Construction method for grading and controlled blasting of rock mass in approach channel excavation

Abstract

The application provides a kind of construction method of near structure channel excavation rock mass grading control blasting, belongs to the technical field of blasting construction.The method comprises: blasting vibration and structure response simulation analysis, carries out basic data collection and verification, constructs fine three-dimensional finite element model, carries out dynamic response calculation and law analysis, optimizes simulation parameters, measures site hole position, assembles self-made rotary drive drilling tool, drills into hole, grades blasting, excavates and transports stone.The application determines the response characteristics of the bridge substructure under the blasting vibration through numerical simulation, divides the work zones based on the blast center distance, the weathering degree of rock mass and the step height, specifically develops the hydraulic breaking and controlled blasting process, realizes the dynamic adjustment of blasting parameters, and considers both safety and efficiency.

Description

Technical Field

[0001] This invention relates to the field of blasting construction technology, and in particular to a graded controlled blasting construction method for excavating rock masses in waterways near structures. Background Technology

[0002] In rock excavation operations for waterway engineering, blasting, as an efficient means of rock breaking, requires careful consideration of excavation efficiency, structural safety of the structures, and stability of surrounding protected objects when near sensitive structures such as bridges. However, traditional blasting schemes have revealed many intractable drawbacks. On the one hand, traditional schemes rely excessively on hydraulic breaking technology, blindly expanding the operating area to avoid vibration risks without scientifically dividing the area according to the actual strength of the structures. This results in decreased construction efficiency, delays in the construction period, and technical redundancy and cost waste. On the other hand, the use of a "one-size-fits-all" approach to controlled blasting, without designing the charge and detonation method according to the distance between the detonator and the rock mass, the degree of rock weathering, and the step height, lacks precise support and is prone to causing excessive blasting vibration. This is especially problematic in stress concentration areas such as the rock-embedded sections of bridge pile foundations and the junction of the abutment and pile foundation, which may lead to concrete cracking and pose safety hazards to surrounding pipelines, structures, and other protected objects, making it difficult to balance safety and economy. Furthermore, traditional drilling rigs rely on dedicated drill frames and hydraulic rods for angle control, which has significant angle limitations. Adjusting the posture requires multiple operations, and the small size of the tracks and poor adaptability to complex terrain further restrict construction efficiency, severely mismatching the precision requirements of the blasting process. Therefore, it is necessary to design a graded controlled blasting method for excavating rock masses near structures in waterways to improve construction efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide a graded controlled blasting method for excavating rock masses near structures in waterways, solving the technical problems of safety redundancy, insufficient risk management, and low drilling efficiency in traditional rock blasting excavation. Through synergistic optimization of "refined blasting parameters + adapted drilling equipment," a unified approach of safety, efficiency, and economy is achieved in rock mass excavation near structures, providing a technical pathway for similar projects.

[0004] This method is applicable to rock blasting excavation projects in waterways with various adjacent structures. It also has significant advantages in rock blasting scenarios where there are protected objects such as pipelines, high-voltage power towers, and premature concrete components, as well as in scenarios where the terrain is complex and traditional drilling equipment is difficult to operate.

[0005] To address the dual requirements of "safety and efficiency" in rock blasting excavation near structures, a three-in-one technical system integrating "hydraulic breaking + graded controlled blasting + optimized drilling equipment" was developed. Based on numerical simulation results and equipment innovation using a self-made rotary drive drilling tool, a comprehensive scientific construction plan was constructed. Regarding blasting protection, a three-dimensional finite element model clearly identifies the pile foundation as the main vibration-bearing component, highlighting the stress concentration at the junction of the pile cap and the pile foundation. Based on vibration attenuation laws and tensile stress criteria, operational zones were divided into three areas: hydraulic breaking within 40m, 8m stepped deep-hole blasting (40-50m), and 9m stepped deep-hole blasting (50m and beyond), with optimized parameters matching the safe charge quantity. In terms of drilling equipment, the self-made rotary drive drilling tool can be quickly installed on existing backhoe excavators, achieving 360° planar rotation and multi-directional angle control, avoiding the limitations of conventional drilling rigs.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for graded controlled blasting of rock mass during channel excavation near structures, the method comprising the following steps: Step 1: Simulation and analysis of blasting vibration and structural response. First, basic data is collected and verified. Then, a refined three-dimensional finite element model is constructed. Finally, dynamic response calculation and law analysis are performed, and simulation parameters are optimized. Step 2: Based on the blasting zones determined by the simulation analysis, the surveyor uses a positioning device to lay out the hole positions. According to the hole network parameters output by the simulation analysis, the hole positions are marked on the working surface. At the same time, the design depth and angle of each hole are marked. The hole position deviation must be ≤150mm. Step 3: Design a self-made rotary drive drill bit. This drill bit does not require the purchase of a special drilling machine and can be quickly installed directly on the existing backhoe excavator. It achieves 360° planar rotation and three-dimensional multi-directional angle control through the rotary drive device, overcoming the shortcomings of traditional drilling machines in terms of angle limitation and weak terrain adaptability. Step 4: Use an excavator with a self-made rotary drive drill bit to drill a hole; Step 5: Load explosives into the borehole to remove unstable rock masses at the edge of the grading zone and control blasting in stages; Step 6: Delineate the excavation and transportation area and the transport channel. Divide the stockpiling area according to the stone particle size and lithology. Use an excavator to excavate in layers. The excavation layer height should match the height of the previous staged blasting steps to avoid over-excavation that could lead to slope instability. Complete the excavation and transportation of the stone.

[0007] Furthermore, in step 1, the specific process of basic data collection and verification is as follows: based on the geotechnical engineering investigation report and design drawings, the lithological parameters of the blasting area and the details of the bridge substructure are clarified. Combined with the existing blasting vibration monitoring data, the particle velocity and stress distribution law of the existing blasting are extracted as the verification basis for simulation analysis to ensure that the model parameters are consistent with the actual situation on site.

[0008] Furthermore, the specific process of constructing the refined three-dimensional finite element model in step 1 is as follows: using finite element software, an integrated model of the bridge substructure, abutment foundation pit, canal bank slope, and blasted rock mass is constructed at a 1:1 scale. Among them, the rock mass adopts the MAT_MOHR_COULOMB material model, the concrete and steel reinforcement adopt the MAT_PLASTIC_KINEMATIC material model, the coupling between steel reinforcement and concrete is CONSTRAINT_LAGRANGIAN_IN_SOLID, and the bonding between the abutment and pier, and between the bank slope and rock mass is CONTACT_TIED_SURFACE_TO_SURFACE, to avoid mesh generation errors caused by shared nodes. The integrated model uses a unified mesh size, with rock mass and concrete components divided by solid elements and reinforcing bars divided by rod elements. Several sets of blast source orientations and blast center distances are set according to the actual blasting scheme to simulate the blasting effect under different construction scenarios.

[0009] Furthermore, in step 1, the specific process of dynamic response calculation and law analysis is to simulate three types of core working conditions: first, the structural vibration velocity distribution under different blast center distances; second, the stress transmission law corresponding to different step heights; and third, the vibration difference of different blast source orientations, to ensure the key construction stages of covering the waterway excavation and central rock spur removal. Through calculation, the peak mass velocity and maximum tensile stress of the substructure of the bridge were extracted. In the velocity distribution, the pile foundation velocity gradually increases with depth, reaching the maximum value at the bottom. There is a velocity amplification effect at the top of the pier. In the stress distribution, stress concentration occurs at the junction of the abutment and the pile foundation, with the maximum tensile stress. The velocity and stress on the blast-facing side are higher than those on the blast-back side. In the attenuation law, the velocity attenuation formula was fitted to provide a quantitative basis for subsequent parameter design.

[0010] Furthermore, in step 1, the specific process of optimizing the simulation parameters is as follows: based on the simulation results, combined with the "Blasting Safety Regulations" and the tensile strength threshold of concrete, the operation zones are delineated: ① For blast center distance < 40m, hydraulic breaking is used, and the vibration velocity during hydraulic breaking construction must not exceed 2.0cm / s or the tensile stress must not exceed the tensile strength of concrete; ② For blast center distance 40m ≤ blast center distance < 50m, 8m step deep hole blasting is used, with a single-stage charge ≤ 20.8kg; ③ For blast center distance ≥ 50m, 9m step deep hole blasting is used, with a single-stage charge ≤ 40.5kg. Compare the simulated parameters with the field test blast data. If the measured vibration velocity exceeds the simulated value by more than 10%, revise the lithology attenuation coefficient or explosive charge in the model to ensure consistency between the simulation results and the field construction. Adjust the charge structure according to different lithologies, and optimize the hole pattern parameters and initiation method for different regions.

[0011] Further, the specific process of step 3 is as follows: First, lower the bucket of the backhoe excavator to the ground, disassemble the stick pin and connecting rod pin, and remove the bucket. During this process, be careful not to get mud and sand on the disassembled stick pin and connecting rod pin, and do not damage the seals at both ends of the bushing. Then, place the self-made rotary drive drill bit flat on the flat ground, align the longitudinal axis of the drill bit with the axis of the excavator stick, and make the mounting base perpendicular to the ground. Operate the excavator to align the stick, connecting rod bushing with the pin hole of the drill bit mounting base, insert the pin, install the locking bolt, apply grease, and complete the mechanical connection. Open the oil seals of the hydraulic oil pipes reserved on both sides of the excavator's boom and connect them to the hydraulic oil pipes of the drill bit. After tightening the bolts, open the hydraulic valves and connect the air pipe of the mobile screw air compressor to the air pipe interface reserved on the drill bit. Use a detachable high-pressure air pipe, with the middle section fixed to the side of the excavator's boom, ensuring that there is no air leakage in the air pipe. Start the excavator and air compressor, test run the hydraulic system and air circuit, and check whether the drill bit rotates 360° smoothly and whether there are any abnormal noises from the impactor.

[0012] Furthermore, the self-made rotary drive drill includes a drill frame, a slide, an impactor, and a rotary drive device. The slide is slidably mounted on the drill frame, the impactor is mounted on the top of the slide, and the rotary drive device is mounted on the slide.

[0013] Further, the specific process of step 4 is as follows: in the blasting area of ​​40~50m and 8m steps, an excavator is used with a self-made rotary drive drill to carry out the operation. The hole layout adopts a quincunx pattern. During the drilling process, the operator precisely controls the drill advance speed through the hydraulic foot valve in the excavator cab, and at the same time manipulates the rotary drive device to flexibly adjust the drilling angle. The operation must be paused after drilling a fixed depth, and the verticality of the hole axis is checked with a plumb bob to avoid hole inclination due to uneven rock properties, and to ensure that the hole axis deviation is ≤1°. Using the 360° rotation function of the self-made rotary drive drill bit, combined with the working radius of the matching backhoe excavator, a single machine position can cover 20 basic blasting holes. When drilling into the moderately weathered rock section, the hydraulic propulsion speed should be appropriately reduced to avoid the impactor being overloaded and damaged due to the increased rock hardness. During drilling, the drill bit reciprocates to drill the rock. When the drill bit is pushed into the impactor and pressed against the drill sleeve, the drill bit is lifted from the bottom of the hole. Compressed gas is then blown through the drill bit to expel the debris from the hole, ensuring that the rock powder at the bottom of the hole is completely removed and avoiding residual rock powder from affecting the subsequent charging effect. At the same time, a special person is assigned to clean the rock cuttings at the hole opening to prevent accumulation.

[0014] Further, the specific process of step 5 is as follows: remove loose rocks, weeds and construction debris in the blasting area; use mechanical pre-prying to remove unstable rock masses at the edge of the graded area to prevent flying rocks from being generated during blasting; check the hole depth, hole diameter and hole condition of the blasting holes in each graded area; and treat unqualified holes with insufficient hole depth or blocked holes as abandoned and re-drilled. The distance between the re-drilled hole and the original hole position must be ≥30cm. Workers must wear anti-static gloves and use wooden or plastic tools to load explosives. Explosives should be loaded in stages according to the corresponding single-hole charge for each grade. Before loading each hole, the total amount of explosives should be weighed using an explosion-proof electronic scale to ensure that the actual charge deviates from the design value by ≤±5%. Continuous loading is used for basic blasting holes, with explosives being loaded into the hole segment by segment. Every 30cm of loading, a plastic tamping stick is used to gently compact the explosives, ensuring they adhere to the hole wall. Intermittent loading is used for rock ridge blasting holes, with dry rock chips used to separate explosive segments to prevent cross-contamination. For holes in areas of strongly weathered rock, the charge amount should be reduced according to design requirements to avoid excessive blasting that could lead to rock mass collapse. Install detonators according to the graded detonation sequence. For basic blasting holes, install the detonator in the center of the hole and fix it in the middle of the explosive section. The lead wire is led out along one side of the hole wall to avoid compression. For rock blasting holes, install the detonator in layers, with one detonator corresponding to every 2m explosive section to ensure uniform detonation energy. After installation, check that the detonator lead wire is not tangled or damaged. Digital detonators need to have their resistance and communication status tested by the detonator. Immediately after loading the explosive, plug the blast hole with dry clay or drill cuttings. The plugging length should be ≥1.2m for the basic blast hole and ≥1.5m for the rock spur blast hole. Fill in layers and gently compact them. The compaction thickness of each layer should be ≤10cm to avoid energy leakage due to loose plugging or damage to the detonator due to excessive tightness. The basic blasting holes are detonated one hole at a time, while the rock spur blasting holes are detonated row by row. After the network connection is completed, the detonator is used to conduct an overall test to confirm that there are no short circuits or disconnections. The detonator operator operates the detonator to detonate in the graded sequence. If a dud occurs, it is necessary to wait 15 minutes and then have a professional drill a parallel hole 30cm away from the dud hole for re-blasting. It is strictly forbidden to directly treat the original hole.

[0015] In the drilling phase, a self-made rotary drive drill was used to optimize drilling operations. This drill consists of a main body, a rotary drive device, and a backhoe excavator mounting base. It can be quickly installed on existing backhoe excavators. The rotary drive device enables 360° planar rotation and multi-directional angle adjustment, avoiding the angle limitations of traditional drills. Furthermore, leveraging the backhoe excavator's 9.85m working radius, a single machine position can cover 20 blasting holes, significantly reducing equipment transfer time. Its large tracks are suitable for steep slopes and undulating terrain, providing efficient drilling support for the precise implementation of subsequent blasting parameters. After drilling, hole cleaning and fill-in operations are performed. High-pressure air is used to remove rock debris from the holes, and any deviated or blocked holes are promptly drilled again to ensure that the hole depth and angle meet design requirements.

[0016] In the blasting phase, based on the analysis results of the three-dimensional finite element model, it was determined that the bridge pile foundation is the main vibration-bearing component, and the joint between the abutment and the pile foundation is prone to stress concentration. Combining the Sadovsky vibration attenuation formula, the process was designed according to the blast center distance. Hydraulic crushing was used within 40m to avoid vibration damage. In the range of 40~150m, 6m bench deep-hole controlled blasting was implemented (cloverleaf pattern of holes, hole spacing of 3m, row spacing of 3m, single hole charge of 13.5kg in the front row and 15kg in the back row). The central rock spur was blasted with 9m bench deep-hole blasting (hole bottom distance of 4~4.5m, maximum single hole charge of 32kg). During the charging, the structure was adjusted according to the lithology. Continuous charging was used for strongly weathered silty mudstone, and intermittent charging was used for moderately weathered rock. The blast holes were filled with drill cuttings. At the same time, digital electronic detonators were used to detonate hole by hole (30ms delay between holes) to control the maximum charge in a single section and avoid excessive blasting vibration (safe vibration velocity of bridge structure ≤2.0cm / s, surrounding buildings ≤1.5cm / s).

[0017] After the blasting, a post-blast inspection was carried out in a timely manner. Five minutes later, technicians entered the site to check for misfires. After confirming safety, two excavators were used to excavate simultaneously to ensure that the slope ratio and flatness of the waterway side met the design requirements, forming a process system that coordinates the entire process of simulation analysis, drilling, graded blasting, and excavation and transportation.

[0018] To address the dual requirements of safety and efficiency in rock blasting excavation near structures, a three-in-one technical system integrating hydraulic breaking, graded controlled blasting, and optimized drilling equipment was developed. Based on numerical simulation results and innovative equipment using a self-made rotary drive drilling tool, a comprehensive scientific construction plan was constructed. Regarding blasting protection, a three-dimensional finite element model clearly identifies the pile foundation as the main vibration-bearing component, highlighting the stress concentration at the junction of the pile cap and the pile foundation. Based on vibration attenuation laws and tensile stress criteria, operational zones were divided into three areas: hydraulic breaking within 40m, 8m bench deep-hole blasting (40-50m), and 9m bench deep-hole blasting (50m and beyond), with optimized parameters to match safe charge quantities. In terms of drilling equipment, the self-made rotary drive drilling tool can be quickly installed on existing backhoe excavators, achieving 360° planar rotation and multi-directional angle control, avoiding the limitations of conventional drilling rigs.

[0019] This method solves the problems of safety redundancy, insufficient risk control, and low drilling efficiency in traditional rock blasting excavation. By refining blasting parameters and adapting drilling equipment for collaborative optimization, it achieves a balance between safety, efficiency, and economy in rock excavation near structures, providing a technical path for similar projects.

[0020] First, the sophisticated design system of tiered blasting breaks through the limitations of the traditional one-size-fits-all approach: The innovative zoning logic based on numerical simulation: Through a three-dimensional finite element model, the response characteristics of bridge pile foundations (the main vibration-bearing components) and the junction of the abutment and pile foundation (stress concentration zone) are accurately identified. Combined with the Sadovsky vibration attenuation formula, the work area is divided according to three-dimensional indicators: blast center distance + rock weathering degree + step height. Hydraulic crushing is carried out within 40m, 8m step blasting is carried out within 40~50m, and 9m step blasting is carried out outside 50m. This achieves quantitative matching of vibration velocity, stress and explosive charge, rather than the traditional extensive zoning.

[0021] Dynamic parameter adaptation adjusts the charge structure (continuous charge / interval charge) for different lithologies (strongly weathered / moderately weathered rocks), and optimizes the hole network parameters (hole diameter, hole spacing, row spacing) and detonation method (30ms delay per hole / 50ms delay between rows) for different regions (base zone / rock spur zone), solving the problem of fixed blasting parameters and poor adaptability in traditional blasting.

[0022] Second, modular innovation in drilling equipment breaks through bottlenecks in complex terrain operations: The integrated design of the self-made rotary drive drilling tool: There is no need to purchase a special drilling machine. It can be quickly installed directly on the existing backhoe excavator. The rotary drive device realizes 360° planar rotation + three-dimensional multi-directional angle control, which overcomes the shortcomings of traditional drilling rigs in terms of angle limitation and weak terrain adaptability. The working radius of a single machine position is up to 9.85m, which can cover 20 blasting holes, greatly reducing the frequency of equipment transfer.

[0023] Terrain Adaptation and Efficiency Collaboration Innovation: Relying on the large-size tracks of the backhoe excavator, it adapts to steep slopes and undulating terrain, solving the problem that traditional drilling rigs are difficult to operate in complex sites; during drilling, high-pressure air is used to clean the holes simultaneously, and the verticality is checked every 3m (deviation ≤1°), providing a basic guarantee for the accurate implementation of subsequent blasting parameters and realizing the process synergy of drilling and blasting.

[0024] The integrated three-in-one technology system achieves a unified technological fusion of safety, efficiency, and economy. It integrates hydraulic crushing (close-range vibration-free operation), graded controlled blasting (medium- and long-range precision blasting), and optimized drilling equipment (efficient hole formation) to form a closed-loop process. This not only overcomes the drawbacks of traditional solutions that rely too much on hydraulic crushing, resulting in low efficiency, or single blasting, resulting in high risks, but also balances safety and efficiency by expanding the deep hole blasting range and reducing the workload of hydraulic crushing.

[0025] Real-time monitoring and simulation linkage innovation: The results of three-dimensional finite element simulation are linked with the data of on-site vibration monitoring (TC-4850 monitoring instrument). If the measured vibration velocity exceeds the simulation value by more than 10%, the lithological attenuation coefficient or dosage is corrected in real time to ensure that the simulation provides dynamic guidance for construction and avoid the problem of disconnect between traditional simulation and on-site conditions.

[0026] The present invention, by adopting the above-described technical solution, has the following beneficial effects: (1) This invention clarifies the response characteristics of the bridge substructure under blasting vibration through numerical simulation, divides the operation zones based on the blast center distance, rock weathering degree and step height, and formulates targeted hydraulic crushing and controlled blasting processes to achieve dynamic adjustment of blasting parameters, taking into account both safety and efficiency.

[0027] (2) The self-made rotary drive drill can be quickly installed on the existing backhoe excavator to achieve 360° planar rotation and three-dimensional multi-directional angle adjustment. The working radius of a single machine position is 9.85m, which can cover more blasting holes, greatly reduce the frequency of equipment transfer, improve drilling efficiency, and reduce construction time costs.

[0028] (3) Establish a blasting vibration-stress attenuation model, combine it with real-time on-site monitoring data, accurately control the amount of blasting charge and vibration, effectively protect key parts such as the joint between bridge pile foundation and abutment, avoid damage such as concrete cracking, and at the same time reduce the safety risks to the protected objects such as surrounding pipelines and structures, and ensure the safety of engineering construction.

[0029] (4) By integrating hydraulic crushing, graded controlled blasting and drilling equipment optimization technologies, we can overcome the safety redundancy or risk out-of-control problems of traditional schemes, and reduce construction costs by reasonably expanding the deep hole blasting range and reducing the workload of hydraulic crushing, thus achieving a safe, efficient and economical unity of rock mass excavation projects near structures. Attached Figure Description

[0030] Figure 1 This is a flowchart of the construction method of the present invention; Figure 2 This is an overall structural diagram of the three-dimensional finite element model of the present invention; Figure 3 This is a diagram showing the dynamic response distribution pattern of the lower structure on the explosion-facing side of the present invention; Figure 4 This is a diagram showing the dynamic response distribution pattern of the lower structure on the back-explosion side of the present invention; Figure 5 This is a blasting operation zoning diagram of the lower structure of the present invention; Figure 6 This is a schematic diagram of the assembly of the self-made rotary drive drill bit of the present invention; Figure 7 This is a construction drawing of the completed assembly of the self-made rotary drive drill bit of this invention. Figure 8 This is a diagram of the on-site drilling process of this invention; Figure 9 This is a diagram showing the coverage area of ​​the blasting holes in the self-made rotary drive drill bit of this invention; Figure 10 This is a field diagram of the in-hole loading of the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the present invention, and these aspects of the invention can be implemented even without these specific details.

[0032] like Figure 1 As shown, the method for graded controlled blasting of rock mass during channel excavation near structures includes the following steps: Step 1.1: Basic Data Collection and Verification Based on the geotechnical investigation report and design drawings, the lithological parameters of the blasting area and the details of the bridge substructure were determined. Combined with vibration monitoring data from the blasting on the left bank, the particle velocity and stress distribution patterns of the existing blasting were extracted as verification data for simulation analysis, ensuring that the model parameters are consistent with the actual site conditions.

[0033] Step 1.2: Construction of a refined 3D finite element model, such as... Figure 2 As shown.

[0034] A 1:1 scale integrated model of the bridge substructure (pile foundation + abutment + pier + tie beam) - abutment pit - canal bank slope - blasted rock mass was constructed using 3D finite element software. The rock mass was modeled using the MAT_MOHR_COULOMB material model, while the concrete and reinforcing steel were modeled using the MAT_PLASTIC_KINEMATIC material model. The coupling between reinforcing steel and concrete was represented by CONSTRAINT_LAGRANGIAN_IN_SOLID, and the bonding between the abutment and pier, and between the bank slope and rock mass, was represented by CONTACT_TIED_SURFACE_TO_SURFACE, avoiding mesh generation errors caused by shared nodes.

[0035] The overall mesh size of the model is uniformly 50cm. Rock mass and concrete components are divided using solid elements, while reinforcing bars are divided using rod elements. Multiple sets of blast source orientations and blast center distances are set according to actual blasting schemes to simulate the blasting effect under different construction scenarios.

[0036] Step 1.3: Dynamic response calculation and pattern analysis, such as... Figure 3-4 As shown.

[0037] The simulation focuses on three core operating conditions: ① structural vibration velocity distribution under different blast center distances (40m / 50m / 60m); ② stress transmission patterns corresponding to different step heights (6m / 8m / 9m); ③ vibration differences between different blast source orientations (the side facing the blast / the side facing away from the blast), ensuring coverage of key construction stages such as channel excavation and central rock removal.

[0038] Through model calculations, the peak mass velocity and maximum tensile stress of the substructure of the bridge were extracted: ① Vibration velocity distribution: The vibration velocity of the pile foundation gradually increases with depth (reaching the maximum value at the bottom), and there is a vibration velocity amplification effect at the top of the pier column; ② Stress distribution: There is obvious stress concentration (maximum tensile stress) at the junction of the abutment and the pile foundation, and the vibration velocity / stress on the blast-facing side is 15% to 20% higher than that on the blast-back side; ③ Attenuation law: The vibration velocity attenuation formula was obtained by fitting, which provides a quantitative basis for subsequent parameter design.

[0039] Step 1.4: Application of simulation results and parameter optimization, such as... Figure 5 As shown.

[0040] Based on the simulation results, and in accordance with the "Safety Regulations for Blasting" (GB6722-2014) and the tensile strength threshold of concrete, the operation zones are defined as follows: ① Blasting center distance < 40m: hydraulic breaking (during hydraulic breaking construction, the vibration velocity shall not exceed 2.0cm / s or the tensile stress shall not exceed the tensile strength of concrete); ② 40m ≤ blasting center distance < 50m: 8m bench deep hole blasting (single-stage charge ≤ 20.8kg); ③ Blasting center distance ≥ 50m: 9m bench deep hole blasting (single-stage charge ≤ 40.5kg).

[0041] Compare the simulated parameters with the field test blast data. If the measured vibration velocity exceeds the simulated value by more than 10%, revise the lithological attenuation coefficient (K / α value) or the explosive charge amount in the model to ensure the consistency between the simulation results and the field construction.

[0042] Step 1.5: On-site borehole location determination Based on the blasting zones determined by simulation analysis, the surface soil, gravel, and weeds of the working face are cleared first, and the slope is trimmed to ensure that there are no obstacles in the drilling area. If there are steep slopes or undulating terrain, the terrain adaptability of the backhoe excavator tracks is used to level the drilling rig parking position in advance to avoid the equipment tilting during the drilling process.

[0043] The surveyor uses GPS to lay out the hole positions. According to the hole network parameters output by the simulation analysis, the hole positions are marked on the working surface. At the same time, the design depth and angle of each hole are marked. The hole position deviation must be ≤150mm.

[0044] Step 2: Assemble the self-made rotary drive drill bit, such as... Figure 6-7 As shown.

[0045] First, lower the backhoe excavator bucket to the ground, disassemble the stick pin and connecting rod pin, and remove the bucket. During this process, be careful not to get mud or sand on the disassembled stick pin and connecting rod pin, and ensure that the seals at both ends of the bushing are not damaged. Next, lay the homemade rotary drive drill bit (including drill frame, carriage, impactor, and rotary drive device) flat on a level surface, aligning the longitudinal axis of the drill bit with the axis of the excavator stick, and ensuring the mounting base is perpendicular to the ground. Operate the excavator to align the stick and connecting rod bushings with the pin holes of the drill bit mounting base, insert the pins, install the locking bolts, apply grease, and complete the mechanical connection.

[0046] Open the oil seals of the pre-reserved hydraulic oil pipes on both sides of the excavator's boom, connect them to the hydraulic oil pipes of the drill bit, tighten the bolts, and then open the hydraulic valves; connect the air pipe of the mobile screw air compressor to the pre-reserved air pipe interface of the drill bit, using a detachable high-pressure air pipe, with the middle section fixed to the side of the excavator's boom, ensuring that the air pipe is leak-free; start the excavator and air compressor, test run the hydraulic system (operating the swing drive control lever) and air circuit, and check whether the drill bit rotates 360° smoothly and whether the impactor makes any abnormal noises.

[0047] Step 3: As Figure 8 As shown, in the 40-50m and 8m stepped areas: excavators were used with self-made rotary drive drills for drilling. The diameter of the blast holes was uniformly 90mm, and the hole depth was controlled at 8.6m (including 0.6m of extra depth). The hole layout adopted a quincunx pattern, with a hole spacing and row spacing of 3m. During drilling, the operator precisely controlled the drill bit advance speed through the hydraulic foot pedal valve in the excavator cab, while simultaneously manipulating the rotary drive device to flexibly adjust the drilling angle. Every 3m of drilling, work was paused to check the verticality of the hole axis using a plumb bob, avoiding hole deviation due to uneven rock conditions, and ensuring that the hole axis deviation was ≤1°.

[0048] Drilling in the 9m bench area (50m away) and the central rock spur area: The 9m bench area was drilled using conventional blasting hole parameters. In the central rock spur area, the borehole diameter was increased to 115mm, with a depth of 10m (including 1m ultra-deep holes), and the bottom-to-bottom distance was controlled at 4-4.5m to meet the rock spur breaking requirements. Utilizing the 360° rotation function of a self-made rotary drive drill bit, combined with the 9.85m working radius of the matching backhoe excavator, a single machine position can cover 20 basic blasting holes. When drilling into the moderately weathered rock section, the hydraulic propulsion speed needs to be appropriately reduced (from the conventional 5-8cm / s to 3-5cm / s) to avoid overloading and damage to the impactor due to increased rock hardness. Figure 9 As shown.

[0049] During drilling, the drill bit reciprocates to drill the rock. When the drill bit is pushed into the impactor and pressed against the drill sleeve, the drill bit is lifted from the bottom of the hole. Compressed gas is then forcefully blown through the drill bit to expel the debris from the hole, ensuring that the rock powder at the bottom of the hole is completely removed. This prevents residual rock powder from affecting the subsequent charging effect. At the same time, a dedicated person is assigned to clean the rock cuttings at the hole opening to prevent accumulation.

[0050] Step 4: Staged blasting, such as... Figure 10 As shown, here is the on-site construction drawing.

[0051] Remove loose rocks, weeds, and construction debris from the blasting area. For unstable rock masses at the edge of the graded areas, use small machinery to pre-pry them away to prevent flying rocks from being generated during blasting. Check the depth, diameter, and internal condition of the blasting holes in each graded area. For unqualified holes with insufficient depth or blockage, treat them as "abandoned + re-drilled". The distance between the re-drilled hole and the original hole must be ≥30cm.

[0052] Workers must wear anti-static gloves and use wooden or plastic tools to load explosives. Explosives should be loaded in stages according to the corresponding single-hole charge for each grade. Before loading each hole, the total amount of explosives should be weighed using an explosion-proof electronic scale to ensure that the actual charge deviates from the design value by ≤±5%. For basic blasting holes, continuous loading is used, with explosives inserted into the hole segment by segment. Every 30cm of explosives is gently compacted with a plastic tamping stick to ensure the explosives adhere to the hole wall. For rock blasting holes, due to their greater depth, intermittent loading is used, with dry rock chips used to separate explosive segments (each segment 1.5~2m in length) to prevent explosives from crossing segments. For holes in highly weathered rock areas, the charge amount should be reduced according to design requirements to avoid over-blasting that could lead to rock mass collapse.

[0053] Install detonators according to the tiered detonation sequence. For basic blasting holes, install the detonator centered inside the hole, fixing it in the middle of the explosive section. The lead wire (or digital detonator data cable) should be led out along one side of the hole wall to avoid compression. For rock blasting holes, install the detonator in layers, with one detonator corresponding to every 2m of explosive section to ensure uniform detonation energy. After installation, check that the detonator lead wire is free from tangling or damage. For digital detonators, the resistance (deviation ≤ ±2Ω) and communication status should be tested using the detonator.

[0054] Immediately after loading the explosive, plug the blast hole with dry clay or drill cuttings. The plugging length should be ≥1.2m for the basic blast hole and ≥1.5m for the rock spur blast hole. Fill in layers and gently compact them. The compaction thickness of each layer should be ≤10cm to avoid energy leakage due to loose plugging or damage to the detonator due to excessive tightness.

[0055] The basic blasting holes are detonated one hole at a time (with a 30ms delay between holes), while the rock spur blasting holes are detonated row by row (with a 50ms delay between rows). After the network connection is completed, the detonator is used to perform an overall test to confirm that there are no short circuits or disconnections. The detonator operator operates the detonator to detonate in the graded sequence. If a dud occurs (if it does not detonate within 5 minutes after detonation), it is necessary to wait 15 minutes and then have a professional drill a parallel hole 30cm away from the dud hole for re-blasting. It is strictly forbidden to directly treat the original hole.

[0056] Fifteen minutes after the blast, the inspection team entered the site in the order of "first the foundation area, then the rock spur area" to check the fragmentation of the blasted rock mass. The rock fragments in the foundation area were ≤50cm in size, and those in the rock spur area were ≤80cm in size, with no large boulders. The team checked the detonation rate of the boreholes (≥98%) and treated any undetonated boreholes as duds. The team also checked the surrounding environment and found no flyrock damage or risk of rock mass collapse.

[0057] Step 5: Excavating and transporting stones The excavation and transportation areas and channels are demarcated. The stockpiling areas are divided according to the stone particle size and lithology (such as strongly weathered rock and moderately weathered rock). The excavation is carried out in layers by excavators. The excavation layer height is matched with the height of the previous blasting steps to avoid over-excavation and slope instability. During excavation, the work is carried out from the edge of the working face to the center. Priority is given to excavating the stones with high looseness after blasting. For local dense areas, the excavator bucket is used to gently loosen them before excavation.

[0058] When unloading stone transport vehicles, the principle of "layered unloading and uniform stacking" must be followed in the designated stacking area. It is forbidden to unload continuously in the same position, which may cause the stack to be too high. After unloading, the vehicle must clean the residual stone in the truck bed to avoid the residual stone from clumping and affecting the next loading. After the transportation is completed, the stacking yard should be leveled in time to ensure sufficient space for subsequent unloading.

[0059] The names, specifications, and main technical indicators of the main materials are shown in Table 1.

[0060] Table 1 shows the main materials. The main machinery and equipment are shown in Table 2.

[0061] Table 2 shows the main machinery and equipment. The construction quality assurance measures are as follows: Strictly verify the simulation parameters of blasting vibration and structural response, compare the model's lithological attenuation coefficient (K / α value) and concrete tensile strength threshold with the on-site geotechnical investigation report and bridge structural design parameters, and revise the model when the deviation exceeds 5% to ensure the effectiveness of the simulation results in guiding construction.

[0062] Before determining the borehole positions, clean the surface of loose soil and gravel. Use dual GPS receivers to verify the borehole positions and ensure that the deviation is ≤150mm and the depth and angle are clearly marked. For laying out in steep slope areas, additional temporary benchmarks need to be set up for verification.

[0063] After assembling the self-made rotary drive drill bit, it is necessary to check the alignment of the drill bit with the axis of the backhoe excavator's boom (deviation ≤ 2mm). During the trial run, verify the smoothness of 360° rotation, the stability of hydraulic propulsion speed, and the air circuit sealing. If there is any jamming or air leakage, the drilling process must not be started.

[0064] During the drilling process, the verticality of the hole axis is checked with a plumb bob every 3m to ensure that the hole axis deviation is ≤1°. In the moderately weathered rock section, the hydraulic propulsion speed is strictly controlled (3~5cm / s). After every 10 holes are completed, one hole is randomly selected to check the hole depth with a measuring rope. If the depth is more than 5% too deep or too shallow, additional drilling is required.

[0065] After drilling is completed, high-pressure air is used to clean the hole, with a cleaning time of ≥30s per hole. After cleaning, check the amount of rock cuttings remaining in the hole. Only when there is no obvious rock powder accumulation at the bottom of the hole can it be accepted. Blocked or deviated holes must be abandoned and re-drilled 30cm away from the original hole position.

[0066] Before grading the blasting charge, the charge amount per hole is checked according to the blasting zone (13.5kg for the front row and 15kg for the back row in the 40-50m zone, and a maximum of 32kg beyond 50m). The charge amount is weighed hole by hole using an electronic scale. The charge amount in the strongly weathered rock area needs to be reduced by 10% to 15% according to the design, and the charge amount is supervised on site by technical personnel.

[0067] Before installing digital detonators, use an initiator to check the resistance (deviation ≤ ±2Ω) and communication status. During installation, ensure that the detonator is fixed in the middle of the explosive section, and that the lead wire is led out along the hole wall without compression. When installing detonators in layers in rock-filled holes, one detonator corresponds to every 2m explosive section. After installation, verify the quantity and position.

[0068] Dry clay blasting mud or drill cuttings are used for plugging blast holes. The plugging length of the foundation blasting hole is ≥1.2m and the plugging length of the rock spur blasting hole is ≥1.5m. When filling in layers, the compaction thickness of each layer is ≤10cm. Use a tamping stick to lightly press and check the compaction to avoid energy leakage due to being too loose or damage to the detonator due to being too tight.

[0069] Before detonation, the detonation sequence is verified (30ms delay for each basic hole and 50ms delay for each row of rock spur holes). The entire network is tested using a detonator. After confirming that there are no short circuits or disconnections, a designated person records the test data. Detonation is not allowed if the test is not passed.

[0070] Enter the site for inspection 15 minutes after the explosion. The rock particle size in the foundation area should be ≤50cm and the rock spur area should be ≤80cm. The detonation rate of the hole should be ≥98%. For unexploded or duds, parallel holes should be drilled 30cm away for re-explosion. It is strictly forbidden to directly treat the original hole. The inspection results must be recorded in writing.

[0071] Throughout the construction process, dynamic monitoring was conducted at the joints of the bridge pile foundation and abutment. Vibration sensors were used to collect vibration velocity in real time (≤2.0cm / s for bridge structures), and stress gauges were used to monitor tensile stress. Construction was immediately suspended when the threshold was exceeded, the cause was analyzed, and the blasting parameters were adjusted.

[0072] When excavating and transporting stones, the excavation layer height should be matched with the blasting bench height. A level instrument should be used to monitor the slope ratio in real time to ensure that it meets the design requirements and avoid over-excavation. Stones should be classified and stacked according to lithology. After transportation, the stockpile should be leveled to prevent the stockpile from collapsing and affecting the quality of subsequent construction.

[0073] The economic benefits achieved by this construction method: By optimizing equipment, integrating processes, and controlling materials, the construction cost of rock excavation projects near adjacent structures was effectively reduced. Verified in two actual projects, compared to traditional blasting methods, the direct economic benefits reached approximately 950,900 yuan, with significant indirect cost savings and efficiency improvements. A detailed analysis follows: Equipment cost savings: The self-made rotary drive drill bit can be directly adapted to existing backhoe excavators, eliminating the need to purchase dedicated drilling equipment (traditional down-the-hole drills cost approximately 400,000 RMB per unit). Only the cost of components such as the drill bit body and rotary drive device is required, amounting to approximately 150,000 RMB, saving approximately 400,000 - 150,000 = 250,000 RMB in equipment purchase costs. At the same time, the drill bit's 360° rotation and 9.85m working radius reduce the number of equipment transfers by approximately 200 times, saving a total of approximately 21 hours of operation time. This also reduces equipment maintenance and fuel consumption. Based on a diesel consumption of 25L / h and a diesel price of 7 RMB / L, fuel costs can be saved by approximately 21 × 25 × 7 = 3,675 RMB.

[0074] Labor and construction period cost savings: By accurately dividing the blasting zones using numerical simulation, the scope of hydraulic crushing operations is reduced, improving construction efficiency by 40% compared to the traditional "large-area hydraulic crushing" process, and shortening the construction period by a total of 37 days; based on the average daily wage of 400 yuan / person for skilled workers and 200 yuan / person for general workers, labor costs can be reduced by approximately 37 × (10 × 400 + 10 × 200) = 222,000 yuan in 37 days.

[0075] Material and resource recycling and conservation: The borehole cuttings recovery rate reaches 80%, which is used to plug the blast holes instead of purchasing externally purchased clay gunning material. The average plugging volume per hole is 0.8m³, and the total plugging material required is about 1920m³. With a cuttings replacement rate of 80%, the purchase of clay gunning material can be saved by 1920m³ × 80% = 1536m³. The unit price of clay gunning material is 200 yuan / m³, and the purchase cost is saved by 1536 × 200 = 307,200 yuan. After blasting, the stone can be used as roadbed filler or sold as building materials, which can realize the recycling of 21,000m³ of stone. Calculated at the market price of roadbed filler at 8 yuan / m³, the recycling revenue is 21,000m³ × 8 yuan / m³ = 168,000 yuan.

[0076] This project effectively solved the industry challenge of balancing safety and efficiency in rock excavation near adjacent structures, providing a replicable technical approach for similar projects and significantly improving construction safety and the stability of the surrounding environment. On one hand, through numerical simulation and graded blasting control, the blasting vibration of the bridge structure was strictly controlled within the safe threshold of ≤2.0 cm / s, preventing concrete cracking in critical components such as pile foundations and abutments, ensuring bridge operational safety, and reducing the impact on surrounding pipelines, high-voltage power towers, and residential areas, thus mitigating construction safety risks and environmental disturbances and maintaining the normal living order of nearby residents. On the other hand, the innovative application of a self-made rotary drive drilling tool overcame the limitations of traditional drilling rigs, which suffered from poor terrain adaptability and low efficiency, providing a highly efficient equipment solution for rock excavation in complex terrain and promoting the technological upgrading of waterway engineering construction equipment. Furthermore, the construction method, through energy conservation, consumption reduction, and resource recycling, reduced construction dust, noise, and solid waste emissions, meeting the requirements of green construction and sustainable development, contributing to ecological civilization construction, shortening the construction period, ensuring project quality, laying the foundation for the timely opening of waterways, improving regional shipping efficiency, and contributing to local economic development.

[0077] Application Examples I. Construction of a certain section of the Western Land-Sea New Corridor (Pinglu) Canal Waterway Project Project Overview The main construction contents include onshore earthwork, dredging and onshore earthwork transportation, reef blasting, and bank protection.

[0078] Construction status This construction method was applied in the land earthwork excavation and reef blasting of the waterway in the bridge area of ​​a certain bridge. For the blasting excavation scenario of the right channel and central rock ridge of the waterway in the bridge area, a three-dimensional finite element model of "bridge substructure-rock mass" was first constructed using finite element software to clarify the zoning scheme of hydraulic breaking within 40m, 8m bench deep-hole blasting from 40 to 50m, and 9m bench deep-hole blasting beyond 50m. In the drilling phase, a Caterpillar 323DL backhoe excavator was used with a self-made rotary drive drill bit in the waterway area of ​​the bridge. On the right side of the channel, blasting holes with a diameter of 90mm and a depth of 8.6m were drilled, and in the central rock ridge area, blasting operations with a diameter of 115mm and a depth of 10m were completed. Each machine position covered 20 blasting holes, reducing equipment transfer time. During staged blasting, the amount of explosives was controlled according to the zone, and digital electronic detonators were used to detonate each hole one by one. At the same time, the vibration velocity of the bridge abutment was monitored in real time using a TC-4850 vibration monitor. In the excavation and transportation process, the excavation was carried out in layers according to the height of the blasting benches to ensure that the bottom elevation of the channel reached the design requirement of 1.7m.

[0079] Engineering Evaluation The application of this construction method in the blasting excavation of the bridge area waterway has yielded significant results. First, through graded blasting and vibration control, no concrete cracking occurred in the bridge pile foundations and abutments. The vibration velocity of the surrounding Luwu Town Central Kindergarten office building (220m from the blasting area) and residential buildings (100m from the blasting area) was ≤1.5cm / s, achieving safety protection for sensitive structures. Second, the self-made rotary drive drilling tool is adapted to complex terrain, increasing drilling efficiency by 40% compared to traditional drilling rigs and reducing equipment transfer time by 6.3min / time, helping to complete the blasting excavation of 272,400 m³ on the right side of the bridge area waterway and 63,450 m³ in the central rock ridge 22 days ahead of schedule. Third, the borehole cuttings recovery rate reached 80%, which was used to plug the blast holes instead of purchasing external clay, saving material costs of 186,000 yuan. At the same time, the stones after blasting can be used as filler for the revetment project, reducing the amount of solid waste transported, which meets the requirements of green construction and provides a technical demonstration for the subsequent bridge area waterway excavation of the Pinglu Canal.

[0080] II. Phase IV Expansion Project of a Certain Waterway in Xiamen Project Overview The project starts from point E' and ends at point E8, west of berth 24 in Haicang, with a total length of 11.50km. The core of the project involves blasting reefs and dredging infrastructure in sections such as berths E'-13 (navigation width 395m, bottom elevation -15.0~-15.5m) and berths 13-17 (navigation width 275m, bottom elevation -15.0m). The blasting volume is 92,800 m³ and the debris removal volume is 728,600 m³. The project needs to ensure the navigation needs of 200,000-ton container ships and other vessels.

[0081] Construction status This construction method was applied in the blasting of reefs in the section of berths 13#-17# and the rock excavation for supporting infrastructure dredging in the section of berth E'-13#. For sensitive areas within the section adjacent to wharf pile foundations and pipelines, numerical simulation was first used to delineate areas within 30m for hydraulic breaking and 30~45m for... The operation was divided into 7m bench blasting and 8m bench blasting at 45m depth. For drilling, a self-made rotary drilling rig was used in conjunction with a backhoe excavator to drill 90mm diameter, 7.6m deep blasting holes in the reef blasting area and 100mm diameter, 8.6m deep holes in the dredging rock excavation area. The 360° rotation of the drilling rig was used to cover scattered blasting holes around the wharf, reducing equipment interference with the wharf work surface. During staged blasting, the charge was adjusted according to the lithology of the navigation section, and digital electronic detonators were used for initiation (50ms delay), while simultaneously monitoring the vibration velocity of the wharf pile foundation (≤2.0cm / s). After blasting, the debris was transported to a designated storage yard using excavation and transportation equipment, with some used for backfilling of the channel revetment and connecting to the dredging construction of the berth section.

[0082] Engineering Evaluation This construction method effectively solved the problem of "coordinating blasting and wharf protection" in the expansion of a waterway in Xiamen. First, through zoned blasting and precise vibration control, the vibration velocity of the pile foundations of the wharf at berths 13#-17# was ≤1.8cm / s throughout, without affecting the structural stability of the existing wharf. After blasting the reef in the E'-13# section, the elevation deviation of the channel bottom was ≤±200mm, meeting the navigation requirements of 200,000-ton container ships. Second, the self-made rotary drive drilling tool has stronger adaptability than traditional down-the-hole drilling rigs, increasing drilling efficiency by 35% in narrow working areas around the wharf and reducing equipment transfers by 60%, helping to complete the blasting project 15 days ahead of schedule and ensuring the waterway expansion schedule. Third, drill cuttings were recycled for blast hole plugging and slag was used for bank revetment backfilling, saving a total of 121,000 yuan in material and transportation costs. At the same time, blasting noise and dust emissions met the requirements, achieving a win-win situation for project construction and ecological protection, and providing a scalable technical solution for blasting reefs and excavating rock masses in sensitive areas of coastal port waterways.

[0083] Matters not covered in this invention are common knowledge.

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for graded controlled blasting of rock mass during channel excavation near structures, characterized in that, The method includes the following steps: Step 1: Simulation and analysis of blasting vibration and structural response. First, basic data is collected and verified. Then, a refined three-dimensional finite element model is constructed. Finally, dynamic response calculation and law analysis are performed, and simulation parameters are optimized. Step 2: Based on the blasting zones determined by the simulation analysis, the surveyor uses a positioning device to lay out the hole positions. According to the hole network parameters output by the simulation analysis, the hole positions are marked on the working surface. At the same time, the design depth and angle of each hole are marked. The hole position deviation must be ≤150mm. Step 3: Design and manufacture a rotary drive drill bit. There is no need to purchase a special drilling machine. It can be quickly installed directly on the existing backhoe excavator. The rotary drive device can achieve 360° planar rotation and three-dimensional multi-directional angle control, which overcomes the shortcomings of traditional drilling machines such as angle limitation and weak terrain adaptability. Step 4: Use an excavator with a self-made rotary drive drill bit to drill a hole; Step 5: Load explosives into the borehole to remove unstable rock masses at the edge of the grading zone and control blasting in stages; Step 6: Delineate the excavation and transportation area and the transport channel. Divide the stockpiling area according to the stone particle size and lithology. Use an excavator to excavate in layers. The excavation layer height should match the height of the previous staged blasting steps to avoid over-excavation that could lead to slope instability. Complete the excavation and transportation of the stone.

2. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: In step 1, the specific process of basic data collection and verification is as follows: based on the geotechnical engineering investigation report and design drawings, the lithological parameters of the blasting area and the details of the bridge substructure are clarified. Combined with the existing blasting vibration monitoring data, the particle vibration velocity and stress distribution law of the existing blasting are extracted as the verification basis for simulation analysis to ensure that the model parameters are consistent with the actual situation on site.

3. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: The specific process of constructing a refined three-dimensional finite element model in step 1 is as follows: using finite element software, an integrated model of the bridge substructure, abutment foundation pit, canal bank slope, and blasted rock mass is constructed at a 1:1 scale. Among them, the rock mass adopts the MAT_MOHR_COULOMB material model, the concrete and steel reinforcement adopt the MAT_PLASTIC_KINEMATIC material model, the coupling between steel reinforcement and concrete is CONSTRAINT_LAGRANGIAN_IN_SOLID, and the bonding between the abutment and pier, and between the bank slope and rock mass is CONTACT_TIED_SURFACE_TO_SURFACE, to avoid mesh generation errors caused by shared nodes. The integrated model uses a unified mesh size, with rock mass and concrete components divided by solid elements and reinforcing bars divided by rod elements. Several sets of blast source orientations and blast center distances are set according to the actual blasting scheme to simulate the blasting effect under different construction scenarios.

4. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: In step 1, the specific process of dynamic response calculation and law analysis is to simulate three types of core working conditions: first, the structural vibration velocity distribution under different blast center distances; second, the stress transmission law corresponding to different step heights; and third, the vibration difference of different blast source orientations, to ensure the key construction stages of covering the waterway excavation and central rock spur removal. Through calculation, the peak mass velocity and maximum tensile stress of the substructure of the bridge were extracted. In the velocity distribution, the pile foundation velocity gradually increases with depth, reaching the maximum value at the bottom. There is a velocity amplification effect at the top of the pier. In the stress distribution, stress concentration occurs at the junction of the abutment and the pile foundation, with the maximum tensile stress. The velocity and stress on the blast-facing side are higher than those on the blast-back side. In the attenuation law, the velocity attenuation formula was fitted to provide a quantitative basis for subsequent parameter design.

5. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: In step 1, the specific process of optimizing the simulation parameters is as follows: Based on the simulation results, combined with the "Blasting Safety Regulations" and the tensile strength threshold of concrete, the operation zones are delineated: ① For blast center distance < 40m, hydraulic breaking is used, and the vibration velocity of hydraulic breaking construction cannot exceed 2.0cm / s, and the tensile stress cannot exceed the tensile strength of concrete; ② For blast center distance 40m ≤ blast center distance < 50m, 8m bench deep-hole blasting is used, and the single-stage charge is ≤ 20.8kg; ③ For blast center distance ≥ 50m, 9m bench deep-hole blasting is used, and the single-stage charge is ≤ 40.5kg. Compare the simulated parameters with the field test blast data. If the measured vibration velocity exceeds the simulated value by more than 10%, revise the lithology attenuation coefficient or explosive charge in the model to ensure consistency between the simulation results and the field construction. Adjust the charge structure according to different lithologies, and optimize the hole pattern parameters and initiation method for different regions.

6. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: Step 3 involves lowering the backhoe excavator bucket to the ground, disassembling the stick pin and connecting rod pin, and removing the bucket. During this process, care must be taken to ensure that the disassembled stick pin and connecting rod pin are not contaminated with mud or sand, and that the seals at both ends of the bushing are not damaged. Then, place the homemade rotary drive drill bit flat on a level surface, aligning the longitudinal axis of the drill bit with the axis of the excavator stick, and ensuring the mounting base is perpendicular to the ground. Operate the excavator to align the stick and connecting rod bushing with the pin holes of the drill bit mounting base, insert the pins, install the locking bolts, apply grease, and complete the mechanical connection. Open the oil seals of the hydraulic oil pipes reserved on both sides of the excavator's boom and connect them to the hydraulic oil pipes of the drill bit. After tightening the bolts, open the hydraulic valves and connect the air pipe of the mobile screw air compressor to the air pipe interface reserved on the drill bit. Use a detachable high-pressure air pipe, with the middle section fixed to the side of the excavator's boom, ensuring that there is no air leakage in the air pipe. Start the excavator and air compressor, test run the hydraulic system and air circuit, and check whether the drill bit rotates 360° smoothly and whether there are any abnormal noises from the impactor.

7. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: The self-made rotary drive drill string includes a drill frame, a slide, an impactor, and a rotary drive device. The slide is slidably mounted on the drill frame, the impactor is mounted on the top of the slide, and the rotary drive device is mounted on the slide.

8. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: Step 4 involves the following process: In the blasting zone of 40-50m and 8m steps, an excavator is used with a self-made rotary drive drill bit to carry out the operation. The hole layout adopts a quincunx pattern. During the drilling process, the operator precisely controls the drill bit advance speed through the hydraulic foot valve in the excavator cab, and at the same time manipulates the rotary drive device to flexibly adjust the drilling angle. The operation must be paused after drilling a fixed depth, and the verticality of the hole axis is checked with a plumb bob to avoid hole inclination due to uneven rock properties, and to ensure that the hole axis deviation is ≤1°. Using the 360° rotation function of the self-made rotary drive drill bit, combined with the working radius of the matching backhoe excavator, a single machine position can cover 20 basic blasting holes. When drilling into the moderately weathered rock section, the hydraulic propulsion speed should be appropriately reduced to avoid the impactor being overloaded and damaged due to the increased rock hardness. During drilling, the drill bit reciprocates to drill the rock. When the drill bit is pushed into the impactor and pressed against the drill sleeve, the drill bit is lifted from the bottom of the hole. Compressed gas is then blown through the drill bit to expel the debris from the hole, ensuring that the rock powder at the bottom of the hole is completely removed and avoiding residual rock powder from affecting the subsequent charging effect. At the same time, a special person is assigned to clean the rock cuttings at the hole opening to prevent accumulation.

9. The method for graded controlled blasting construction of waterway excavation near structures according to claim 1, characterized in that: The specific process of step 5 is as follows: remove loose rocks, weeds and construction debris in the blasting area; use mechanical pre-prying to remove unstable rock masses at the edge of the graded area to prevent flying rocks during blasting; check the hole depth, hole diameter and hole condition of the blasting holes in each graded area; and treat unqualified holes with insufficient depth or blockage as abandoned or re-drilled. The distance between the re-drilled hole and the original hole must be ≥30cm. Workers must wear anti-static gloves and use wooden or plastic tools to load explosives. Explosives should be loaded in stages according to the corresponding single-hole charge for each grade. Before loading each hole, the total amount of explosives should be weighed using an explosion-proof electronic scale to ensure that the actual charge deviates from the design value by ≤±5%. Continuous loading is used for basic blasting holes, with explosives being loaded into the hole segment by segment. Every 30cm of loading, a plastic tamping stick is used to gently compact the explosives, ensuring they adhere to the hole wall. Intermittent loading is used for rock ridge blasting holes, with dry rock chips used to separate explosive segments to prevent cross-contamination. For holes in areas of strongly weathered rock, the charge amount should be reduced according to design requirements to avoid excessive blasting that could lead to rock mass collapse. Install detonators according to the graded detonation sequence. For basic blasting holes, install the detonator in the center of the hole and fix it in the middle of the explosive section. The lead wire is led out along one side of the hole wall to avoid compression. For rock blasting holes, install the detonator in layers, with one detonator corresponding to every 2m explosive section to ensure uniform detonation energy. After installation, check that the detonator lead wire is not tangled or damaged. Digital detonators need to have their resistance and communication status tested by the detonator. Immediately after loading the explosive, plug the blast hole with dry clay or drill cuttings. The plugging length should be ≥1.2m for the basic blast hole and ≥1.5m for the rock spur blast hole. Fill in layers and gently compact them. The compaction thickness of each layer should be ≤10cm to avoid energy leakage due to loose plugging or damage to the detonator due to excessive tightness. The basic blasting holes are detonated one hole at a time, while the rock spur blasting holes are detonated row by row. After the network connection is completed, the detonator is used to conduct an overall test to confirm that there are no short circuits or disconnections. The detonator operator operates the detonator to detonate in the graded sequence. If a dud occurs, it is necessary to wait 15 minutes and then have a professional drill a parallel hole 30cm away from the dud hole for re-blasting. It is strictly forbidden to directly treat the original hole.

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