorbing pad;

[0012] E. Charge structure processing: Emulsion explosives are used, each segment of explosives is 10cm long, φ32mm in diameter, and weighs 100g; the explosive segments are connected in series with detonating cords at designed intervals and tied to bamboo strips with waterproof insulating tape;

[0013] F. Installation of charging structure: install the processed charging structure in the first blast hole and the second blast hole respectively, and block the hole mouth with gun mud with a length of not less than 20cm; the exposed length of the detonating cord at the hole mouth shall be not less than 30cm;

[0014] G. Connecting detonating cord and digital electronic detonator: Using micro-difference blasting technology, the detonating cord is connected to the digital electronic detonator, and the delay of the digital electronic detonator is set according to the following conditions: the detonation direction is to detonate layer by layer from the first blast hole and the second blast hole adjacent to the inner wall of the second lining to the first blast hole and the second blast hole on the outer side of the second lining respectively; the detonation sequence is to detonate the first blast holes on both sides of the arch waist at the same time, and then detonate the adjacent first blast holes in the longitudinal direction of the tunnel with a delay of 100ms in sequence; based on the cross section where the openings of the first blast hole and the second blast hole are located, after the first blast hole in the same cross section is detonated, it is delayed for half a second and then the second blast holes on the side walls on both sides are detonated at the same time;

[0015] H, connect the detonator and detonate: connect the detonator, evacuate the personnel in the tunnel to a safe area and implement the alert before detonating; after detonation, the secondary lining concrete in the blasting area of ​​the arch waist on both sides of the tunnel will be broken first, and the concrete fragments will be separated from the steel bars to form a weak area in the arch waist. At this time, the secondary lining concrete of the arch top in the non-explosion section will fall down by relying on its own weight to overcome the steel bar supporting force in the weak area of ​​the arch waist; the secondary lining concrete in the blasting area of ​​the side walls on both sides of the tunnel will be broken immediately, and the concrete fragments will be separated from the steel bars to form a weak area of ​​the side wall. The secondary lining concrete of the arch top drives the secondary lining concrete of the arch wall in the non-explosion section to deflect around the weak area of ​​the side wall until the secondary lining concrete falls to the ground;

[0016] I. Crushing and transportation of lining concrete: Use an excavator with a breaker to crush the second lining concrete and the remaining side wall concrete that have fallen to the ground, clean the steel bars in the concrete and transport them separately from the concrete slag.

[0017] The present invention provides a controlled explosion removal charging structure and construction method for a tunnel reinforced concrete secondary lining, which is suitable for the removal of a tunnel reinforced concrete secondary lining and has the following advantages:

[0018] (1) Blasting zones are set symmetrically at the haunches and side walls on both sides of the tunnel. The dense blast holes are conducive to the fragmentation of the secondary lining concrete in the blasting section and the formation of weak areas in the blasting zone.

[0019] (2) The inclined blastholes increase the blasting open surface. The discontinuous interval charging structure is adopted and the blasting is carried out layer by layer from the blastholes close to the inner wall of the second lining to the blastholes outside the second lining. This is conducive to breaking the concrete layer by layer and realizing the separation of concrete and steel bars.

[0020] (3) While the secondary lining concrete of the arch crown and arch wall in the non-blasting section is pulled by the steel skeleton, it uses its own weight to overcome the resistance of the steel bars in the weak area to achieve gradual landing, reducing the impact force on the ground.

[0021] (4) The use of segmented delayed blasting technology reduces blasting vibration.

[0022] The principle is that the use of dense blastholes and discontinuous interval charging structure can easily cause the concrete in the blasting area to break into pieces. The concrete pieces are separated from the steel bars and form weak areas in the arch waist and side walls respectively. The secondary lining concrete of the arch crown in the non-blasting section overcomes the steel bar supporting force in the weak area of ​​the arch waist by its own weight and falls down, and drives the secondary lining concrete of the arch wall in the non-blasting section to deflect around the weak area of ​​the side wall until the secondary lining concrete falls to the ground. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the structural diagram of the reinforced concrete secondary lining demolition on the tunnel cross section;

[0024] Figure 2 yes Figure 1 The Ⅰ-Ⅰ section view and Ⅱ-Ⅱ section view are also the blasthole arrangement view in the vertical section and the blasthole arrangement view in the horizontal section respectively;

[0025] Figure 3It is a schematic diagram of the discontinuous interval charge structure;

[0026] Figure 4 This is a schematic diagram of the fall of the reinforced concrete of the secondary lining after blasting;

[0027] Figure 5 This is a schematic diagram of the second lining reinforced concrete landing after blasting.

[0028] Among them: arch waist blasting area 1, drill hole 3A in the arch waist blasting area, the first blast hole 301A; side wall blasting area 2, drill hole 3B in the side wall blasting area, the second blast hole 301B; arch waist weak area 401, side wall weak area 402, arch top second lining concrete 501, arch wall second lining concrete 502, explosives 601, detonating cord 602, bamboo strips 603, gun mud 604, digital electronic detonator 605. DETAILED DESCRIPTION

[0029] The following will be combined with the attached Figure 1-Figure 5 The present invention is described in detail, and the technical solutions in the embodiments of the present invention are clearly and completely described. 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.

[0030] The present invention provides a tunnel reinforced concrete secondary lining controlled explosion removal charging structure, such as Figure 1-Figure 5 As shown, it can be implemented in the following manner: the demolition is divided into sections according to the location of the construction joint of the second lining concrete, and the arch waist blasting area 1 is symmetrically arranged at the arch waist on both sides of the second lining. Five vertical sections are arranged in the arch waist blasting area 1, and the interval between adjacent sections is 25cm to 40cm. The boreholes 3A in the arch waist blasting area in each section are parallel and inclined upward; the side wall blasting area 2 is symmetrically arranged at the side walls on both sides of the second lining. Four horizontal sections are arranged in the side wall blasting area 2, and the interval between adjacent sections is 25cm to 40cm. The boreholes 3B in the side wall blasting area in each section are parallel and inclined toward the outside of the tunnel. The boreholes 3A in the arch waist blasting area adopt a discontinuous interval charging structure to form the first blasthole 301A, and the boreholes 3B in the side wall blasting area also adopt a discontinuous interval charging structure to form the second blasthole 301B. The detonation direction is to detonate layer by layer from the blastholes adjacent to the inner side of the second lining concrete to the blastholes outside the second lining concrete. The detonation sequence is as follows: first, the first blast holes 301A on both sides of the arch waist are detonated simultaneously, and the first blast holes 301A adjacent to each other in the longitudinal direction of the tunnel are detonated in sequence with a delay of 100ms; based on the cross section where the openings of the first blast holes 301A and the second blast holes 301B are located, after the first blast hole 301A of the same cross section is detonated, the second blast holes 301B on both sides of the side walls are detonated with a delay of half a second.

[0031] When the present invention is implemented; Figure 2As shown, the included angles between the borehole 3A in the arch waist blasting area and the borehole 3B in the side wall blasting area and the inner wall of the secondary lining concrete are both 30°, the center distance between the boreholes 3A in the adjacent arch waist blasting areas in the same section is 30cm to 40cm, and the center distance between the boreholes 3B in the adjacent side wall blasting areas in the same section is 30cm to 50cm. The diameters of the boreholes 3A in the arch waist blasting area and the boreholes 3B in the side wall blasting area are 42mm, and neither penetrates the secondary lining concrete, leaving a 3cm thick secondary lining concrete at the bottom of the hole as a protective layer.

[0032] When the present invention is implemented; Figure 3 As shown, the discontinuous interval charge structure 6 is an emulsified strip explosive 601 with a segment length of 10 cm and a diameter of φ32 mm. The bottom explosive 601 is installed about 10 cm away from the bottom of the first blast hole 301A and the second blast hole 301B. The net distance between the second section of explosive 601 and the bottom explosive 601 is 40 to 50 cm, and the net distance between the remaining sections of explosive 601 is 30 to 40 cm. The explosive 601 is connected in series with a detonating cord 602 and is tied to a bamboo strip 603 with a waterproof insulating tape for easy installation. The hole mouth is blocked with a tapping mud 604 with a length of not less than 20 cm.

[0033] The principle is that, Figure 1-Figure 5 As shown, the use of dense blastholes and discontinuous interval charging structure can easily cause the concrete in the blasting area to break into pieces. The concrete pieces are separated from the steel bars and form the arch waist weak area 401 and the side wall weak area 402 respectively. The arch crown secondary lining concrete 501 in the non-blasting section overcomes the steel bar supporting force of the arch waist weak area 401 by its own weight and falls down, and drives the arch wall secondary lining concrete 502 in the non-blasting section to deflect around the side wall weak area 402 until the secondary lining concrete falls to the ground.

[0034] The invention provides a controlled explosion removal charging structure and a construction method for a tunnel reinforced concrete secondary lining, which is suitable for the removal of a tunnel reinforced concrete secondary lining.

[0035] Implement it as follows:

[0036] A. Blasting parameter design: Design parameters such as drilling profile spacing, drilling hole center distance, and explosive net distance of discontinuous interval charging structure according to reinforced concrete secondary lining thickness, concrete strength, and blasting flying stone distance.

[0037] B. Measurement and setting out: Figure 1As shown, the survey and layout are as follows: the horizontal section line is laid out at a height of 1.0m from the design datum plane of the tunnel invert backfill, and the horizontal section line is used as the baseline. Three horizontal section lines are laid out above it at the designed interval height. The horizontal sections are all parallel to the longitudinal slope of the route; the vertical section line is laid out on the inner wall of the second lining concrete at a height of 3.6m from the design datum plane of the tunnel invert backfill, and the vertical section line is used as the baseline. Four vertical section lines are laid out in the direction of the tunnel centerline at the designed horizontal distance. The construction joints are divided into sections, and the center positions of the boreholes 3A in the arch waist blasting area and the boreholes 3B in the side wall blasting area are laid out at the designed interval on each section line from one end of the second lining concrete to the other end.

[0038] C. Drilling: Use a hydraulic drilling trolley to drill a hole about 5 cm deep vertically along the center of the hole opening of the borehole 3A in the arch waist blasting area, forming an inclined drilling focus point, and then drill according to the designed inclination direction. The diameter of the drill hole is 42 mm, and it does not penetrate the second lining concrete. Leave a 3 cm thick second lining concrete at the bottom of the hole as a protective layer. Figure 3 shown.

[0039] D. Installation of shock-absorbing pads on the ground inside the cave: A layer of sand bags is laid on the ground inside the cave as a shock-absorbing pad.

[0040] E. Charge structure processing: Figure 3 As shown, emulsion explosive 601 is used, each segment of explosive 601 is 10 cm long, φ32 mm in diameter, and weighs 100 g. The segments of explosive 601 are connected in series with detonating cord 602 at designed intervals and tied to bamboo strips 603 with waterproof insulating tape.

[0041] F. Installation of charge structure: The processed charge structure is installed in the first blast hole 301A and the second blast hole 301B respectively, and the hole opening is blocked with a gun mud 604 with a length of not less than 20 cm. The exposed length of the hole opening detonating cord 602 is not less than 30 cm.

[0042] G. Connecting detonating cord and digital electronic detonator: using micro-difference blasting technology, connecting detonating cord 602 to digital electronic detonator 605, the delay of digital electronic detonator 605 is set according to the following conditions: the detonation direction is to detonate layer by layer from the first blast hole 301A and the second blast hole 301B adjacent to the inner wall of the second lining to the first blast hole 301A and the second blast hole 301B outside the second lining respectively; the detonation sequence is to detonate the first blast holes 301A on both sides of the arch waist at the same time, and then detonate the first blast holes 301A adjacent to each other in the longitudinal direction of the tunnel with a delay of 100ms in sequence; based on the cross section where the openings of the first blast hole 301A and the second blast hole 301B are located, after the first blast hole 301A of the same cross section is detonated, it is delayed for half a second and then the second blast holes 301B on the side walls on both sides are detonated at the same time.

[0043] H. Connect the detonator and detonate: Connect the detonator, evacuate the personnel in the cave to a safe area and implement the alert before detonating. Figure 4-Figure 5 As shown, after detonation, the secondary lining concrete in the blasting area 1 of the arch waist on both sides of the tunnel will be broken first, and the concrete fragments will be separated from the steel bars to form the arch waist weak area 401. At this time, the arch crown secondary lining concrete 501 in the non-explosion section will fall down by relying on its own weight to overcome the steel bar supporting force of the arch waist weak area 401; the secondary lining concrete in the blasting area 2 of the side wall on both sides of the tunnel will be broken immediately, and the concrete fragments will be separated from the steel bars to form the side wall weak area 402. The arch crown secondary lining concrete 501 drives the arch wall secondary lining concrete 502 in the non-explosion section to deflect around the side wall weak area 402 until the secondary lining concrete falls to the ground.

[0044] I. Crushing and transportation of lining concrete: Use an excavator with a breaker to crush the second lining concrete and the remaining side wall concrete that have fallen to the ground, clean the steel bars in the concrete and transport them separately from the concrete slag.

[0045] The present invention has the following improvements and advantages:

[0046] First, blasting areas are set symmetrically at the haunches and side walls on both sides of the tunnel. The dense blast holes are conducive to the fragmentation of the secondary lining concrete in the blasting section and form weak areas in the blasting area.

[0047] Secondly, the inclined blastholes increase the blasting open surface, and the discontinuous interval charging structure is adopted, and the blasting is performed layer by layer from the blastholes close to the inner wall of the second lining to the blastholes on the outer side of the second lining, which is conducive to breaking the concrete layer by layer and realizing the separation of concrete and steel bars.

[0048] Thirdly, while the secondary lining concrete of the arch crown and arch wall in the non-blasting section is pulled by the steel skeleton, it uses its own weight to overcome the resistance of the steel bars in the weak area to achieve gradual landing and reduce the impact force on the ground.

[0049] Fourthly, the use of segmented delayed blasting technology reduces blasting vibration.

[0050] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A controlled explosion removal charging structure for reinforced concrete secondary lining of a tunnel, characterized by: The demolition sections are divided according to the positions of the secondary lining concrete construction joints. The arch waist blasting area (1) is symmetrically arranged at the arch waists on both sides of the secondary lining. Five vertical sections are arranged in the arch waist blasting area (1). The interval between adjacent sections is 25 cm to 40 cm. The drill holes (3A) in the arch waist blasting area in each section are parallel and inclined upward. The side wall blasting area (2) is symmetrically arranged at the side walls on both sides of the secondary lining. Four horizontal sections are arranged in the side wall blasting area (2). The interval between adjacent sections is 25 cm to 40 cm. The drill holes (3B) in the side wall blasting area in each section are parallel and inclined toward the outside of the tunnel. The first blast hole is formed in the drill hole (3A) in the arch waist blasting area using a discontinuous interval charging structure. (301A), the drill hole (3B) in the side wall blasting area also adopts a discontinuous interval charging structure to form the second blast hole (301B); the detonation direction is to detonate layer by layer from the blast hole adjacent to the inner side of the second lining concrete to the blast hole outside the second lining concrete; the detonation sequence is to detonate the first blast holes (301A) on both sides of the arch waist at the same time, and then the first blast holes (301A) adjacent to each other along the longitudinal direction of the tunnel are detonated in sequence after a delay of 100ms; based on the cross section where the openings of the first blast hole (301A) and the second blast hole (301B) are located, after the first blast hole (301A) of the same cross section is detonated, it is delayed for half a second before the second blast holes (301B) on both sides of the side wall are detonated at the same time; The principle is that the use of dense blastholes and discontinuous interval charging structure can easily cause the concrete in the blasting area to break into pieces, and the concrete pieces are separated from the steel bars to form a weak area (401) in the arch waist and a weak area (402) in the side wall respectively. The arch top secondary lining concrete (501) in the non-blasting section overcomes the steel bar support force of the arch waist weak area (401) by its own weight and falls down, and drives the arch wall secondary lining concrete (502) in the non-blasting section to deflect around the side wall weak area (402) until the secondary lining concrete falls to the ground.

2. The controlled explosion removal charging structure for the reinforced concrete secondary lining of a tunnel according to claim 1 is characterized in that; The included angles between the drill holes (3A) in the arch waist blasting area and the drill holes (3B) in the side wall blasting area and the inner wall of the secondary lining concrete are both 30°; the center distance between the drill holes (3A) in the adjacent arch waist blasting areas in the same section is 30cm to 40cm, and the center distance between the drill holes (3B) in the adjacent side wall blasting areas in the same section is 30cm to 50cm; the diameters of the drill holes (3A) in the arch waist blasting area and the drill holes (3B) in the side wall blasting area are 42mm, and neither of them penetrates the secondary lining concrete, leaving a 3cm thick secondary lining concrete at the bottom of the hole as a protective layer.

3. The controlled explosion removal charging structure for the reinforced concrete secondary lining of a tunnel according to claim 1 is characterized in that; The discontinuous interval charging structure adopts an emulsified strip explosive (601) with a segment length of 10 cm and a diameter of φ32 mm. The bottom hole explosive (601) is installed about 10 cm away from the bottom of the first blasthole (301A) and the second blasthole (301B). The net distance between the second section of explosive (601) and the bottom hole explosive (601) is 40 to 50 cm, and the net distance between the remaining sections of explosive (601) is 30 to 40 cm. The explosive (601) is connected in series with a detonating cord (602) and is tied to a bamboo strip (603) with a waterproof insulating tape for easy installation; the hole opening is blocked with a gun mud (604) with a length of not less than 20 cm.

4. A construction method for removing the charge structure of the reinforced concrete secondary lining of a tunnel according to claim 1, characterized in that: Proceed as follows; A. Blasting parameter design: design parameters such as drilling profile spacing, drilling hole center distance, and explosive net distance of discontinuous interval charging structure according to the thickness of reinforced concrete secondary lining, concrete strength, and blasting flying stone distance; B. Surveying and setting out: Stake out the horizontal section line at a height of 1.0m from the design datum plane of the tunnel invert backfill, and take the horizontal section line as the baseline, and then set out 3 horizontal section lines at the designed interval height above it. The horizontal sections are all parallel to the longitudinal slope of the route; Stake out the vertical section line on the inner wall of the secondary lining concrete at a height of 3.6m from the design datum plane of the tunnel invert backfill, and take the vertical section line as the baseline, and then set out 4 vertical section lines in the direction of the tunnel centerline according to the designed horizontal distance; Divide the construction joints into sections, and from one end of the secondary lining concrete to the other end, on each section line, stake out the center positions of the boreholes (3A) in the arch waist blasting area and the boreholes (3B) in the side wall blasting area according to the designed spacing; C. Drilling: Use a hydraulic drilling trolley to drill a hole about 5 cm deep vertically along the center of the hole opening of the drill hole (3A) in the arch waist blasting area, forming an inclined drilling point, and then drill according to the designed inclination direction. The diameter of the drill hole is 42 mm, and it does not penetrate the second lining concrete. Leave a 3 cm thick second lining concrete at the bottom of the hole as a protective layer; D. Installation of shock-absorbing pads on the ground inside the cave: a layer of sand bags is laid on the ground inside the cave as a shock-absorbing pad; E. Charge structure processing: using emulsion explosive (601), each segment of explosive (601) is 10 cm long, φ32 mm in diameter, and weighs 100 g; connecting the segments of explosive (601) in series with detonating cord (602) at designed intervals and tying them to bamboo strips (603) with waterproof insulating tape; F. Installation of the charge structure: The processed charge structure is installed in the first blast hole (301A) and the second blast hole (301B) respectively, and the hole openings are blocked with gun mud (604) with a length of not less than 20 cm; the exposed length of the detonating cord (602) at the hole opening is not less than 30 cm; G. Connecting the detonating cord and the digital electronic detonator: using the micro-difference blasting technology, the detonating cord (602) is connected to the digital electronic detonator (605), and the delay of the digital electronic detonator (605) is set according to the following conditions: wherein the detonation direction is to detonate layer by layer from the first blast hole (301A) and the second blast hole (301B) adjacent to the inner wall of the second lining to the first blast hole (301A) and the second blast hole (301B) outside the second lining respectively; wherein the detonation sequence is to detonate the first blast holes (301A) on both sides of the arch waist at the same time, and then detonate the adjacent first blast holes (301A) along the longitudinal direction of the tunnel with a delay of 100ms in sequence; based on the cross section where the openings of the first blast hole (301A) and the second blast hole (301B) are located, after the first blast hole (301A) of the same cross section is detonated, it is delayed for half a second and then the second blast holes (301B) on the side walls on both sides are detonated at the same time; H, connect the detonator and detonate: connect the detonator, evacuate the personnel in the tunnel to a safe area and implement the alert before detonating; after detonation, the secondary lining concrete in the arch waist blasting area (1) on both sides of the tunnel will be broken first, and the concrete fragments will be separated from the steel bars to form the arch waist weak area (401). At this time, the arch crown secondary lining concrete (501) in the non-explosion section will fall down by relying on its own weight to overcome the steel bar support force of the arch waist weak area (401); the secondary lining concrete in the side wall blasting area (2) on both sides of the tunnel will be broken immediately, and the concrete fragments will be separated from the steel bars to form the side wall weak area (402). The arch crown secondary lining concrete (501) drives the arch wall secondary lining concrete (502) in the non-explosion section to deflect around the side wall weak area (402) until the secondary lining concrete falls to the ground; I. Crushing and transportation of lining concrete: Use an excavator with a breaker to crush the second lining concrete and the remaining side wall concrete that have fallen to the ground, clean the steel bars in the concrete and transport them separately from the concrete slag.

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