Working face water burst advanced detection and accurate grouting method

Abstract

The invention discloses a working face water gushing advanced detection and accurate grouting method, which relates to the technical field of mine safety, and comprises the following steps: connecting a logging-while-drilling instrument with a drilling structure, and constructing an advanced exploring hole in the to-be-tunneled direction of a roadway; in the advanced hole exploration drilling process, a logging-while-drilling tool is used for obtaining a relation curve of the hole depth and the resistivity and a relation curve of the hole depth and the porosity; determining a position meeting a preset resistivity condition and a preset porosity condition as a crushed zone water burst point based on the curve; placing a stop-grouting plug at a preset distance in front of the crushed zone water bursting point, and blocking the crushed zone water bursting point through grouting equipment; a mode of synchronous drilling of an LWD logging-while-drilling instrument and a drill bit is adopted, resistivity and porosity data are collected in real time in the drilling process, a complete basis is provided for water burst point positioning, and accurate positioning of the crushed zone water burst point is achieved through the quantitative standard that the resistivity is lower than a mean value line by 20% or above and the porosity is larger than 10%.

Description

Technical Field

[0001] This invention belongs to the field of mine safety technology, specifically a method for advanced detection and precise grouting of water inrush at working faces. Background Technology

[0002] Underground mine tunnels are underground passages or spaces excavated during underground mining to facilitate functions such as ore extraction, personnel passage, equipment transportation, ventilation, drainage, and power supply. They are an important component of the underground mine production system. Before the planned excavation of an underground mine tunnel, there may be unknown confined aquifers, water accumulation in old goaf areas, water-conducting fault fracture zones, karst caves, or seepage channels from surface water bodies. Once these water sources are exposed at the working face, high-pressure water can instantly surge into the tunnel, easily causing significant casualties, equipment damage, or even mine flooding. Therefore, proactive exploration and grouting are used before excavating underground mine tunnels to prevent water inrush accidents during excavation.

[0003] Currently, advanced exploration of underground mine roadways generally adopts a combination of geophysical exploration and drilling. Geophysical exploration is an indirect exploration method, and the results are often ambiguous, so drilling is generally required for verification. However, at present, drilling exploration mainly determines the location of water inflow points based on the water inflow at the borehole opening, which has a certain degree of error. As a result, grouting treatment often involves sealing the borehole opening with full-hole grouting instead of directly sealing the water inflow point. This can easily lead to the need for multiple borehole sweeps and repeated grouting, or even grouting and sealing failure, which cannot meet people's needs. Summary of the Invention

[0004] The present invention aims to solve the technical problems existing in the prior art; to this end, the present invention proposes a method for advance detection and precise grouting of water inrush at the working face.

[0005] A method for advanced detection and precise grouting of water inrush at the working face, applied to a roadway working face, includes the following steps: S1: Connect the logging-while-drilling tool to the borehole structure and construct advance exploratory boreholes in the direction of the planned tunnel excavation. S2: During the advance exploratory drilling process, the logging-while-drilling tool is used to obtain the curves of the relationship between hole depth and resistivity and the curves of the relationship between hole depth and porosity. S3: Based on the curve, the location that meets the preset resistivity and preset porosity conditions is the water inrush point of the fracture zone; S4: Place the grout stop plug at a preset distance in front of the water inflow point in the fractured zone, and seal the water inflow point in the fractured zone using grouting equipment.

[0006] As a further aspect of the present invention: in step S1, the drilling structure includes a drill rod coaxially fixed with the logging-while-drilling tool and a drilling rig that controls the operation of the drill rod.

[0007] As a further aspect of the present invention: the front end of the logging-while-drilling tool is equipped with a φ127mm drill bit; and a φ130mm advance exploratory hole is constructed on the working face of the roadway using a drilling rig.

[0008] As a further aspect of the present invention: in step S2, the advance probe reveals the water inflow point in the fractured zone, and the water inflow at the advance probe orifice Q > 100m³. 3 At / h, the logging-while-drilling tool and drill bit are withdrawn from the advance exploratory borehole, the memory card in the logging-while-drilling tool is taken out, and the borehole depth-resistivity curve and borehole depth-porosity curve are generated on the computer. The logging-while-drilling tool is set to LWD logging-while-drilling tool.

[0009] As a further aspect of the present invention: In step S3, in the borehole depth-resistivity curve, the location of the point where the resistivity drops significantly and the porosity is greater than 10% is determined as the location of the water inflow point in the fractured zone, wherein the point where the resistivity drops significantly is the location where the resistivity is 20% or more below the mean line; the borehole depth-resistivity curve (resistivity abrupt change points indicate water-rich areas); the borehole depth-porosity curve (porosity > 10% indicates fractured zones), after drilling is stopped, data is extracted, and the intersection of the mean line where the resistivity drops ≥ 20% and the porosity is > 10% is the water inflow point in the fractured zone, which has a high accuracy advantage. Compared with the traditional borehole water inflow judgment method, the positioning error is reduced from ±10m to ±1m.

[0010] In advance detection of water inflow, the LWD (Logging While Drilling) tool plays a crucial role. Due to changes in rock physical parameters such as rock saturation and porosity at the water inflow point, the resistivity and porosity curves show a significant difference compared to non-water inflow areas. From a resistivity perspective, the resistivity of normal formations is relatively stable, remaining within a certain average range. However, as the water inflow approaches, the increased conductivity of the formation due to the water flow causes a significant drop in resistivity. Typically, the resistivity at the water inflow point is 20% or more below the normal average. This significant resistivity change allows for clear identification of potential water inflow points on the borehole depth-resistivity curve. Regarding porosity, the fractured zone provides channels for groundwater storage and migration due to its fracture-pore system, and its porosity can be used as an important parameter for evaluating formation water inflow. Studies have shown that the porosity at the water outlet location is usually greater than 10%. The depth-porosity curve obtained by the LWD (Logging While Drilling) tool can intuitively show the changes in porosity, thereby helping to determine the location of the water outlet. By comprehensively utilizing the characteristics of these two curves, when a point of significant decrease in resistivity is found in the depth-resistivity curve, and the porosity at that location is greater than 10% in the corresponding depth-porosity curve, the location of the water inflow point in the fractured zone can be determined relatively accurately, providing a key basis for subsequent precise grouting and sealing work.

[0011] As a further aspect of the present invention: In step S4, the grout stopper is set as a φ89mm grout stopper; the φ89mm grout stopper is lowered 2m before the water inrush point of the fracture zone revealed by the advance probe hole; the grout stopper is the "sealing barrier" of the grouting system, and its core function is to form an isolation seal in the grouting hole, creating conditions for precise sealing.

[0012] As a further aspect of the present invention: a grouting pipe is installed on the φ89mm grout stop plug; the grouting pipe is connected to the grout delivery pipe through a tee; and a grouting assembly is provided at one end of the grout delivery pipe.

[0013] As a further aspect of the present invention: the tee is equipped with a pressure gauge for the grouting orifice pressure and a control valve for controlling the opening and closing of the grouting pipe; the core function of the pressure gauge is to dynamically feedback the pressure changes at the grouting orifice: if the pressure spikes abnormally, it may mean that the grout is blocked in the hole or the cracks are filled, and grouting must be stopped in time to avoid the grouting pipe bursting, the hole wall collapsing, or the grout back impacting the equipment due to excessive pressure; if the pressure remains low and does not show an upward trend, it indicates that a large amount of grout may be lost, and the grouting parameters need to be adjusted to ensure effective grout filling; the control valve is the "switch" and "throttle valve" of the grouting pipe: it can be quickly closed in case of emergencies (such as a sudden increase in water flow or abnormal pressure). Interruption of grouting is necessary to avoid grout waste or equipment damage. Grouting flow can be controlled by adjusting the opening (in conjunction with grouting pump parameters) to achieve precise operations such as "small flow with stable pressure" or "gradual pressure increase," adapting to the filling needs of different fissures. After grouting, the valve must be closed, as the grout needs time to solidify in the injection hole. If there is no valve control on the tee, the grout will leak out along the grouting pipe under the pressure of groundwater in the hole. A water pump is installed on the grout stop plug. The function of the water pump is to drive the grout stop plug to expand, forming a reliable seal. Opening the control valve and the water pump connected to the φ89mm grout stop plug pressurizes water into the φ89mm grout stop plug, causing it to expand. The final pressure of the water pump is equal to... Three times the water pressure; the grout stopper is usually made of rubber and needs to expand by pressurized water to fit tightly against the borehole wall; the pressurized water pump injects high-pressure water into the grout stopper, increasing its diameter (e.g., an 89mm grout stopper can fit against the borehole wall of a 130mm advanced probe after expansion), blocking grout leakage from the gap between the borehole opening and the grouting pipe; compared to manual pressurization, the pressurized water pump can precisely control the expansion pressure, avoiding grout stopper seal failure due to insufficient pressure or rubber rupture due to excessive pressure; the reason for setting the final pressurization pressure of the pressurized water pump to three times the water pressure is: to ensure sealing reliability and resist the impact of grouting pressure; the basic seal to resist water inrush pressure: the water pressure at the water inrush point in the fracture zone is set to P. If the expansion pressure of the grout stopper is ≤ P, water inrush... It can overflow from the gap between the grout stop plug and the borehole wall, damaging the seal; 3 times the water pressure can form an excess sealing force, completely blocking the reverse impact of the gushing water; it can withstand the superimposed load of grouting pressure: during the grouting process, the grouting pressure ≥ 2.5 times the water pressure will be transmitted to the grout stop plug through the grout, plus the original gushing water pressure, the total pressure actually borne by the grout stop plug may be close to or exceed 3 times the water pressure; if the final water pressure is less than 3 times, the grout stop plug may be pushed open, causing the grout to flow back, and all previous efforts will be wasted; it can adapt to complex working conditions with uneven borehole walls: the borehole walls of the advanced exploration boreholes in the fracture zone are often uneven, and the expansion force of 3 times the water pressure can allow the grout stop plug to fully fill the small cracks and irregularities in the borehole wall, forming a seal without dead angles and avoiding local leakage.

[0014] As a further aspect of the present invention: the grouting assembly includes a grouting pump connected to the grout delivery pipe and a mixing tank connected to the grouting pump via a suction pipe; water and 425# cement are added to the mixing tank at a water-cement ratio of 0.8:1 to 1:1, and after being stirred evenly, a grout is formed. The grouting pump is used to precisely seal the water seepage points in the fractured zone. Grouting can be stopped when the grouting pressure is greater than or equal to 2.5 times the water pressure and is stabilized for 20 minutes, and the grouting flow rate Q ≤ 20 L / min; this ensures that the grout has good fluidity (facilitating injection into the fractured zone) and forms a stone body with sufficient strength (usually > 15 MPa) after solidification, thus satisfying the sealing requirements. For pressure resistance requirements, 425# cement (28-day compressive strength ≥ 42.5 MPa) has moderate early strength and setting speed, making it suitable for underground engineering grouting. In fractured zones, there is continuous water pressure at water inflow points (denoted as P). If the grouting pressure is ≤ 2 times P, the grout is easily "pushed back" by the water flow and cannot penetrate deep into the fractures. However, a pressure of 2.5 times P forces the grout to overcome water flow resistance and penetrate into the tiny pores and fractures of the fractured zone, achieving a "water-driving-filling" effect. It can also compress the already filled grout, reducing the porosity after solidification and improving the sealing density. A safety margin needs to be reserved for the grouting pressure. Groundwater levels may fluctuate due to changes in geological conditions (e.g., (Replenishment from adjacent aquifers) A water pressure of 2.5 times the pressure ensures that the aggregate remains stable during short-term water level rises, preventing re-leakage. After the grouting pressure reaches 2.5 times the water pressure, stabilizing the pressure for 20 minutes is to: observe whether the pressure remains stable (without significant drop), determine whether the grout has filled all fissures, and whether the aggregate has begun to set (possessing initial strength); if the pressure drops suddenly during the stabilization process, it indicates the existence of unsealed channels, requiring continued grouting to avoid "false blockage"; the initial setting time of cement grout is usually 1-3 hours. The continuous pressure during the stabilization stage helps the grout to "compact" within the fissures and gradually harden through hydration. This lays the foundation for long-term stable sealing. The grouting flow rate should be ≤20L / min to avoid grout loss and excessive flow rate (>20L / min) in the borehole: the grout may be washed away by the water flow before it solidifies (especially at high-velocity water flow points), resulting in material waste and failure to form an effective seal; at the same time, high-speed grout may impact the borehole wall, causing the collapse of the fracture zone and expanding the water flow channel; when the flow rate is ≤20L / min, the crack filling status can be judged by real-time monitoring of flow rate changes: when the flow rate gradually decreases to a stable low value, it indicates that the grout has filled the channel, and grouting can be stopped at this time to avoid over-grouting (saving materials) or under-grouting (incomplete sealing).

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) This invention adopts a method of advanced water inrush detection and precise grouting, and uses the LWD logging-while-drilling tool and drill bit to drill synchronously. During the drilling process, continuous resistivity and porosity data are obtained, which effectively makes up for the lag and uncertainty of the traditional method of judging water inrush points by changes in wellhead return water. It provides key data support for the precise location of water inrush points. The precise location of water inrush points in fractured zones is achieved by using the quantitative standard of "resistivity 20% or more below the mean line + porosity greater than 10%"; and "wellhead water inrush Q > 100m 3 Using " / h" as the key detection trigger condition, this approach avoids over-processing of small-flow water inrushes, focuses on high-risk scenarios, and improves the utilization efficiency of detection resources. Based on the precisely located water inrush point, the grout stop plug is placed 2m in front of the water inrush point to achieve "point-to-point" sealing. Compared with traditional full-section grouting, the consumption of materials such as cement is reduced, significantly lowering project costs. The φ89mm grout stop plug is expanded and sealed by a water pump with 3 times the water pressure. Combined with a pressure gauge and control valve in a three-way valve, it can withstand the dual pressure impact of water inrush and grouting, improving the sealing success rate. This method improves efficiency and solves the sealing failure problem caused by "grout leakage" in traditional grouting methods. It can pre-locate the water inrush point and water pressure and volume parameters in the fractured zone, allowing time for adjusting the construction plan and avoiding casualties or equipment damage caused by sudden large-scale water inrush during tunneling. It significantly reduces the incidence of water-related accidents. The integrated process design from detection to grouting shortens the interval between key processes to less than 2 hours, avoiding borehole collapse or tunnel flooding caused by increased water inrush. Compared with traditional step-by-step construction, it saves construction time. Attached Figure Description

[0016] Figure 1 This is a flowchart of the detection and grouting method of the present invention.

[0017] Figure 2 This is a partial structural diagram of the advanced water inrush detection method in this invention.

[0018] Figure 3 This is a partial structural diagram of the precise grouting process in this invention.

[0019] Figure 4 This is a schematic diagram of the resistivity and porosity relationship curves in this invention.

[0020] In the diagram: 1. Tunnel working face; 2. Pre-exploration borehole; 3. Drill pipe; 4. Logging while drilling instrument; 5. Drill bit; 6. Drilling rig; 7. Water inrush point in fractured zone; 8. Grout stop plug; 9. Grouting pipe; 10. Tee; 11. Water pump; 12. Grout delivery pipe; 13. Grouting pump; 14. Suction pipe; 15. Mixing tank; 16. Grout. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Please see Figure 1 - Figure 4 This application provides a method for advance detection and precise grouting of water inrush at a working face, applied to working face 1 of a roadway, comprising the following steps: S1: Connect the logging-while-drilling tool 4 to the borehole structure and construct a pre-exploration borehole in the direction of the planned tunnel excavation. S2: During the advance exploratory drilling process, the logging-while-drilling tool 4 is used to obtain the curves of the relationship between hole depth and resistivity and the curves of the relationship between hole depth and porosity. S3: Based on the curve, the location that meets the preset resistivity and preset porosity conditions is determined as the water inrush point 7 in the fracture zone; S4: Place the grout stop plug 8 at a preset distance in front of the water inrush point 7 in the fractured zone, and seal the water inrush point 7 in the fractured zone using grouting equipment.

[0023] In step S1, the drilling structure includes a drill pipe 3 that is coaxially fixed with the logging-while-drilling tool 4 and a drilling rig 6 that controls the operation of the drill pipe 3.

[0024] The LWD (Log-While-Drilling) tool 4 is installed behind the φ127mm drill bit 5 and then connected to the drilling rig 6 via drill pipe 3. The drilling rig 6 is used to construct a φ130mm advance borehole 2 on the working face 1 of the roadway. The LWD tool 4 measures resistivity and porosity in real time during the drilling process. The advance borehole 2 reveals a water inflow point 7 in the fractured zone, and the water inflow at the borehole 2 is Q > 100m³. 3At / h, the drill pipe 3, LWD logging-while-drilling tool 4, and drill bit 5 are removed from the advance test hole 2. The memory card in the LWD logging-while-drilling tool 4 is taken out, and the hole depth-resistivity curve and hole depth-porosity curve are generated on the computer. Then, the location of the water inrush point 7 in the fractured zone is determined. The φ89mm grout stop plug 8 is lowered 2m before the water inrush point 7 in the fractured zone revealed by the advance test hole 2. A tee 10 is installed on the grouting pipe 9 of the φ89mm grout stop plug 8 and the valve is opened. The water pump 11 connected to the φ89mm grout stop plug 8 is turned on to pressurize water into the φ89mm grout stop plug 8, so that the φ8 The 9mm grout stopper 8 expands, and the water pump 11 pressurizes water to a final pressure equal to 3 times the water pressure. The grouting pump 13 is connected to the tee 10 through the grout delivery pipe 12. The valve on the tee 10 is closed. The mixing tank 15 is connected to the grouting pump 13 through the grout suction pipe 14. Water and 425# cement are added to the mixing tank 15 according to the water-cement ratio of 0.8:1 to 1:1. After mixing evenly, the grouting pump 13 is used to accurately seal the water seepage point 7 in the broken zone. When the grouting pressure is greater than or equal to 2.5 times the water pressure and stabilized for 20 minutes, and the grouting flow rate Q ≤ 20L / min, the grouting can be stopped.

[0025] Example 2 Reference Figure 2 - Figure 4 This is the second embodiment of the present invention, wherein the front end of the logging-while-drilling tool 4 of the present invention is provided with a φ127mm drill bit 5; and a φ130mm advance exploratory hole 2 is constructed on the working face 1 of the roadway using a drilling rig 6.

[0026] In step S2, the advance borehole 2 reveals a water inflow point 7 in the fractured zone, and the water inflow rate Q at the borehole opening of the advance borehole 2 is greater than 100 m³ / s. 3 At / h, the logging-while-drilling tool 4 and drill bit 5 are withdrawn from the advance exploratory borehole 2, the memory card in the logging-while-drilling tool 4 is taken out, and the borehole depth-resistivity curve and borehole depth-porosity curve are generated on the computer. The logging-while-drilling tool 4 is set to LWD logging-while-drilling tool 4.

[0027] In step S3, the location of the water inrush point 7 in the borehole depth-resistivity curve is determined as the point where the resistivity drops significantly and the porosity is greater than 10%. The point where the resistivity drops significantly is the location where the resistivity is 20% or more below the mean line. After drilling is stopped, the data is extracted from the borehole depth-resistivity curve and the borehole depth-porosity curve. The intersection of the mean line where the resistivity drops ≥20% and the porosity is >10% is the water inrush point 7 in the fractured zone. This method has a high accuracy advantage. Compared with the traditional borehole water inrush judgment method, the positioning error is reduced from ±10m to ±1m.

[0028] During advance detection of water inflow, the LWD (Log-while-Drilling) tool plays a crucial role. Due to changes in rock physical parameters such as rock saturation and porosity at the water inflow point, the resistivity and porosity curves show significant differences compared to non-water inflow areas. From a resistivity perspective, the resistivity of normal formations is relatively stable, remaining within a certain average range. However, as the water inflow approaches, the increased conductivity of the formation due to the presence of water causes a significant drop in resistivity. Typically, the resistivity at the water inflow point is 20% or more below the normal average. This significant resistivity change allows for clear identification of potential water inflow points on the borehole depth-resistivity curve. Regarding porosity, the fractured zone, with its fracture-pore system providing channels for groundwater storage and migration, has porosity that serves as an important parameter for evaluating formation water inflow. Studies have shown that the porosity at the water outlet location is usually greater than 10%. The depth-porosity curve obtained by the LWD logging-while-drilling tool 4 can intuitively show the changes in porosity, thereby helping to determine the location of the water outlet. By combining the characteristics of these two curves, when a point of significant decrease in resistivity is found in the depth-resistivity curve, and the porosity at that location is greater than 10% in the corresponding depth-porosity curve, the location of the water inrush point 7 in the fractured zone can be determined relatively accurately, providing a key basis for subsequent precise grouting and sealing work.

[0029] In step S4, the grout stop plug 8 is set to φ89mm grout stop plug 8; the φ89mm grout stop plug 8 is lowered 2m before the water inrush point 7 of the fracture zone revealed by the advance probe hole 2; the grout stop plug 8 is the "sealing barrier" of the grouting system, and its core function is to form an isolation seal in the grouting hole, creating conditions for precise sealing.

[0030] A grouting pipe 9 is installed on the φ89mm grout stop plug 8; the grouting pipe 9 is connected to the grout delivery pipe 12 through a tee 10; a grouting assembly is provided at one end of the grout delivery pipe 12.

[0031] The tee 10 is equipped with a pressure gauge for the grouting orifice pressure and a control valve for controlling the opening and closing of the grouting pipe 9. The core function of the pressure gauge is to dynamically provide feedback on pressure changes at the grouting orifice: if the pressure spikes abnormally, it may mean that the grout is blocking the hole or the cracks are filled, and grouting must be stopped immediately to avoid the grouting pipe 9 bursting, the hole wall collapsing, or the grout back impacting the equipment due to excessive pressure; if the pressure remains low and does not show an upward trend, it indicates that a large amount of grout may be lost, and the grouting parameters need to be adjusted to ensure effective grout filling; the control valve is the "switch" and "throttle valve" of the grouting pipe 9: it can be quickly closed in case of emergencies such as a sudden increase in water flow or abnormal pressure to interrupt grouting and avoid grout waste or equipment damage. Damaged; the grouting flow rate can be controlled by adjusting the opening degree to achieve refined operations such as "small flow rate stabilization" or "gradual pressure increase" to adapt to the filling needs of different cracks. In addition, after grouting, the valve must be closed. The grout 16 needs time to solidify in the hole. If there is no valve control on the tee, the grout will leak out along the grouting pipe under the action of groundwater pressure in the hole. A water pump 11 is installed on the grout stop plug 8. The function of the water pump 11 is to drive the grout stop plug to expand and form a reliable seal. Opening the control valve and opening the water pump 11 connected to the φ89mm grout stop plug 8 pressurizes water into the φ89mm grout stop plug 8, causing the φ89mm grout stop plug 8 to expand. The final pressure of the water pump 11 is equal to 3 times the water pressure. The grout stop plug 8 is usually Made of rubber, it needs to expand under pressure to adhere tightly to the borehole wall. The water pump 11 injects high-pressure water into the grout stop plug, increasing its diameter (e.g., φ89mm). After expansion, the grout stop plug can fit tightly against the wall of the φ130mm advanced probe borehole, preventing grout leakage from the gap between the borehole opening and the grouting pipe. Compared to manual pressurization, the water pump 11 can precisely control the expansion pressure, preventing the grout stop plug 8 from failing to seal due to insufficient pressure or the rubber from rupturing due to excessive pressure. The reason for setting the final water pressure of the water pump 11 to 3 times the water pressure is: to ensure sealing reliability and resist the impact of grouting pressure; and to provide a basic seal against inrush water pressure. The inrush point 7 in the fractured zone itself has a water pressure of P. If the expansion pressure of the grout stop plug 8 is ≤ P, inrush water will flow from the grout stop plug. 8. Overflow from the gap between the plug and the borehole wall will damage the seal; 3 times the water pressure can form an excess sealing force, completely blocking the reverse impact of the gushing water; withstand the superimposed load of grouting pressure: during the grouting process, the grouting pressure ≥ 2.5 times the water pressure will be transmitted to the plug 8 through the grout. In addition to the original gushing water pressure, the total pressure actually borne by the plug 8 may be close to or exceed 3 times the water pressure; if the final water pressure is less than 3 times, the plug 8 may be pushed open, causing the grout to flow back and all previous efforts to be wasted; adapt to the complex working conditions of uneven borehole walls: the borehole wall of the advanced exploration borehole 2 in the fracture zone is often uneven. The expansion force of 3 times the water pressure can allow the plug 8 to fully fill the small cracks and irregularities in the borehole wall, forming a seal without dead angles and avoiding local leakage.

[0032] The grouting assembly includes a grouting pump 13 connected to the grout delivery pipe 12 and a mixing tank 15 connected to the grouting pump 13 via a grout suction pipe 14.

[0033] Add water and 425# cement to mixing tank 15 at a water-cement ratio of 0.8:1 to 1:1, and mix thoroughly to form grout 16. Use grouting pump 3 to precisely seal the water seepage point 7 in the fracture zone. Grouting can be stopped when the grouting pressure is greater than or equal to 2.5 times the water pressure and stabilized for 20 minutes, and the grouting flow rate Q ≤ 20 L / min. This method ensures that the grout has good fluidity and forms a stone body with sufficient strength after solidification, meeting the sealing and pressure resistance requirements. 425# cement has moderate early strength and setting speed, making it suitable for underground engineering grouting. At point 7 in the fractured zone, there is a continuous water pressure, designated as P. If the grouting pressure is ≤2 times P, the grout is easily "pushed back" by the water flow and cannot penetrate deep into the fractures. However, a pressure of 2.5 times P forces the grout to overcome the water flow resistance and penetrate into the tiny pores and fractures of the fractured zone, achieving a "water-driving-filling" effect. It can also compress the already filled grout, reducing the porosity after solidification and improving the sealing density. A safety margin must be reserved for the grouting pressure: the groundwater level may fluctuate due to changes in geological conditions, and a water pressure of 2.5 times P ensures that the stone body remains stable even when the water level rises in the short term. To prevent re-leakage, after the grouting pressure reaches 2.5 times the water pressure, stabilizing the pressure for 20 minutes is to: observe whether the pressure remains stable, determine whether the grout has filled all cracks, and whether the stone has begun to set; if the pressure drops suddenly during the stabilization process, it indicates that there are unsealed channels, and grouting needs to continue to avoid "false sealing"; the initial setting time of cement grout is usually 1-3 hours. The continuous pressure during the stabilization stage helps the grout to "compact" within the cracks and gradually harden through hydration reaction, laying the foundation for long-term stable sealing; the grouting flow rate should be ≤20L / min. To avoid grout loss and excessive flow rate disturbance within the borehole (e.g., >20L / min): The grout may be washed away by the gushing water before it solidifies (especially at high-velocity gushing points), resulting in material waste and failure to form an effective seal; at the same time, high-speed grout may impact the borehole wall, causing the fracture zone to collapse, which in turn expands the gushing water channel; when the flow rate is ≤20L / min, the fracture filling status can be judged by real-time monitoring of flow rate changes: when the flow rate gradually decreases to a stable low value, it indicates that the grout has filled the channel, and grouting can be stopped at this time to avoid over-grouting (saving materials) or under-grouting (incomplete sealing).

[0034] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for advanced detection and precise grouting of water inrush at a working face, applied to a roadway working face (1), characterized in that, Includes the following steps: S1: Connect the logging-while-drilling tool (4) to the borehole structure and construct an advance exploratory borehole in the direction of the planned tunnel excavation. S2: During the advance exploration drilling process, the logging-while-drilling tool (4) is used to obtain the curves of hole depth and resistivity and the curves of hole depth and porosity. S3: Based on the curve, the location that meets the preset resistivity and preset porosity conditions is the water inrush point of the fracture zone (7). S4: Place the grout stopper (8) at a preset distance in front of the water inrush point (7) in the fractured zone, and seal the water inrush point (7) in the fractured zone using grouting equipment.

2. The method for advanced detection and precise grouting of water inrush at a working face according to claim 1, characterized in that, In step S1, the drilling structure includes a drill rod (3) coaxially fixed with the logging-while-drilling tool (4) and a drilling rig (6) that controls the operation of the drill rod (3).

3. The method for advanced detection and precise grouting of water inrush at a working face according to claim 2, characterized in that, The front end of the logging-while-drilling tool (4) is equipped with a φ127mm drill bit (5); Using a drilling rig (6), a φ130mm advance exploratory hole (2) was constructed on the working face (1) of the roadway.

4. The method for advanced detection and precise grouting of water inrush at a working face according to claim 3, characterized in that, In step S2, the advance probe (2) reveals the water inflow point (7) in the fractured zone, and the water inflow at the orifice of the advance probe (2) is Q > 100m³. 3 At / h, the logging-while-drilling tool (4) and drill bit (5) are removed from the advance exploratory hole (2), the memory card in the logging-while-drilling tool (4) is taken out, and the hole depth-resistivity curve and hole depth-porosity curve are generated on the computer.

5. The method for advance detection and precise grouting of water inrush at a working face according to claim 4, characterized in that, In step S3, the location of the point where the resistivity drops significantly and the porosity is greater than 10% in the hole depth-resistivity curve is determined as the location of the water inrush point (7) in the broken zone, wherein the point where the resistivity drops significantly is the location where the resistivity is 20% or more below the mean line.

6. The method for advanced detection and precise grouting of water inrush at a working face according to claim 1, characterized in that, In step S4, the grout stopper (8) is set to φ89mm grout stopper (8). The φ89mm grout stop plug (8) is inserted 2m before the water inrush point (7) of the fractured zone revealed by the advance probe hole (2).

7. The method for advance detection and precise grouting of water inrush at a working face according to claim 6, characterized in that, A grouting pipe (9) is installed on the φ89mm grout stop plug (8). The grouting pipe (9) is connected to the grout delivery pipe (12) via a tee (10); One end of the grout delivery pipe (12) is equipped with a grouting assembly.

8. The method for advance detection and precise grouting of water inrush at a working face according to claim 7, characterized in that, The tee (10) is equipped with a pressure gauge for the pressure at the grouting orifice and a control valve for controlling the opening and closing of the grouting pipe (9); A water pump (11) is installed on the grout stop plug (8). Open the control valve and the water pump (11) connected to the φ89mm grout stop plug (8) to press water into the φ89mm grout stop plug (8), causing the φ89mm grout stop plug (8) to expand. The final pressure of the water pump (11) is equal to 3 times the water pressure.

9. The method for advanced detection and precise grouting of water inrush at a working face according to claim 7, characterized in that, The grouting assembly includes a grouting pump (13) connected to a grouting pipe (12) and a mixing tank (15) connected to the grouting pump (13) via a suction pipe (14).

10. The method for advance detection and precise grouting of water inrush at a working face according to claim 9, characterized in that, Add water and 425# cement to the mixing tank (15) at a water-cement ratio of 0.8:1 to 1:1 respectively, and stir evenly to form slurry (16). Use the grouting pump (13) to accurately seal the water gushing point (7) of the broken zone. When the grouting pressure is greater than or equal to 2.5 times the water pressure and stabilized for 20 minutes, and the grouting flow rate Q≤20L / min, the grouting can be stopped.

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