Grouting quantity calculation method based on residual porosity test in coal mine goaf

Abstract

The present invention provides a method for calculating the amount of grouting based on residual porosity testing in coal mine goafs, comprising: determining the location of the fracture zone and the collapse zone in the coal mine goaf, and performing differential pressure and concentration grouting when the exploration hole in the coal mine goaf is drilled to the location of the fracture zone and the collapse zone; sealing the exploration hole and coring the hole after the slurry in the hole solidifies, and arranging multiple coring holes around the exploration hole for coring; processing multiple cored samples at different plane positions and different depths to obtain the volume of the solidified slurry and the volume of the rock block in the sample, and calculating the porosity at different plane positions and different depths; obtaining a spatial distribution function of the porosity based on the obtained porosity, performing an integral calculation on the porosity, and obtaining the total pore volume of the coal mine goaf, and using this to determine the grouting amount of the coal mine goaf. The present application improves the accuracy of grouting amount calculation in coal mine goafs by accurately determining the spatial distribution characteristics and total volume of residual pores in coal mine goafs.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine goaf repair, and in particular to a grouting amount calculation method based on residual porosity testing of coal mine goaf. Background Art

[0002] After underground coal mining, the upper rock strata gradually bend and deform. When their strength reaches its limit, they break and collapse into the goaf. This movement and deformation propagates upward, vertically dividing the rock strata into a collapse zone with irregularly arranged rock blocks, a fracture zone with well-developed pores and fissures, and a curved and subsided zone dominated by bending and subsidence, known as the "three zones." In the comprehensive management and utilization of coal mining subsidence areas, the spatial distribution of residual pores and fissures between rock blocks within these "three zones" is often used to estimate the grouting volume in the goaf and serve as the basis for cost estimation.

[0003] Currently, the most commonly used method for estimating grouting volume in goaf areas is to calculate the residual voids (not considering pores) within the mining subsidence area based on the expansion coefficient and residual expansion coefficient (generally 1.05 to 1.25) of the broken rock blocks after coal mining. Grouting volume is then estimated based on the grouting density or roof contact ratio. This method is the most effective and universal method for calculating grouting volume. However, the residual expansion coefficient in this method is determined based on experience, and differences in empirical values ​​can significantly affect the grouting volume calculation results.

[0004] Some researchers have proposed using numerical simulation to study the movement and deformation state and porosity distribution patterns within the overburden. Using image processing techniques, they estimate the voids and pore volume within the overburden, thereby enabling numerical simulation to guide the pore development patterns and calculate the grouting volume in goaf areas. This approach essentially involves numerically simulating the formation parameters, which must be reduced by 1 / 10 to 1 / 2 based on the parameters obtained from laboratory physical and mechanical property tests. The parameters for rock joints and fissures vary even more widely (often by more than an order of magnitude), requiring empirical values ​​to be selected and gradually corrected. Therefore, the method of estimating the pore and fissure development characteristics within the overburden through numerical simulation, and thus the grouting volume, differs significantly from actual practice.

[0005] Regarding the goaf-side tunneling technology for small-scale underground construction, some scholars have also attempted to conduct roof separation drilling and borehole peeks in the goaf-side tunneling of the lagging mining area, and based on the distribution range of mining-induced fissures that can be visually observed, different concentrations of slurry are proportioned to guide each zone to control the required degree of roof through grouting. In the coal mine water prevention and control work for regional stratum reinforcement and management, the original joints and fissures of the coal seam roof are grouting-transformed, and the grouting volume of the branch holes for grouting-transformation of the coal seam roof is estimated based on the lithology and the degree of development of the inherent joints and fissures of the rock formation. Since the borehole peek method is a visual assessment of the pore and fissure development characteristics in the overburden, it is a reflection of the surface characteristics of the pores in the borehole. However, the pores are uneven in size and irregular in distribution, and it is impossible to accurately determine the actual proportion of fissures along the depth development direction, resulting in inaccurate estimated grouting volume. Summary of the Invention

[0006] The present invention provides a grouting quantity calculation method based on residual porosity test of coal mine goaf, which is used to solve the defect of inaccurate grouting quantity estimation in the prior art and improve the accuracy of grouting quantity estimation.

[0007] The present invention provides a grouting amount calculation method based on residual porosity testing of coal mine goaf, comprising: determining the location of a fracture zone and a collapse zone in the coal mine goaf, and performing differential grouting with pressure and concentration when an exploration hole in the coal mine goaf is drilled to the location of the fracture zone and the collapse zone;

[0008] After the exploration hole is sealed and the grouting liquid in the hole solidifies, the exploration hole is casing-cored, and a plurality of coring holes are arranged around the exploration hole according to the diffusion radius of the grouting liquid during the pressure grouting and the distribution of the goaf for coring;

[0009] Processing core samples at different plane positions and depths to obtain the volume of slurry solidified bodies and the volume of rock blocks corresponding to pressure grouting in the core samples, and obtaining porosity at different plane positions and depths based on the volume of the slurry solidified bodies and the volume of the rock blocks;

[0010] According to the porosity at different plane positions and different depths, the spatial distribution function of the porosity is obtained, the spatial distribution function of the porosity is integrated and calculated to obtain the total pore volume of the coal mine goaf, and the grouting amount of the coal mine goaf is determined according to the total pore volume.

[0011] According to a method for calculating the grouting amount based on residual porosity testing of a coal mine goaf provided by the present invention, before the step of coring the exploration hole after the exploration hole is sealed and the grouting liquid in the hole solidifies, the method further includes:

[0012] Using a color borehole television to obtain an expanded image of the wall of the exploration hole;

[0013] determining, based on the expanded image of the hole wall of the exploration hole, the surface expanded area ratio of the slurry solidified body at different depths in the exploration hole to the hole wall of the exploration hole;

[0014] After the step of arranging a plurality of coring holes around the exploration hole according to the diffusion radius of the grouting liquid of the pressure grouting to perform coring, the method further includes:

[0015] Using the color drilling television to obtain an expanded image of the wall of the coring hole;

[0016] determining, based on the expanded image of the coring hole wall, a ratio of the surface expanded area of ​​the slurry solidified body at different depths in the coring hole to the surface expanded area of ​​the coring hole wall;

[0017] The step of obtaining the spatial distribution function of the porosity according to the porosity at different plane positions and different depths comprises:

[0018] When the difference between the porosity and the surface area ratio at the same depth corresponding to the survey hole is less than a first preset threshold, and the difference between the porosity and the surface area ratio at the same depth corresponding to the core sampling hole is less than the first preset threshold, the spatial distribution function of the porosity is obtained according to the porosities at different depths corresponding to the survey hole and the core sampling hole.

[0019] According to a method for calculating grouting amount based on residual porosity testing in coal mine goaf provided by the present invention, before the step of obtaining the spatial distribution function of the porosity according to the porosity at different plane positions and different depths, the method further includes:

[0020] In the case where the porosity at any depth corresponding to the survey hole or the core hole is missing, the surface developed area ratio at any depth corresponding to the survey hole or the core hole is used as the porosity at any depth corresponding to the survey hole or the core hole.

[0021] According to a method for calculating grouting volume based on residual porosity testing of a coal mine goaf provided by the present invention, before the step of obtaining an expanded image of the wall of the coring hole using the color borehole television, the method further includes:

[0022] After the grouting liquid solidifies, the hole wall of the exploration hole is cleaned.

[0023] According to a method for calculating grouting volume based on residual porosity testing of a coal mine goaf provided by the present invention, the steps of determining the locations of crack zones and collapse zones in the coal mine goaf include:

[0024] Drilling the exploration hole with a flushing fluid having a concentration less than a second preset threshold value;

[0025] During the drilling of the exploration hole, if the consumption rate of the flushing fluid is greater than a third preset threshold value and the water level reduction rate of the exploration hole is greater than a fourth preset threshold value, it is determined that the exploration hole has been drilled to the fracture zone position;

[0026] If the drill drop frequency and / or drill stuck frequency during the drilling process of the exploration hole is greater than a fifth preset threshold, it is determined that the exploration hole has been drilled to the collapse zone position.

[0027] According to a method for calculating grouting volume based on residual porosity testing of a coal mine goaf provided by the present invention, the steps of determining the locations of crack zones and collapse zones in the coal mine goaf include:

[0028] During the drilling of the exploration hole, the development of pores and fractures in the rock formation of the exploration hole is obtained by taking an expanded image of the exploration hole wall using a drilling core revelation method or color borehole television;

[0029] The locations of the fracture zones and collapse zones in the coal mine goaf are determined based on the development of pores and fissures inside the rock formation, the consumption rate of the flushing fluid, the water level reduction rate of the exploration hole, and the drill drop and / or drill sticking frequencies.

[0030] According to a method for calculating the grouting amount based on residual porosity testing in a coal mine goaf provided by the present invention, the step of performing differential grouting in terms of pressure and concentration when the exploration hole in the coal mine goaf is drilled to the fracture zone and the collapse zone comprises:

[0031] When the exploration hole in the coal mine goaf is drilled to the position of the fracture zone, grouting the exploration hole with a grouting liquid of a first concentration using a surface mud pump pressure grouting method;

[0032] When the exploration hole in the coal mine goaf is drilled to the location of the collapse zone, the exploration hole is grouted using the grouting liquid of the second concentration by using the surface mud pump pressure grouting method;

[0033] Wherein, the first concentration is less than the second concentration.

[0034] According to a method for calculating grouting volume based on residual porosity testing in coal mine goafs provided by the present invention, the steps of processing core samples at different plane positions and depths to obtain the volume of slurry solidification and the volume of rock blocks corresponding to pressure grouting in the core samples include:

[0035] Conducting crushing tests on core samples at different plane positions and depths to separate the slurry solidified body and the rock block;

[0036] The volume of the slurry solid and the volume of the rock mass are determined using the water displacement method or the wax seal method.

[0037] According to a method for calculating grouting volume based on residual porosity testing in coal mine goaf provided by the present invention, the step of obtaining a spatial distribution function of the porosity according to the porosity at different plane positions and different depths comprises:

[0038] Fitting the porosity at different plane positions and different depths to obtain a functional relationship equation of the porosity varying with the plane position and depth;

[0039] A local coordinate system is established according to the working face boundary of the coal mine goaf, and coordinate transformation is performed on the plane position and depth in the functional relationship equation according to the local coordinate system to obtain the spatial distribution function of the porosity.

[0040] According to a method for calculating the grouting amount based on residual porosity testing of a coal mine goaf provided by the present invention, after the step of determining the grouting amount of the coal mine goaf according to the total pore volume, the method further comprises:

[0041] The cost of treating the coal mine goaf is determined based on the grouting volume, grouting concentration and grouting material ratio of the coal mine goaf.

[0042] The present invention provides a method for calculating the grouting volume based on the residual porosity test of the coal mine goaf. The method obtains the actual porosity at different depths and plane positions of the coal mine goaf by performing core drilling after differential grouting of the crack zone and the collapse zone in the coal mine goaf with pressure and concentration. The actual spatial distribution of the porosity of the coal mine goaf is obtained according to the actual porosity. The total pore volume of the coal mine goaf is accurately calculated according to the actual spatial distribution, thereby improving the accuracy of the grouting volume calculation of the coal mine goaf. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 It is a flow chart of a method for calculating grouting volume based on residual porosity testing of coal mine goaf provided by the present invention. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0046] The following combination Figure 1 The present invention describes a method for calculating grouting amount based on residual porosity testing of a coal mine goaf, the method comprising:

[0047] Step 101, determining the locations of the fracture zone and the collapse zone in the coal mine goaf, and performing differential pressure and concentration grouting when the exploration hole in the coal mine goaf reaches the locations of the fracture zone and the collapse zone;

[0048] Optionally, the locations of the fracture zone and the collapse zone in the coal mine goaf can be determined by information collected during the exploration hole drilling process. This embodiment does not limit the method for determining the locations of the fracture zone and the collapse zone.

[0049] Design the location of exploration holes in the surface goaf based on the coal mining engineering plan or the surveyed goaf occurrence plan, along with the working face mining process. This includes the design of the goaf exploration hole's plan location, hole depth, diameter, coring, retaining walls, and drilling techniques for crossing fracture and collapse zones.

[0050] Through geological drilling, ground drilling rigs are used to drill downward to construct exploration holes.

[0051] When the exploration hole is drilled to the fracture zone, pressure grouting is performed on the fracture zone through the exploration hole, so that the grouting liquid diffuses into the gaps around the exploration hole.

[0052] After the grouting liquid in the crack zone solidifies, continue drilling the exploration hole to the collapse zone. Pressure grouting is performed on the collapse zone through the exploration hole, allowing the grouting liquid to spread into the gaps around the exploration hole.

[0053] When pressure grouting is performed on cracked or collapsed zones, the grouting work is completed in multiple stages, with the grouting pressure gradually increasing. The number of grouting stages is generally 3 to 5.

[0054] It should be noted that the initial grouting pressure in the crack zone is greater than that in the collapse zone, in order to control the diffusion range of the grouting liquid during grouting so that it can fill the gaps around the exploration hole.

[0055] Step 102: After the exploration hole is sealed and the grouting liquid in the hole solidifies, the exploration hole is cored, and multiple coring holes are arranged around the exploration hole according to the diffusion radius of the grouting liquid during the pressure grouting and the distribution of the goaf for coring;

[0056] After the collapsed zone is densely grouted and the grouting liquid solidifies, the exploration hole is grout-sealed.

[0057] Alternatively, a gravity method is used, where a grouting drill pipe is used to inject cement slurry from the bottom of the exploration hole to the hole mouth until the grouting returns to the hole mouth. After the grouting liquid solidifies, the exploration hole is sealed.

[0058] Coring is the process of drilling and coring a hole using a drill bit with a larger diameter than the exploration hole. The hole is then sealed, making it easier to retrieve a complete core sample.

[0059] It should be noted that when coring, the difference between the diameter of the casing hole and the diameter of the exploration hole is greater than a preset threshold value. The preset threshold value is set based on experience to ensure that the solidified slurry of the pressure grouting taken out has a certain thickness.

[0060] Optionally, the exploration hole is drilled with a 70 mm diameter drill bit and the core is taken with a 108 mm diameter drill bit.

[0061] Determine the location of the core holes around the exploration hole. Optionally, within the goaf, evenly arrange multiple survey lines centered on the exploration hole, with multiple core holes spaced along the survey lines. Use a 108mm diameter drill bit to drill the entire core hole, starting from the nearest to the exploration hole and moving further away.

[0062] Because the solidified grout and rock have different colors and properties, the diffusion radius of the grouting liquid can be determined by observing the core sample taken from the core hole. When the core sample does not contain the solidified grouting liquid, coring the entire core hole is stopped.

[0063] Step 103: Processing core samples at different plane positions and depths to obtain the volume of slurry solidification and the volume of rock blocks corresponding to pressure grouting in the core samples, and obtaining the porosity at different plane positions and depths based on the volume of the slurry solidification and the volume of the rock blocks;

[0064] The solidified slurry corresponding to pressure grouting is the solidified grouting liquid after pressure grouting the exploration hole. Therefore, the volume of the solidified slurry is the volume of the pores. Core samples include those obtained by cased cores and those obtained by coring multiple cores.

[0065] For core samples at different plane positions and depths, the rock blocks and slurry solids of each core sample are distinguished and separated by color, and then the volume V1 of the slurry solids and the volume V2 of the rock blocks corresponding to the pressure grouting in each core sample are calculated respectively.

[0066] The porosity at the plane position and depth corresponding to the current core sample can be calculated as V1 / (V1+V2). By calculating the porosity of core samples at different plane positions and depths, the porosity at different plane positions and depths of the goaf can be obtained.

[0067] Step 104: obtain the spatial distribution function of the porosity according to the porosity at different plane positions and different depths, perform integral calculation on the spatial distribution function of the porosity to obtain the total pore volume of the coal mine goaf, and determine the grouting amount of the coal mine goaf according to the total pore volume.

[0068] The porosity at different depths at each plane position is known, and the three-dimensional spatial distribution of the porosity is obtained according to the porosity of each core sampling point in the three-dimensional space. This embodiment does not limit the method for obtaining the three-dimensional spatial distribution.

[0069] By calculating the porosity at different plane positions and different depths, optionally, a coordinate system is established with the exploration hole position as the origin, two perpendicular lines on the plane as the X-axis and Y-axis, and the vertical direction as the Z-axis to fit the spatial distribution function η(x, y, z) of the porosity.

[0070] By integrating the obtained spatial distribution function of porosity, the total pore volume of the coal mine goaf can be obtained. Among them, a and b refer to the boundary coordinates of the plane determined according to the goaf in the X-axis direction, and their values ​​are related to the properties of the rock and soil layer. c and d refer to the boundary coordinates of the plane in the Y-axis direction. H refers to the burial depth of the coal seam corresponding to the goaf of the coal mine.

[0071] The grouting volume of the coal mine goaf can be calculated by combining the total volume of the coal mine goaf with the properties of the grouting liquid in the goaf, such as the shrinkage rate and water absorption rate.

[0072] This embodiment obtains the actual porosity of the coal mine goaf at different depths and plane positions after differentially grouting the crack zone and collapse zone in the coal mine goaf with pressure and concentration, and then conducts drilling and coring. The actual spatial distribution of the porosity of the coal mine goaf is obtained based on the actual porosity, and the total pore volume of the coal mine goaf is accurately calculated based on the actual spatial distribution, thereby improving the accuracy of the calculation of the grouting amount of the coal mine goaf.

[0073] Based on the above embodiment, this embodiment further includes the following steps before coring the exploration hole after the exploration hole is sealed and the grouting liquid in the hole solidifies:

[0074] Using a color borehole television to obtain an expanded image of the wall of the exploration hole;

[0075] The color borehole TV is a 360° rotating borehole TV. After the grouting liquid from the pressure injection in the exploration hole has diffused and solidified, the color borehole TV is inserted into the exploration hole to record the wall of the exploration hole in 360° and throughout the entire depth of the hole.

[0076] The color borehole television video is processed into a flat unfolded image at a fixed depth using image processing software. Optionally, the fixed depth can be 1 meter or 2 meters.

[0077] determining, based on the expanded image of the hole wall of the exploration hole, the surface expanded area ratio of the slurry solidified body at different depths in the exploration hole to the hole wall of the exploration hole;

[0078] Based on the pre-acquired planar expansion image of the exploration hole wall at a fixed depth, the slurry solidification body and rock blocks in the planar expansion image of the hole wall are distinguished by color, and the area ratio of the surface expansion area of ​​the slurry solidification body under different grouting pressures to the surface expansion area of ​​the hole wall at that depth is calculated to characterize the pore development in the exploration hole at the corresponding depth.

[0079] After the step of arranging a plurality of coring holes around the exploration hole according to the diffusion radius of the grouting liquid of the pressure grouting to perform coring, the method further includes:

[0080] Using the color drilling television to obtain an expanded image of the wall of the coring hole;

[0081] The color drilling TV is a 360° rotating drilling TV. Insert the color drilling TV into the core hole to record the core hole wall in 360° and full depth.

[0082] The color borehole television video is processed into a flat unfolded image at a fixed depth using image processing software. Optionally, the fixed depth can be 1 meter or 2 meters.

[0083] determining, based on the expanded image of the coring hole wall, a ratio of the surface expanded area of ​​the slurry solidified body at different depths in the coring hole to the surface expanded area of ​​the coring hole wall;

[0084] Based on the pre-acquired planar expansion image of the core hole wall at a fixed depth, the slurry solidification body and rock blocks in the planar expansion image of the hole wall are distinguished by color, and the area ratio of the surface expansion area of ​​the slurry solidification body under different grouting pressures to the surface expansion area of ​​the core hole wall at the depth is calculated to characterize the pore development in the core hole at the corresponding depth.

[0085] The step of obtaining the spatial distribution function of porosity according to the porosity at different plane positions and different depths comprises:

[0086] When the difference between the porosity and the surface area ratio at the same depth corresponding to the survey hole is less than a first preset threshold, and the difference between the porosity and the surface area ratio at the same depth corresponding to the core sampling hole is less than the first preset threshold, the spatial distribution function of the porosity is obtained according to the porosities at different depths corresponding to the survey hole and the core sampling hole.

[0087] The first preset threshold is set based on experience. Because processing the core sample may destroy the slurry solidification in the core sample, the resulting porosity may be biased. This embodiment uses the surface area ratio of the exploration hole to the core hole to verify the accuracy of the porosity derived from the core sample volume.

[0088] If the difference between the porosity and the surface area ratio at the same depth corresponding to the same exploration hole is less than the first preset threshold, it means that the difference between the two is small and the porosity deviation is small. The porosity at the depth corresponding to the exploration hole can be used to fit the spatial distribution function of the porosity.

[0089] If the difference between the porosity and the surface area ratio at the same depth corresponding to the same core hole is less than the first preset threshold, it means that the difference between the two is small and the porosity deviation is small. The porosity at the depth corresponding to the core hole can be used to fit the spatial distribution function of the porosity.

[0090] Based on the above embodiment, before the step of obtaining the spatial distribution function of the porosity according to the porosity at different plane positions and at different depths, this embodiment further includes:

[0091] In the case where the porosity at any depth corresponding to the survey hole or the core hole is missing, the surface developed area ratio at any depth corresponding to the survey hole or the core hole is used as the porosity at any depth corresponding to the survey hole or the core hole.

[0092] When coring an exploration hole or a core sampling hole, the core sample may be damaged, resulting in the core sample at the coring location being unable to be used to calculate the porosity at a certain depth corresponding to the coring location, thereby resulting in the loss of the porosity at the depth corresponding to the exploration hole or the core sampling hole.

[0093] At this time, the surface area ratio of the slurry solidified body surface at a certain depth corresponding to the coring location to the surface area of ​​the hole wall is used as the porosity at a certain depth at the coring location, thereby ensuring the integrity of the porosity data.

[0094] Based on the above embodiment, before the step of using the color borehole television to obtain the expanded image of the wall of the coring hole, this embodiment further includes:

[0095] After the grouting liquid solidifies, the hole wall of the exploration hole is cleaned.

[0096] When the core sample from the exploration hole contains residual coal, it means that the goaf has been drilled out and the coal seam has been reached. At this time, drilling is stopped, the hole depth and coal seam depth are adjusted, and the residue on the exploration hole wall is cleaned with clean water to prevent the residue from affecting the subsequent color borehole TV shooting results. At the same time, it facilitates the color borehole TV to extend into the exploration hole bottom for shooting.

[0097] Alternatively, if there is a lot of residue on the wall of the survey hole, pour in alum, let it stand for 24 hours, and then wash it with clean water.

[0098] Based on the above embodiment, in this embodiment, the step of determining the location of the crack zone and the location of the collapse zone in the coal mine goaf includes:

[0099] Drilling the exploration hole with a flushing fluid having a concentration less than a second preset threshold value;

[0100] The second preset threshold limits the use of a slurry as the flushing fluid for the exploration hole, set based on experience. Using a slurry-wall drilling method protects the exploration hole wall, effectively preventing wall collapse or the generation of large amounts of debris that could affect the integrity of the core sample during subsequent coring or the accuracy of the color borehole video recording.

[0101] During the drilling of the exploration hole, if the consumption rate of the flushing fluid is greater than a third preset threshold value and the water level reduction rate of the exploration hole is greater than a fourth preset threshold value, it is determined that the exploration hole has been drilled to the fracture zone position;

[0102] Measure the water level in the exploration hole after pulling out of the drill and before drilling down. When drilling is stopped for a long time, observe the water level in the exploration hole every 5 to 10 minutes. At the same time, record the slurry consumption in the mud pit, the depth of the exploration hole, the time of each water level measurement, and the water level value in the hole. The water level value must be accurate to two decimal places.

[0103] The speed at which the water level in the hole decreases is calculated by the change in the water level height in the hole and the time difference between each water level measurement.

[0104] The third preset threshold and the fourth preset threshold are set based on experience.

[0105] When the flushing fluid is consumed at a high rate and the water level in the exploration hole drops rapidly, it indicates that cracks have appeared at the drilling location, thus confirming that the exploration hole has been drilled into the fracture zone. At this time, the surface drill rig pulls up the drill to take a core and record the drilling depth.

[0106] If the drill drop frequency and / or drill stuck frequency during the drilling process of the exploration hole is greater than a fifth preset threshold, it is determined that the exploration hole has been drilled to the top layer of the collapse zone.

[0107] The fifth preset threshold is set based on experience.

[0108] The well-developed porosity and fissures within the collapse zone increase the frequency of drill sticking and / or drill drop during drilling. A high frequency of drill drop and / or drill sticking during drilling of the exploration hole indicates that the exploration hole has reached the top layer of the collapse zone.

[0109] At this time, the ground drill rig lifts the drill to take the core and records the drilling depth.

[0110] Based on the above embodiment, the steps of determining the locations of the crack zone and the collapse zone in the coal mine goaf in this embodiment include:

[0111] During the drilling of the exploration hole, the development of pores and fractures in the rock formation of the exploration hole is obtained by taking an expanded image of the exploration hole wall using a drilling core revelation method or color borehole television;

[0112] The development of pores and fractures inside the rock formations of the exploration holes can be obtained by using core samples obtained through the drilling core revelation method or by taking images of the exploration hole walls using color borehole television. Among them, the pores and fractures of the core samples located in the collapse zone are relatively well developed, while the pores and fractures of the core samples located in the fracture zone are poorly developed. This helps determine the locations of the fracture zone and collapse zone.

[0113] The locations of the fracture zones and collapse zones in the coal mine goaf are determined based on the development of pores and fissures inside the rock formation, the consumption rate of the flushing fluid, the water level reduction rate of the exploration hole, and the frequency of drill drops and / or drill sticking.

[0114] When the consumption rate of the flushing fluid is greater than the third preset threshold and the water level drop rate in the exploration hole is greater than the fourth preset threshold, the drill is lifted to take core samples or a color drilling TV is inserted into the exploration hole to obtain an image of the exploration hole wall to determine whether it meets the pore and fracture development conditions of the fracture zone. If so, the drilling position of the exploration hole is determined to be in the fracture zone, thereby improving the accuracy of establishing the fracture zone position.

[0115] When the frequency of drill drop / drill jam on the ground drilling rig is greater than the fifth preset threshold, the drill is lifted to take cores or a color drilling TV is inserted into the exploration hole to obtain an image of the exploration hole wall to determine whether it meets the pore and fracture development conditions of the collapse zone. If so, the drilling position of the exploration hole is determined to be in the collapse zone, thereby improving the accuracy of establishing the collapse zone position.

[0116] Based on the above embodiment, the step of performing pressure and concentration differential grouting when the exploration hole in the coal mine goaf is drilled to the fracture zone and the collapse zone in this embodiment includes:

[0117] When the exploration hole in the coal mine goaf is drilled to the position of the fracture zone, grouting the exploration hole with a grouting liquid of a first concentration using a surface mud pump pressure grouting method;

[0118] When the exploration hole is drilled to the fracture zone, the first concentration of cement slurry is prepared according to a certain water-solid ratio. Since the cracks in the fracture zone are small, the grouting liquid is a thin cement slurry with low concentration and good fluidity.

[0119] The ground mud pump pressure grouting method is used to grout the exploration holes in the crack zone, so that the grouting liquid can spread and fill the cracks around the exploration holes.

[0120] When the exploration hole in the coal mine goaf is drilled to the location of the collapse zone, the exploration hole is grouted using the grouting liquid of the second concentration by using the surface mud pump pressure grouting method;

[0121] Wherein, the first concentration is less than the second concentration.

[0122] When the exploration hole is drilled to the collapse zone, due to the good degree of rock fragmentation and the more developed cracks in the collapse zone, a grouting liquid with a higher concentration is used to limit the diffusion distance of the grouting liquid to ensure that the grouting liquid fills the cracks around the exploration hole.

[0123] Based on the above embodiment, the steps of processing core samples at different plane positions and depths in this embodiment to obtain the volume of the solidified slurry and the volume of the rock block corresponding to the pressure grouting in the core sample include:

[0124] Conducting crushing tests on core samples at different plane positions and depths to separate the slurry solidified body and the rock block;

[0125] The core samples taken from different plane positions and depths are crushed by a crusher, and the crushed rock blocks and slurry solids are distinguished by color, and the fragments and pieces of the slurry solids and rock blocks are collected separately.

[0126] The volume of the slurry solid and the volume of the rock mass are determined using the water displacement method or the wax seal method.

[0127] When the rock block and slurry solidified material fragments are relatively intact, their volumes are determined using the water displacement method. This method involves placing the rock block and slurry solidified material fragments in separate containers filled with water. The volume of the overflowing water is collected and measured to determine the volume of the rock block and slurry solidified material.

[0128] When rock block fragments and slurry solidified material fragments are highly fragmented, their volumes are determined using the wax sealing method. This method involves immersing each rock block fragment and slurry solidified material fragment in melted paraffin wax, leaving them with a complete paraffin shell. The volumes of the rock block fragment and slurry solidified material fragment, respectively, are calculated based on the principle of buoyancy by weighing the paraffin-shelled rock block fragment and slurry solidified material fragment in air and water, respectively.

[0129] Based on the above embodiment, the step of obtaining the spatial distribution function of the porosity according to the porosity at different plane positions and different depths in this embodiment includes:

[0130] Fitting the porosity at different plane positions and different depths to obtain a functional relationship equation of the porosity varying with the plane position and depth;

[0131] A coordinate system with the exploration hole as the origin is established, and the porosities at different plane positions and depths are fitted to obtain the functional relationship equation of the porosity changing with plane position and depth.

[0132] A local coordinate system is established according to the working face boundary of the coal mine goaf, and coordinate transformation is performed on the plane position and depth in the functional relationship equation according to the local coordinate system to obtain the spatial distribution function of the porosity.

[0133] A local coordinate system is established with the two adjacent boundaries of the working face of the coal mine goaf as the X-axis and Y-axis, the vertical direction as the Z-axis, and the intersection of the two adjacent boundaries as the origin. After coordinate transformation of the functional relationship equation of porosity changing with plane position and depth, the spatial distribution function of porosity is obtained.

[0134] In this embodiment, a local coordinate system is established based on the boundary of the working surface, which can more conveniently calculate the required total pore volume of the coal mine goaf.

[0135] Based on the above embodiment, after the step of determining the grouting amount of the coal mine goaf according to the total pore volume, this embodiment further includes:

[0136] The cost of treating the coal mine goaf is determined based on the grouting volume, grouting concentration and grouting material ratio of the coal mine goaf.

[0137] The grouting volume of the coal mine goaf is determined based on the total pore volume of the coal mine goaf. A proportion test is carried out based on the pre-determined grouting material proportion and grouting concentration.

[0138] Based on the test results and the grouting volume required for the goaf of the coal mine, the amount of various materials required for goaf treatment is calculated, and then the cost of goaf treatment is determined.

[0139] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for calculating grouting volume based on residual porosity test of coal mine goaf, characterized in that: include: Determine the location of the fracture zone and the collapse zone in the coal mine goaf, and perform differential pressure and concentration grouting when the exploration hole in the coal mine goaf reaches the location of the fracture zone and the collapse zone; After the exploration hole is sealed and the grouting liquid in the hole solidifies, the exploration hole is casing-cored, and a plurality of coring holes are arranged around the exploration hole according to the diffusion radius of the grouting liquid during the pressure grouting and the distribution of the goaf for coring; Processing core samples at different plane positions and depths to obtain the volume of slurry solidified bodies and the volume of rock blocks corresponding to pressure grouting in the core samples, and obtaining porosity at different plane positions and depths based on the volume of the slurry solidified bodies and the volume of the rock blocks; According to the porosity at different plane positions and different depths, a spatial distribution function of the porosity is obtained, the spatial distribution function of the porosity is integrated and calculated to obtain the total pore volume of the coal mine goaf, and the grouting amount of the coal mine goaf is determined according to the total pore volume; After the exploration hole is sealed and the grouting liquid in the hole solidifies, before the step of coring the exploration hole, the method further includes: Using a color borehole television to obtain an expanded image of the wall of the exploration hole; determining, based on the expanded image of the hole wall of the exploration hole, the surface expanded area ratio of the slurry solidified body at different depths in the exploration hole to the hole wall of the exploration hole; After the step of arranging a plurality of coring holes around the exploration hole according to the diffusion radius of the grouting liquid of the pressure grouting to perform coring, the method further includes: Using the color drilling television to obtain an expanded image of the wall of the coring hole; determining, based on the expanded image of the coring hole wall, a ratio of the surface expanded area of ​​the slurry solidified body at different depths in the coring hole to the surface expanded area of ​​the coring hole wall; The step of obtaining the spatial distribution function of the porosity according to the porosity at different plane positions and different depths comprises: When the difference between the porosity and the surface area ratio at the same depth corresponding to the survey hole is less than a first preset threshold, and the difference between the porosity and the surface area ratio at the same depth corresponding to the core sampling hole is less than the first preset threshold, obtaining the spatial distribution function of the porosity according to the porosities at different depths corresponding to the survey hole and the core sampling hole; Before the step of obtaining the spatial distribution function of the porosity according to the porosities at different plane positions and different depths, the method further includes: In the case where the porosity at any depth corresponding to the survey hole or the core hole is missing, the surface developed area ratio at any depth corresponding to the survey hole or the core hole is used as the porosity at any depth corresponding to the survey hole or the core hole.

2. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to claim 1, characterized in that: Before the step of using the color borehole television to obtain the expanded image of the wall of the coring hole, the method further includes: After the grouting liquid solidifies, the hole wall of the exploration hole is cleaned.

3. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to any one of claims 1 to 2, characterized in that: The steps of determining the locations of the crack zones and the collapse zones in the coal mine goaf include: Drilling the exploration hole with a flushing fluid having a concentration less than a second preset threshold value; During the drilling of the exploration hole, if the consumption rate of the flushing fluid is greater than a third preset threshold value and the water level reduction rate of the exploration hole is greater than a fourth preset threshold value, it is determined that the exploration hole has been drilled to the fracture zone position; If the drill drop frequency and / or drill stuck frequency during the drilling process of the exploration hole is greater than a fifth preset threshold, it is determined that the exploration hole has been drilled to the collapse zone position.

4. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to claim 3, characterized in that: The steps of determining the locations of the crack zones and the collapse zones in the coal mine goaf include: During the drilling of the exploration hole, the development of pores and fractures in the rock formation of the exploration hole is obtained by taking an expanded image of the exploration hole wall using a drilling core revelation method or color borehole television; The locations of the fracture zones and collapse zones in the coal mine goaf are determined based on the development of pores and fissures inside the rock formation, the consumption rate of the flushing fluid, the water level reduction rate of the exploration hole, and the drill drop and / or drill sticking frequencies.

5. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to any one of claims 1 to 2, characterized in that: The step of performing pressure and concentration differential grouting when the exploration hole in the coal mine goaf is drilled to the crack zone position and the collapse zone position comprises: When the exploration hole in the coal mine goaf is drilled to the position of the fracture zone, grouting the exploration hole with a grouting liquid of a first concentration using a surface mud pump pressure grouting method; When the exploration hole in the coal mine goaf is drilled to the location of the collapse zone, the exploration hole is grouted using the grouting liquid of the second concentration by using the surface mud pump pressure grouting method; Wherein, the first concentration is less than the second concentration.

6. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to any one of claims 1 to 2, characterized in that: The step of processing the core samples at different plane positions and different depths to obtain the volume of the slurry solidified body and the volume of the rock block corresponding to the pressure grouting in the core samples comprises: Conducting crushing tests on core samples at different plane positions and depths to separate the slurry solidified body and the rock block; The volume of the slurry solid and the volume of the rock mass are determined using the water displacement method or the wax seal method.

7. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to any one of claims 1 to 2, characterized in that: The step of obtaining the spatial distribution function of the porosity according to the porosity at different plane positions and different depths comprises: Fitting the porosity at different plane positions and different depths to obtain a functional relationship equation of the porosity varying with the plane position and depth; A local coordinate system is established according to the working face boundary of the coal mine goaf, and coordinate transformation is performed on the plane position and depth in the functional relationship equation according to the local coordinate system to obtain the spatial distribution function of the porosity.

8. The method for calculating the grouting amount based on the residual porosity test of the coal mine goaf according to any one of claims 1 to 2, characterized in that: After the step of determining the grouting amount of the coal mine goaf according to the total pore volume, the following steps are further included: The cost of treating the coal mine goaf is determined based on the grouting volume, grouting concentration and grouting material ratio of the coal mine goaf.

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