Method for controlling surface subsidence by reconstructing bearing layer through directional drilling and grouting

Abstract

The invention discloses a method for controlling surface subsidence by reconstructing a bearing layer through directional drilling and grouting, particularly relates to the technical field of surface subsidence control of a coal mine goaf, and aims at solving the problems that a filling body formed by an existing separation layer grouting technology is loose in structure and insufficient in bearing efficiency. The method comprises the following steps: determining a bearing layer reconstruction position through drilling actual measurement and rock stratum movement theory calculation; dividing a core reinforcement area and an edge diffusion area based on fracture development characteristics, and designing a coupling scheme of longitudinal grouting piles and transverse grouting plates; a directional drilling technology is adopted to accurately convey the grouting pipe to a target layer; slurry with different viscosities is injected in a partitioned manner to form columnar and platy solidified bodies; after solidification, verifying that the pile plates are crosslinked to form an integral bearing structure; the settlement control efficiency is confirmed through vibration energy attenuation rate monitoring, a high-strength space grid structure is constructed at the overlying strata key horizon, and effective transfer and dispersion of overlying loads are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mine goaf surface subsidence control, more particularly, the present application relates to a method for controlling surface subsidence by directional drilling and grouting reconstruction of bearing layer. BACKGROUND

[0002] In the process of underground coal mining, the formation of goaf will cause the destruction and deformation of overlying strata. This destruction and deformation is transmitted to the surface, causing surface subsidence, resulting in damage to land resources, damage to surface buildings and destruction of the ecological environment of the mining area. In order to reduce such damage, one of the core ideas of engineering practice is to control the deformation of key strata, thereby inhibiting surface subsidence. The existing technology mainly realizes it through two ways: one is to adjust the mining process, such as setting up coal pillars, limiting the mining height or changing the mining method, aiming to control the damage range of overlying strata; the other is to implement separation grouting, by injecting grout into the separation fissures between overlying strata, filling the space and limiting the movement range of strata.

[0003] However, the existing technical means for controlling surface subsidence has significant limitations. The adjustment of mining process often sacrifices part of the recoverable coal resources or increases the complexity of underground operation, and the conventional separation grouting technology is limited by the grouting process, and it is difficult to form a high-strength bearing structure with sufficient integrity and long-term stability at the target layer in a precise and controllable manner. The bearing efficiency of the filling body formed by it is limited, and it cannot effectively and durably bear the load of overlying strata to inhibit surface subsidence. SUMMARY

[0004] In order to overcome the above-mentioned defects of the prior art, the present application provides a method for controlling surface subsidence by directional drilling and grouting reconstruction of bearing layer to solve the problems raised in the background art.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A method for controlling surface subsidence by directional drilling and grouting reconstruction of bearing layer, comprising the following steps:

[0007] S1, obtaining the position and lithology information of the main bearing layer in the overlying strata of the goaf through drilling and surveying, and determining the reconstruction position of the bearing layer combined with geological exploration data and strata movement theory calculation;

[0008] S2, dividing the grouting area based on the reconstruction position of the bearing layer, and designing a coupled grouting scheme of longitudinal grouting to form grouting piles and transverse grouting to form grouting plates by directional drilling;

[0009] S3, using directional drilling technology to transport the grouting pipe to the target grouting area at the reconstruction position of the bearing layer;

[0010] S4. Injecting slurry into the target grouting area through the directional drilling grouting pipe, so that the slurry diffuses, fills and cements in the separation and fissure at the reconstruction position of the bearing layer;

[0011] S5. After the injected slurry solidifies, an integral bearing structure layer composed of the grouting pile and the grouting plate is formed at the reconstruction position of the bearing layer;

[0012] S6. Vibration sensors are arranged in the lower and upper rock layers respectively below and above the integral bearing structure layer, to monitor the vibration energy attenuation rate of the lower rock layer transmitted to the upper rock layer; when the vibration energy attenuation rate exceeds a preset threshold, it is confirmed that the vibration energy isolation function is achieved.

[0013] Further, the position and lithology information of the main bearing layer in the overburden rock layer above the goaf are obtained through drilling measurement, and the reconstruction position of the bearing layer is determined by combining geological exploration data and rock layer movement theory calculation, including:

[0014] Drilling exploration holes are constructed within the influence range of the goaf, and the depth and rock mechanics parameters of the main bearing layer are determined by lithology identification of the drilling core samples;

[0015] The interlayer fissure development characteristics of the main bearing layer are observed and recorded by the drilling peephole instrument, including the fissure dip angle, density and extension range;

[0016] The stratigraphic dip angle and fault distribution data in the geological exploration data are extracted;

[0017] A rock beam mechanics model is established based on the rock mechanics parameters, interlayer fissure development characteristics and stratigraphic dip angle;

[0018] The separation development height and stress concentration area range of the main bearing layer under the influence of mining are calculated by the overburden rock beam mechanics model;

[0019] The layer position where the maximum separation development height is located is selected, and the fault distribution area and stress concentration area range are avoided to determine the reconstruction position of the bearing layer.

[0020] Further, the separation development height and stress concentration area range of the main bearing layer under the influence of mining are calculated by the overburden rock beam mechanics model, including:

[0021] The rock mechanics parameters and interlayer fissure development characteristics are input into the overburden rock beam mechanics model, and the mining load is set as the boundary condition;

[0022] The deflection differential equation of the overburden rock beam under the action of the mining load is solved to obtain the bending moment extreme point of each position of the overburden rock beam;

[0023] The bending moment extreme point position is taken as the separation development height, and the area where the bending moment change rate exceeds the rock layer bending stiffness threshold is taken as the stress concentration area range.

[0024] Further, the grouting area is divided based on the bearing layer reconstruction position, and a coupling grouting scheme is designed to implement longitudinal grouting to form grouting piles and transverse grouting to form grouting plates by directional drilling, including:

[0025] Based on the interlayer fracture development characteristics and rock mechanics parameters corresponding to the bearing layer reconstruction position, the grouting area is divided into a core reinforcement area with a fracture density higher than a preset value and an edge diffusion area with a fracture density lower than the preset value;

[0026] A longitudinal directional drilling arrangement scheme is designed for the core reinforcement area, so that the grouting piles formed by longitudinal grouting penetrate the high-density fracture zone;

[0027] A transverse directional drilling arrangement scheme is designed for the edge diffusion area, so that the grouting plates formed by transverse grouting cover the low-density fracture zone;

[0028] The intersection position of the grouting piles and the grouting plates is set to ensure that the maximum stress transmission direction of the grouting piles is perpendicular to the extension direction of the grouting plates.

[0029] Further, the grouting pipe is delivered to the target grouting area at the bearing layer reconstruction position by directional drilling technology, including:

[0030] According to the longitudinal directional drilling arrangement scheme corresponding to the core reinforcement area and the transverse directional drilling arrangement scheme corresponding to the edge diffusion area, directional drilling trajectories are designed respectively;

[0031] Directional drilling is performed at the bearing layer reconstruction position, and a measurement-while-drilling system is used to monitor the drilling inclination and azimuth in real time;

[0032] Based on the monitoring data of the measurement-while-drilling system, the drilling trajectory is adjusted so that the end of the grouting pipe reaches the longitudinal grouting target point of the core reinforcement area or the transverse grouting target point of the edge diffusion area;

[0033] After verifying that the deviation value between the position of the end of the grouting pipe and the center coordinates of the target grouting area is less than the allowable error threshold, the position of the grouting pipe is fixed.

[0034] Further, based on the monitoring data of the measurement-while-drilling system, the drilling trajectory is adjusted so that the end of the grouting pipe reaches the longitudinal grouting target point of the core reinforcement area or the transverse grouting target point of the edge diffusion area, including:

[0035] The drilling inclination and azimuth returned by the measurement-while-drilling system in real time are compared with the target inclination and azimuth of the designed trajectory;

[0036] When the horizontal deviation is greater than the diameter of the directional drilling or the vertical deviation is greater than the length of the grouting pipe, the direction of the push force of the drilling tool guide hydraulic cylinder is adjusted;

[0037] The monitoring and adjustment are repeated until the coordinates of the end of the grouting pipe fall within the allowable error sphere of the longitudinal grouting target point or the transverse grouting target point.

[0038] Further, the slurry is injected into the target grouting area through the directional drilling grouting pipe, and the slurry is diffused, filled and cemented in the separation and cracks at the bearing layer reconstruction position, including:

[0039] The high-viscosity slurry is injected into the longitudinal grouting target point of the core reinforcement area, and the grouting pressure is controlled to make the high-viscosity slurry directionally diffuse in the longitudinal cracks to form columnar solidification bodies;

[0040] The low-viscosity slurry is injected into the transverse grouting target point of the edge diffusion area, and the grouting pressure is controlled to make the low-viscosity slurry extend and diffuse in the transverse separation to form plate-shaped solidification bodies;

[0041] The outlet pressure of the grouting pipe is monitored in real time, and when the pressure value exceeds the critical pressure threshold value corresponding to the core reinforcement area or the edge diffusion area, the grouting is suspended and the grouting rate is adjusted;

[0042] After the slurry is filled in the separation and cracks, a stable pressure state is maintained until the grouting pipe pressure value is stabilized in the rock mass closure pressure range of the bearing layer reconstruction position.

[0043] Further, after the injected slurry solidifies, an integral bearing structure layer is formed at the bearing layer reconstruction position, which is composed of the grouting pile and the grouting plate coupled with each other, including:

[0044] The connection interface cementation state of the columnar solidification body and the plate-shaped solidification body is monitored during the slurry solidification process;

[0045] The longitudinal wave velocity of the grouting pile and the transverse wave velocity of the grouting plate are measured by the acoustic wave detector;

[0046] When the longitudinal wave velocity of the grouting pile reaches the design wave velocity threshold corresponding to the rock mechanics parameters and the transverse wave velocity of the grouting plate reaches the design wave velocity threshold corresponding to the rock mechanics parameters, it is confirmed that the columnar solidification body is converted into the grouting pile and the plate-shaped solidification body is converted into the grouting plate;

[0047] The crosslinking point position of the grouting pile and the grouting plate is verified to form a continuous stress transfer path, and it is confirmed that the grouting pile and the grouting plate are coupled to form an integral bearing structure layer.

[0048] Further, the crosslinking point position of the grouting pile and the grouting plate is verified to form a continuous stress transfer path, including:

[0049] An acoustic emission sensor array is arranged at the crosslinking point position to collect acoustic emission events of the interface between the grouting pile and the grouting plate under load;

[0050] If the spatial distribution density of the acoustic emission events decreases along the extension direction of the grouting plate and there is no local high-density aggregation, it is determined that a continuous stress transfer path is formed.

[0051] Further, vibration sensors are arranged in the lower stratum and the upper stratum below the integral bearing structure layer respectively to monitor the vibration energy attenuation rate of the lower stratum transmitted to the upper stratum; when the vibration energy attenuation rate exceeds a preset threshold, it is confirmed that the integral bearing structure layer has the vibration energy isolation function, including:

[0052] Vibration sensors are installed at the first monitoring point of the lower stratum and the second monitoring point of the upper stratum respectively below the integral bearing structure layer;

[0053] The original vibration energy signal under the mining load is collected by the vibration sensor of the lower stratum;

[0054] The vibration energy signal attenuated by the integral bearing structure layer is collected by the vibration sensor of the upper stratum;

[0055] The ratio of the original vibration energy signal and the attenuated vibration energy signal is calculated to obtain the vibration energy attenuation rate;

[0056] When the vibration energy attenuation rate exceeds a preset threshold, it is confirmed that the integral bearing structure layer has the vibration energy isolation function.

[0057] Compared with the prior art, the present application has the following beneficial effects:

[0058] 1. The pile-plate coupled bearing structure is accurately constructed at the key stratum of overburden by directional drilling grouting, breaking through the random filling limitation of conventional separation grouting, the stress transmission channel is formed by the longitudinal grouting pile penetrating the high-density fracture zone, the continuous bearing surface is formed by the transverse grouting plate covering the low-density separation zone, and the space grid-shaped integral structure is formed by the orthogonal coupling of the two at the crosslinking point, the axial compression property of the grouting pile and the shear property of the grouting plate are synergistically acted to convert the overburden load into a uniform stress field, the deformation resistance of the bearing layer is significantly improved, and thus the transmission of stratum movement to the surface is inhibited.

[0059] 2. Compared with the traditional process, first, the reconstruction layer is accurately positioned based on the overburden beam mechanics model to avoid faults and stress concentration areas; second, the directional drilling is differentially grouted according to the fracture development characteristics, the high-viscosity grout forms a rigid column in the core area, and the low-viscosity grout forms an extended plate in the edge area; third, the sound wave and vibration dual-mode verify the integrity of the bearing structure to ensure that the vibration energy attenuation rate continuously meets the standard, and finally, the active control of surface subsidence is realized under the premise of ensuring the recovery rate of coal resources. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 The flowchart of the method for reconstructing the bearing layer by directional drilling grouting to control surface subsidence. DETAILED DESCRIPTION

[0061] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0062] Embodiments: Figure 1 A method for controlling ground subsidence by reconstructing a bearing layer through directional drilling and grouting is provided, which comprises the following steps:

[0063] S1, obtaining the position and lithology information of the main bearing layer in the overlying strata of the goaf through drilling and surveying, and determining the reconstruction position of the bearing layer in combination with geological exploration data and strata movement theory calculation;

[0064] S2, dividing the grouting area based on the reconstruction position of the bearing layer, and designing a coupling grouting scheme of forming a grouting pile through longitudinal grouting and forming a grouting plate through transverse grouting by directional drilling;

[0065] S3, transporting the grouting pipe to the target grouting area at the reconstruction position of the bearing layer by using directional drilling technology;

[0066] S4, injecting grout into the target grouting area through the grouting pipe by directional drilling, so that the grout diffuses, fills and cements in the separation and fissure at the reconstruction position of the bearing layer;

[0067] S5, after the injected grout solidifies, forming an integral bearing structure layer composed of a grouting pile and a grouting plate coupled with each other at the reconstruction position of the bearing layer;

[0068] S6, arranging vibration sensors in the lower strata and the upper strata below and above the integral bearing structure layer respectively, monitoring the vibration energy attenuation rate transmitted from the lower strata to the upper strata, and confirming the vibration energy isolation function when the vibration energy attenuation rate exceeds a preset threshold.

[0069] A plurality of exploration drill holes are arranged within an extension of 50 meters, for example, outside the boundary of the goaf, and are constructed to a target depth above the coal seam roof by using a drill, such as an XY-180 drill. The lithology of the drill core samples is identified: after cutting standard rock samples, the uniaxial compressive strength, elastic modulus and Poisson's ratio and other rock mechanics parameters are tested by a press, and the depth of the main bearing layer is recorded. For example, the sandstone layer in a certain drill hole has a depth of 52.3 meters, and the uniaxial compressive strength is 48.5 MPa, and the elastic modulus is 12.3 GPa.

[0070] The borehole camera is used to observe the main bearing layer at a constant speed, and the image analysis is used to identify the development characteristics of the interlayer fissure. For example, in the depth of 52.1-52.8 meters, the fissure inclination angle is 65°-82°, the average density is 3.2 per meter, and the maximum extension range is 1.7 meters. The stratum inclination angle data (e.g. 28°) and fault distribution coordinates (e.g. the influence radius of F8 fault is 35 meters) in the geological exploration data are extracted.

[0071] Based on the rock mechanics parameters, the interlayer fissure development characteristics and the stratum inclination angle, the overburden rock beam mechanical model is established: the rock stratum is simplified as a beam with both ends fixed, the beam length is taken as the length of the working face inclination, for example 200 meters, and the cross-section height is set according to the thickness of the bearing layer, for example 8 meters. The mining load is set as a uniform load, and its value is calculated according to the overburden density and the mining height, for example 100 kilopascals according to the overburden density of 25 kilonewtons per cubic meter and the mining height of 4 meters. The elastic modulus and the fissure density are input to modify the bending stiffness of the beam, and the fissure inclination angle is converted into equivalent boundary constraint conditions (e.g. when the inclination angle is greater than 75°, it is treated as a fixed support).

[0072] The development height of the separation and the range of the stress concentration zone are calculated by the overburden rock beam mechanical model: the beam bending differential equation is solved to calculate the bending moment value at each position. The position of the bending moment extreme value is determined as the development height of the separation, for example the elevation of-352.6 meters. The bending moment change rate of the adjacent nodes is calculated, and when the change rate exceeds the threshold value of the bending stiffness of the rock stratum (the critical value is measured by the bending test of the rock sample in the laboratory, for example 0.005 radian per meter), it is marked as the stress concentration zone, for example the section from the elevation of-352.6 meters to-348.1 meters.

[0073] The layer position where the maximum value of the separation development height is located (e.g. -352.6 meters) is selected, and the candidate area is divided with the elevation as the center. The overlapping area within the influence radius of the fault (e.g. within 35 meters of F8 fault) is excluded; the stress concentration zone range (e.g. from-352.6 meters to-348.1 meters) is compared and removed. Finally, the bearing layer reconstruction position is determined, for example the cylindrical area with the center coordinate (X=12605, Y=8721) as the center, the diameter of 40 meters and the center elevation of-360.5 meters.

[0074] Based on the interlayer fissure development characteristics and the rock mechanics parameters corresponding to the bearing layer reconstruction position, the grouting area is divided into the core reinforcement zone and the edge diffusion zone. Specifically, by counting the distribution density of all fissures within the range of the bearing layer reconstruction position, the fissure density preset value is set to be, for example, 5 per meter; when the fissure density of a certain sub-area is higher than the preset value, it is classified into the core reinforcement zone, for example, if the fissure density of a certain area is 7.2 per meter, it is classified into the core reinforcement zone; when the fissure density is lower than the preset value, it is classified into the edge diffusion zone, for example, if the fissure density of a certain area is 3.1 per meter, it is classified into the edge diffusion zone. The basis for setting the fissure density preset value is that, through the analysis of historical grouting engineering data, when the fissure density is higher than 5 per meter, the grout is prone to local aggregation, and high-viscosity grout needs to be used for directional injection.

[0075] Design a longitudinal directional drilling layout for the core reinforcement zone. First, extract the fracture extension range data in the core reinforcement zone, such as an average fracture extension range of 1.7 meters. Determine the drilling spacing as 0.8 times the fracture extension range, such as 1.36 meters. Design the drilling trajectory within a ±10° deviation range to ensure that the grouting pipe can penetrate the high-density fracture zone. Determine the drilling depth based on the fracture zone height, such as a penetration depth of 8 meters plus a 2-meter safety margin, so the drilling depth is designed to be 10 meters.

[0076] Design a horizontal directional drilling layout for the edge diffusion zone. First, analyze the distribution direction of the low-density fracture zone, such as determining the main dominant direction to be 75° through fracture dip angle statistics. Design the drilling trajectory along this dominant direction with a tilt angle deviation controlled within ±5°. Calculate the drilling spacing based on the elastic modulus in the rock mechanics parameters, such as an elastic modulus of 12.3 GPa corresponding to a maximum diffusion radius of 4.1 meters, taking 0.7 times the diffusion radius as the design spacing, which is 2.87 meters. The drilling length covers the low-density fracture zone boundary extension, such as 3 meters, ensuring that the grouting plate completely covers the target area.

[0077] Set the cross-linking point position of the grouting pile and the grouting plate. First, select the stress transfer key node at the junction of the core reinforcement zone and the edge diffusion zone. Calculate the maximum stress transfer direction of the grouting pile: based on the elastic modulus and Poisson's ratio in the rock mechanics parameters, use the elastic mechanics formula to solve the principal stress direction, such as the maximum principal stress direction of a certain node being vertically downward. The extension direction of the grouting plate is determined according to the horizontal drilling trajectory, such as 75°. Verify the perpendicular relationship between the two directions: calculate the dot product of the two direction vectors to see if it tends to zero, such as the absolute value of the dot product of the vertical direction vector (0, 0, 1) and the 75° direction vector (sin75°, 0, cos75°) being less than 0.1, which is determined to be perpendicular. Finally, determine the node coordinates that meet the perpendicular condition as the cross-linking point position, such as coordinates (X=12568, Y=8743).

[0078] According to the longitudinal directional drilling layout scheme corresponding to the core reinforcement area and the transverse directional drilling layout scheme corresponding to the edge diffusion area, the directional drilling trajectory is designed respectively. For the longitudinal grouting target point of the core reinforcement area, the crosslinking point position is taken as the reference point, and the drilling axis is designed along the vertical direction, and the trajectory deviation is controlled within ±1°. For example, the coordinates of a certain longitudinal grouting target point are (X=12568, Y=8743, Z=-360.5), and the designed trajectory is a straight line from the ground point (X=12568, Y=8743, Z=0) to the target point, with an azimuth angle of 0° and an inclination angle of 90°. For the transverse grouting target point of the edge diffusion area, the drilling trajectory is designed according to the extension direction 75° of the transverse grouting plate, for example, the target point (X=12622, Y=8695, Z=-362.1), and the starting point of the designed trajectory is (X=12510, Y=8780, Z=-355), and the terminal azimuth angle is 75° and the inclination angle is 15°. In the design process, the influence of the elastic modulus in the rock mechanics parameters is considered, and the trajectory curvature radius is reduced in the high elastic modulus area, for example, when the elastic modulus is greater than 10 gigapascals, the curvature radius is not less than 50 meters.

[0079] The directional drilling is constructed at the bearing layer reconstruction position, and the drilling inclination and azimuth are monitored in real time by using the measurement-while-drilling system. The measurement-while-drilling system includes a three-axis accelerometer and a magnetometer, the accelerometer measures the gravity vector component to calculate the inclination, and the magnetometer measures the geomagnetic field component to calculate the azimuth. Data is collected every 0.5 meters of drilling, for example, when drilling to a depth of 200 meters, the real-time returned inclination is 89.2° and the azimuth is 1.3°, which is compared with the designed value (90°, 0°) to generate a deviation report. The monitoring data is transmitted to the ground control console in real time through the shielded cable, the data transmission rate is 2 groups per second, and the signal sampling frequency is 100 hertz. The drilling construction adopts a composite drilling process, a rotary drilling mode is used in the homogeneous rock section, and a sliding drilling mode is used in the fracture development section, and the drilling pressure is adjusted according to the uniaxial compressive strength of the rock, for example, when the compressive strength is 48.5 megapascals, the drilling pressure is controlled at 80 kilonewtons.

[0080] The drilling trajectory is adjusted based on the monitoring data of the measurement-while-drilling system, and the horizontal deviation and vertical deviation of the real-time coordinates from the target point are calculated. The horizontal deviation calculation formula is: the difference between the measured azimuth and the designed azimuth multiplied by the current hole depth and then multiplied by π / 180. For example, when the azimuth deviation is 1.3° and the hole depth is 200 meters, the horizontal deviation is 1.3×200×3.1416 / 180≈4.5 meters. The vertical deviation calculation formula is: the difference between the measured inclination and the designed inclination multiplied by the hole depth and then multiplied by π / 180. For example, when the inclination deviation is 0.8° and the hole depth is 200 meters, the vertical deviation is 0.8×200×3.1416 / 180≈2.8 meters. When the horizontal deviation is greater than the diameter of the directional drilling (for example, the diameter is 0.15 meters) or the vertical deviation is greater than the length of a single section of the grouting pipe (for example, the length of a single section is 3 meters), the adjustment program is started: first, the deviation direction vector is calculated, the horizontal deviation direction is determined by the positive or negative sign of the azimuth deviation, and the vertical deviation direction is determined by the positive or negative sign of the inclination deviation; then, the drill tool guide hydraulic cylinder thrust vector is calculated according to the deviation direction. For example, when the horizontal deviation is 1.3° east, the west side hydraulic cylinder pressure is increased, and the pressure value is linearly adjusted according to the deviation distance, with a pressure increment of 4 MPa per meter of deviation, and a pressure of 18 MPa corresponding to a deviation of 4.5 meters. After adjustment, continue drilling for 2 meters, and re-monitor and compare the data.

[0081] The monitoring and adjustment process is repeated until the coordinates of the end of the grouting pipe meet the allowable error sphere condition. The allowable error sphere is a three-dimensional spherical space centered on the target point, and the sphere radius is set according to 50% of the slurry diffusion radius. The slurry diffusion radius is calculated by the formula: the diffusion radius is equal to the grouting volume divided by π, then divided by the fracture opening, and then divided by the cube root of the grouting efficiency coefficient, where the grouting efficiency coefficient is 0.35. For example, when the grouting volume is 0.5 cubic meters and the fracture opening is 0.002 meters, the diffusion radius is about 0.6 meters, and the corresponding sphere radius is 0.3 meters. The real-time coordinates (X, Y, Z) are obtained by the end positioning module of the measurement-while-drilling system, and the spatial distance from the target point (X0, Y0, Z0) is calculated: the distance is equal to the square root of [(X-X0)²+(Y-Y0)²+(Z-Z0)²]. For example, the measured coordinates (12568.2, 8743.1, -360.6) and the distance from the target point (12568, 8743, -360.5) are calculated: ΔX=0.2, ΔY=0.1, ΔZ=-0.1, and the distance is equal to the square root of (0.2²+0.1²+0.1²), which is equal to 0.2449 meters, which is less than the threshold value of 0.3 meters. When the distance is less than the sphere radius in three consecutive measurements, it is determined that the condition is met.

[0082] After the end of the grouting pipe is verified to meet the requirements, the grouting pipe position is fixed. The grouting pipe is anchored by a hydraulic locking device. The locking device includes three hydraulic slips distributed at 120 degrees. The slip opening diameter is designed to be 1.2 times the diameter of the borehole. For example, when the borehole diameter is 0.15 meters, the slip opening diameter is 0.18 meters. The locking force is set according to the compressive strength of the rock. The calculation formula is: the locking force is equal to the uniaxial compressive strength of the rock multiplied by the contact area of the slip multiplied by the safety factor 0.3. For example, when the compressive strength is 48.5 MPa and the contact area is 0.008 square meters, the locking force is 48.5 x 10 6 ×0.008 x 0.3 ≈ 116.4 kN. The displacement after fixation is verified by the re-measurement system: after locking, a test load of 10% of the working tension is applied. For example, when the working tension is 100 kN, a test force of 10 kN is applied. The displacement of the grouting pipe is measured. If the displacement is less than 0.1 mm, the fixation is considered effective. The final record of the end coordinate deviation from the target point is recorded. For example, the horizontal deviation is 0.15 meters, and the vertical deviation is 0.08 meters. The spatial distance is calculated as the square root of (0.15² + 0.08²) ≈ 0.17 meters, which is less than the allowable error threshold of 0.3 meters. After the fixation is completed, the drill hole is cleared of debris and the grouting pipe joint sealing device is installed.

[0083] High-viscosity grout is injected into the longitudinal grouting target point of the core reinforcement area. The high-viscosity grout is a cement-based grout with a water-cement ratio of 0.6:1 and 5% bentonite thickener, with a viscosity controlled in the range of 800-1200 centipoise. The grouting pressure is controlled in the range of 3-5 MPa to enable the high-viscosity grout to diffuse directionally in the longitudinal fracture. The grouting rate is adjusted according to the fracture opening, for example, when the fracture opening is 0.2 mm, the grouting rate is 30 liters per minute. The longitudinal preferential diffusion is achieved by controlling the pressure gradient, which is set to increase by 0.05 MPa per meter along the axial direction of the borehole, forming a columnar solid with a diameter of 0.8-1.2 meters and a height of 8-12 meters. During the formation of the columnar solid, the grout diffusion radius is recorded every 5 minutes. When the difference between the adjacent two measurements is less than 5%, the diffusion is considered complete.

[0084] Low-viscosity grout is injected into the transverse grouting target point of the edge diffusion area. The low-viscosity grout is a cement grout with a water-cement ratio of 1:1 and 0.2% water reducing agent, with a viscosity controlled in the range of 150-250 centipoise. The grouting pressure is controlled in the range of 1-2 MPa to enable the low-viscosity grout to spread and diffuse in the transverse separation layer. The grouting rate is adjusted according to the separation layer thickness, for example, when the separation layer thickness is 5 mm, the grouting rate is 50 liters per minute. The horizontal spread is achieved by controlling the uniform distribution of pressure. Four symmetrically distributed shunt holes are set in the radial direction of the grouting pipe, with the pressure difference of each shunt hole controlled within ±0.1 MPa, forming a plate-shaped solid with a thickness of 0.3-0.5 meters and an area of 15-25 square meters. During the formation of the plate-shaped solid, the grout front morphology is monitored by borehole television. When the front curvature radius is greater than 5 meters, the spread is considered effective.

[0085] The outlet pressure of the grouting pipe is monitored in real time. A pressure sensor is installed 0.5 meters away from the end of the grouting pipe, and the sampling frequency is 10 Hz. The critical pressure threshold corresponding to the core reinforcement area is set according to the tensile strength of the rock, and the calculation formula is that the critical pressure threshold is equal to 1.5 times the tensile strength of the rock. For example, when the tensile strength of the rock is 2.1 MPa, the critical pressure threshold is 3.15 MPa. The critical pressure threshold corresponding to the edge diffusion area is set according to the overburden stress, and the calculation formula is that the critical pressure threshold is equal to the overburden density multiplied by the buried depth and then multiplied by 0.8. For example, when the overburden density is 25 kN / m3 and the buried depth is 360 meters, the critical pressure threshold is 7.2 MPa. When the pressure value exceeds the critical pressure threshold, the grouting is suspended and the grouting rate is adjusted: first, the grouting rate is reduced to 50% of the original rate, and after maintaining for 3 minutes, the pressure change is re-evaluated; if the pressure is still higher than the threshold, the grouting rate is decreased by 10% each time until the pressure is stable below the threshold.

[0086] After the slurry fills the separation layer and the fissure, the filling completion state is determined according to the grouting amount-pressure curve: when the grouting amount continues to increase and the pressure fluctuation amplitude is less than ±5%, it is determined that the filling is completed. The stable pressure value is set to 90% of the current grouting pressure, and the stable pressure time is determined according to the initial setting time of the slurry. For example, if the initial setting time of ordinary Portland cement slurry is 120 minutes, the stable pressure is 100 minutes. The grouting pipe pressure value is monitored in real time during the stable pressure process, and the stable pressure pump output is adjusted to make the pressure value stable within the rock mass closure pressure range of the bearing layer reconstruction position. The rock mass closure pressure range is obtained by geostress testing. For example, the minimum horizontal principal stress is 8.5 MPa, the maximum horizontal principal stress is 11.2 MPa, and the vertical stress is 9.0 MPa, so the closure pressure range is 8.5-11.2 MPa. When the pressure value fluctuates within the range with an amplitude of less than ±0.2 MPa and lasts for 30 minutes, the stable pressure is ended and the grouting valve is closed.

[0087] The connection interface cementation state of columnar and platy solidification bodies is monitored during the solidification process of the slurry. A distributed optical fiber temperature sensing system is used for monitoring. The specific implementation includes: arranging optical fiber sensors along the axial direction of the grouting pipe, with a sensor spacing of 0.5 meters, and a spacing of 0.2 meters at the cross-linking point position. The temperature field change during the solidification process is monitored, and the temperature sampling frequency is 1 time per minute. The cementation state is determined by the temperature change curve: when the temperature gradient at the interface is less than 0.5°C / m and the temperature curve shows continuous and smooth characteristics, it is determined that the cementation is good; when the temperature gradient is greater than 1.0°C / m or a temperature mutation point appears, it is determined that the cementation is defective. For example, the temperature gradient from 45°C to 35°C at a certain cross-linking point position is 0.3°C / m, which meets the good cementation standard. The cementation defect treatment measures include: secondary grouting reinforcement is carried out at the defect position, and 2% of the accelerator is added to the reinforcement slurry to shorten the solidification time.

[0088] The longitudinal wave velocity of the grouting pile and the transverse wave velocity of the grouting plate are measured by a sound wave detector. The measurement system includes a seismic source device and an array of receiving sensors. For the grouting pile, a hydraulic seismic source is installed at the top of the columnar solidification body, and 8 receiving sensors are arranged in a ring at the bottom with a spacing of 1.0 meters. A pulse signal with a frequency of 5 kHz is excited, and the first arrival wave propagation time is recorded. The longitudinal wave velocity is calculated by dividing the propagation path length by the propagation time. For example, for a grouting pile with a height of 10 meters and a propagation time of 2.1 milliseconds, the longitudinal wave velocity is 10 / 0.0021≈4762 m / s. For the grouting plate, an electromagnetic seismic source is installed at the edge of the plate-shaped solidification body, and a 5x5 grid of receiving sensors is arranged on the plate surface with a grid spacing of 0.8 meters. A shear wave signal with a frequency of 2 kHz is excited, and the transverse wave velocity is calculated by dividing the time difference between adjacent sensors by the sensor spacing. For example, with a sensor spacing of 0.8 meters and a time difference of 0.42 milliseconds, the transverse wave velocity is 0.8 / 0.00042≈1905 m / s.

[0089] When the longitudinal wave velocity of the grouting pile reaches the design wave velocity threshold corresponding to the rock mechanical parameters, and the transverse wave velocity of the grouting plate reaches the design wave velocity threshold corresponding to the rock mechanical parameters, it is confirmed that the columnar solidification body is converted into a grouting pile and the plate-shaped solidification body is converted into a grouting plate. The design wave velocity threshold is calculated according to the rock mechanical parameters obtained by S1: the longitudinal wave velocity design threshold of the grouting pile is equal to 0.85 times the original rock longitudinal wave velocity, and the transverse wave velocity design threshold of the grouting plate is equal to 0.75 times the original rock transverse wave velocity. The original rock wave velocity is obtained by sound wave testing of the S1 borehole rock sample, for example, the original rock longitudinal wave velocity is 5600 m / s, and the grouting pile design threshold is 4760 m / s, and the original rock transverse wave velocity is 2500 m / s, and the grouting plate design threshold is 1875 m / s. The judgment condition is that the measured value is greater than the design threshold for three consecutive times, and the fluctuation amplitude of adjacent measured values is less than 3%. For example, the longitudinal wave velocity of a certain grouting pile is measured three times as 4762, 4758, and 4765 m / s, all of which are greater than the threshold of 4760 m / s, and the fluctuation amplitude (4765-4758) / 4760=0.15%<3%, so it is determined to be converted into a grouting pile.

[0090] The crosslinking point position of the grouting pile and the grouting plate is verified to form a continuous stress transfer path, and an acoustic emission sensor array is arranged at the crosslinking point position. The array consists of 16 sensors arranged in a 4x4 grid with a grid size of 1.0x1.0 meters, and the sensors are installed at the interface between the grouting pile and the grouting plate. A step load is applied: the initial load is 10% of the design bearing capacity, each level increases by 10%, the holding time is 5 minutes, and the maximum load is 80% of the design bearing capacity. Acoustic emission events under load are collected with a sampling frequency of 1 MHz and a trigger threshold of 40 dB. The three-dimensional coordinates and energy values of each acoustic emission event are recorded, and the spatial distribution density is calculated with a 0.5x0.5x0.5 meter cube as the statistical unit. The density value is obtained by dividing the number of events in the unit volume by the unit volume.

[0091] If the spatial distribution density of the acoustic emission events decreases along the extension direction of the grouting plate and there is no local high-density aggregation, it is determined that a continuous stress transmission path is formed. The decreasing judgment criterion is that the density drop rate per meter along the extension direction of the grouting plate is greater than 5%, and the density difference between adjacent units is not more than 20%. The high-density aggregation judgment criterion is that the density of any statistical unit is more than 1.5 times the average density. For example, the average density of a certain crosslinking point area is 12 events per cubic meter, and the density changes to 15→13→11→9 events per cubic meter along the 75° extension direction of the grouting plate, and the drop rate per meter is 13.3%>5%; the maximum density is 15<18 (12x1.5), and there is no local aggregation. Finally, it is confirmed that the grouting pile and the grouting plate are coupled to form an integral bearing structure layer.

[0092] A vibration sensor is installed at a first monitoring point of the rock layer below the integral bearing structure layer and a second monitoring point of the rock layer above the integral bearing structure layer. The first monitoring point is located 5 meters below the bottom plate of the integral bearing structure layer, and the second monitoring point is located 5 meters above the top plate of the integral bearing structure layer. The sensor is a three-axis acceleration sensor with a range of ±5g and a frequency response range of 0.1-200 Hz. Before installation, the sensor needs to be drilled and cleaned. The drilling diameter is 50 mm, and the depth is 1 m. When installing, the sensor is fixed to the hole wall with epoxy resin glue to ensure that the verticality error of the sensor axis and the horizontal plane is less than 1°. The sensor cable is led to the ground data acquisition station through an armored protection pipe. The sampling frequency is set to 200 Hz, and the resolution is 16 bits.

[0093] The original vibration energy signal under the mining load is collected by the vibration sensor of the rock layer below. The mining load is derived from the roof fracture and mine pressure appearance in the working face advancing process. The signal collection is started when the blasting operation or mechanical coal dropping is performed within a range of 50 meters from the monitoring point. The signal collection duration is the complete mining cycle, for example, about 8 hours from the first roof weighting to the end of the periodic weighting. The original vibration energy signal contains an effective frequency band (1-100 Hz) and environmental noise. The signal is preprocessed by a fourth-order Butterworth band-pass filter. The effective value calculation formula of the filtered signal is: square the time domain signal, take the average value, and then take the square root. The time window is 0.5 seconds.

[0094] The vibration energy signal attenuated by the integral bearing structure layer is collected by the vibration sensor of the rock layer above. The collection time is strictly synchronized with the signal of the rock layer below. A GPS time module is used to ensure that the time synchronization error is less than 1 millisecond. The attenuated signal needs to be processed by the same band-pass filter as the original signal. The same time window parameter is used when calculating the effective value. In order to eliminate the influence of local rock mass inhomogeneity, 4 groups of monitoring point pairs are uniformly arranged around the integral bearing structure layer. Each group contains a first monitoring point and a second monitoring point corresponding to each other. The final vibration energy signal is the arithmetic mean value of the data of the 4 groups of monitoring points.

[0095] The ratio of the original vibration energy signal and the attenuated vibration energy signal is calculated to obtain the vibration energy attenuation rate. The calculation formula is: attenuation rate equals 1 minus (attenuated signal effective value divided by original signal effective value), and then multiplied by 100% to convert to percentage form. For example, the original signal effective value at a certain time is 0.25g, and the attenuated signal effective value is 0.03g, then the attenuation rate is equal to (1-0.03 / 0.25) x 100% = 88%. The calculation process is continuously performed in 0.5 second time windows, and 28800 attenuation rate data points are generated for each mining period (8 hours x 3600 seconds / hour x 2 points / second). The final attenuation rate takes the 90th percentile value of all data points, eliminating the influence of transient interference.

[0096] When the vibration energy attenuation rate exceeds the preset threshold value, it is confirmed that the integrity bearing structure layer has the vibration energy isolation function. The preset threshold value is set according to the mining depth and the surface subsidence control standard: the threshold value corresponding to the mining depth H (m) is equal to 80% plus 0.05% times H, for example, when the mining depth is 300 meters, the threshold value is 80% + 0.05% x 300 = 95%. The formula is based on: when the attenuation rate is greater than 95%, the surface subsidence can be controlled within 30mm / month (based on 10 mine area measured data regression analysis). The judgment condition is that the attenuation rates of the continuous three mining periods are all greater than the preset threshold value, and the data fluctuation coefficient (standard deviation / average value) in the period is less than 15%. For example, the mining depth of a certain project is 280 meters, the threshold value is 94%, the measured three-period attenuation rates are 95.2%, 95.7%, and 96.1%, and the fluctuation coefficient is 4.3%. It is determined that the integrity bearing structure layer has effective vibration energy isolation function.

[0097] The scheme of the embodiment couples the overburden rock beam mechanics model with the directional drilling grouting process depth to form a closed-loop technical path of "precise positioning-structure construction-function verification". In the prior art, only the crack filling rate is concerned in the separation grouting, and it is found in the scheme that the bearing layer reconstruction position needs to avoid the stress concentration area and construct a differentiated structure based on the crack development characteristics: the longitudinal grouting pile penetrates the high-density crack zone to form an axial force transmission channel, the transverse grouting plate covers the low-density separation layer to form a shear bearing surface, and the two are orthogonally coupled at the crosslinking point to form a spatial grid structure. The structure realizes efficient dissipation of overburden rock movement energy through the stress transmission of the pile body and the load dispersion of the plate body.

[0098] The calculations involved in the embodiment are all dimensionless numerical calculations, and the preset parameters and threshold values in the calculations are set by a person skilled in the art according to the actual situation.

[0099] The above embodiments can be realized in whole or in part by software, hardware, firmware or any other combination. When realized by software, the above embodiments can be realized in whole or in part in the form of a computer program product.

[0100] Those skilled in the art can understand that the modules and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and the constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0101] In addition, each functional module in each embodiment of the present application can be integrated into one processing module, or each module can exist physically independently, or two or more modules can be integrated into one module.

[0102] In several embodiments provided by the present application, it should be understood that the disclosed system, device and method can be implemented by other ways. For example, the device embodiments described above are merely illustrative, for example, the division of the modules is only a logical function division, and actual implementation can have another division manner, for example, multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the displayed or discussed each other can be indirect coupling or communication connection through some interfaces, devices or modules, which can be electrical, mechanical or other forms.

[0103] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0104] Finally: the above only describes the preferred embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer, characterized in that, Includes the following steps: S1. Obtain the location and lithological information of the main bearing layer in the overlying strata of the goaf through drilling and field measurement. Combine geological exploration data with strata movement theory calculation to determine the reconstructed location of the bearing layer. S2. Based on the reconstructed location of the bearing layer, the grouting area is divided, and a coupled grouting scheme is designed to form grouting piles by longitudinal grouting through directional drilling and grouting plates by transverse grouting. S3. Use directional drilling technology to deliver the grouting pipe to the target grouting area at the location of the bearing layer reconstruction; S4. Inject grout into the target grouting area through a directional drilling grouting pipe, allowing the grout to diffuse, fill, and cement in the delamination and cracks at the reconstructed location of the bearing layer. S5. After the injected grout solidifies, an integral bearing structure layer consisting of grouting piles and grouting plates coupled together is formed at the reconstructed location of the bearing layer. S6. Vibration sensors are installed in the rock strata below and above the integral load-bearing structure layer to monitor the attenuation rate of vibration energy transmitted from the lower rock strata to the upper rock strata; when the vibration energy attenuation rate exceeds the preset threshold, it is confirmed that the vibration energy isolation function is available.

2. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 1, characterized in that, The location and lithological information of the main bearing layer in the overlying strata of the goaf were obtained through drilling and field measurements. Combined with geological exploration data and calculations based on strata movement theory, the reconstructed location of the bearing layer was determined, including: Within the affected area of ​​the goaf, exploratory boreholes are drilled, and the lithological analysis of core samples is used to determine the stratigraphic depth and rock mechanical parameters of the main bearing layer. The development characteristics of interlayer fractures in the main load-bearing layer were observed using a borehole inspection instrument, and the fracture dip angle, density, and extension range were recorded. Extract stratigraphic dip angle and fault distribution data from geological exploration data; A mechanical model of the overlying beam was established based on rock mechanics parameters, interlayer fracture development characteristics, and stratum dip angle. The delamination height and stress concentration zone range of the main bearing stratum under the influence of mining were calculated using the strata strata mechanical model. The layer with the maximum delamination height was selected, avoiding fault distribution areas and stress concentration zones, to determine the location for the reconstruction of the bearing layer.

3. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 2, characterized in that, The delamination height and stress concentration zone range of the main bearing strata under mining influence were calculated using a strata strata mechanical model, including: Rock mechanics parameters and interlayer fracture development characteristics are input into the overburden beam mechanical model, and mining load is set as the boundary condition. Solve the differential equation of deflection of the overburden beam under mining load to obtain the extreme point of bending moment at each location of the overburden beam. The location of the extreme point of bending moment is taken as the delamination development height, and the area where the rate of change of bending moment exceeds the threshold of the stratum's bending stiffness is taken as the stress concentration zone.

4. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 2, characterized in that, Based on the location of the reconstructed bearing layer, the grouting area is divided, and a coupled grouting scheme is designed, which uses directional drilling to perform longitudinal grouting to form grouting piles and transverse grouting to form grouting plates, including: Based on the interlayer fracture development characteristics and rock mechanics parameters corresponding to the reconstructed location of the bearing layer, the grouting area is divided into a core reinforcement zone with fracture density higher than the preset value and an edge diffusion zone with fracture density lower than the preset value. A longitudinal directional drilling layout was designed for the core reinforcement area, so that the grouting piles formed by longitudinal grouting could penetrate the high-density fracture zone. A transverse directional drilling layout scheme was designed for the edge diffusion zone so that the grouting plate formed by transverse grouting covers the low-density fracture zone; Set the location of the cross-linking point between the grouting pile and the grouting plate to ensure that the maximum stress transmission direction of the grouting pile is perpendicular to the extension direction of the grouting plate.

5. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 4, characterized in that, Directional drilling technology is used to deliver grouting pipes to the target grouting area at the location of the bearing layer reconstruction, including: Based on the longitudinal directional drilling layout scheme corresponding to the core reinforcement area and the transverse directional drilling layout scheme corresponding to the edge diffusion area, directional drilling trajectories are designed respectively. Directional drilling was carried out at the location of the load-bearing layer reconstruction, and the borehole inclination and azimuth were monitored in real time using a drilling measurement system. Adjust the borehole trajectory based on the monitoring data of the measurement while drilling system so that the end of the grouting pipe reaches the longitudinal grouting target point in the core reinforcement zone or the transverse grouting target point in the edge diffusion zone. After verifying that the deviation between the end position of the grouting pipe and the center coordinates of the target grouting area is less than the allowable error threshold, the position of the grouting pipe is fixed.

6. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 5, characterized in that, Based on monitoring data from the measurement-while-drilling system, the borehole trajectory is adjusted to ensure that the end of the grouting pipe reaches the longitudinal grouting target point in the core reinforcement zone or the transverse grouting target point in the edge diffusion zone, including: Compare the borehole inclination and azimuth angles returned in real time by the drilling measurement system with the target inclination and azimuth angles of the design trajectory; When the horizontal deviation is greater than the diameter of the directional borehole or the vertical deviation is greater than the length of the grouting pipe, adjust the thrust direction of the drill guide hydraulic cylinder; Repeated monitoring and adjustment until the coordinates of the end of the grouting pipe fall within the allowable error range of the longitudinal or transverse grouting target point.

7. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 5, characterized in that, Grout is injected into the target grouting area through directional drilling grouting pipes, allowing the grout to diffuse, fill, and cement in the delamination and cracks at the location of the load-bearing layer reconstruction, including: High-viscosity grout is injected into the longitudinal grouting target points of the core reinforcement area, and the grouting pressure is controlled to make the high-viscosity grout diffuse in the longitudinal cracks to form columnar solidified solids. Low-viscosity grout is injected into the transverse grouting target point in the edge diffusion zone, and the grouting pressure is controlled to allow the low-viscosity grout to extend and diffuse in the transverse delamination to form a plate-like solidified material; Real-time monitoring of the grouting pipe outlet pressure; when the pressure value exceeds the critical pressure threshold corresponding to the core reinforcement zone or the edge diffusion zone, grouting is paused and the grouting rate is adjusted. After the grout has filled the delamination and fissures, maintain a stable pressure until the pressure value of the grouting pipe stabilizes within the rock mass closure pressure range at the reconstructed location of the bearing layer.

8. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 7, characterized in that, After the injected grout solidifies, an integral load-bearing structural layer consisting of grouting piles and grouting plates coupled together is formed at the reconstructed location of the load-bearing layer, including: Monitor the bonding state of the interface between columnar and plate-shaped solidified solids during the slurry solidification process; The longitudinal wave velocity of the grouting pile and the transverse wave velocity of the grouting plate were measured using an acoustic wave detector. When the longitudinal wave velocity of the grouting pile reaches the design wave velocity threshold corresponding to the rock mechanics parameters and the transverse wave velocity of the grouting plate reaches the design wave velocity threshold corresponding to the rock mechanics parameters, it is confirmed that the columnar solidified body is transformed into a grouting pile and the plate-shaped solidified body is transformed into a grouting plate. Verify that the cross-linking point between the grouting pile and the grouting plate forms a continuous stress transmission path, and confirm that the grouting pile and the grouting plate are coupled together to form an integral load-bearing structural layer.

9. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 8, characterized in that, Verify that the cross-linking point between the grouting pile and the grouting plate forms a continuous stress transfer path, including: An array of acoustic emission sensors was deployed at the cross-linking point to collect acoustic emission events at the interface between the grouting pile and the grouting plate under load. If the spatial distribution density of acoustic emission events decreases along the extension direction of the grouting plate and there is no local high-density accumulation, then it is determined that a continuous stress transmission path has been formed.

10. The method for controlling surface subsidence by directional drilling and grouting to reconstruct the bearing layer according to claim 8, characterized in that, Vibration sensors were installed in the rock strata below and above the integral load-bearing structure layer to monitor the attenuation rate of vibration energy transmitted from the lower rock strata to the upper rock strata. When the vibration energy attenuation rate exceeds a preset threshold, the vibration energy isolation function is confirmed, including: Vibration sensors were installed at the first monitoring point of the rock stratum below the integral load-bearing structure layer and the second monitoring point of the rock stratum above it. The original vibration energy signal under mining load is collected by vibration sensors in the underlying rock strata. Vibration energy signals, attenuated by the integral load-bearing structure layer, are collected by vibration sensors in the upper rock strata. Calculate the ratio of the original vibration energy signal to the attenuated vibration energy signal to obtain the vibration energy attenuation rate; When the vibration energy attenuation rate exceeds the preset threshold, it is confirmed that the overall load-bearing structure layer has the function of vibration energy isolation.

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