Dry ice energy gathering directional fracturing rock breaking method

Abstract

The invention discloses a dry ice energy gathering directional fracturing rock breaking method which comprises the following steps: firstly, drilling a fracturing hole, filling a fracturing pipe with dry ice and an energy gathering agent, and installing an energy absorption system, a side wall energy release groove and an adjustable flow deflector; then, rock mass parameters are input through a wireless terminal to automatically match blasting parameters; then an initiation signal is sent to ignite the energy gathering agent, the delay powder and the initiating explosive, the energy gathering agent is ignited in a segmented mode through chemical delay design, dry ice gasification is accelerated, and rock breaking work is conducted; in the rock breaking process, blasting parameters are dynamically adjusted according to rock mass fracture signals fed back in real time, and directional rock breaking is achieved; after the rock breaking work is finished, the fracturing pipe is recycled, and the integrity of the assembly is checked; the fracture length is obtained and compared with a theoretical value, and deviation is recorded and stored in a historical blasting database; and finally, the ratio of the fracture length to the energy serves as a reward function, and blasting parameters are updated through machine learning iteration by using a historical blasting database. According to the invention, intelligent regulation and control of the dry ice energy-gathered directional fracturing rock breaking process are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering blasting, and particularly relates to a method for dry ice energy-gathering directional fracturing of rock. Background Art

[0002] In the field of engineering blasting, rock-breaking technology has always been a hot and difficult research topic. With the continuous advancement of infrastructure construction, the demand for efficient, safe, and environmentally friendly rock-breaking technology is becoming increasingly urgent. At present, the commonly used rock-breaking processes for rock mass excavation include drill and blast method, mechanical method, static (expansion agent) blasting method, hydraulic fracturing method, etc., but these methods all have different degrees of limitations. For example, the drill and blast method is widely used, but the phenomena such as vibration and flying rocks generated by it have a greater impact on the surrounding environment, and it is difficult to precisely control the rock-breaking effect; the mechanical rock-breaking method has problems such as low rock-breaking efficiency, high manual labor intensity, and difficulty in breaking hard rocks; the static blasting method has disadvantages such as high cost and uncertain expansion direction, which limit its application scope; the hydraulic fracturing method has technical bottlenecks such as environmental pollution.

[0003] In recent years, as an emerging rock-breaking technology, the carbon dioxide phase change fracturing technology has gradually attracted attention. This technology uses the high-pressure gas generated by the gasification of dry ice to achieve the fracturing of rock mass, and has the advantages of good safety, convenient operation, controllable rock-breaking direction, and small vibration pollution. However, there are still many problems in the existing carbon dioxide fracturing technology, such as high risk of flying pipes, insufficient energy release, lack of real-time feedback in detonator control, and parameter adjustment relying on manual experience. These problems lead to unstable blasting effects and are difficult to meet the complex and changeable engineering requirements. Summary of the Invention

[0004] The main purpose of the present invention is to overcome the disadvantages and deficiencies of the existing technology, and provide a method for dry ice energy-gathering directional fracturing of rock. By introducing an advanced electronic detonator intelligent control system, an energy absorption system, and a dynamic adjustment mechanism, it aims to achieve precise control of the blasting process and significant improvement of the rock-breaking effect, thereby overcoming the disadvantages of the existing technology and meeting the urgent needs of the engineering blasting field for efficient, safe, and environmentally friendly rock-breaking technology.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: A method for dry ice energy-gathering directional fracturing of rock, comprising the following steps: Drilling a fracturing hole in the rock mass to be blasted; the diameter, depth, and inclination angle of the fracturing hole are dynamically designed according to the hardness of the rock mass; Filling dry ice and an energy-gathering agent into the fracturing tube and completing the sealing; an electronic detonator intelligent control system is installed in the fracturing tube; the electronic detonator intelligent control system includes an electronic control module, a high-sensitivity microseismic monitoring sensor, a bridge wire discharge module, delay charge, and detonating charge; An energy absorption system is installed at the top of the fracturing tube, a sidewall energy dissipation groove is provided on the sidewall of the fracturing tube, and an adjustable guide vane is installed below the exhaust hole of the fracturing tube. The sidewall energy dissipation groove and the adjustable guide vane are both connected to the electronic detonator intelligent control system via an electric control cable. The energy absorption system is used to dissipate the blasting impact energy and suppress the upward throw or deviation of the fracturing tube body. The sidewall energy dissipation groove controls the gas flow rate and direction through the cross-sectional area, adjusting the distribution of the blasting energy. The adjustable guide vane is used to adjust the injection angle of the airflow and control the direction of the crack expansion in the rock mass to be blasted. The fracturing tube is placed in the drilled fracturing hole, and rock mass parameters are input through a wireless terminal, and the electronic control module automatically matches the blasting parameters; the rock mass parameters include hardness, density, elastic modulus, Poisson's ratio, and fracture toughness; the blasting parameters include guide vane angle, energy dissipation groove cross-sectional area, charge amount, fracturing hole spacing, fracturing hole diameter, fracturing hole depth, and detonator delay; A detonation signal is sent to the fracturing tube via a wireless terminal. The electronic control module receives the signal and generates an encrypted detonation command, which is then transmitted to the bridge wire discharge module via a foot line. The bridge wire discharge module then discharges the signal to generate high-temperature energy, igniting the energy-gathering agent, which in turn ignites the delay charge and the detonator. The energy-gathering agent is detonated in stages through a chemical delay design, accelerating the gasification of dry ice for rock breaking. During rock breaking, the electronic control module obtains real-time feedback from the highly sensitive microseismic monitoring sensor on rock fracture signals, dynamically adjusts blasting parameters, and conducts targeted rock breaking. If the highly sensitive microseismic monitoring sensor fails, the electronic control module automatically switches to the preset conservative parameters and triggers an audible and visual alarm. After the rock breaking work is completed, the fracturing pipe is recovered and the integrity of the components is checked; Obtain the crack length and compare it with the theoretical value, record the deviation and store it in the historical blasting database; The ratio of crack length to energy is used as the reward function, and the blasting parameters are iteratively updated through machine learning using a historical blasting database.

[0006] As a preferred technical solution, the fracturing pipe adopts a double-layer composite pipe body design; The outer tube body is made of elastic composite material to absorb the impact blasting energy; the fiber volume fraction of the elastic composite material is greater than 60%; The inner tube body is made of high-strength alloy steel to absorb impact and prevent dry ice from vaporizing; the yield strength of the high-strength alloy steel is σ y ≥800MPa, wall thickness meets: , in, t 0 is the wall thickness of the inner layer of high-strength alloy steel, P max is the maximum working pressure, unit: MPa;r is the inner radius, unit: mm; η is the welding coefficient; Δ t corr is the corrosion allowance, unit: mm; The central chamber of the double-layer composite pipe body is filled with dry ice, which directly contacts the inner wall of the high-strength alloy steel of the inner pipe body; the inner wall is coated with a heat-insulating coating; the periphery of the dry ice is evenly wrapped with an energy-gathering agent and is in close contact with the dry ice; the energy-gathering agent releases energy through a chemical reaction after detonation, accelerating the gasification of the dry ice; An electronic detonator intelligent control system is installed in the annular space between the outer pipe body and the inner pipe body of the double-layer composite pipe body; the electronic detonator intelligent control system is fixed by a bracket or a card slot and is connected to an external wireless terminal through a leg wire led out from the outer pipe body.

[0007] As a preferred technical solution, the energy absorption system is a three-stage energy absorption system, including a damping energy absorption mechanism, an oil pressure energy absorption mechanism, and a stiffness energy absorption mechanism; The damping energy absorption mechanism is connected to the oil pressure energy absorption mechanism and contacts the wall of the fracture hole, and absorbs the initial impact energy of the rock-breaking work by adjusting the damping force through a magnetic field; The oil pressure energy absorption mechanism provides buffering and resists the oil pressure by compressing hydraulic oil; The stiffness energy absorption mechanism absorbs the residual impact energy through a non-linear change in stiffness; the bottom of the stiffness energy absorption mechanism is welded to the top cover of the fracture pipe.

[0008] As a preferred technical solution, the damping energy absorption mechanism includes a horizontally telescopic stop mechanism and a magnetorheological fluid damper; the horizontally telescopic stop mechanism is composed of a bolt and a hydraulic cylinder driving a transverse telescopic arm; the end of the hydraulic cylinder driving the transverse telescopic arm is connected to the magnetorheological fluid damper; the bolt is connected and fixed to the oil pressure energy absorption mechanism; the horizontally telescopic stop mechanism is located on the outermost side of the fracture pipe, uses the hydraulic cylinder to provide power, and makes the hydraulic cylinder drive the transverse telescopic arm to move horizontally and contact the wall of the fracture hole by adjusting the bolt; the magnetorheological fluid damper is internally provided with a piston and magnetorheological fluid, the piston rod is rigidly connected to the horizontally telescopic stop mechanism, and absorbs the initial impact energy generated by blasting by adjusting the damping force through a magnetic field; the formula for the magnetorheological fluid damper to adjust the damping force through a magnetic field is: F d = ( F η + F τ )∙ A p , where, F η is the viscous damping force, F τ is the magnetic field-induced shear force,A p is the piston area; The hydraulic pressure energy absorption mechanism includes an oil cylinder, hydraulic oil, a flow limiting orifice, and an anti-hydraulic pressure rubber plug; the oil cylinder is located below the damping energy absorption mechanism, and the cylinder body is bolted to the base of the magnetorheological damper; the hydraulic oil fills 85% - 90% of the volume of the oil cylinder; the anti-hydraulic pressure rubber plug is installed at the bottom of the oil cylinder and contacts the top of the spring of the stiffness energy absorption mechanism; the flow limiting orifice is provided on the side of the cylinder body; The stiffness energy absorption mechanism includes a spring and a guide rail; the spring adopts a variable pitch design and is installed inside the guide rail, with an initial pre-compression amount in contact with the anti-hydraulic pressure rubber plug; the guide rail wraps the spring to limit the freedom degree of the spring in the horizontal direction; the stiffness of the spring changes non-linearly as: , and the stiffness characteristic satisfies: , wherein, k ( x ) is the instantaneous stiffness of the spring, unit: N / m; x is the compression amount of the spring, unit: m; G is the shear modulus of the spring material, unit: Pa; d is the diameter of the spring, unit: m; D is the mean diameter of the spring, unit: m; n is the number of effective turns of the spring; L 0 is the free length of the spring, i.e., the original length when not under force, unit: m; m p is the mass of the pipe body of the fracturing pipe, v p is the estimated impact velocity.

[0009] As a preferred technical solution, the side wall energy dissipation groove is of a Venturi structure; the adjustable flow guiding vane adopts a NACA airfoil profile.

[0010] As a preferred technical solution, after the fracturing pipe is placed into the drilled fracturing hole, rotate the bolt of the horizontally telescopic stop mechanism so that the contact pressure between the magnetorheological damper and the fracturing hole wall is greater than or equal to 5 MPa to trigger the linkage of the three-stage energy absorption system.

[0011] As a preferred technical solution, the blasting parameters are dynamically adjusted to carry out rock breaking work directionally, specifically: Based on the feedback gas pressure of the pressure sensor, the cross-sectional area of the energy dissipation groove is dynamically adjusted, and the dynamic adjustment method is: , wherein, A newis the cross-sectional area of the energy-dissipating groove after adjustment, A old is the cross-sectional area of the energy-dissipating groove before adjustment, P actual is the actual gas pressure measured by the pressure sensor, P target is the target gas pressure; Dynamically adjust the angle of the deflector based on the inclination angle of the fracturing hole and the target fracture direction and in combination with manual adjustment. The dynamic adjustment formula is: , where, θ is the angle of the deflector after adjustment, k a is the inclination angle coupling coefficient; Δ θ adj is the manual adjustment increment, with a range of ±5°; α and β are the inclination angle of the fracturing hole and the target fracture direction respectively. The drilling inclination angle is the angle between the fracturing hole and the horizontal plane; the target fracture direction is the preset fracture propagation direction; According to the rock mass vibration frequency monitored by the high-sensitivity microseismic sensor f , if f > 50Hz, dynamically adjust the detonator delay according to the following formula t : , where, t is the detonator delay after adjustment, t base is the reference detonator delay, f is the rock mass vibration frequency monitored by the microseismic sensor, K H is the hardness coefficient.

[0012] As a preferred technical solution, the recovery of the fracturing tube and the inspection of the component integrity are specifically as follows: Conduct targeted inspection on the damping energy-absorbing mechanism, but there is no need for full disassembly and maintenance after each blasting; Check the integrity of the oil cylinder. If the integrity is good, replenish the hydraulic oil to 90% ± 5% of the volume; Check the spring loss. If the spring loss is less than the set allowable loss, recover and continue to use; Clean the residues in the energy-dissipating groove and the exhaust hole of the fracturing tube; Recover the deflector and check and maintain its structural integrity and angle adjustment function.

[0013] As a preferred technical solution, the calculation formula for the ratio of the fracture length to the energy is: , Among them, L is the crack propagation length, unit: m; K is the fracture toughness of the rock mass, unit: ; E is the energy release, unit: J; σ t is the tensile strength of the rock mass, unit: Pa.

[0014] As an optimal technical solution, the ratio of the crack length to the energy is used as the reward function, and the Actor-Critic algorithm is used to iteratively optimize the blasting parameters through the dual mechanisms of policy evaluation and value function update. Specifically: Construct an Actor network and a Critic network, and define the environment, state, and action; the environment consists of rock mass parameters, sensor data, and crack propagation results; the state consists of blasting parameters; the action consists of the adjustment method of blasting parameters; The Actor network generates a policy s t according to the input state π θ , selects an action a t and interacts with the environment to obtain a reward and the next state s t+1 ; the Critic network uses the value function V π to evaluate the state s t and the next state s t+1 of the state value V π ( s t ), V π ( s t+1 ), calculates the temporal difference error δ t to provide a basis for policy generation; the temporal difference error calculation formula is: δ t = r t + γV π ( s t+1 ) - V π ( s t ), Among them, γ is the discount factor, r tis an immediate reward; δ t is the estimated error; V π ( s t ) and V π ( s t+1 ) are the state values estimated by the Critic network for the current state s t and the next state s t+1 respectively; The Actor network updates its parameters through policy gradients: , where represents the gradient of the objective function J ( θ ) with respect to the set of Actor network parameters θ ; represents the expectation operation under the policy π θ ; π θ ( a t | s t ) is the probability that the Actor network selects the action s t in the state a t ; Iterative training is performed until the convergence condition is reached; The convergence condition includes that the fluctuation of the reward function is less than the set reward threshold, the deviation of the crack length is within the set deviation threshold, and the energy consumption is maintained in the range of 95% - 105% of the theoretical value; During the training process, when the blasting for a continuous set number of times meets the conditions, the optimal policy parameters are locked.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. Through the double - layer composite pipe body design and the three - stage energy absorption system, the present invention solves the problems of high risk of flying pipes and insufficient energy release in the existing related technologies. The combined design of the outer elastic composite material and the inner high - strength alloy steel can absorb the blasting impact energy and ensure the stability of the high - pressure pipe body. The three - stage energy absorption system (damping energy absorption mechanism, oil - pressure energy absorption mechanism, and stiffness energy absorption mechanism) dissipates energy step by step, inhibits the upward throwing or deviation of the pipe body, and improves the pipe body recovery rate.

[0016] 2. The present invention introduces an intelligent control system for electronic detonators and a real-time dynamic adjustment mechanism, overcoming the limitation in traditional technologies that parameter adjustment relies on manual experience. Through the real-time feedback of highly sensitive microseismic monitoring sensors, the system dynamically adjusts key parameters such as the cross-sectional area of the energy-dissipating groove, the angle of the flow guide vane, and the detonator delay time, achieving precise distribution of blasting energy and accurate control of the crack propagation direction. Even in the case of sensor failure, the system can automatically switch to preset conservative parameters and trigger an alarm, ensuring the safety and reliability of the blasting process.

[0017] 3. After blasting, the present invention uses machine learning algorithms (such as the Actor-Critic algorithm) to iteratively optimize the blasting parameters, improving the adaptability and intelligence level of the technology. By using the ratio of crack length to energy as the reward function, the system can continuously optimize the parameter combination based on historical blasting data, gradually reducing the dependence on manual experience.

[0018] 4. The recyclable design of the fracturing tube assembly in the present invention makes maintenance more convenient and reduces the long-term use cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a schematic flowchart of the implementation process of the dry ice energy-gathering directional fracturing rock-breaking method in the embodiment of the present invention.

[0021] Figure 2 It is a schematic structural diagram of the dry ice fracturing tube in the embodiment of the present invention.

[0022] Figure 3 It is a schematic structural diagram of the intelligent control system for electronic detonators in the embodiment of the present invention.

[0023] Reference numerals: 1. Bolt; 2. Horizontally telescopic stop mechanism; 3. Magnetorheological damper; 4. Current-limiting orifice; 5. Hydraulic oil; 6. Oil cylinder; 7. Oil-pressure-resistant rubber plug; 8. Spring; 9. Guide rail; 10. Intelligent control system for electronic detonators; 11. Energy-gathering agent; 12. Dry ice; 13. Heat-insulating coating; 14. Elastic composite outer layer tube; 15. High-strength alloy steel inner layer tube; 16. Sidewall energy-dissipating groove; 17. Flow guide vane; 18. Leg wire; 19. Highly sensitive microseismic monitoring sensor; 20. Electronic control module; 21. Bridge wire discharge module; 22. Delay charge; 23. Detonating charge. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of this application.

[0025] In this application, the mention of "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of this application. The phrase appears in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described in this application can be combined with other embodiments.

[0026] As Figures 1 - 3 shown, this embodiment provides a method for dry ice energy-gathering directional rock fracturing, including the following steps: S1. Drill fracturing holes in the rock mass to be blasted. Among them, the diameter, depth and inclination angle of the fracturing holes are dynamically designed according to the hardness of the rock mass; for example, for hard rock (such as granite), dense hole arrangement (spacing ≤ 1.5 times the hole diameter) is adopted, and for soft rock (such as sandstone), it can be appropriately relaxed to 2 times the hole diameter.

[0027] S2. Fill dry ice (12) and energy-gathering agent (11) into the fracturing tube and complete the sealing, and control the filling density of dry ice to balance the gasification rate and pressure stability; an electronic detonator intelligent control system (10) is installed in the fracturing tube, and the system includes an electronic control module (20), a high-sensitivity microseismic monitoring sensor (19), a bridge wire discharge module (21), delay charge (22) and detonating charge (23).

[0028] S3. Install an energy absorption system at the top of the fracturing tube, set side wall energy-discharging grooves (16) on the side wall of the fracturing tube, and install adjustable flow guiding vanes (17) below the exhaust holes of the fracturing tube; the above components are all connected to the electronic detonator intelligent control system (10) through electric control cables and work in coordination under its instructions. Among them, the energy absorption system (10) is used to dissipate the blasting impact energy and inhibit the upward throwing or deviation of the fracturing tube body; the side wall energy-discharging grooves (16) control the pressure and direction of the explosion-discharging jet by adjusting the cross-sectional area and adjust the distribution of the blasting energy; the adjustable flow guiding vanes (17) are used to adjust the jet angle of the air flow and control the propagation direction of the explosion-generated cracks in the rock mass to be blasted.

[0029] Further, the fracturing pipe adopts a double-layer composite pipe body design. The outer pipe body (14) is made of an elastic composite material with a fiber volume fraction > 60% to absorb the impact energy of blasting and ensure the structural integrity of the pipe body. The inner pipe body (15) is made of high-strength alloy steel to absorb impact and prevent dry ice gasification. Among them, the yield strength of the high-strength alloy steel σ y ≥ 800 MPa, and the wall thickness satisfies: , where t 0 is the wall thickness of the inner high-strength alloy steel, P max is the maximum working pressure, unit: MPa; r is the inner radius, unit: mm; η is the welding coefficient; Δ t corr is the corrosion allowance, unit: mm.

[0030] The central chamber of the double-layer composite pipe body is filled with dry ice, which directly contacts the inner wall of the high-strength alloy steel of the inner pipe body. The inner wall is coated with a heat insulation coating (13) to reduce heat dissipation during the gasification of dry ice and ensure that dry ice quickly gasifies to generate high-pressure gas under controlled conditions. The shaped charge is evenly wrapped around the dry ice and is in close contact with the dry ice. The shaped charge releases energy through a chemical reaction after detonation to accelerate the gasification of dry ice. In the annular space between the outer pipe body and the inner pipe body, an electronic detonator intelligent control system is installed. The system is fixed by brackets or chucks, and the leg wires are led out from the outer pipe body and connected to an external wireless terminal.

[0031] Further, the energy absorption system of the present application is a three-stage energy absorption system, which can not only dissipate the blasting impact energy step by step, suppress the upward throwing or deviation of the pipe body (i.e., flying pipe), and improve the pipe body recovery rate, but also dynamically respond to the transient change of the blasting pressure through the cooperation of different components. The three-stage energy absorption system includes a damping energy absorption mechanism, an oil pressure energy absorption mechanism, and a stiffness energy absorption mechanism. Among them, the damping energy absorption mechanism is connected to the oil pressure energy absorption mechanism and contacts the fracture hole wall, and absorbs the initial impact energy of the rock breaking work by adjusting the damping force through a magnetic field. The oil pressure energy absorption mechanism provides buffering and resists the oil pressure by compressing hydraulic oil. The stiffness energy absorption mechanism absorbs the residual impact energy through the non-linear change of stiffness, and its bottom is welded to the top cover of the fracturing pipe.

[0032] Furthermore, the damping and energy absorption mechanism includes a horizontally telescopic stop mechanism (2) and a magnetorheological fluid damper (3). Among them, the horizontally telescopic stop mechanism (2) is composed of a bolt (1) and a laterally telescopic arm driven by a hydraulic cylinder. The end of the laterally telescopic arm driven by the hydraulic cylinder is connected to the magnetorheological fluid damper (3); the damping and energy absorption mechanism is fixedly connected to the hydraulic pressure energy absorption mechanism through the bolt (1). The horizontally telescopic stop mechanism (2) is located on the outermost side of the fracturing pipe. Using the power provided by the hydraulic cylinder, the laterally telescopic arm driven by the hydraulic cylinder is horizontally moved to contact the wall of the fracturing hole. The magnetorheological fluid damper (3) is internally provided with a piston and magnetorheological fluid. The piston rod is rigidly connected to the horizontally telescopic stop mechanism, and the damping force is adjusted through a magnetic field to absorb the initial impact energy generated by blasting and prevent the fracturing pipe from being thrown up or offset. The damping force adjustment formula is: F d = ( F η + F τ )∙ A p , wherein, F η is the viscous damping force, F τ is the magnetic field-induced shear force, A p is the piston area.

[0033] For the hydraulic pressure energy absorption mechanism, it includes an oil cylinder (6), hydraulic oil (5), a flow-limiting orifice (4), and an anti-hydraulic pressure rubber plug (7); the oil cylinder (6) is located below the damping and energy absorption mechanism, and the cylinder body is bolt-fixed to the base of the magnetorheological fluid damper (3); the hydraulic oil (5) fills 85% - 90% of the volume of the oil cylinder (6), leaving a compression space; the anti-hydraulic pressure rubber plug (7) is installed at the bottom of the oil cylinder (6) and contacts the top of the spring (8) of the stiffness energy absorption mechanism; the flow-limiting orifice (4) is arranged on the side of the cylinder body. During the rock-breaking operation, when the explosion-relieving energy comes, the high-pressure gas will push the anti-hydraulic pressure rubber plug (7) to compress the hydraulic oil (5), and the hydraulic oil (5) will slowly release pressure through the flow-limiting orifice (4) to provide buffering and resist the hydraulic pressure, converting the kinetic energy into heat energy to prevent the pipe body from flying out and offsetting caused by blasting vibration. For the stiffness energy absorption mechanism, it includes a spring (8) and a guide rail (9). Among them, the spring (8) adopts a variable pitch design and is installed inside the guide rail (9). The guide rail (9) wraps the spring and restricts the horizontal freedom of the spring, and the bottom is welded to the top cover of the fracturing pipe. The initial pre-compression of the spring (8) contacts the anti-hydraulic pressure rubber plug (7). The spring (8) absorbs the residual impact energy through the non-linear change of stiffness; the non-linear change of the stiffness of the spring (6) is: , and the stiffness characteristic satisfies: , Among them, k ( x ) is the instantaneous stiffness of the spring, unit: N / m; x is the compression of the spring, unit: m; G is the shear modulus of the spring material, unit: Pa; d is the diameter of the spring, unit: m; D is the mean diameter of the spring, i.e., the average diameter, unit: m; n is the number of active coils of the spring; L 0 is the free length of the spring, i.e., the original length when not under force, unit: m; m p is the mass of the pipe body of the fracturing pipe, v p is the estimated impact velocity; the residual impact energy is further absorbed through the non-linear compression of the spring.

[0034] Further, the side wall energy-discharging groove on the side wall of the fracturing pipe is a Venturi structure with a cross-sectional area that can be adjusted in real time, realizing the directional distribution of the horizontal explosion energy. The adjustable deflector uses a NACA airfoil profile and is installed below the exhaust hole of the fracturing pipe, and the directional control of the rock-breaking work is achieved by adjusting its injection angle.

[0035] S4. Place the fracturing pipe into the drilled fracturing hole, input the rock mass parameters through the wireless terminal, and the electronic control module automatically matches the blasting parameters; among them, the rock mass parameters include hardness, density, elastic modulus, Poisson's ratio, fracture toughness, etc.; the blasting parameters include deflector angle, cross-sectional area of the energy-discharging groove, charge amount, fracturing hole spacing, fracturing hole diameter and depth, and detonator delay, etc.

[0036] Further, after placing the fracturing pipe into the drilled fracturing hole, rotate the bolt of the horizontally telescopic stop mechanism so that the contact pressure between the magnetorheological damper and the fracturing hole wall is greater than or equal to 5 MPa, triggering the linkage of the three-stage energy absorption system.

[0037] S5. Send a detonation command to the fracturing pipe through the wireless terminal. After receiving it, the electronic control module generates an encrypted detonation signal and transmits it to the bridge wire discharge module through the leg wire; the bridge wire discharge module ignites the delay charge and the primary explosive, detonates the shaped charge in segments, and accelerates the gasification of dry ice for rock-breaking work.

[0038] The intelligent control system (10) of electronic detonators of the present application is used to safely and reliably detonate the dry ice phase change fracturing tube device. Its core functions include remote control of initiation, precise energy release, and real-time monitoring and feedback. The initiation process and effect are controlled through the cooperation between modules. Among them, the electronic control module (20) is used to remotely transmit and receive the initiation signal sent by the wireless terminal, and generate an encrypted initiation instruction, which is transmitted to the bridge wire discharge module (21) through the leg wire; after receiving the encrypted initiation instruction, the bridge wire discharge module (21) instantaneously discharges the bridge wire to generate high temperature (up to thousands of degrees Celsius), igniting the shaped charge (11) (such as oxidant, sensitizer, etc.), and at the same time igniting the delay charge (22) and the primary explosive (23). The shaped charge (11) is detonated in segments through chemical delay design. After being excited by the high temperature of the bridge wire, the primary explosive (23) rapidly deflagrates, accelerating the gasification of dry ice to generate high-pressure gas for rock breaking work; the high-sensitivity microseismic monitoring sensor (19) (frequency range 0.1 - 100 Hz) can capture the vibration signal of rock mass rupture in real time and feedback it to the wireless terminal to evaluate the blasting effect.

[0039] S6. During the rock breaking work, the electronic control module obtains the rock mass rupture signal real-time feedback by the high-sensitivity microseismic monitoring sensor, dynamically adjusts the blasting parameters, and conducts the rock breaking work directionally; if the high-sensitivity microseismic monitoring sensor fails, the electronic control module automatically switches to the preset conservative parameters (the cross-sectional area of the energy discharge groove is enlarged by 20%, and the angle of the deflector is reset to zero), and triggers an audible and visual alarm.

[0040] Furthermore, during the rock breaking work, the intelligent control system (10) of electronic detonators can monitor the environmental parameters through sensors and dynamically adjust the blasting parameters according to the real-time conditions. Specifically: Dynamically adjust the cross-sectional area of the energy discharge groove based on the feedback gas pressure of the pressure sensor. The dynamic adjustment method is: , where, A new is the adjusted cross-sectional area of the energy discharge groove (m 2 ), A old is the cross-sectional area of the energy discharge groove before adjustment (m 2 ), P actual is the actual gas pressure measured by the pressure sensor (Pa), P target is the target gas pressure (Pa).

[0041] Dynamically adjust the angle of the deflector based on the inclination angle of the fracturing hole and the target fracture direction and in combination with manual adjustment. The dynamic adjustment formula is: , where, θ is the angle of the deflector after adjustment,k a is the dip angle coupling coefficient; Δ θ adj is the manual adjustment increment, with a range of ±5°, used for fine-tuning; α and β are the dip angle of the fracture initiation hole and the target fracture direction respectively. The drilling angle is the angle between the fracture initiation hole and the horizontal plane; the target fracture direction is the preset fracture propagation direction. In this embodiment, the dip angle coupling coefficient is taken in the range of 0.8 - 1.2 based on the rock mass type, and the highest value is taken for hard rock.

[0042] According to the vibration frequency of the rock mass monitored by the high-sensitivity microseismic sensor f , if f > 50Hz, the detonator delay is dynamically adjusted according to the following formula t : , where, t is the adjusted detonator delay, t base is the reference detonator delay, f is the vibration frequency of the rock mass monitored by the microseismic sensor, K H is the hardness coefficient. In this embodiment, the reference detonator delay and the hardness coefficient are determined according to the rock mass type. Among them, the reference detonator delay for soft rock is 20 ms, and the reference detonator delay for hard rock is 15 ms; the hardness coefficient for hard rock is 1.2, and the hardness coefficient for soft rock is 0.8.

[0043] S7. After the rock breaking work is completed, recover the fracturing tube and check the integrity of the components.

[0044] Furthermore, after the rock breaking work is completed, the components need to be recovered and the integrity of the components is checked to ensure whether they can be reused again to reduce costs. Specifically: Conduct targeted inspections on the damping and energy absorption mechanism, but there is no need to completely disassemble and maintain it after each blasting; Check the integrity of the oil cylinder. If the integrity is good, replenish the hydraulic oil to 90% ± 5% of the volume; Check the spring loss. If the spring loss is less than the set allowable loss, recover and continue to use it; Clean the residues in the energy dissipation groove and the exhaust hole of the fracturing tube; Recover the deflector and check and focus on maintaining its structural integrity and angle adjustment function.

[0045] In this embodiment, the set allowable loss of the spring is 2 turns.

[0046] S8. Obtain the fracture length and compare it with the theoretical value, record the deviation and store it in the historical blasting database.

[0047] Further, the calculation formula for the ratio of fracture length to energy is: , where L is the fracture propagation length, unit: m; K is the rock mass fracture toughness, unit: ; E is the energy release, unit: J; σ t is the rock mass tensile strength, unit: Pa. By controlling the energy release of the energy accumulator, the length and direction of fracture propagation can be precisely controlled.

[0048] S9. Taking the ratio of fracture length to energy as the reward function, use the historical blasting database to iteratively update the blasting parameters through machine learning.

[0049] Further, the present invention also adopts a machine learning algorithm to iteratively optimize the blasting parameters to better adapt to subsequent blasting operations; the present invention takes the ratio of fracture length to energy as the reward function and uses the Actor-Critic algorithm to iteratively optimize the blasting parameters through the dual mechanisms of policy evaluation and value function update; in the Actor-Critic algorithm, the environment is jointly composed of rock mass parameters (such as hardness, density, fracture toughness), real-time sensor data (such as gas pressure, microseismic frequency), and the fracture propagation results after blasting. The state ( s t ) is defined as the combination of current blasting parameters, including the deflector angle, the cross-sectional area of the energy-dissipating groove, the charge amount, the spacing of the fracture-causing holes, the diameter and depth of the fracture-causing holes, and the detonator delay, etc., and at the same time includes the rock mass response data monitored in real time. The action ( a t ) is the adjustment method of the blasting parameters, for example, dynamically adjusting the cross-sectional area of the energy-dissipating groove based on the feedback gas pressure of the pressure sensor A new . The specific optimization process is as follows: Construct an Actor network and a Critic network, and define the environment, state, and action; among them, the environment is composed of rock mass parameters, sensor data, and fracture propagation results; the state is composed of blasting parameters; the action is composed of the adjustment methods of blasting parameters; The Actor network generates a policy s t according to the input state π θ , and under the goal of maximizing the reward function (i.e., the ratio of fracture length to energy release), select the action a t and interact with the environment to obtain the reward and the next state s t+1 . The Critic network then uses the value functionV π Evaluation status s t and the next state s t+1 of the state value V π ( s t )、 V π ( s t+1 ) to calculate the temporal difference error δ t (TD error) to provide a basis for policy generation; where the temporal difference error δ t The calculation formula is: δ t = r t + γV π ( s t+1 ) - V π ( s t ), where, γ is the discount factor, r t is the immediate reward; δ t is the estimated error; V π ( s t ) and V π ( s t+1 ) are the state values estimated by the Critic network for the current state s t and the next state s t+1 respectively. The state value calculation combines the fracture length deviation and the energy consumption efficiency, and its goal is to minimize the difference between the theoretical value and the actual value.

[0050] The Actor network updates the parameters through policy gradients: , where, represents the gradient of the objective function J ( θ ]>) with respect to the set of Actor network parameters θ , that is is the gradient of a certain function with respect to θ ;​ To represent the expected (mean) operation under the policy π θ below, π θ ( a t | s t ) is the probability that the Actor network selects an action at state s t below; a t of; δ t is the temporal difference error, representing the deviation between the actual reward and the expected reward; θ is the set of parameters of the Actor network (such as neural network weights), and the above parameters are all dimensionless.

[0051] Iterative training is carried out until the convergence condition is reached; the convergence condition includes that the fluctuation of the reward function is less than the set reward threshold, the deviation of the fracture length is within the set deviation threshold, and the energy consumption is maintained in the range of 95% - 105% of the theoretical value.

[0052] During the training process, when the blasting of a continuous set number of times meets the conditions, the optimal policy parameters are locked to ensure the stability and repeatability of the blasting effect. This process gradually reduces the dependence on manual experience through real-time data feedback and machine learning iteration, and realizes the precise control of the dry ice energy-gathering rock fracturing process.

[0053] In this embodiment, the convergence condition is set as the fluctuation of the reward function is less than 5%, the deviation of the fracture length is within 8%, and the energy consumption is maintained in the range of 95% - 105% of the theoretical value. When the blasting of every continuous 20 times meets the conditions, the optimal policy parameters are locked.

[0054] It should be noted that for the foregoing method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present invention is not limited by the described action sequence, because according to the present invention, certain steps can be carried out in other sequences or simultaneously.

[0055] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combinations of these technical features do not conflict, they should all be considered as the scope described in this specification.

[0056] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for directional fracturing of rocks by using the energy accumulation of dry ice, characterized in that, It includes the following steps: Drill fracture holes in the rock mass to be blasted; the diameter, depth and inclination angle of the fracture holes are dynamically designed according to the hardness of the rock mass; Fill dry ice and energy-gathering agent into the fracture tube and complete the sealing; an electronic detonator intelligent control system is installed in the fracture tube; the electronic detonator intelligent control system includes an electronic control module, a high-sensitivity microseismic monitoring sensor, a bridge wire discharge module, delay charge and detonating charge; Install an energy absorption system at the top of the fracture tube, set side wall energy-dissipating grooves on the side wall of the fracture tube, and install adjustable flow deflectors below the exhaust holes of the fracture tube; Both the side wall energy-dissipating grooves and the adjustable flow deflectors are connected to the electronic detonator intelligent control system through electric control cables; the energy absorption system is used to dissipate the blasting impact energy and inhibit the upward throwing or deviation of the fracture tube body; the side wall energy-dissipating grooves control the pressure and direction of the explosion-discharged jet by adjusting the cross-sectional area; the adjustable flow deflectors are used to adjust the spraying angle of the airflow and control the propagation direction of the explosion-generated cracks in the rock mass to be blasted; Put the fracture tube into the drilled fracture hole, input the rock mass parameters through the wireless terminal, and the electronic control module automatically matches the blasting parameters; the rock mass parameters include hardness, density, elastic modulus, Poisson's ratio and fracture toughness; the blasting parameters include the deflector angle, the cross-sectional area of the energy-dissipating groove, the charge amount, the fracture hole spacing, the fracture hole diameter, the fracture hole depth and the detonator delay; Send a detonation signal to the fracture tube through the wireless terminal, and after receiving it, the electronic control module generates an encrypted detonation instruction and transmits it to the bridge wire discharge module through the leg wire; after receiving the encrypted detonation instruction, the bridge wire discharge module discharges to generate high temperature to ignite the energy-gathering agent, and at the same time ignite the delay charge and the detonating charge, and the energy-gathering agent is detonated in segments through chemical delay design to accelerate the gasification of dry ice for rock breaking work; During the rock breaking work, the electronic control module obtains the rock mass fracture signals real-time fed back by the high-sensitivity microseismic monitoring sensor, dynamically adjusts the blasting parameters, and conducts rock breaking work directionally; if the high-sensitivity microseismic monitoring sensor fails, the electronic control module automatically switches to the preset conservative parameters and triggers an audible and visual alarm; After the rock breaking work is completed, recover the fracture tube and check the integrity of the components; Obtain the crack length and compare it with the theoretical value, record the deviation and store it in the historical blasting database; Use the ratio of the crack length to the energy as the reward function, and use the historical blasting database to iteratively update the blasting parameters through machine learning.

2. The method for directional rock fragmentation by dry ice energy accumulation according to claim 1, characterized in that, The fracture tube adopts a double-layer composite tube body design; The outer tube body uses an elastic composite material to absorb the impact blasting energy; the fiber volume fraction in the elastic composite material > 60%; The inner tube body is made of high-strength alloy steel to absorb impact and prevent the gasification of dry ice; the yield strength of the high-strength alloy steel σ y ≥800 MPa, and the wall thickness meets the requirement: ， Among them, t 0 is the wall thickness of the inner high-strength alloy steel, P max is the maximum working pressure, unit: MPa; r is the inner radius, unit: mm; η is the welding coefficient; Δ t corr is the corrosion allowance, unit: mm; The central chamber of the double-layer composite tube body is filled with dry ice, which directly contacts the inner wall of the high-strength alloy steel of the inner tube body; the inner wall is coated with a heat-insulating coating; the dry ice is evenly wrapped with an energy-gathering agent around it, which is in close contact with the dry ice; the energy-gathering agent releases energy through a chemical reaction after detonation to accelerate the gasification of dry ice; An electronic detonator intelligent control system is installed in the annular space between the outer tube body and the inner tube body of the double-layer composite tube body; the electronic detonator intelligent control system is fixed by brackets or chucks and is connected to the external wireless terminal through the leg wire led out from the outer tube body.

3. The method for dry ice energy-gathering and directional rock fracturing according to claim 1, wherein The energy absorption system is a three-stage energy absorption system, including a damping energy absorption mechanism, an oil pressure energy absorption mechanism and a rigidity energy absorption mechanism; The damping energy absorbing mechanism is connected to the oil pressure energy absorbing mechanism and contacts the crack hole wall, and adjusts the damping force through the magnetic field to absorb the initial impact energy of the rock breaking operation; The oil pressure energy absorbing mechanism provides buffering and resists oil pressure by compressing hydraulic oil; The stiffness energy absorbing mechanism absorbs residual impact energy through nonlinear stiffness change; the bottom of the stiffness energy absorbing mechanism is welded to the top cover of the fracturing pipe.

4. The method for directional rock fragmentation by dry ice energy accumulation according to claim 3, characterized in that, The damping energy absorption mechanism includes a horizontally retractable stop mechanism and a magnetofluid damper; the horizontally retractable stop mechanism is composed of a bolt and a hydraulic cylinder driving a transverse telescopic arm; the end of the hydraulic cylinder driving the transverse telescopic arm is connected to the magnetofluid damper; the bolt is fixedly connected to the oil pressure energy absorption mechanism; the horizontally retractable stop mechanism is located at the outermost side of the fracturing tube, and is powered by the hydraulic cylinder. By adjusting the bolt, the hydraulic cylinder drives the transverse telescopic arm to move horizontally and contact the wall of the fracturing hole; the magnetofluid damper has a built-in piston and magnetorheological fluid, and the piston rod is rigidly connected to the horizontally retractable stop mechanism. The damping force is adjusted by the magnetic field to absorb the initial impact energy generated by the explosion; the formula for adjusting the damping force of the magnetofluid damper by the magnetic field is: F d = ( F η + F τ )∙ A p ， Among them, F η is the viscous damping force, F τ is the magnetic field-induced shear force, A p is the piston area; The oil pressure energy absorption mechanism includes an oil cylinder, hydraulic oil, a flow restriction hole, and an oil pressure-resistant rubber plug; the oil cylinder is located below the damping energy absorption mechanism, and the cylinder body is bolted to the base of the magnetic fluid damper; the hydraulic oil fills 85% to 90% of the oil cylinder volume; the oil pressure-resistant rubber plug is installed at the bottom of the oil cylinder and contacts the top of the spring of the stiffness energy absorption mechanism; the flow restriction hole is set on the side of the cylinder body; The stiffness energy absorption mechanism includes a spring and a guide rail. The spring adopts a variable pitch design and is installed inside the guide rail. The initial pre-compression amount contacts the oil pressure-resistant rubber plug. The guide rail wraps the spring to limit the horizontal degree of freedom of the spring. The nonlinear change of the stiffness of the spring is: ， And the stiffness characteristics satisfy: ， Among them, k ( x ) is the instantaneous stiffness of the spring, unit: N / m; x is the compression of the spring, unit: m; G is the shear modulus of the spring material, unit: Pa; d is the diameter of the spring, unit: m; D is the mean diameter of the spring, i.e., the average diameter, unit: m; n is the number of active coils of the spring; L 0 is the free length of the spring, i.e., the original length when not under force, unit: m; m p is the tube body mass of the fracturing tube, v p is the estimated impact velocity.

5. The method for directional rock fragmentation by dry ice energy accumulation according to claim 1, characterized in that The side wall energy dissipation groove is a Venturi structure; the adjustable guide vane adopts a NACA airfoil section.

6. The method for dry ice energy-gathering and directional rock fracturing according to claim 4, wherein After placing the fracturing tube into the drilled fracturing hole, rotate the bolt of the horizontally retractable stop mechanism to make the contact pressure between the magnetofluid damper and the fracturing hole wall greater than or equal to 5MPa, triggering the linkage of the three-stage energy absorption system.

7. The method for directional rock fragmentation by dry ice energy accumulation according to claim 1, characterized in that The dynamic adjustment of blasting parameters and the targeted rock breaking work are specifically as follows: The cross-sectional area of the energy dissipation groove is dynamically adjusted based on the feedback gas pressure of the pressure sensor. The dynamic adjustment method is: ， Among them, A new is the cross-sectional area of the energy-discharging groove after adjustment, A old is the cross-sectional area of the energy-discharging groove before adjustment, P actual is the actual gas pressure measured by the pressure sensor, P target is the target gas pressure; The guide vane angle is dynamically adjusted based on the crack hole inclination and the target crack direction in combination with manual adjustment. The dynamic adjustment formula is: ， Among them, θ is the adjusted deflector angle, k a is the dip angle coupling coefficient; Δ θ adj is the manual adjustment increment, with a range of ±5°; α and β are the fracture hole dip angle and the target fracture direction respectively. The drilling hole dip angle is the angle between the fracture hole and the horizontal plane; the target fracture direction is the preset fracture propagation direction; According to the rock mass vibration frequency monitored by high-sensitivity microseismic sensors f , if f > 50Hz, dynamically adjust the detonator delay according to the following formula t : ， Among them, t is the adjusted detonator delay time, t base is the reference detonator delay time, f is the rock mass vibration frequency monitored by the microseismic sensor, K H is the hardness coefficient.

8. The method for dry ice energy-gathering directional rock fracture according to claim 4, characterized in that, The recovering of the fractured pipe and checking the integrity of the assembly are specifically as follows: Conduct targeted inspections on the damping energy absorption mechanism, but do not need to completely dismantle and maintain it after each blast; Check the integrity of the oil cylinder. If the integrity is good, add hydraulic oil to 90% ± 5% of the volume; Check the spring loss. If the spring loss is less than the set allowable loss, recycle it and continue to use it; Clean the residue in the energy release groove and the exhaust hole of the fracturing pipe; Recover the deflector and inspect and maintain its structural integrity and angular adjustment function.

9. The method for directional rock fragmentation by dry ice energy accumulation according to claim 4, characterized in that, The calculation formula of the ratio of the crack length to the energy is: ， Among them, L is the crack propagation length, unit: m; K is the rock mass fracture toughness, unit: ; E is the energy release, unit: J; σ t is the rock mass tensile strength, unit: Pa.

10. The method for dry ice energy-gathering directional fracturing of rock according to claim 1, wherein Taking the ratio of fracture length to energy as the reward function, the Actor-Critic algorithm is used to iteratively optimize the blasting parameters through the dual mechanisms of policy evaluation and value function update, specifically as follows: Construct an Actor network and a Critic network, and define the environment, state, and action; the environment consists of rock mass parameters, sensor data, and fracture propagation results; the state consists of blasting parameters; the action consists of the adjustment methods of blasting parameters; The Actor network is based on the input state s t Generation Strategy π θ , select an action a t and interact with the environment to obtain rewards and next states s t+1 ; Critic network uses value function V π Assessment Status s t and the next state s t+1 Status value V π ( s t ), V π ( s t+1 ), calculate the timing difference error δ t Provide a basis for strategy generation; the temporal difference error calculation formula is: δ t = r t + γV π ( s t+1 ) - V π ( s t )， Among them, γ is the discount factor, r t is the immediate reward; δ t is the estimated error; V π ( s t ) and V π ( s t+1 ) are the state values estimated by the Critic network for the current state s t and the next state s t+1 respectively. The Actor network updates the parameters through policy gradients: ， Among them, represents the objective function J ( θ ) the gradient with respect to the set of Actor network parameters θ ; represents the expectation operation under the policy π θ ; π θ ( a t | s t ) is the probability that the Actor network selects the action s t in the state a t ; Perform iterative training until the convergence condition is reached; The convergence conditions include that the fluctuation of the reward function is less than the set reward threshold, the fracture length deviation is within the set deviation threshold, and the energy consumption is maintained in the range of 95%-105% of the theoretical value; During the training process, when the blasting of continuously set times meets the conditions, the optimal policy parameters are locked.

Images