Tunnel weak surrounding rock smooth blasting construction method

Abstract

The invention discloses a tunnel weak surrounding rock smooth blasting construction method, and relates to the technical field of tunnel construction.The tunnel face of a soft rock tunnel is drilled in a preset construction area so that a plurality of grouting holes distributed at intervals can be formed in the tunnel face, and a grouting pipe is installed in each grouting hole; a piston nail is arranged on each grout outlet hole of each grouting pipe, grouting equipment is sequentially communicated with the grouting pipes, grouting operation is conducted on the corresponding grouting holes through the grouting pipes, so that the piston nails in all the grout outlet holes are pushed to be anchored to the hole walls of the grouting holes, and grouting reinforcement operation is completed. After the hardness of the slurry injected into the tunnel face reaches the preset strength, drilling equipment is used for conducting secondary drilling on the grouting pipe on the tunnel face so as to form a blasting drill hole, explosive columns and water bags are installed in the blasting drill hole in a spaced mode, the explosive columns are detonated, smooth blasting construction is completed, over-excavation of a tunnel cannot be caused, and the service life of the tunnel is prolonged. And the forming quality of the tunnel is ensured.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for smooth blasting construction in soft surrounding rock of tunnels. Background Technology

[0002] In existing technologies, milling and other methods are commonly used for excavation of weak surrounding rock. While these methods can form tunnels, the presence of high-altitude areas can cause milling equipment to malfunction. To address this, blasting methods are sometimes employed for excavation of weak surrounding rock. Although blasting can create tunnel structures, the inherent geological structure and deformation of the weak surrounding rock can lead to over-excavation or under-excavation during the blasting process, affecting the quality of the tunnel's formation. Summary of the Invention

[0003] The main objective of this invention is to propose a smooth blasting construction method for tunnels in weak surrounding rock, aiming to solve the technical problem that, in actual operation, the geological structure and deformation of the weak surrounding rock itself lead to over-excavation or under-excavation during blasting, which affects the quality of tunnel formation.

[0004] To achieve the above objectives, in a first aspect, the present invention proposes a method for smooth blasting construction in soft surrounding rock of tunnels, comprising the following steps: In the pre-designated construction area, drilling operations are carried out on the working face of the soft rock tunnel to form multiple spaced grouting holes on the working face; A grouting pipe is installed in each of the grouting holes; wherein, the grouting pipe is provided with a plurality of grout outlet holes distributed at intervals; A piston nail is provided on each of the grout outlet holes of each of the grouting pipes; wherein, explosives are installed inside the piston nail; The grouting equipment is connected to each of the grouting pipes in sequence, and grouting is performed on the corresponding grouting holes through the grouting pipes, so that the piston nails in all the grout outlet holes are pushed into the hole wall anchored to the grouting hole, thus completing the grouting reinforcement operation. After the grout injected into the working face reaches a preset hardness, a drilling device is used to drill a secondary hole in the grouting pipe on the working face to form a blasting hole. Explosive charges and water bags are installed at intervals inside the blasting borehole. The explosive charges are detonated to complete the smooth blasting operation. The explosive charges and water bags are arranged alternately, and the explosive charges are set close to the borehole wall.

[0005] In one embodiment, the step of drilling at the face of a soft rock tunnel in a predetermined construction area to form a plurality of spaced grouting holes on the face includes: Based on the geological conditions of the tunnel face and the tunnel cross-sectional dimensions, determine the layout scheme of the grouting holes; According to the hole layout scheme, drilling equipment is used to drill holes on the working face to form the plurality of grouting holes; wherein the spacing between adjacent grouting holes is 0.5 meters to 1.5 meters, and the hole depth of the grouting holes is 1.1 to 1.3 times the designed excavation advance of the tunnel.

[0006] In one embodiment, before the step of determining the arrangement of the grouting holes based on the geological conditions of the tunnel face and the tunnel cross-section dimensions, the method further includes: Geological surveys were conducted on the working face to obtain the strength parameters of the surrounding rock and the development of joints and fissures. Based on the surrounding rock strength parameters and the development of joints and fissures, determine whether the working face belongs to weak surrounding rock; If the tunnel face is in a weak surrounding rock, then the step of determining the arrangement of the grouting holes based on the geological conditions of the tunnel face and the tunnel cross-section dimensions shall be performed.

[0007] In one embodiment, the step of installing a grouting pipe in each of the grouting holes includes: Insert the grouting pipe into the grouting hole so that the front end of the grouting pipe reaches the bottom of the grouting hole; A sealing material is filled between the grouting pipe and the wall of the grouting hole to prevent the grout from flowing back along the outer wall of the grouting pipe; wherein, a plurality of grout outlet holes are provided on the grouting pipe at intervals along the axial direction, and the distance between adjacent grout outlet holes is 20 cm to 50 cm.

[0008] In one embodiment, the piston nail includes a nail body and a medicated bag disposed inside the nail body, wherein the outer diameter of the nail body matches the inner diameter of the slurry outlet. The step of setting a piston nail on each of the grout outlet holes of the grouting pipe includes: The piston nails are pushed in sequentially from the rear end of the grouting pipe, so that the nail body of each piston nail blocks the corresponding grout outlet hole; wherein, when the piston nail is subjected to grouting pressure, it can be pushed out of the grout outlet hole and anchored to the hole wall of the grouting hole.

[0009] In one embodiment, the step of sequentially connecting the grouting equipment to each of the grouting pipes and performing grouting operations on the corresponding grouting holes through the grouting pipes includes: Connect the grout outlet of the grouting equipment to the rear end of the first grouting pipe; The grouting equipment is started to inject grout into the grouting hole at a preset grouting pressure; wherein the preset grouting pressure is 2 MPa to 5 MPa. Grouting is stopped when grout is detected returning from the rear end of the grouting pipe or when the grouting pressure reaches the preset upper limit. Repeat the above grouting operation for the remaining grouting pipes in sequence until the grouting operation of all the grouting holes is completed.

[0010] In one embodiment, the grout is a cement grout or a chemical grout, wherein the water-cement ratio of the cement grout is 0.5 to 1.0, and the chemical grout includes water glass grout or polyurethane grout; The condition for determining whether the hardness of the grout injected into the working face reaches the preset strength is: the curing time of the grout reaches 12 to 48 hours, and the compressive strength of the grout reaches 5 to 15 MPa.

[0011] In one embodiment, the step of using drilling equipment to perform secondary drilling on the grouting pipe at the working face to form a blasting borehole includes: Based on the smooth blasting design scheme, determine the hole position, diameter, and depth parameters of the blasting borehole; The drilling equipment is used to drill along the axial direction of the grouting pipe to form the blasting borehole; wherein the diameter of the blasting borehole is 40 mm to 60 mm, and the depth of the blasting borehole is the same as or slightly less than the depth of the grouting hole.

[0012] In one embodiment, the step of installing explosive charges and water bags at intervals within the blasting borehole, detonating the explosive charges, and completing the smooth blasting operation includes: A guide rod is installed inside the blasting borehole; The explosive charge and the water bag are alternately connected in series along the guide rod, so that the explosive charge is close to the hole wall of the blasting borehole, and the water bag is located at the center of the blasting borehole; A plug is installed at the opening of the blasting borehole, and an initiation device is connected to detonate the explosive charge and complete the smooth blasting operation; wherein, the ratio of the number of explosive charges to the number of water bags is 1:1 or 2:1, the length of a single explosive charge is 20 cm to 40 cm, and the length of a single water bag is 10 cm to 30 cm.

[0013] In one embodiment, the step of installing a plug at the opening of the blasting borehole, connecting a detonating device, detonating the explosive charge, and completing the smooth blasting operation includes: A plug is installed at the opening of the blasting borehole, and an initiation device is connected. Check the connection status of the explosive charge and the detonation device in all the blasting boreholes; Confirm that all personnel and equipment within the pre-designated construction area have been evacuated to a safe area; The detonation device is activated to detonate the explosive charge. After the blasting is completed, ventilation and smoke removal are carried out. After the smoke and dust have dissipated, the pre-designated construction area is entered to check the blasting effect and carry out surrounding rock support work, thus completing the smooth blasting construction.

[0014] The technical solution of this invention involves drilling at the face of a soft rock tunnel within a predetermined construction area to form multiple spaced grouting holes. A grouting pipe is installed in each grouting hole, and a piston pin is installed at each outlet of each grouting pipe. Grouting equipment is sequentially connected to each grouting pipe, and grouting is performed on the corresponding grouting holes through the grouting pipes. This pushes the piston pins in all outlet holes into the hole wall, anchoring them to the grouting hole, thus completing the grouting reinforcement operation. After the grout injected into the tunnel face reaches a predetermined hardness, drilling is used... The drilling equipment performs secondary drilling on the grouting pipe at the working face to form a blasting borehole. Explosive charges and water bags are installed at intervals within the blasting borehole. The explosive charges are detonated to complete the smooth blasting operation. This invention allows for tunnel excavation operations based on geological conditions. Furthermore, during tunnel blasting, grouting reinforcement is required. Piston nails equipped with explosives are used in conjunction with the explosive charges during reinforcement, thus preventing over-excavation and ensuring the quality of tunnel formation. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 The flowchart of the tunnel soft surrounding rock smooth blasting construction method provided by the present invention.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0020] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0021] During the blasting excavation of tunnels in weak surrounding rock, the instability and deformability of the surrounding rock geological structure can easily lead to over-excavation or under-excavation, resulting in a decline in the quality of the tunnel cross-section and affecting the adaptability of the surrounding rock support structure and the overall stability of the tunnel.

[0022] For example, during the construction of a soft rock tunnel in a plateau region, the joint and fissure development characteristics of the surrounding rock at the tunnel face were observed. After blasting, some areas were over-excavated due to insufficient strength of the surrounding rock, while other areas were under-excavated because the blasting energy could not be fully released due to localized density of the surrounding rock. As a result, the tunnel cross-section was irregular, and additional repair work was required.

[0023] This invention proposes a method, apparatus, equipment, and medium for smooth blasting construction in soft surrounding rock of tunnels.

[0024] Please see Figure 1 To facilitate understanding, this method for smooth blasting construction in soft surrounding rock tunnels includes the following steps: S100. Drilling operations are carried out on the face of the soft rock tunnel in the pre-designated construction area to form multiple grouting holes distributed at intervals on the face. S200. A grouting pipe is installed in each of the grouting holes; wherein, the grouting pipe is provided with a plurality of spaced-apart grout outlet holes; S300. A piston nail is provided on each of the grout outlet holes of each of the grouting pipes; wherein, explosives are installed inside the piston nail; S400. Connect the grouting equipment to each of the grouting pipes in sequence, and perform grouting operation on the corresponding grouting holes through the grouting pipes, so as to push the piston nails in all the grout outlet holes into the hole wall anchored to the grouting hole, and complete the grouting reinforcement operation. S500. After the grout injected into the working face reaches a preset strength, a drilling device is used to drill a secondary hole in the grouting pipe on the working face to form a blasting hole. S600. Explosive charges and water bags are installed at intervals inside the blasting borehole, and the explosive charges are detonated to complete the smooth blasting operation; wherein the explosive charges and water bags are alternately arranged, and the explosive charges are set close to the borehole wall of the blasting borehole.

[0025] Specifically, within the designated construction area, drilling operations are performed on the tunnel face of the soft rock tunnel to create multiple spaced grouting holes. In practice, drilling can be carried out using a handheld drill after manual marking of the location, or a simple drilling template can be used for positioning. The depth and spacing of the holes can be set based on experience; for example, a fixed depth and fixed spacing can be set to ensure that the tunnel face is evenly covered.

[0026] A grouting pipe is installed in each grouting hole; the grouting pipe has multiple spaced-apart grout outlets. The grouting pipe is installed to effectively deliver grout to the depth of the grouting hole. During installation, the grouting pipe can be directly inserted into the borehole, with its tip reaching the bottom of the hole. The grout outlets on the grouting pipe can be formed by pre-drilling, and their spacing can be evenly distributed according to the length of the grouting pipe and the grouting requirements.

[0027] A piston pin is installed at each grout outlet of each grouting pipe; the piston pin contains explosives. The installation of the piston pin is a key step in this method, organically combining grouting and blasting functions. The piston pins can be prefabricated with internal explosives and then pushed one by one into the grout outlets of the grouting pipes, either manually or mechanically, to block the outlets. The external dimensions of the piston pin should match the inner diameter of the outlet to ensure effective blocking.

[0028] The grouting equipment is connected sequentially to each grouting pipe, and grouting is performed on the corresponding grouting holes through these pipes. This pushes the piston pins in all the grout outlet holes into the hole walls, anchoring them to the hole walls and completing the grouting reinforcement operation. A conventional grouting pump can be used, connected to the rear end of the grouting pipes via a flexible hose. Ordinary cement grout can be used, injected at a certain pressure. During grouting, the grout pressure acts on the piston pins, pushing them out of the outlet holes and anchoring them to the hole walls, thus sealing the outlet holes and pre-positioning the explosives. The completion of the grouting operation can be determined by the pressure gauge reading of the grouting pump or the grout backflow situation.

[0029] After the grout injected into the working face reaches a preset hardness, a secondary borehole is drilled into the grouting pipe on the working face using drilling equipment to create a blasting borehole. After grouting reinforcement is completed, it is necessary to wait for the grout to reach a certain hardness to ensure the surrounding rock has sufficient bearing capacity. Grout hardness can be determined based on experience, for example, by waiting for a fixed curing time. The purpose of the secondary drilling is to create a cavity in the reinforced surrounding rock for blasting. This drilling operation can be performed using conventional drilling equipment, drilling along the axis of the grouting pipe to ensure the blasting borehole is coaxial with the grouting pipe.

[0030] Explosive charges and water bags are installed at intervals within the blasting borehole. The explosive charge is detonated to complete the smooth blasting operation. The explosive charge and water bag are alternately placed, with the explosive charge positioned close to the borehole wall. The explosive charge and water bag can be manually placed alternately within the blasting borehole. The explosive charge should be placed as close to the borehole wall as possible, while the water bag fills the remaining space within the borehole. After the detonation device is connected, the explosive charge is detonated safely to complete the smooth blasting.

[0031] In this embodiment, drilling operations are performed on the face of a soft rock tunnel within a predetermined construction area to form multiple spaced grouting holes. A grouting pipe is installed in each grouting hole, and a piston pin is installed at each outlet of each grouting pipe. The grouting equipment is connected to each grouting pipe sequentially, and grouting operations are performed on the corresponding grouting holes through the grouting pipes. This pushes the piston pins in all outlet holes into the hole wall anchored to the grouting hole, completing the grouting reinforcement operation. After the grout injected into the face reaches a predetermined hardness, drilling is then performed. The equipment performs secondary drilling on the grouting pipe at the working face to form blasting boreholes. Explosive charges and water bags are installed at intervals within these boreholes. The explosive charges are detonated to complete smooth blasting. This invention allows for tunnel excavation operations based on geological conditions. Furthermore, during tunnel blasting, grouting reinforcement is required. Piston nails equipped with explosives are used in conjunction with the explosive charges during reinforcement, preventing over-excavation and ensuring the quality of tunnel formation.

[0032] In one embodiment, step S100 includes: S110. Based on the geological conditions of the tunnel face and the tunnel cross-sectional dimensions, determine the layout scheme of the grouting holes; S120. According to the hole layout scheme, drilling equipment is used to drill holes on the working face to form the plurality of grouting holes; wherein the spacing between adjacent grouting holes is 0.5 meters to 1.5 meters, and the hole depth of the grouting hole is 1.1 to 1.3 times the designed excavation advance of the tunnel.

[0033] In this embodiment, drilling operations are performed on the face of the soft rock tunnel within a pre-defined construction area to create multiple spaced grouting holes. Specifically, the hole layout is first scientifically determined based on the geological conditions of the face and the tunnel cross-sectional dimensions. Once the layout is finalized, drilling equipment is used to precisely drill holes on the face, creating multiple grouting holes. During drilling, the spacing between adjacent grouting holes is strictly controlled between 0.5 and 1.5 meters to ensure that the grout diffusion range in the surrounding rock overlaps, forming a continuous and uniform reinforcement zone, thereby effectively improving the overall stability of the surrounding rock. Simultaneously, the hole depth is set to 1.1 to 1.3 times the designed excavation depth of the tunnel, ensuring that the grouting reinforcement extends slightly beyond the current excavation face, pre-reinforcing the surrounding rock ahead. This effectively suppresses deformation and instability of the weak surrounding rock before excavation, providing a more stable working face for subsequent blasting and support. Through meticulous drilling operations, this method lays a solid foundation for subsequent grouting pipe installation, piston nail setting, grouting reinforcement, and final smooth blasting, significantly improving the safety, efficiency, and blasting quality of tunnel construction in weak surrounding rock.

[0034] In one embodiment, prior to step S110, the method further includes: S111. Conduct geological surveys on the working face to obtain the strength parameters of the surrounding rock and the development of joints and fissures at the working face; S112. Based on the surrounding rock strength parameters and the development of joints and fissures, determine whether the working face belongs to weak surrounding rock; S113. If the tunnel face is in weak surrounding rock, then the step of determining the arrangement of the grouting holes based on the geological conditions of the tunnel face and the tunnel cross-section dimensions shall be performed.

[0035] In this embodiment, by introducing a step of geological exploration of the working face, obtaining surrounding rock strength parameters and joint and fissure development status before determining the grouting hole layout, and judging whether it belongs to weak surrounding rock, the layout of grouting holes is no longer blind or empirical, but can fully consider the actual geological characteristics of weak surrounding rock. For example, in areas with developed joints and fissures, the density of grouting holes can be increased, or the depth of grouting holes can be adjusted to cover potential weak zones. This conditional decision-making process based on actual geological conditions ensures that grouting reinforcement operations can be applied more accurately to the areas requiring reinforcement, improving the grouting effect and providing a more stable surrounding rock foundation for subsequent smooth blasting. The logic of first exploration, then judgment, and then decision-making effectively avoids unnecessary detailed design in non-weak surrounding rock areas, improves the targeting and economy of construction, and significantly enhances the reinforcement effect and construction safety in weak surrounding rock areas.

[0036] In one embodiment, step S200 includes: S210. Insert the grouting pipe into the grouting hole, so that the front end of the grouting pipe reaches the bottom of the grouting hole; S220. Fill the space between the grouting pipe and the wall of the grouting hole with sealing material to prevent the grout from flowing back along the outer wall of the grouting pipe; wherein, a plurality of grout outlet holes are provided on the grouting pipe at intervals along the axial direction, and the distance between adjacent grout outlet holes is 20 cm to 50 cm.

[0037] In this embodiment, by precisely inserting the front end of the grouting pipe to the bottom of the grouting hole, it is ensured that the grout can fill upwards from the deepest part of the grouting hole, avoiding grouting blind spots in the bottom area. Simultaneously, sealing material is filled between the grouting pipe and the hole wall, effectively sealing the annular space between them. This prevents the grout from flowing back to the hole opening along the outer wall of the grouting pipe during grouting, ensuring effective transmission of grouting pressure and sufficient grout injection. Furthermore, multiple grout outlet holes spaced axially on the grouting pipe, with a spacing of 20 cm to 50 cm, allow the grout to penetrate and diffuse evenly into the surrounding rock along the entire depth range of the grouting hole. This ensures that the weak surrounding rock is comprehensively and uniformly reinforced, avoiding insufficient strength in localized areas due to inadequate grouting, thus significantly improving the quality and efficiency of grouting reinforcement and providing a stable foundation for subsequent smooth blasting construction.

[0038] In one embodiment, the piston nail includes a nail body and a medicated bag disposed inside the nail body, the outer diameter of the nail body matching the inner diameter of the slurry outlet; step S300 includes: The piston nails are pushed in sequentially from the rear end of the grouting pipe, so that the nail body of each piston nail blocks the corresponding grout outlet hole; wherein, when the piston nail is subjected to grouting pressure, it can be pushed out of the grout outlet hole and anchored to the hole wall of the grouting hole.

[0039] In this embodiment, by optimizing the structural design of the piston nail and its installation and working mechanism, the effective connection between grouting reinforcement and blasting operations is ensured. Specifically, the piston nail body is precisely matched with the inner diameter of the grout outlet hole, enabling a reliable initial seal to be formed after the piston nail is pushed in sequentially from the rear end of the grouting pipe and blocks the grout outlet hole. This effectively prevents grout leakage from the grout outlet hole in the initial stage of grouting, ensuring that the grout can penetrate deep into the surrounding rock according to a predetermined path and pressure, thereby improving the efficiency and uniformity of grouting reinforcement. When the grouting equipment is started and grout is injected into the grouting hole, the grout pressure gradually increases, acting on the piston nail body. Once the grout pressure reaches a preset threshold, the piston nail body overcomes the friction with the grout outlet hole and is precisely pushed out of the grout outlet hole. After being pushed out, the piston nail, thanks to its specific structural design, can be quickly and firmly anchored to the hole wall of the grouting hole, thereby providing additional support and stability to the surrounding rock after the grouting reinforcement is completed. Meanwhile, the explosive charge inside the piston nail is effectively protected by the nail body throughout the grouting process, avoiding grout erosion and external environmental influences, thus ensuring its reliability in subsequent blasting operations. This allows grouting reinforcement and blasting preparation to be completed efficiently at the same hole location, avoiding the tedious process of repeated drilling and installation, and significantly improving the overall efficiency and safety of the construction.

[0040] In one embodiment, the step of sequentially connecting the grouting equipment to each of the grouting pipes and performing grouting operations on the corresponding grouting holes through the grouting pipes includes: S410. Connect the grout outlet of the grouting equipment to the rear end of the first grouting pipe; S420. Start the grouting equipment and inject grout into the grouting hole at a preset grouting pressure; wherein the preset grouting pressure is 2 MPa to 5 MPa; S430. When grout is detected returning from the rear end of the grouting pipe or the grouting pressure reaches the preset upper limit value, grouting is stopped. S440. Repeat the above grouting operation on the remaining grouting pipes in sequence until the grouting operation of all the grouting holes is completed.

[0041] In this embodiment, a sealed connection is first established between the grouting equipment and a single grouting pipe to ensure that the grout can be delivered into the grouting hole without damage. Then, the grouting equipment is activated, injecting grout into the grouting hole at a preset grouting pressure (2 MPa to 5 MPa). This is not only sufficient to overcome the resistance of the weak surrounding rock and promote effective grout penetration, but more importantly, it can push the aforementioned piston pin out of the grout outlet and anchor it to the hole wall, thereby achieving effective sealing of the grouting hole and initial reinforcement of the surrounding rock. During the grouting process, the grouting saturation state of a single grouting hole is accurately determined by real-time monitoring of whether grout returns from the rear end of the grouting pipe or whether the grouting pressure reaches the preset upper limit. Once either condition is met, the operation of the current grouting hole is stopped, avoiding over-injection and waste of grout. Subsequently, the grouting equipment is connected to the remaining grouting pipes in sequence, repeating the above controlled grouting operation until all grouting holes have been grouted and reinforced.

[0042] In one embodiment, the grout is a cement grout or a chemical grout, wherein the water-cement ratio of the cement grout is 0.5 to 1.0, and the chemical grout includes water glass grout or polyurethane grout; The condition for determining whether the hardness of the grout injected into the working face reaches the preset strength is: the curing time of the grout reaches 12 to 48 hours, and the compressive strength of the grout reaches 5 to 15 MPa.

[0043] In this embodiment, by precisely controlling the type, proportion, and hardness of the grout to achieve the preset strength, sufficient and reliable pre-reinforcement of the tunnel face is ensured during smooth blasting in weak surrounding rock. After grouting, by selecting cement or chemical grout suitable for the weak surrounding rock geological conditions and strictly controlling the water-cement ratio of the cement grout, the grout can effectively penetrate and consolidate the surrounding rock fissures after being injected into the grouting hole, forming a reinforced ring with a certain strength and integrity. Furthermore, by setting the curing time of the grout between 12 and 48 hours and requiring the grout's compressive strength to reach 5 to 15 MPa, clear quality control standards are provided for subsequent secondary drilling and blasting operations. Secondary drilling and blasting operations are only carried out when the grout's curing time and compressive strength both meet the preset conditions, thus avoiding blasting under insufficient surrounding rock reinforcement and effectively preventing problems such as surrounding rock instability, over-excavation, or under-excavation that may occur during blasting.

[0044] In one embodiment, step S500 includes: S510. Based on the smooth blasting design scheme, determine the hole position, hole diameter, and hole depth parameters of the blasting borehole; S520. Using the drilling equipment, a hole is drilled along the axial direction of the grouting pipe to form the blasting hole; wherein, the diameter of the blasting hole is 40 mm to 60 mm, and the depth of the blasting hole is the same as or slightly less than the depth of the grouting hole.

[0045] In this embodiment, after the grout injected into the working face reaches a preset hardness, a secondary drilling operation is performed on the grouting pipe at the working face using drilling equipment to form a blasting borehole. Specifically, firstly, based on the smooth blasting design scheme, the hole position, diameter, and depth parameters of the blasting borehole are precisely determined, providing basic guidance for subsequent precise drilling. Subsequently, drilling is performed along the axial direction of the grouting pipe, which has been solidified in the surrounding rock, using drilling equipment. Since the grouting pipe has been precisely installed according to the preset hole position and anchored by grout during the initial construction, its axial direction provides a natural and stable guide, enabling the secondary drilling to proceed with high precision along the predetermined trajectory, thereby ensuring the accuracy of the blasting borehole position. Meanwhile, the diameter of the blasting borehole is limited to the range of 40 mm to 60 mm, and its depth is the same as or slightly less than that of the grouting hole. This ensures that the blasting energy can be applied evenly to the grouting reinforcement area, avoiding uneven blasting effects or damage to the reinforced surrounding rock caused by improper drilling parameters.

[0046] In one embodiment, step S600 includes: S610. A guide rod is installed inside the blasting borehole; S620. The explosive charge and the water bag are alternately connected in series along the guide rod, so that the explosive charge is close to the hole wall of the blasting borehole and the water bag is located at the center of the blasting borehole. S630. Install a plug at the opening of the blasting borehole and connect an initiation device to detonate the explosive charge and complete the smooth blasting operation; wherein, the ratio of the number of explosive charges to the number of water bags is 1:1 or 2:1, the length of a single explosive charge is 20 cm to 40 cm, and the length of a single water bag is 10 cm to 30 cm.

[0047] In this embodiment, a guide rod is installed inside the blasting borehole, providing a physical path and positioning reference for the precise installation of the explosive charge and water bag. Then, the explosive charge and water bag are alternately connected in series along the guide rod, making the loading process smoother and more efficient, ensuring the continuity of the blasting medium. The design allows the explosive charge to be close to the borehole wall, while the water bag is located at the center of the borehole. The explosive charge's close contact with the borehole wall allows the blasting energy to act more directly and concentratedly on the surrounding rock, effectively cutting through the rock mass and forming a smooth blasting surface, thereby reducing over-excavation and under-excavation. Simultaneously, the water bag located at the center acts as an energy buffer and transfer mechanism during blasting, absorbing part of the blast shock wave, reducing excessive damage to the surrounding rock, and helping to evenly transfer the blasting energy to the borehole wall, further promoting the formation of a smooth blasting profile. By controlling the ratio of explosive charges to water bags and the length of each charge and water bag, the distribution and effect of the blasting energy can be precisely adjusted according to the specific surrounding rock conditions and blasting requirements. Finally, plugs are installed at the borehole openings of the blasting boreholes to effectively seal the openings, prevent the blasting energy from leaking out, ensure that the blasting energy acts on the surrounding rock to the maximum extent, and achieve precise detonation by connecting to the detonation device, thereby completing efficient and high-quality smooth blasting construction.

[0048] In one embodiment, step S630 includes: S631. Install a plug at the opening of the blasting borehole and connect an initiation device; S632. Check the connection status of the explosive charge and the detonation device in all the blasting boreholes; S633. Confirm that the personnel and equipment in the preset construction area have been evacuated to a safe area; S634. Activate the detonation device to detonate the explosive charge; S635. After the blasting is completed, ventilation and smoke removal are carried out. After the smoke and dust have dissipated, the pre-set construction area is entered to check the blasting effect and carry out surrounding rock support work to complete the smooth blasting construction.

[0049] In this embodiment, a systematic blasting execution process ensures the safety, effectiveness, and controllability of smooth blasting construction in weak surrounding rock of tunnels. First, installing plugs at the borehole opening effectively concentrates blasting energy, improves blasting efficiency, and significantly reduces flyrock and shock waves that may occur during blasting, thereby minimizing potential hazards to the surrounding environment and personnel. Subsequently, a comprehensive inspection of the explosive charge and detonation device connection status is crucial to avoid misfires and incomplete blasting, ensuring not only the uniformity of the blasting effect and the smoothness of the profile but also eliminating safety hazards caused by unexploded ordnance. The detonation device is only activated after confirming that all personnel and equipment have been evacuated to a safe area, further minimizing the risks of the blasting operation. Immediately after blasting, ventilation and smoke extraction are carried out, rapidly improving the working environment and protecting the health of subsequent workers. The subsequent inspection of the blasting effect allows for timely assessment of the blasting quality, providing accurate data for subsequent surrounding rock support. Ultimately, timely implementation of surrounding rock support effectively prevented instability of the surrounding rock after blasting, ensuring the safety and stability of the tunnel structure and creating a safe and reliable working face for subsequent construction. The entire process was interconnected, forming a closed-loop management system that greatly improved the overall safety and efficiency of smooth blasting construction in weak surrounding rock.

[0050] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of the present invention. Any equivalent structural transformations made based on the technical concept of the present invention and the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A method for smooth blasting construction in soft surrounding rock of tunnels, characterized in that, Includes the following steps: In the pre-designated construction area, drilling operations are carried out on the working face of the soft rock tunnel to form multiple spaced grouting holes on the working face; A grouting pipe is installed in each of the grouting holes; wherein, the grouting pipe is provided with a plurality of grout outlet holes distributed at intervals; A piston nail is provided on each of the grout outlet holes of each of the grouting pipes; wherein, explosives are installed inside the piston nail; The grouting equipment is connected to each of the grouting pipes in sequence, and grouting is performed on the corresponding grouting holes through the grouting pipes, so that the piston nails in all the grout outlet holes are pushed into the hole wall anchored to the grouting hole, thus completing the grouting reinforcement operation. After the grout injected into the working face reaches a preset hardness, a drilling device is used to drill a secondary hole in the grouting pipe on the working face to form a blasting hole. Explosive charges and water bags are installed at intervals inside the blasting borehole. The explosive charges are detonated to complete the smooth blasting operation. The explosive charges and water bags are arranged alternately, and the explosive charges are set close to the borehole wall.

2. The tunnel soft surrounding rock smooth blasting construction method as described in claim 1, characterized in that, The step of drilling at the face of a soft rock tunnel within a predetermined construction area to form multiple spaced grouting holes on the face includes: Based on the geological conditions of the tunnel face and the tunnel cross-sectional dimensions, determine the layout scheme of the grouting holes; According to the hole layout scheme, drilling equipment is used to drill holes on the working face to form the plurality of grouting holes; wherein the spacing between adjacent grouting holes is 0.5 meters to 1.5 meters, and the hole depth of the grouting holes is 1.1 to 1.3 times the designed excavation advance of the tunnel.

3. The tunnel soft surrounding rock smooth blasting construction method as described in claim 2, characterized in that, Before the step of determining the arrangement of the grouting holes based on the geological conditions of the tunnel face and the tunnel cross-sectional dimensions, the method further includes: Geological surveys were conducted on the working face to obtain the strength parameters of the surrounding rock and the development of joints and fissures. Based on the surrounding rock strength parameters and the development of joints and fissures, determine whether the working face belongs to weak surrounding rock; If the tunnel face is in a weak surrounding rock, then the step of determining the arrangement of the grouting holes based on the geological conditions of the tunnel face and the tunnel cross-section dimensions shall be performed.

4. The method for smooth blasting construction in weak surrounding rock of a tunnel as described in claim 1, characterized in that, The step of installing a grouting pipe in each of the grouting holes includes: Insert the grouting pipe into the grouting hole so that the front end of the grouting pipe reaches the bottom of the grouting hole; A sealing material is filled between the grouting pipe and the wall of the grouting hole to prevent the grout from flowing back along the outer wall of the grouting pipe; wherein, a plurality of grout outlet holes are provided on the grouting pipe at intervals along the axial direction, and the distance between adjacent grout outlet holes is 20 cm to 50 cm.

5. The tunnel soft surrounding rock smooth blasting construction method as described in claim 4, characterized in that, The piston nail includes a nail body and a medicine bag disposed inside the nail body, wherein the outer diameter of the nail body matches the inner diameter of the slurry outlet hole; The step of setting a piston nail on each of the grout outlet holes of the grouting pipe includes: The piston nails are pushed in sequentially from the rear end of the grouting pipe, so that the nail body of each piston nail blocks the corresponding grout outlet hole; wherein, when the piston nail is subjected to grouting pressure, it can be pushed out of the grout outlet hole and anchored to the hole wall of the grouting hole.

6. The tunnel soft surrounding rock smooth blasting construction method as described in claim 5, characterized in that, The step of sequentially connecting the grouting equipment to each of the grouting pipes and performing grouting operations on the corresponding grouting holes through the grouting pipes includes: Connect the grout outlet of the grouting equipment to the rear end of the first grouting pipe; The grouting equipment is started to inject grout into the grouting hole at a preset grouting pressure; wherein the preset grouting pressure is 2 MPa to 5 MPa. Grouting is stopped when grout is detected returning from the rear end of the grouting pipe or when the grouting pressure reaches the preset upper limit. Repeat the above grouting operation for the remaining grouting pipes in sequence until the grouting operation of all the grouting holes is completed.

7. The tunnel soft surrounding rock smooth blasting construction method as described in claim 6, characterized in that, The grout is a cement grout or a chemical grout, wherein the water-cement ratio of the cement grout is 0.5 to 1.0, and the chemical grout includes water glass grout or polyurethane grout; The condition for determining whether the hardness of the grout injected into the working face reaches the preset strength is: the curing time of the grout reaches 12 to 48 hours, and the compressive strength of the grout reaches 5 to 15 MPa.

8. The tunnel soft surrounding rock smooth blasting construction method according to any one of claims 1 to 7, characterized in that, The step of using drilling equipment to perform secondary drilling on the grouting pipe on the working face to form a blasting borehole includes: Based on the smooth blasting design scheme, determine the hole position, diameter, and depth parameters of the blasting borehole; The drilling equipment is used to drill along the axial direction of the grouting pipe to form the blasting borehole; wherein the diameter of the blasting borehole is 40 mm to 60 mm, and the depth of the blasting borehole is the same as or slightly less than the depth of the grouting hole.

9. The method for smooth blasting construction in weak surrounding rock of a tunnel as described in claim 8, characterized in that, The steps of installing explosive charges and water bags at intervals within the blasting borehole, detonating the explosive charges, and completing the smooth blasting operation include: A guide rod is installed inside the blasting borehole; The explosive charge and the water bag are alternately connected in series along the guide rod, so that the explosive charge is close to the hole wall of the blasting borehole, and the water bag is located at the center of the blasting borehole; A plug is installed at the opening of the blasting borehole, and an initiation device is connected to detonate the explosive charge and complete the smooth blasting operation; wherein, the ratio of the number of explosive charges to the number of water bags is 1:1 or 2:1, the length of a single explosive charge is 20 cm to 40 cm, and the length of a single water bag is 10 cm to 30 cm.

10. The method for smooth blasting construction in weak surrounding rock of a tunnel as described in claim 9, characterized in that, The steps of installing a plug at the opening of the blasting borehole, connecting a detonating device, detonating the explosive charge, and completing the smooth blasting operation include: A plug is installed at the opening of the blasting borehole, and an initiation device is connected. Check the connection status of the explosive charge and the detonation device in all the blasting boreholes; Confirm that all personnel and equipment within the pre-designated construction area have been evacuated to a safe area; The detonation device is activated to detonate the explosive charge. After the blasting is completed, ventilation and smoke removal are carried out. After the smoke and dust have dissipated, the pre-designated construction area is entered to check the blasting effect and carry out surrounding rock support work, thus completing the smooth blasting construction.

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