Tunnel blasting distinguishing charging structure and tunnel refined blasting construction method

Abstract

The invention provides a distinguishing charging structure for tunnel blasting and a construction method for fine tunnel blasting, and belongs to the technical field of tunnel engineering.An axial gap is formed between a first axial water bag and a cartridge, and a radial water bag is arranged on the radial side, close to a pre-blasting surrounding rock side, of the cartridge in a surrounding mode; an arc-shaped energy guide pipe is arranged on the radial side, close to the reserved surrounding rock side, of the cartridge in a surrounding mode, and a radial gap is formed between the arc-shaped energy guide pipe and the cartridge. When the shot hole is in a complete state, a second axial water bag is arranged in the shot hole; and when the shot hole is in an incomplete state, a first vibration isolation sponge is arranged in the shot hole, the first vibration isolation sponge is located on the inner side of the cartridge, and the radial gap is filled with a second vibration isolation sponge. According to the distinguishing charging structure for tunnel blasting, based on consideration of actual working conditions, charging structures in different modes are arranged for shot holes in a complete state and a non-complete state in the shot hole arrangement process, the integrity of the shot holes can be kept, and the damage range of the non-complete shot holes is prevented from being further expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of tunnel engineering, and more specifically, relates to a differential charging structure for tunnel blasting and a construction method for refined tunnel blasting. Background Technique

[0002] With the continuous advancement of China's urbanization process, the underground space is continuously developed and utilized, and tunnel engineering gradually expands into deep complex strata, urban dense areas, and ecologically sensitive zones. In this context, it is necessary to implement refined control over tunnel blasting construction to cope with the complex and changeable engineering geological challenges. The charging structure of tunnel blasting is the core technical element for controlling blasting effects, ensuring the stability of surrounding rocks, and construction safety.

[0003] Traditional charging structures (water-coupled charging, air-coupled charging) all have certain defects. Air-coupled charging has problems such as too fast attenuation of stress waves, low energy transfer efficiency, and a large amount of dust generated. While water-coupled charging has problems such as uncontrollable blasting energy and poor environmental adaptability. At the same time, traditional charging structures lack consideration of actual working conditions, and during the layout of blast holes, it is easy to damage the blast holes, resulting in poor integrity of the blast holes. Summary of the Invention

[0004] The purpose of the present invention is to provide a differential charging structure for tunnel blasting, aiming to solve the problem that traditional charging structures lack consideration of actual working conditions, and during the layout of blast holes, it is easy to damage the blast holes, resulting in poor integrity of the blast holes.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: providing a differential charging structure for tunnel blasting, including a blast hole opened on the heading face, where a cartridge, a first axial water bag, and stemming are sequentially arranged axially from the inside to the outside of the blast hole. A detonator is arranged inside the cartridge, and the detonator is led to the outside of the blast hole through a lead wire. An axial gap is formed between the first axial water bag and the cartridge. A radial water bag is arranged around the radial side of the cartridge close to the pre-blast surrounding rock, and an arc-shaped energy guide tube is arranged around the radial side of the cartridge close to the reserved surrounding rock. A radial gap is formed between the arc-shaped energy guide tube and the cartridge; When the blast hole is in a complete state, a second axial water bag is arranged inside the blast hole, and the second axial water bag is located inside the cartridge; When the blast hole is in an incomplete state, a first vibration isolation sponge is arranged inside the blast hole, and the first vibration isolation sponge is located inside the cartridge, and the radial gap is filled with a second vibration isolation sponge.

[0006] In a possible implementation manner, the outer diameters of both the first axial water bag and the second axial water bag are the same as the inner diameter of the blast hole.

[0007] In a possible implementation, the arc-shaped energy guiding tube is a PVC tube, and both the first vibration isolation sponge and the second vibration isolation sponge are EVA vibration isolation sponges. The beneficial effects of a differential charge structure for tunnel blasting provided by the present invention are as follows: Compared with the prior art, when arranging blast holes, by setting the radial gap between the arc-shaped energy guiding tube and the cartridge, and in cooperation with the design of the cartridge close to the reserved surrounding rock side, the direction and magnitude of the blasting energy transmission can be effectively adjusted. The arc-shaped energy guiding tube plays a role in guiding the blasting energy directionally, enabling more energy to be transmitted to the pre-blasting side, reducing the impact on the reserved surrounding rock side, and reducing the damage to the reserved surrounding rock side caused by blasting, thereby controlling the overbreak and underbreak amounts, avoiding the fragmentation of the surrounding rock around the blast holes and the deterioration of the integrity of the blast holes due to excessive blasting, and ensuring the stability of the surrounding rock and the relative integrity of the blast holes. Different charging methods are adopted according to the complete state of the blast holes. When the blast hole is in an incomplete state, a first vibration isolation sponge is arranged inside the cartridge, and the second vibration isolation sponge is filled in the radial gap. When an incomplete blast hole is blasted, the detonation wave is likely to propagate along the crack, expanding the damage range. And these vibration isolation sponges can effectively absorb and buffer the energy generated by blasting, reduce the further expansion of the detonation wave to the surrounding rock cracks, reduce the disturbance of the surrounding rock caused by initiation, prevent the further deterioration of the integrity of the blast holes during the blasting process, and contribute to maintaining the structural integrity of the blast holes. The axial water bag can extend the action time of the blasting energy in the blast hole, enable more energy to be used for rock fragmentation, improve the utilization efficiency of the blasting energy, reduce the unnecessary energy diffusion to the surrounding rock, indirectly reduce the damage to the surrounding rock around the blast holes, and is beneficial to maintaining the integrity of the blast holes. At the same time, the radial water bag can effectively suppress the dust generated by blasting, improve the construction environment, and further ensure the integrity of the blast holes. A differential charge structure for tunnel blasting provided by the present invention, considering the actual working conditions, adopts different charge structures for blast holes in a complete state and an incomplete state during the blast hole arrangement process, which is beneficial to maintaining the integrity of the blast holes and avoiding the further expansion of the damage range of the incomplete blast holes.

[0008] The present invention also provides a construction method for refined tunnel blasting, including the following steps: S1: Conduct drilling exploration on the heading face and measure the surrounding rock parameters, drill blast holes according to the surrounding rock parameters, and preset blasting parameters; S2: Evaluate the integrity of the blast holes, and differentially charge the blast holes in a complete state and the blast holes in an incomplete state by using the differential charge structure for tunnel blasting as described in any one of claims 1-3; S3: Arrange short holes outside the peripheral holes of the blast holes and install water bags, connect and check the initiation network for pre-blasting; S4: Scan the blasting contour surface to calculate the overbreak and underbreak amounts, the average rock particle size, and the ventilation time, dynamically adjust the preset blasting parameters until the best blasting effect is achieved, and adjust the refined blasting parameters in combination with the surrounding rock characteristics.

[0009] In a possible implementation, in step S2, when drilling and exploring the tunnel face, the number of exploration holes is not less than 3, with one cycle every 25 m, and the distance between adjacent exploration holes is not less than 5 m.

[0010] In a possible implementation, in step S2, when evaluating the integrity of the blast holes: If a hole collapse occurs and the collapse length is greater than 10%, re-drilling is required; If the crack width in the hole is greater than 3 mm or there is a through connection with the adjacent hole, re-drilling is required.

[0011] In a possible implementation, when evaluating the integrity of the blast holes: If the hole depth deviation is less than or equal to 3% and the hole diameter deviation is less than or equal to 5%, the blast hole is evaluated to be in a complete state; If the hole depth deviation is greater than 3% and the hole diameter deviation is greater than 5%, the blast hole is evaluated to be in an incomplete state; If a hole collapse occurs and the collapse length is less than or equal to 10%, the blast hole is evaluated to be in an incomplete state; If the crack width in the hole is less than or equal to 3 mm and there is no through connection with the adjacent hole, the blast hole is evaluated to be in an incomplete state.

[0012] In a possible implementation, in step S4, when dynamically adjusting the preset blasting parameters: When the average linear overbreak is greater than 15 cm, the average rock particle size is between 15 and 20 cm, or the ventilation time after blasting is greater than 30 min, the charge amount is reduced by 5% and the water charge amount is increased by 10%; for the local area with an average linear overbreak greater than 15 cm, the charge amount of the peripheral holes at the corresponding position is adjusted to increase by 10%; when the average linear overbreak is less than 15 cm, but there is a local area with an average linear overbreak greater than 15 cm, the overall charge amount remains unchanged, and the charge amount of the corresponding peripheral holes is reduced by 5%; When the average linear underbreak is greater than 5 cm or the average rock particle size is greater than 20 cm, the overall charge amount is increased by 5%, and for the local area with an average linear underbreak greater than 10 cm, the charge amount of the peripheral holes at the corresponding position is adjusted to increase by 10%; when the average linear underbreak is less than 5 cm, but there is a partial area with an average linear underbreak greater than 5 cm, the overall charge amount remains unchanged, and the charge amount of the corresponding peripheral holes is increased by 5%.

[0013] In a possible implementation, after each blasting, the surrounding rock crushed stones are preliminarily inspected. After passing the preliminary inspection and meeting the relevant rock mechanics requirements, samples are taken and sent to the laboratory for final inspection to obtain the surrounding rock crushed stones that meet the requirements.

[0014] In a possible implementation, the surrounding rock gravel that meets the requirements is screened. The gravel with a diameter greater than 500 mm is first broken by a jaw crusher. The gravel with a diameter less than 130 mm after the first break and the screened gravel with a diameter of 10 - 50 mm are then broken by a counter - impact crusher. The gravel with a particle size of 5 - 10 mm is screened out from the gravel after the second break, sampled and tested. After meeting the standards, it is transported to the concrete mixing plant for recycling as aggregate.

[0015] The beneficial effects of the construction method for refined blasting of tunnels provided by the present invention are as follows: Compared with the prior art, the surrounding rock parameters are obtained through precise drilling exploration, providing a scientific basis for the design of blasting parameters. Combining with the dynamic adjustment mechanism of "one blast, one analysis", the over - break and under - break amounts can be accurately controlled. Compared with the traditional blasting construction method, the over - break amount is significantly reduced, reducing the engineering quantity and cost of subsequent treatment of the over - broken part. At the same time, it also avoids the impact of under - break on the tunnel structure and construction safety. While ensuring the blasting efficiency, the integrity of the surrounding rock is maximally protected, improving the stability of the tunnel surrounding rock, reducing the risk of safety accidents caused by the instability of the surrounding rock, and reducing the support cost and construction difficulty. It effectively reduces the dust generated by blasting, reduces the harm of dust to the respiratory system of construction workers, and improves the construction efficiency. For the crushed stone waste residue generated after blasting, it is classified and recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is the axial sectional view of the blast hole in the complete state provided by the present invention; Figure 2 It is the axial sectional view of the blast hole in the non - complete state provided by the present invention; Figure 3 It is the radial sectional view of the blast hole in the complete state provided by the present invention; Figure 4 It is the radial sectional view of the blast hole in the non - complete state provided by the present invention; Figure 5 It is the step diagram of the construction method for refined blasting of tunnels provided by the present invention; Figure 6 It is the flow chart of the construction method for refined blasting of tunnels provided by the present invention.

[0018] In the figure: 1, explosive cartridge; 2, detonator; 3, stemming; 4, fuse; 5, first axial water bag; 6, reserved surrounding rock side; 7, arc-shaped energy guiding tube; 8, radial water bag; 9, pre-blast surrounding rock side; 10, second axial water bag; 11, first vibration isolation sponge; 12, second vibration isolation sponge. Detailed implementation manners

[0019] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Unless otherwise clearly defined, when using terms such as "first", "second" or "third", etc., they are all used to distinguish different objects and are not used to describe a specific order.

[0021] Unless otherwise clearly defined, for orientation terms, when using terms such as "center", "transverse", "longitudinal", "horizontal", "vertical", "top", "bottom", "inner", "outer", "upper", "lower", "front", "rear", "left", "right", "clockwise", "counterclockwise", "high", "low", etc. to indicate the orientation or position relationship, it is based on the orientation and position relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as limiting the specific protection scope of the present invention.

[0022] Please refer to Figures 1 to 4 , and now a tunnel blasting differential charging structure provided by the present invention will be described. A tunnel blasting differential charging structure includes a blast hole opened on the heading face. The axial direction of the blast hole is sequentially provided with an explosive cartridge 1, a first axial water bag 5 and stemming 3 from inside to outside. A detonator 2 is arranged in the explosive cartridge 1, and the detonator 2 is led to the outside of the blast hole through a fuse 4. An axial gap is formed between the first axial water bag 5 and the explosive cartridge 1. A radial water bag 8 is arranged around the radial side of the explosive cartridge 1 close to the pre-blast surrounding rock side 9. An arc-shaped energy guiding tube 7 is arranged around the radial side of the explosive cartridge 1 close to the reserved surrounding rock side 6. A radial gap is formed between the arc-shaped energy guiding tube 7 and the explosive cartridge 1; when the blast hole is in a complete state, a second axial water bag 10 is arranged in the blast hole, and the second axial water bag 10 is located inside the explosive cartridge 1; when the blast hole is in an incomplete state, a first vibration isolation sponge 11 is arranged in the blast hole, the first vibration isolation sponge 11 is located inside the explosive cartridge 1, and the radial gap is filled with a second vibration isolation sponge 12.

[0023] A differential charge structure for tunnel blasting provided by the present invention, compared with the prior art, when arranging blast holes, by setting the radial gap between the arc-shaped energy guiding tube 7 and the cartridge 1, and cooperating with the design that the cartridge 1 is close to the reserved surrounding rock side 6, it can effectively adjust the direction and magnitude of the transmission of blasting energy. The arc-shaped energy guiding tube 7 plays the role of guiding the blasting energy directionally, making the energy transfer more to the pre-blasting side, reducing the impact on the reserved surrounding rock side 6, reducing the damage caused to the reserved surrounding rock side 6 by blasting, thereby controlling the overbreak and underbreak amount, avoiding the fragmentation of the surrounding rock around the blast hole and the deterioration of the integrity of the blast hole due to excessive blasting, and ensuring the stability of the surrounding rock and the relative integrity of the blast hole. Different charging methods are adopted according to the complete state of the blast hole. When the blast hole is in an incomplete state, a first vibration isolation sponge 11 is arranged inside the cartridge 1, and a second vibration isolation sponge 12 is filled in the radial gap. When an incomplete blast hole is blasted, the detonation wave is easy to propagate along the crack, expanding the damage range. And these vibration isolation sponges can effectively absorb and buffer the energy generated by blasting, reduce the further expansion of the detonation wave to the surrounding rock cracks, reduce the disturbance of the surrounding rock during detonation, prevent the further deterioration of the integrity of the blast hole during the blasting process, and help maintain the structural integrity of the blast hole. The axial water bag can extend the action time of the blasting energy in the blast hole, make more energy used for rock fragmentation, improve the utilization efficiency of the blasting energy, reduce the unnecessary energy diffusion to the surrounding rock, indirectly reduce the damage to the surrounding rock around the blast hole, and is beneficial to maintaining the integrity of the blast hole. At the same time, the radial water bag 8 can effectively suppress the dust generated by blasting, improve the construction environment, and further ensure the integrity of the blast hole. A differential charge structure for tunnel blasting provided by the present invention, considering the actual working conditions, adopts different charge structures for complete and incomplete blast holes respectively during the blast hole arrangement process, which is beneficial to maintaining the integrity of the blast hole and avoiding the further expansion of the damage range of incomplete blast holes.

[0024] Among them, the preparation materials of the above-mentioned axial water bag and the radial water bag 8 are both water and polyolefin plastics. The axial water bag is made according to the radius of the blast hole in the blasting plan. At the same time, two-thirds of the water volume in the axial water bag is reduced to make the radial water bag 8, and finally it is sealed with a sealing machine. Before installing the axial water bag and the radial water bag 8, they are wrapped with a layer of kraft paper to prevent being scratched during the process of placing the water bag.

[0025] Specifically, the arc-shaped energy guiding tube 7 is a PVC tube. The arc-shaped energy guiding tube 7 made of PVC material has a relatively hard texture and stable chemical properties. During blasting, it can guide the blasting energy more stably and direct the energy more accurately to the pre-blasting side surrounding rock. Compared with other materials, the PVC tube can better maintain its own structure and will not be easily deformed or damaged due to blasting impact, ensuring the stability of the energy transmission path, more effectively reducing the diffusion of energy to the reserved side surrounding rock, and further reducing the damage to the reserved side surrounding rock, which has a positive effect on protecting the surrounding rock structure around the blast hole and maintaining the integrity of the blast hole.

[0026] Both the first vibration isolation sponge 11 and the second vibration isolation sponge 12 are EVA vibration isolation sponges. The EVA vibration isolation sponge has good flexibility, elasticity and energy absorption characteristics. When the blast hole is in an incomplete state, the EVA vibration isolation sponge inside the cartridge 1, that is, the first vibration isolation sponge 11, can efficiently absorb part of the energy generated by the explosion of the explosive at the moment of blasting, buffer the explosion shock, reduce the energy transmission to the surrounding rock at the bottom of the blast hole, and avoid the fragmentation and loosening of the surrounding rock at the bottom due to excessive impact, thereby protecting the integrity of the bottom of the blast hole. The EVA vibration isolation sponge filled in the radial gap, that is, the second vibration isolation sponge 12, can absorb the energy diffused radially from the cartridge 1, inhibit the propagation of the detonation wave along the cracks in the blast hole, reduce the disturbance to the reserved side surrounding rock, prevent the further expansion of the surrounding rock cracks due to blasting, and maintain the stability of the surrounding rock around the blast hole, ensuring the integrity of the blast hole in many aspects.

[0027] Please refer to Figure 5 and Figure 6 , the present invention also provides a construction method for refined blasting of tunnels, including the following steps: S1: Conduct borehole exploration on the heading face and measure the surrounding rock parameters, drill blast holes according to the surrounding rock parameters, and preset blasting parameters.

[0028] During the tunnel construction process, as the forefront area of construction, the geological conditions of the heading face play a decisive role in the safety and effect of blasting construction. First, use the electromagnetic wave reflection method (ground penetrating radar) to conduct a detailed geological forecast within about 30m in front of the heading face, and detect key geological information such as karst morphology, filling material properties, and karst cavities. Uniformly arrange multiple detection holes in each section (direction). The detection holes are in a cycle of 25m, the single-hole length is about 30m, and at least 5m of overlapping length is set between adjacent detection holes to ensure the continuity and accuracy of geological data. Take rock cores through these detection holes to obtain the mechanical parameters of the surrounding rock, such as the compressive strength, tensile strength, elastic modulus of the rock, etc., and then evaluate the stability of the surrounding rock.

[0029] Based on the obtained mechanical parameters of the surrounding rock, combined with engineering experience and the principle of smooth blasting, preliminarily design the initiation scheme: In terms of estimating the number of blast holes, according to the formula N = q×S / αr, where S is the cross-sectional area of the tunnel (taking 55.27m²), the linear charge density r of the explosive is taken as 1Kg / m, the average value of the linear charge coefficient α is 0.5, and the unit explosive consumption q is temporarily taken as 1.3Kg / m³ according to the construction experience of the same-level geology in the past. It is calculated that the number of blast holes is about 144, and 144 are actually designed. The total amount of explosives for each cycle is calculated according to the formula Q = qSLη, where η is the blast hole utilization rate (taking 0.87). After calculation, the total amount of explosives is about 106.3Kg, and this value is actually used in the design.

[0030] For the depths, hole spacings, and burden distances of various types of holes, detailed designs were also carried out according to the surrounding rock conditions and construction convenience. The depth of the cut holes was designed to be 2.56 m, the depth of the auxiliary holes was 2.3 m, the depth of the arch holes was 2.4 m, and the length of the bottom holes was 2.4 m. The distance from the mouth of each perimeter hole to the contour line was 10 cm, and the bottom of the hole extended 10 cm beyond the excavation contour line. The burden distance \(W_{light}\) of the smooth blasting holes was taken as 70 cm, and the hole spacing \(a_{arch}\) was taken as 50 cm; the hole spacing of the auxiliary holes was 90 - 93 cm, and the burden distance was 60 - 90 cm; the hole spacing \(a\) of the bottom holes was 110 cm. In terms of the charge amount per single hole, the charge amount per meter \(a_{cut}\) of the cut holes was taken as 0.55 - 0.6 kg / m, and actually 1.7 kg was taken; the charge amount per meter \(a_{auxiliary}\) of the auxiliary holes was taken as 0.55 kg / m, and actually 1 kg was taken; the charge amount per meter \(a_{bottom}\) of the bottom holes was taken as 0.6 kg / m, and actually 1.45 kg was taken; the charge amount per meter \(a_{arch}\) of the arch holes was taken as 0.2 kg / m, and actually 0.5 kg was taken. Through the presetting of these parameters, basic data and operation basis were provided for the subsequent blasting construction.

[0031] S2: Evaluate the integrity of the blast holes, and charge the blast holes in a complete state and those in an incomplete state differently using the described differential charge structure for tunnel blasting.

[0032] The integrity of the blast holes directly affects the blasting effect and the stability of the surrounding rock. Before charging, a comprehensive integrity assessment of the blast holes is required. First, check the hole depth and hole diameter deviation of the blast holes. It is required that the hole depth deviation is not greater than 3%, and the hole diameter deviation is not greater than 5%. If there is a phenomenon of hole collapse, when the collapse length is greater than 10%, in order to ensure the blasting quality and safety, the hole needs to be re-drilled; if the collapse length is less than 10%, it is treated as a blast hole in an incomplete state. At the same time, evaluate the width of the crack in the hole. If the crack width is greater than 3 mm or there is a through - connection phenomenon with the adjacent hole, this blast hole is treated as a waste hole and needs to be re - drilled; if the crack width is less than 3 mm, it is treated as a blast hole in an incomplete state.

[0033] When charging the blast holes in a complete state, first place the second axial water bag 10 at the bottom of the blast hole, then load the required cartridges 1 according to the blasting design scheme and install the detonator 2. Install the radial water bag 8 on the side of the pre - blasted surrounding rock 9, install the arc - shaped energy - guiding tube 7 on the side of the reserved surrounding rock 6, leave a radial gap between the arc - shaped energy - guiding tube 7 and the cartridge 1, and finally load the first axial water bag 5 and stemming 3 in sequence for plugging, and leave air between the first axial water bag 5 and the cartridge 1 to achieve axial decoupling charging.

[0034] When charging the incomplete blasthole, a first vibration isolation sponge 11 with a length equal to the second axial water bag 10 is installed at the bottom of the blasthole, and then the required medicine roll 1 is loaded and the detonator 2 is installed according to the blasting design plan, and an arc energy conductor 7 is installed on the reserved surrounding rock side 6. A second vibration isolation sponge 12 is installed between the arc energy conductor 7 and the medicine roll 1, and a radial water bag 8 is installed on the pre-blasting surrounding rock side 9. After the radial uncoupled charging is completed, the first axial water bag 5 is added and air is reserved, and finally the taphole mud 3 is used for plugging.

[0035] S3: Arrange short holes outside the peripheral holes of the blasthole and install water bags, connect and check the detonation network for pre-blasting.

[0036] The total station is used to accurately measure and lay out along the tunnel contour, and short holes are arranged around the outer side of the peripheral holes and water bags are added. For the IV-level surrounding rock, when the length of the peripheral hole is 3 meters, the length of the short hole filled with water is 1.2 meters; for the V-level surrounding rock, when the length of the peripheral hole is 2 meters, the length of the short hole filled with water is 1 meter. The starting position of the short hole is 3 cm inside the designed excavation contour, and a small empty hole without explosives is drilled in the middle of the peripheral hole to effectively control the blasting of the peripheral hole. This layout method can utilize the buffering effect of the water bag, reduce the over-excavation of the bottom of the blasthole caused by the external insertion angle, and reduce the disturbance to the surrounding surrounding rock.

[0037] After completing the blasthole charging and short hole layout, carefully connect and fully inspect the blasting network. Check whether the connection of detonators such as detonator 2 and detonating cord is reliable to ensure that the detonation sequence can be accurately controlled. Before the blasting operation is implemented, all personnel and equipment in the warning area must be removed in strict accordance with safety regulations to ensure the safety of personnel and equipment. After the blasting operation is completed, immediately start the tunnel ventilation and dust reduction operation, and use ventilation equipment to discharge the dust generated by the blasting out of the tunnel. After the dust concentration test meets the standard, the subsequent construction operation can be resumed.

[0038] S4: Scan the blasting profile to calculate the over-excavation and under-excavation, average rock particle size and ventilation time, so as to dynamically adjust the preset blasting parameters until the best blasting effect is achieved, and adjust the refined blasting parameters based on the surrounding rock characteristics.

[0039] After the blasting operation is completed, the excavation surface is re-measured using a 3D laser scanning device to accurately record the deviation between the actual contour and the designed contour, and the linear over-excavation is calculated. At the same time, the rock block size after blasting is analyzed to obtain the average rock particle size, and the ventilation time required for dust settling after blasting is recorded. Based on these re-measured data, the blasting parameters for the next cycle are dynamically adjusted.

[0040] When the average linear overbreak is greater than 15 cm, or the rock particle size is between 15 - 20 cm and the ventilation time after blasting is greater than 30 min, the overall charge amount is reduced by 5%, and at the same time, the water charge amount is increased by 10%. For the local area where the linear overbreak is greater than 15 cm, the charge amount of the perimeter holes at the corresponding positions is increased by 10%. If the average linear overbreak is less than 15 cm, but there is a situation where the linear overbreak in the local area is greater than 15 cm, the overall charge amount remains unchanged, and only the charge amount of the corresponding perimeter holes is reduced by 5%.

[0041] When the average linear underbreak is greater than 5 cm or the average rock particle size is greater than 20 cm, the overall charge amount is increased by 5%. For the areas with larger linear underbreak (such as key parts like the arch foot and arch crown), the charge amount of the perimeter holes at the corresponding positions is increased by 10%. If the average linear underbreak is less than 5 cm, but there is a situation where the linear underbreak in some areas is greater than 5 cm, the overall charge amount remains unchanged, and the charge amount of the corresponding perimeter holes is increased by 5%. By continuously adjusting the parameters until the results of linear over - underbreak, the average rock particle size, and the ventilation time meet the engineering design indicators. Implement blasting based on the adjusted parameters, and record the linear over - underbreak of each cycle in real - time. Once it is found that the linear over - underbreak shows an increasing trend, immediately adjust the charge amount in real - time to ensure that the blasting construction is always in the best state. Combining the actual situation after each blasting, fully considering the characteristics of the surrounding rock, further adjust the refined blasting parameters to make the blasting construction more adaptable to complex geological conditions.

[0042] Obtain the surrounding rock parameters through precise borehole exploration to provide a scientific basis for the design of blasting parameters. Combining with the dynamic adjustment mechanism of "analyzing each blast", it is possible to accurately control the over - underbreak amount. Under the measure of arranging short holes and installing water bags outside the perimeter holes, the bottom overbreak of the perimeter holes in grade Ⅳ surrounding rock is about 9 cm, and the average linear overbreak is 11.6 cm; the bottom overbreak of the perimeter holes in grade Ⅴ surrounding rock is about 9 cm, and the average linear overbreak is 12.3 cm. Compared with the traditional blasting construction method, the overbreak amount is greatly reduced, reducing the engineering quantity and cost of dealing with the overbreak part in the follow - up, and at the same time avoiding the impact of underbreak on the tunnel structure and construction safety. When facing complex rock mass geological conditions, such as when the tunnel passes through various different strata such as the Ziliujing Formation, Zhenzhuchong Formation sandstone and mudstone, Xujiahe Formation sandstone, Jialingjiang Formation, and Feixianguan Formation limestone, this refined blasting construction method can quickly adapt to the rock characteristics of different strata through the feedback mechanism of "analyzing each blast" and dynamic parameter adjustment, maintaining a stable and good blasting effect. This characteristic makes this method have a wide application prospect in tunnel construction under complex geological conditions. Compared with the traditional blasting method, it greatly reduces the construction delays and quality problems caused by geological changes.

[0043] The integrity of the blast holes was evaluated and a differential charging structure was adopted. For the blast holes with relatively poor integrity, vibration isolation protection measures were taken, such as using EVA vibration isolation sponge on one side of the reserved rock mass, effectively reducing the damage of blasting to the reserved rock mass. While ensuring the blasting efficiency, the integrity of the surrounding rock was maximally protected, the stability of the tunnel surrounding rock was improved, the risk of safety accidents caused by the instability of the surrounding rock was reduced, and the support cost and construction difficulty were lowered.

[0044] During the blasting construction process, the methods of using water decoupled charging, installing environmental protection water bags axially, and arranging short holes and installing water bags outside the perimeter holes were adopted, effectively reducing the dust generated by blasting. Timely ventilation and dust reduction operations were started after blasting, which could quickly reduce the dust concentration in the tunnel, creating a safer and healthier construction environment for the construction workers, reducing the harm of dust to the respiratory systems of the construction workers, and improving the construction efficiency.

[0045] In the tunnel blasting construction process, the treatment link of the crushed rock of the surrounding rock after blasting is crucial, which is directly related to the resource utilization efficiency and engineering cost control. After each blasting, a series of treatment processes will be carried out orderly for the crushed rock of the surrounding rock.

[0046] In the preliminary inspection stage, the staff made a visual inspection based on experience, observing the appearance, texture and other characteristics of the crushed rock, and at the same time using tools to knock and listen to the sound to preliminarily judge the density and internal structure of the crushed rock. Only the crushed rock that meets the relevant rock mechanics requirements after preliminary detection is eligible to enter the subsequent process. This step effectively eliminates those crushed rocks that obviously do not meet the requirements, avoids subsequent ineffective processing, and improves the processing efficiency.

[0047] Then, the crushed rock that meets the preliminary requirements is sampled and sent to the laboratory for final detection. The laboratory uses professional equipment and precise detection methods to strictly measure the key performance indicators of the crushed rock, such as compressive strength, crushing index, content of needle-like and flaky particles, etc. Only the crushed rock of the surrounding rock whose indicators all meet the established standards will be further processed and utilized.

[0048] The crushed rock of the surrounding rock that meets the requirements enters the screening process. The screening equipment classifies according to the particle size of the crushed rock. Among them, the large crushed rock with a diameter greater than 500mm, due to its too large size, cannot directly enter the subsequent processing process and will be sent to the jaw crusher for primary crushing. The jaw crusher breaks the large crushed rock into smaller particles through powerful extrusion and splitting actions, and the diameter of the crushed rock after crushing is less than 130mm.

[0049] These crushed rocks after primary crushing, together with the crushed rocks with a particle size of 10 - 50mm screened out, enter the impact crusher for secondary crushing. The impact crusher uses a high-speed rotating rotor to drive the plate hammer, so that the crushed rock is repeatedly impacted, collided and rebounded in the crushing cavity, and thus is further crushed and refined.

[0050] The crushed stones after the second crushing are screened again, and the crushed stones with a particle size of 5-10 mm are screened out. The crushed stones in this particle size range have good filling performance and grading effect in concrete aggregates, which helps to improve the strength and workability of concrete. To ensure quality, these crushed stones will be sampled and tested again. Only after meeting the requirements of Grade II standard in "Pebbles and Crushed Stones for Construction" GB / T 14685-2022 will they be transported to the concrete mixing plant. In the mixing plant, these crushed stones are used as aggregates to participate in the production of concrete, realizing the recycling of resources, reducing the dependence on natural aggregates, reducing the ecological damage caused by the exploitation of natural aggregates, saving the engineering material cost at the same time, and providing strong support for the sustainable development of tunnel projects. For the crushed stone waste residue generated after blasting, it is classified and recycled. For the hard rock crushed stones with higher strength, they can be used in other process constructions after preliminary processing in the temporary crushed stone plant; the excess concrete generated during the construction process is rationally utilized by means of processing and making into arch support cushion components, reserving the working face for subsequent processes, and overall allocation across work areas. This way of resource recycling not only reduces the occupation of land resources and the pressure on the ecological environment by the crushed stone waste residue, but also reduces the material cost of the project construction.

[0051] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A differential charge structure for tunnel blasting, characterized in that, It includes blast holes drilled on the heading face. An explosive cartridge (1), a first axial water bag (5), and stemming (3) are successively arranged axially from inside to outside in the blast hole. A detonator (2) is arranged in the explosive cartridge (1), and the detonator (2) is led to the outside of the blast hole through a lead wire (4). An axial gap is formed between the first axial water bag (5) and the explosive cartridge (1). A radial water bag (8) is arranged around the radial side of the explosive cartridge (1) close to the pre-blast surrounding rock side (9). An arc-shaped energy guiding tube (7) is arranged around the radial side of the explosive cartridge (1) close to the reserved surrounding rock side (6). A radial gap is formed between the arc-shaped energy guiding tube (7) and the explosive cartridge (1). When the blast hole is in a complete state, a second axial water bag (10) is arranged in the blast hole, and the second axial water bag (10) is located inside the explosive cartridge (1). When the blast hole is in an incomplete state, a first vibration isolation sponge (11) is arranged in the blast hole, the first vibration isolation sponge (11) is located inside the explosive cartridge (1), and the radial gap is filled with a second vibration isolation sponge (12).

2. The differential charge structure for tunnel blasting according to claim 1, characterized in that, The outer diameters of the first axial water bag (5) and the second axial water bag (10) are both the same as the inner diameter of the blast hole.

3. The differential charge structure for tunnel blasting according to claim 1, wherein The arc-shaped energy guiding tube (7) is a PVC tube, and both the first vibration isolation sponge (11) and the second vibration isolation sponge (12) are EVA vibration isolation sponges.

4. A construction method for refined blasting in tunnels, characterized in that, It includes the following steps: S1: Conduct borehole exploration on the heading face and measure the surrounding rock parameters. Drill blast holes according to the surrounding rock parameters and preset blasting parameters. S2: Evaluate the integrity of the blast holes, and use the tunnel blasting differential charging structure described in any one of claims 1-3 to differentially charge the blast holes in a complete state and the blast holes in an incomplete state. S3: Arrange short holes outside the perimeter holes of the blast holes and install water bags, connect and check the initiation network for pre-blasting. S4: Scan the blasting contour surface to calculate the overbreak and underbreak amount, the average rock particle size, and the ventilation time, dynamically adjust the preset blasting parameters until the best blasting effect is achieved, and adjust the refined blasting parameters in combination with the surrounding rock characteristics.

5. The construction method of refined blasting in a tunnel according to claim 4, characterized in that, In step S2, when conducting borehole exploration on the heading face, the number of exploration holes is not less than 3, one cycle for every 25 m for the exploration holes, and the distance between adjacent exploration holes is not less than 5 m.

6. The construction method of refined blasting in a tunnel according to claim 5, characterized in that, In step S2, when evaluating the integrity of the blast holes: If there is a hole collapse phenomenon and the collapse length is greater than 10%, it is necessary to re-drill the hole. If the crack width in the hole is greater than 3 mm or there is a through phenomenon with the adjacent hole, it is necessary to re-drill the hole.

7. The construction method of fine blasting in a tunnel according to claim 6, characterized in that, When evaluating the integrity of the blast holes: If the hole depth deviation is less than or equal to 3% and the hole diameter deviation is less than or equal to 5%, the blast hole is evaluated to be in a complete state. If the hole depth deviation is greater than 3% and the hole diameter deviation is greater than 5%, the blast hole is evaluated to be in an incomplete state. If there is a hole collapse phenomenon and the collapse length is less than or equal to 10%, the blast hole is evaluated to be in an incomplete state. If the crack width in the hole is less than or equal to 3 mm and there is no through phenomenon with the adjacent hole, the blast hole is evaluated to be in an incomplete state.

8. The construction method of refined blasting in a tunnel according to claim 4, characterized in that, In step S4, when dynamically adjusting the preset blasting parameters: When the average linear overbreak is greater than 15 cm, the average rock particle size is between 15 and 20 cm, or the ventilation time after blasting is greater than 30 min, the explosive charge is reduced by 5% and the water charge is increased by 10%. For the local area with a linear overbreak greater than 15 cm, the charge of the perimeter holes at the corresponding positions is adjusted to increase by 10%. When the average linear overbreak is less than 15 cm, but there is a local area with a linear overbreak greater than 15 cm, the overall explosive charge remains unchanged, and the charge of the corresponding perimeter holes is reduced by 5%. When the average linear underbreak is greater than 5 cm or the average rock particle size is greater than 20 cm, the overall explosive charge is increased by 5%. For the local area with a linear underbreak greater than 10 cm, the charge of the perimeter holes at the corresponding positions is adjusted to increase by 10%. When the average linear underbreak is less than 5 cm, but there is a partial area with a linear underbreak greater than 5 cm, the overall explosive charge remains unchanged, and the charge of the corresponding perimeter holes is increased by 5%.

9. The construction method of fine tunneling blasting according to claim 4, characterized in that, After each blasting, the surrounding rock crushed stones are preliminarily inspected. After passing the preliminary inspection and meeting the relevant rock mechanics requirements, samples are taken and sent to the laboratory for final inspection to obtain the surrounding rock crushed stones that meet the requirements.

10. The construction method of refined blasting in a tunnel according to claim 9, characterized in that, The surrounding rock crushed stones that meet the requirements are screened. For the crushed stones with a diameter greater than 500 mm, a jaw crusher is used for the first crushing. After the first crushing, the crushed stones with a diameter less than 130 mm and the 10 - 50 mm crushed stones obtained from screening are crushed by a counter - impact crusher for the second crushing. The crushed stones from the second crushing are screened to separate the crushed stones with a particle size of 5 - 10 mm, and samples are taken for testing. After meeting the standards, they are transported to the concrete mixing plant for recycling as aggregates.

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