Underwater gas phase change rock cracking method and system

Abstract

The invention discloses an underwater gas phase change rock cracking method and system, and belongs to the technical field of underwater rock crushing construction. The method comprises the steps of construction preparation, drilling hole positioning, fracturing pipe mounting and filling, drilling hole plugging, safety alert and network connection, liquid phase material excitation to enable rock to be broken, fracturing pipe release condition confirmation, slag removal and the like. According to the method, construction parameters are accurately designed according to the rock hardness, the hole diameter and the hole distance of drill holes are determined according to the compressive strength, the length of a fracturing pipe is matched with the hole depth, and strict operation requirements are met in the links of filling, plugging, warning, excitation and the like. The system covers gas phase change, temperature control and monitoring, pressure monitoring and feedback and other parts, and can accurately control the gas phase change process. According to the method, geological conditions can be accurately matched, the construction efficiency and safety are improved, the cost is reduced, the construction quality is improved, the environmental influence is reduced, the method is suitable for various underwater rock projects, and an efficient and environment-friendly solution is provided for underwater rock crushing construction.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater rock crushing construction, and in particular to a method and a related system for realizing rock crushing by utilizing gas phase change in an underwater environment having high requirements on the ecological environment of a construction area. Background Art

[0002] In recent years, with the development and progress of economic construction, construction work has paid more and more attention to the protection of the ecological environment in the construction area. At the same time, the promotion of green construction technology has become a trend, especially in terms of water environment protection. For example, some projects involve underwater rock crushing and cannot cause sensitive areas with severe vibration or sensitive areas with high requirements for aquatic environment and ecological protection. Therefore, the implementation of traditional chiseling and crushing methods will be limited, and then the underwater gas phase change rock cracking method can be used.

[0003] Patent document CN202311411145.6 A method for directional fracturing of hard rock under hydraulic fracturing-carbon dioxide phase change coupling belongs to the field of coal mine technology. It includes the following steps: S1. Site selection: According to the on-site rock engineering geological conditions and design plan, determine the excavation construction area; S2. Drilling and hole cleaning: According to the on-site rock engineering geological conditions and design plan, drill blasting holes to the designed depth in the designed excavation area, and wash the holes after the construction is completed to clean up the impurities in the holes; S3. Hydraulic fracturing; S4. Secondary hole cleaning; S5. Install equipment; S6. Block the borehole; S7. Start blasting. Through hydraulic fracturing, the strength of the rock mass is weakened in advance, the mechanical properties of the rock mass are reduced, and the initial cracks are induced inside the rock mass, which can reduce the initial pressure of the rock mass cracking under the action of the carbon dioxide phase change blasting pressure, and guide the blasting cracks to further expand and expand along the predetermined direction, so as to achieve the purpose of directional fracturing.

[0004] Patent document CN202410606327.7 discloses a rock excavation construction method based on supercritical fluid impact rock breaking equipment, which belongs to the field of rock excavation technology. Through real-time monitoring of the pressure value of the explosive gas by a pressure sensor, the high-pressure impact energy can be accurately adjusted for different construction scenes or rock types, thereby improving the quality of rock breaking and improving the work efficiency. The rock excavation construction method based on supercritical fluid impact rock breaking equipment includes the following steps: S1, site cleaning: S2, opening up the initial open face: S3, drilling holes: S4, pressure relief head entering the hole: S5, filling the pressurized energy-gathering agent: S6, hole sealing: starting the packer to squeeze the sealing capsule to make it fully expand and complete the hole sealing; S7, covering the blasting blanket or sandbag: S8, safety alert, filling with air: S9, excitation: setting the gas release pressure value according to the drilling parameters and the rock conditions within the hole range, and stimulating the combustion reaction of the pressurized energy-gathering agent; S10, on-site inspection: S11, equipment displacement, mechanical slag removal. It achieves energy-controllable, high-safety, and environmentally friendly rock-breaking effects, improves construction efficiency, reduces noise and environmental impact, and is suitable for medium-hard rock and hard rock conditions. The rock-breaking efficiency is about 2-3 times that of mechanical crushing.

[0005] However, the above-mentioned existing technologies do not take into account the underwater rock types and the complex underwater geological environment, and cannot accurately control the crushing effect for different rock types. Summary of the invention

[0006] In view of the problem that the phase change method in the prior art cannot be applied to a variety of underwater rock types and complex underwater geological environments, the present invention selects appropriate drilling hole diameters and drilling hole spacings according to the hardness of the rock. When the underwater rock is broken, the original aquatic environment is subject to little vibration, little noise, little solid and liquid pollution, and little overall impact, thereby playing a certain role in ecological protection and water resource protection.

[0007] In order to achieve the above object, the present invention provides an underwater gas phase transformation rock cracking method, comprising the following steps:

[0008] S1, construction preparation, including removal of overburden and opening of lateral free surface;

[0009] S2, positioning drilling, the borehole diameter and spacing are determined according to the compressive strength of the rock on site;

[0010] S3, install the fracturing tube and fill it with liquid material. The outer diameter of the fracturing tube should be smaller than the borehole diameter, and the length of the fracturing tube is selected according to the borehole depth;

[0011] S4, sealing the borehole, using a hole sealer to seal the borehole;

[0012] S5, security alert and network connection;

[0013] S5, stimulating liquid phase materials, using the liquid to transform into gas under specific temperature and pressure conditions to generate expansion force, increase pressure, and crack rocks;

[0014] S5, the equipment operator confirms the release of the fracturing pipe. If the fracturing pipe is not triggered, the operator shall immediately report it, set up a danger sign, and take safety measures such as cutting off the power supply and short-circuiting the triggering network. If the fracturing pipe is not triggered due to the triggering network, it can be reconnected and triggered. If the fracturing pipe is not triggered due to other reasons, the fracturing pipe should be destroyed;

[0015] S6, slag removal.

[0016] Furthermore, in S2, the borehole diameter is determined according to the on-site rock compressive strength as follows:

[0017] When f r >60, drilling hole diameter D=100+0.33×f r , D unit mm, f r It is the hardness of rock, in MPa, but the upper limit of D must be limited to 200mm;

[0018] When 60 ≥ f r >30, drilling hole diameter D=70+0.5×(f r -30), D in mm, f r It is the hardness of rock, in MPa;

[0019] When 30 ≥ f r >15, the drilling hole diameter D=50+1×(f r -15), D in mm, f r It is the hardness of rock, in MPa;

[0020] When 15 ≥ f r >5, the drilling hole diameter D=70+0.67×(f r -5), D in mm, f r It is the hardness of rock, unit is MPa.

[0021] Furthermore, in S2, the drilling hole spacing is determined according to the on-site rock compressive strength as follows:

[0022] When f r >60, drilling hole spacing L=1000+5×(f r -60), L in mm, f r It is the hardness of rock, in MPa, but the upper limit of D must be limited to 1500mm;

[0023] When 60 ≥ f r >30, drilling hole spacing L = 1000-10×(f r-30), L in mm, f r is the rock hardness, in Mpa;

[0024] When 30 ≥ f r > 15, the drilling hole spacing L = 1500 + 5×(f r - 15), L in mm, f r is the rock hardness, in Mpa;

[0025] When 15 ≥ f r > 5, the drilling hole diameter L = 1000 + 10×(f r - 5), L in mm, f r is the rock hardness, in Mpa.

[0026] Furthermore, the filling pressure of the fracturing tube is controlled between 5 MPa and 10 MPa.

[0027] Furthermore, the outer diameter of the fracturing tube should be 10 mm to 20 mm smaller than the drilling hole diameter; the length of the fracturing tube should be selected according to the drilling hole depth.

[0028] Furthermore, the length of the fracturing tube should be selected according to the drilling hole depth specifically as follows:

[0029] For each range of the drilling hole depth H, the length L of the fracturing tube can be determined by L = a·H + b, where a and b are coefficients determined according to the hole depth range;

[0030] For 1800 mm ≤ H ≤ 2800 mm, take a = 0.5 and b = 0, L = 0.5·H;

[0031] For 2800 mm < H ≤ 3800 mm, take a = 0.5 and b = - 400, L = 0.5·H - 400;

[0032] For 3800 mm < H ≤ 4500 mm, take a = 0.5 and b = - 1000, L = 0.5·H - 1000.

[0033] Furthermore, before filling the liquid phase material, the safety valve, the fracturing tube, the excitation element and the excitation lead wire should be checked for integrity.

[0034] Furthermore, the fracturing tube should reserve a sufficient length of excitation lead wire, and the lead wire should be avoided from being damaged when blocking the drilling hole; the length of the drilling hole blockage should not be less than the distance from the fracturing tube to the lateral free surface.

[0035] Furthermore, in step S5, the warning range should be determined according to the water depth. When the water depth is greater than 4m, the warning range should not be less than 30m; when the water depth is between 2m and 4m, the warning range should not be less than 60m; when the water depth is less than 2m, the warning range should not be less than 100m; after taking warning measures to confirm safety, the fracture-causing pipe should be immediately activated, and after activation, it should wait for more than 5 minutes before entering the site for inspection.

[0036] The present invention also provides a system for the above-mentioned underwater gas phase change rock cracking method, comprising:

[0037] The gas phase change system can generate high-pressure gas. The adjustable pressure range is determined according to the rock hardness requirements. It has good sealing performance and pressure control accuracy to ensure stable output of high-pressure gas.

[0038] Temperature control and monitoring system: arrange temperature sensors in the gas phase change system to monitor the gas temperature changes in real time, and equip heating or cooling elements to timely adjust the temperature when the gas temperature deviates from the optimal temperature range required for phase change, to ensure that the gas accurately changes phase when it reaches the predetermined position inside the rock. The specific temperature range of temperature control during the gas phase change process is determined according to the phase change characteristics of the selected gas;

[0039] The pressure monitoring and feedback system installs a pressure sensor in the gas phase change system to monitor the gas pressure changes in real time and transmit the pressure data to the control system. When the pressure reaches the preset phase change trigger pressure value, the control system accurately controls the gas release and phase change process. At the same time, it adjusts the output pressure of the high-pressure gas generating device in time according to the pressure feedback information to ensure the stability and effectiveness of the rock cracking process.

[0040] The beneficial effects of the present invention are:

[0041] Accurately adapt to rock characteristics: Determine the drilling diameter and hole spacing based on the rock compressive strength to avoid one-size-fits-all design, make the construction parameters highly match the actual geological conditions, and improve scientificity and rationality.

[0042] Improve construction efficiency: Select appropriate drilling equipment and construction methods to reduce the number of drilling times and equipment adjustment frequency for rocks with higher hardness; design appropriate hole spacing to optimize blasting and other process effects, reduce rework and equipment failures, ensure construction continuity and stability, and improve time and resource utilization efficiency.

[0043] Ensure construction safety: Reasonable design can better control the stress distribution and energy release during construction, avoid the risk of excessive crushing and collapse of low compressive strength rocks, ensure the effective transfer and release of construction energy of high compressive strength rocks, reduce safety accidents caused by energy accumulation, and help predict risk points and take safety measures.

[0044] Reduce costs: Improve construction efficiency and reduce manpower, material and time costs; accurate design avoids material waste, extends the service life of construction equipment, and reduces equipment loss and maintenance costs.

[0045] Improve construction quality: Set a specific fracturing tube length calculation formula for different drilling depth ranges to match the hole depth, so that the rock can be broken more evenly, achieving the expected fracturing effect and avoiding material waste and re-construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0047] Figure 1 It is a flow chart of the underwater gas phase transformation rock cracking method. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0049] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections.

[0050] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0051] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0052] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of the various components of the present invention are not absolute but relative. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, the indications of these directions also change accordingly.

[0053] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0055] In this embodiment, a method is used in which certain liquids are instantly changed from liquid to gaseous under different temperature and pressure conditions to cause cracking and crushing. Phase change expansion rock crushing should be stimulated simultaneously in the same row. Liquid storage tanks should be filled as needed and should not be stored for a long time; liquid storage tanks and filling equipment should be replaced in time when they have defects such as corrosion, damage, cracks, etc.; the liquid storage tank equipment should be placed in a ventilated and cool place and should not be violently shaken, collided or exposed to the sun. When transporting and filling liquids, operators should keep a safe distance from the exhaust holes. Liquid storage fracturing tubes that are not used within 3 days should be emptied and recycled.

[0056] Figure 1 is a construction flow chart in this embodiment, including

[0057] The following steps are involved:

[0058] S1, construction preparation, including removal of overburden and opening of lateral free surface;

[0059] If the thickness of the covering layer is greater than 0.3m, the covering layer will be removed; if the thickness of the covering layer is less than or equal to 0.3m, the positioning drilling stage will be started.

[0060] S2, positioning drilling, the borehole diameter and spacing are determined according to the compressive strength of the rock on site;

[0061] The drilling depth should be determined based on the on-site rock surface elevation, the designed bottom elevation and the over-depth value. The hole should be inspected after the drilling is completed. The drilling parameters should be determined based on the rock strength, the degree of joint development, the free surface, etc.

[0062]

[0063]

[0064] The borehole diameter is determined according to the compressive strength of the rock on site:

[0065] When f r >60, drilling hole diameter D=100+0.33×f r , D unit mm, fr It is the hardness of rock, in MPa, but the upper limit of D must be limited to 200mm;

[0066] When 60 ≥ f r >30, drilling hole diameter D=70+0.5×(f r -30), D in mm, f r It is the hardness of rock, in MPa;

[0067] When 30 ≥ f r >15, the drilling hole diameter D=50+1×(f r -15), D in mm, f r It is the hardness of rock, in MPa;

[0068] When 15 ≥ f r >5, the drilling hole diameter D=70+0.67×(f r -5), D in mm, f r It is the hardness of rock, unit is MPa.

[0069] The drilling hole spacing is determined according to the on-site rock compressive strength:

[0070] When f r >60, drilling hole spacing L=1000+5×(f r -60), L in mm, f r It is the hardness of rock, in MPa, but the upper limit of D must be limited to 1500mm;

[0071] When 60 ≥ f r >30, drilling hole spacing L = 1000-10×(f r -30), L in mm, f r It is the hardness of rock, in MPa;

[0072] When 30 ≥ f r >15, drilling hole spacing L=1500+5×(f r -15), L in mm, f r It is the hardness of rock, in MPa;

[0073] When 15 ≥ f r >5, the drilling hole diameter L=1000+10×(f r -5), L in mm, f r It is the hardness of rock, unit is MPa.

[0074] This design fully considers the key factor of rock compressive strength. Different strengths of rocks correspond to different drilling diameters and hole spacing designs. This design can accurately adapt to the characteristics of the rock, avoid a one-size-fits-all design, make the construction parameters highly match the actual geological conditions, and improve the scientificity and rationality of the construction. Through precise parameter design, more suitable drilling equipment and construction methods can be selected during the construction process. For example, for rocks with higher hardness, larger drilling diameters and reasonable hole spacing can reduce the number of drilling times and the frequency of equipment adjustment, thereby speeding up the construction progress and improving the overall construction efficiency. At the same time, the appropriate hole spacing design helps to optimize the effects of blasting or other construction processes and further improve construction efficiency. It reduces problems such as rework and equipment failure caused by mismatched construction parameters, ensures the continuity and stability of construction, and improves efficiency in terms of time and resource utilization.

[0075] At the same time, reasonable drilling hole diameter and hole spacing design can better control the stress distribution and energy release during the construction process. When the rock compressive strength is low, a smaller drilling hole diameter and appropriate hole spacing can avoid safety risks such as excessive crushing and collapse; in rocks with high compressive strength, a larger hole diameter and hole spacing can ensure the effective transmission and release of construction energy and reduce safety accidents caused by energy accumulation. This refined design based on rock characteristics helps construction personnel to predict risk points in the construction process in advance and take corresponding safety measures, thereby greatly improving the safety of construction.

[0076] Due to the improvement of construction efficiency, the reduction of rework and equipment failure, etc., the manpower, material and time costs are directly reduced. At the same time, the precise design avoids unnecessary waste of materials. In the long run, this design helps to extend the service life of construction equipment, reduce equipment loss and maintenance costs, and further reduce the overall construction cost. In summary, the design of determining the borehole diameter and hole spacing according to the on-site rock compressive strength has many advantages and beneficial effects, and can play an important role in improving construction efficiency, ensuring construction safety, reducing costs, improving construction quality, protecting the environment, and enhancing adaptability.

[0077] S3, install the fracturing tube and fill it with liquid material. The outer diameter of the fracturing tube should be smaller than the borehole diameter, and the length of the fracturing tube is selected according to the borehole depth;

[0078] The outer diameter of the fracturing tube should be 10mm to 20mm smaller than the diameter of the drilled hole. The length of the fracturing tube should be selected according to the depth of the drilled hole and should meet the proportion requirements.

[0079] For each borehole depth H range, the length L of the fracturing tube can be determined by L = aH + b, where a and b are coefficients determined according to the borehole depth range;

[0080] For 1800mm ≤ H ≤ 2800mm, we can take a = 0.5 and b = 0, which means L = 0.5H;

[0081] For 2800mm < H ≤ 3800mm, we can take a = 0.5 and b = -400, which means L = 0.5H - 400;

[0082] For 3800mm < H ≤ 4500mm, we can take a = 0.5 and b = -1000, which means L = 0.5H - 1000.

[0083] Specific calculation formulas for the length of the fracturing pipe are set for different drilling hole depth ranges, so that the length of the fracturing pipe matches the hole depth. Construction workers can quickly calculate the required length of the fracturing pipe according to the hole depth, without cumbersome measurement and adjustment, reducing the construction preparation time and improving the overall construction progress; when switching construction between different hole depth ranges, due to the clear and simple formula, construction workers can quickly adapt and carry out the corresponding preparation work for the fracturing pipe, ensuring the smoothness of the construction process, avoiding construction delays caused by inappropriate fracturing pipe length, and the appropriate fracturing pipe length can better play the fracturing role. At different hole depths, the stress conditions and fragmentation requirements of the rock are different. Through this segmented design method, the fracturing energy can be more effectively transmitted and distributed within different hole depth ranges. For example, shorter fracturing pipes in deeper holes can avoid excessive energy concentration at the bottom or the mouth of the hole, thus making the rock fragmentation more uniform, improving the construction quality, and achieving the expected fracturing effect. It avoids the overuse or waste of fracturing pipes. If precise design is not carried out according to the hole depth, there may be a situation where the fracturing pipe is too long, resulting in material waste, or too short to achieve the fracturing effect and requiring re - construction. Through this segmented design, the length of the fracturing pipe can be accurately calculated according to the actual hole depth, and materials can be accurately purchased and used, thereby reducing the consumption of fracturing pipes and the material cost.

[0084] In an embodiment, for a hole depth of 1800mm - 2800mm, the length of the fracturing pipe should be preferably 800mm - 1400mm. For a hole depth of 2800mm - 3800mm, the length of the fracturing pipe should be preferably 1400mm - 2000mm. For a hole depth of 3800mm - 4500mm, the length of the fracturing pipe should be preferably 2000mm - 2500mm.

[0085] Before filling the liquid phase material, the safety valve, fracturing pipe, excitation element and excitation lead wire should be checked for integrity. Connect the filling equipment to fill the liquid phase material into the fracturing pipe, and the filling pressure should be controlled within 5MPa - 10MPa: it is preferably filled in the hole. When it is difficult to fill in the hole, external filling can be adopted. Before filling in high - temperature weather, the fracturing pipe should be cooled down. The fracturing pipe should reserve a sufficient length of excitation lead wire, and care should be taken to avoid damaging the lead wire when blocking the drilling hole. The length of the drilling hole blockage should not be less than the distance from the fracturing pipe to the lateral free surface.

[0086] S4, sealing the borehole, using a hole sealer to seal the borehole;

[0087] The medium with larger friction factor and density should be used for drilling plugging. The exciting element and fracturing tube used in the same time should be the same batch of products from the same factory.

[0088] S5, security alert and network connection;

[0089] The warning range should be determined according to the water depth. When the water depth is greater than 4m, the warning range should not be less than 30m; when the water depth is between 2m and 4m, the warning range should not be less than 60m; when the water depth is less than 2m, the warning range should not be less than 100m; after taking warning measures to confirm safety, the fracture pipe should be immediately stimulated, and after stimulation, it should wait for more than 5 minutes before entering the site for inspection;

[0090] S5, stimulating liquid phase materials, using the liquid to transform into gas under specific temperature and pressure conditions to generate expansion force, increase pressure, and crack rocks;

[0091] The excitation element should be tested with a special instrument with an output current less than 30mA to 40mA. It should be carried out before the fracturing pipe is filled with liquid materials and after the inlet hole is installed and blocked. The excitation network should be connected in series and in the direction of water flow. The network should be kept in a short-circuit state before excitation. The resistance value of each excitation element and wire should be tested before the network is connected, and it should be confirmed that the resistance value is stable, the contact is firm, and the insulation is good.

[0092] S5, the equipment operator confirms the release of the fracturing pipe. If the fracturing pipe is not triggered, the operator shall immediately report it, set up a danger sign, and take safety measures such as cutting off the power supply and short-circuiting the triggering network. If the fracturing pipe is not triggered due to the triggering network, it can be reconnected and triggered. If the fracturing pipe is not triggered due to other reasons, the fracturing pipe should be destroyed;

[0093] S6: After completing a section of construction, the slag should be cleared in time.

[0094] Another embodiment also discloses a system for the above-mentioned underwater gas phase change rock cracking method, comprising:

[0095] The gas phase change system can generate high-pressure gas. The adjustable pressure range is determined according to the rock hardness requirements. It has good sealing performance and pressure control accuracy to ensure stable output of high-pressure gas.

[0096] Temperature control and monitoring system: arrange temperature sensors in the gas phase change system to monitor the gas temperature changes in real time, and equip heating or cooling elements to timely adjust the temperature when the gas temperature deviates from the optimal temperature range required for phase change, to ensure that the gas accurately changes phase when it reaches the predetermined position inside the rock. The specific temperature range of temperature control during the gas phase change process is determined according to the phase change characteristics of the selected gas;

[0097] The pressure monitoring and feedback system installs a pressure sensor in the gas phase change system to monitor the gas pressure changes in real time and transmit the pressure data to the control system. When the pressure reaches the preset phase change trigger pressure value, the control system accurately controls the gas release and phase change process. At the same time, it adjusts the output pressure of the high-pressure gas generating device in time according to the pressure feedback information to ensure the stability and effectiveness of the rock cracking process.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An underwater gas phase transformation rock cracking method, characterized in that: It includes the following steps: S1. Construction preparation, including removing the overburden layer and creating a lateral free face; S2. Positioning and drilling. The borehole diameter and spacing are determined according to the on-site rock compressive strength; S3. Installing the fracturing tube and filling it with liquid-phase material. The outer diameter of the fracturing tube should be smaller than the borehole diameter, and the length of the fracturing tube is selected according to the borehole depth; S4. Sealing the borehole, using a hole sealer to seal the borehole; S5. Safety warning and network connection; S5. Triggering the liquid-phase material, using the expansion force generated by the phase change of the liquid into gas under specific temperature and pressure conditions to pressurize and fracture the rock for fragmentation; S5. The equipment operator confirms the release situation of the fracturing tube. When an untriggered fracturing tube is found, immediately report, set up a danger sign, and take safety measures such as cutting off the power supply and short-circuiting the triggering network. If the untriggered fracturing tube is caused by the triggering network, it can be reconnected and triggered. If the untriggered fracturing tube is caused by other reasons, the fracturing tube should be destroyed; S6. Clearing the slag.

2. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: In S2, the borehole diameter is determined according to the on-site rock compressive strength specifically as: When f r >60, drilling hole diameter D=100+0.33×f r , D unit mm, f r It is the hardness of rock, in MPa, but the upper limit of D must be limited to 200mm; When 60 ≥ f r >30, drilling hole diameter D=70+0.5×(f r -30), D in mm, f r It is the hardness of rock, in MPa; When 30 ≥ f r >15, the drilling hole diameter D=50+1×(f r -15), D in mm, f r It is the hardness of rock, in MPa; When 15 ≥ f r >5, the drilling hole diameter D=70+0.67×(f r -5), D in mm, f r It is the hardness of rock, unit is MPa.

3. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: In S2, the borehole spacing is determined according to the on-site rock compressive strength specifically as: When f r >60, drilling hole spacing L=1000+5×(f r -60), L in mm, f r It is the hardness of rock, in MPa, but the upper limit of D must be limited to 1500mm; When 60 ≥ f r >30, drilling hole spacing L = 1000-10×(f r -30), L in mm, f r It is the hardness of rock, in MPa; When 30 ≥ f r >15, drilling hole spacing L=1500+5×(f r -15), L in mm, f r It is the hardness of rock, in MPa; When 15 ≥ f r >5, the drilling hole diameter L=1000+10×(f r -5), L in mm, f r It is the hardness of rock, unit is MPa.

4. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: The filling pressure of the fracturing tube is controlled between 5 MPa and 10 MPa.

5. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: The outer diameter of the fracturing tube should be 10 mm - 20 mm smaller than the borehole diameter; the length of the fracturing tube should be selected according to the borehole depth.

6. The underwater gas phase transformation rock cracking method according to claim 5, characterized in that: The length of the fracturing tube should be selected according to the borehole depth specifically as: For each range of borehole depth H, the length L of the fracturing tube can be determined by L = a·H + b, where a and b are coefficients determined according to the range of borehole depth; For 1800 mm ≤ H ≤ 2800 mm, take a = 0.5 and b = 0, L = 0.5·H; For 2800 mm < H ≤ 3800 mm, take a = 0.5 and b = -400, L = 0.5·H - 400; For 3800 mm < H ≤ 4500 mm, take a = 0.5 and b = -1000, L = 0.5·H - 1000.

7. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: Before filling the liquid-phase material, the safety valve, fracturing tube, triggering element, and triggering lead wire should be checked for integrity.

8. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: The fracturing tube should reserve a sufficient length of triggering lead wire. When blocking the borehole, the lead wire should be avoided from being damaged; the blocking length of the borehole should not be less than the distance from the fracturing tube to the lateral free face.

9. The underwater gas phase transformation rock cracking method according to claim 1, characterized in that: In step S5, the warning range should be determined according to the water depth. When the water depth is greater than 4 m, the warning range should not be less than 30 m; when the water depth is between 2 m and 4 m, the warning range should not be less than 60 m; when the water depth is less than 2 m, the warning range should not be less than 100 m; after taking warning measures and confirming safety, the fracturing tube should be triggered immediately. After triggering, wait for more than 5 minutes before entering the site for inspection.

10. A system for the underwater gas phase transformation rock cracking method according to any one of claims 1 to 9, characterized in that: It includes: A gas phase change system that can generate high-pressure gas. The adjustable pressure range is determined according to the rock hardness requirement, with good sealing performance and pressure control accuracy to ensure stable output of high-pressure gas; A temperature control and monitoring system. Temperature sensors are arranged in the gas phase change system to monitor the gas temperature change in real time. Heating or cooling elements are equipped. When the gas temperature deviates from the optimal temperature range required for phase change, the temperature is adjusted in time to ensure that the gas accurately undergoes phase change when reaching the predetermined position inside the rock. The specific temperature range for temperature control during the gas phase change process is determined according to the phase change characteristics of the selected gas; The pressure monitoring and feedback system installs a pressure sensor in the gas phase change system to monitor the gas pressure changes in real time and transmit the pressure data to the control system. When the pressure reaches the preset phase change trigger pressure value, the control system accurately controls the gas release and phase change process. At the same time, it adjusts the output pressure of the high-pressure gas generating device in time according to the pressure feedback information to ensure the stability and effectiveness of the rock cracking process.

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