Directional grouting test device for goaf and visual test method

Abstract

The invention discloses a directional grouting test device and a visual test method for a goaf, and the method comprises the steps: building a bed rock, laying a mineral product to be mined, laying and filling an area to be reinforced, burying a soil pressure gauge and a water pressure gauge, burying a grouting floral tube, arranging a grouting inner tube, communicating a grouting system, and setting a particle imaging velocimeter PIV. In the test process, the seepage and diffusion process in the slurry and the stress state of the rock-soil body are monitored by using a soil pressure meter and a water pressure meter; calculating the total amount of slurry flowing into the model through a slurry barrel outer scale; after grouting is finished, original-state sampling is conducted on the grouting permeation reinforcement area, a mechanical property test and a microcosmic test are conducted, and the grout permeation and reinforcement effect is analyzed; the grouting pressure-seepage distance-mechanical property relation is obtained. The goaf directional grouting permeation simulation device can carry out goaf directional grouting permeation simulation, facilitates mechanical property test of original state sampling, and has the characteristics of visualization, simulation, monitoring and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of mining engineering, and relates to a ground directional grouting test device for a goaf and a visualization test method. Background Technique

[0002] With the continuous exploitation of underground mineral resources, problems such as the stability of surrounding rocks and groundwater often occur in goafs, further causing engineering safety accidents. Directional borehole grouting reinforcement is one of the main methods to solve this problem at present.

[0003] Through directional boreholes, the grout is injected into the formation, so that the cracks originally filled with water and air are compressed, displaced, and blocked, sealing the water flow channels, thereby achieving the purpose of strengthening the surrounding rocks and preventing water bodies from flowing into the bottom of the mine or the goaf. In order to fully contact the water storage space and water-conducting channels of the surrounding rock aquifer and make efficient use of the boreholes, the technology of ground directional near-horizontal bedding branch borehole groups has been used in many places for the grouting transformation of surrounding rocks.

[0004] Studying the diffusion law of the grout in directional borehole grouting and exploring the diffusion characteristics and effects of the grout in the aquifer have important theoretical and engineering significance for solving the problems of the stability of surrounding rocks and groundwater in goafs. Zhang Weijie et al. developed a three-dimensional grouting model test system, which consists of a bearing test bench, a servo constant-pressure water supply unit, a grouting unit, a multi-information monitoring unit, and an image acquisition unit. They carried out single-hole grouting and multi-hole grouting model tests in clay media, and studied the variation characteristics of grouting pressure and the spatio-temporal evolution law of the physical field inside the rock mass. Li Jian et al. designed a grouting filling grout diffusion simulation system, carried out experimental studies on the grout diffusion law, and studied the grout diffusion law in the non-pressure stage. Shang Hongbo et al. obtained the physical property parameters of single-fluid cement grout for curtain grouting materials through indoor tests and carried out research on the diffusion law of single-fluid cement grout. Li Tao et al. developed a single-hole water discharge experimental device and supporting use technology based on the analysis of the characteristics of water disaster prevention in the floor of the Weibei Coalfield. On the basis of carrying out single-hole water discharge experiments, they proposed a floor classification grouting technology in combination with the theory of water inrush dominant plane. Wang Xiaochen et al. carried out grouting diffusion simulation tests based on a self-developed crack grouting simulation test platform. Taking the proportion of the solid phase volume after the grout is completely dewatered and settled in the total volume as the characterization of the grout concentration in the crack, they obtained the concentration distribution characteristics of the grout along the diffusion path under different crack apertures and water-cement ratios. Yu Yongqiang et al. developed a set of experimental devices for grouting in fractured rock masses under high-temperature and water-rich environments, and carried out multiple groups of crack grouting tests using the uniform design method. They analyzed the sensitivity of factors such as formation temperature, unit time flow rate, and water-cement ratio to the grout diffusion law, and systematically discussed the variation law of the shape of the grout stone body with the change of the unit time grouting flow rate under the action of formation temperature.

[0005] However, although the above grouting penetration reinforcement test device system has a certain degree of advancement, in view of the stability of the surrounding rock in the goaf and groundwater problems, the above test device cannot effectively implement the grouting penetration reinforcement using the technology of ground-directed nearly horizontal bedding branch borehole groups. Disadvantages of the prior art: (1) The prior art cannot effectively simulate the grouting penetration reinforcement of the ground-directed branch borehole group technology in the goaf under nearly horizontal stratum conditions; (2) The prior art cannot effectively implement the grouting reinforcement under complex geological conditions such as sandy gravel layers, fractured and extremely fractured rock masses, soft soil layers, and karst caves; (3) It cannot provide a high-permeability pressure grouting simulation environment and cannot effectively study the diffusion law of high-permeability pressure grout; (4) Due to the setting of high-permeability pressure, the requirements for the stiffness and airtightness of the test device are relatively high. Therefore, most test devices are made of steel and cannot achieve visualization.

[0006] In view of the above disadvantages, the present invention aims at the characteristics of the engineering of directional grouting penetration reinforcement of the surrounding rock in the goaf, and proposes a ground-directed grouting penetration test device and a visualization test method for the goaf. At the same time, it is convenient to take undisturbed samples for mechanical property tests, and has the characteristics of visualization, simulation, and monitorability. Summary of the Invention

[0007] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide a directional grouting test device and a visualization test method for the goaf, to overcome the above disadvantages in the prior art, and to propose a ground-directed grouting penetration test device and a visualization test method for the goaf according to the characteristics of the engineering of directional grouting penetration reinforcement of the surrounding rock in the goaf. At the same time, it is convenient to take undisturbed samples for mechanical property tests, and has the characteristics of visualization, simulation, and monitorability.

[0008] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0009] A directional grouting visualization test method for the goaf includes the following steps:

[0010] Step 1, construct the bedrock: Use gypsum, bricks and mortar to construct the bedrock in the test model box. The inclination angle of the bedrock is the same as that of the mineral layer to be mined and the area to be reinforced;

[0011] Step 2, lay the mineral to be mined: Use silt as the laying material, and lay silt layer by layer on the bedrock. After scraping the surface of each layer of filling, lay the next layer. Its moisture content should be such that the top surface can be leveled smoothly without obvious air holes;

[0012] Step 3, fill the area to be reinforced: Precast test blocks using cement, sand and water. The size of the test blocks is considered according to the actual geological conditions to simulate the rock mass fissures and joint structures; after the test blocks are cured, lay them in layers on the mineral to be mined according to the actual engineering geological conditions to simulate the layered rock mass;

[0013] Step 4, embedding earth pressure gauges and water pressure gauges: According to the actual engineering situation, embed earth pressure gauges and water pressure gauges respectively in the area to be reinforced, and connect them to a data acquisition instrument through the pressure gauge data acquisition line to monitor the changes in earth pressure and water pressure during the test, so as to realize the visualization of the internal earth and water pressure changes during the grouting process;

[0014] Step 5, embedding grouting perforated pipes: Embed steel perforated pipes in the middle and upper parts of the model respectively, including the ground directional bedding grouting steel perforated pipes and the non-bedding ground directional grouting steel perforated pipes;

[0015] Step 6, arranging the inner grouting pipes: The inner grouting pipes pass through the reserved holes at the bottom of the steel perforated pipes to ensure that the grout diffuses to the surrounding soil layers through the holes in the outer pipes; The inner grouting pipes are fixed to the steel perforated pipes to avoid displacement during grouting;

[0016] Step 7, connecting the grouting system: Connect the slurry delivery pipes to the inner grouting pipes and the slurry bucket respectively, connect the slurry bucket to the air compressor, and control the grouting pressure through the pressure gauge to dynamically adjust the grouting process;

[0017] Step 8, setting up the Particle Image Velocimetry (PIV): Observe the slurry seepage and diffusion process on the side wall of the test model box through the Particle Image Velocimetry, and realize the visualization of the slurry seepage and diffusion process during the grouting process through PIV monitoring;

[0018] Step 9, during the test, use the earth pressure gauges and water pressure gauges to monitor the slurry internal seepage and diffusion process and the stress state of the rock and soil mass;

[0019] Step 10, calculate the total amount of slurry flowing into the model interior through the external scale of the slurry bucket, and obtain the relationship between the slurry penetration pressure - the total amount of slurry - the penetration distance based on the results of Steps 7 to 9;

[0020] Step 11, after grouting, turn off the air compressor and the slurry delivery pipes; Take undisturbed samples from the grouting penetration and reinforcement area, and then conduct mechanical property tests and microscopic tests to analyze the slurry penetration and reinforcement effects;

[0021] Step 12, based on the results of Steps 7 to 11, the relationship between the grouting pressure - the penetration distance - the mechanical properties can be obtained.

[0022] The present invention further includes the following technical features:

[0023] Specifically, in Step 2, design the strike, dip, and dip angle of the mineral layer to be mined according to the actual engineering geological conditions to meet the needs of the actual project.

[0024] Specifically, in Step 2, the paving thickness of each layer of the paving material is 2 cm.

[0025] Specifically, in step 3, when the strata of the overlying area to be reinforced for mineral mining are uneven, cement, sand, and water materials with different ratios are used to simulate complex strata layer by layer and region by region.

[0026] Specifically, in step 5, the included angle between the vertical grouting pipe and the bedding grouting pipe of the ground directional bedding grouting steel pipe is 120° - 160°.

[0027] Specifically, in step 6, the inner grouting pipe is a PVC pipe, which is used to directly transport the grout to the target area.

[0028] A directional grouting test device for a goaf, which is used for the directional grouting visualization test method for the goaf; the device includes a test model box, bedrock, minerals to be mined, and areas to be reinforced laid in sequence from bottom to top in the test model box, earth pressure gauges and water pressure gauges arranged in the areas to be reinforced, pressure gauge data acquisition lines, data acquisition instruments, ground directional bedding grouting steel pipes, non-bedding ground directional grouting steel pipes, inner grouting pipes, slurry pipes, slurry barrels, pressure gauges, air compressors, and particle image velocimetry PIV.

[0029] Specifically, the test model box is made of transparent toughened glass, and the joints of the test model box are sealed with waterproof and high-strength sealant to ensure the sealing property during the test process.

[0030] Specifically, the steel pipes of the ground directional bedding grouting steel pipes and the ground directional grouting steel pipes are both seamless 304 stainless steel pipes, and grouting holes are drilled on the pipe body, and the holes are arranged in a plum blossom shape or symmetrically to enhance the slurry diffusion ability;

[0031] The inner grouting pipe passes through the reserved hole at the bottom of the steel pipe to ensure that the slurry diffuses to the surrounding soil layer through the outer pipe holes, and the inner grouting pipe is fixed to the steel pipe.

[0032] Specifically, the slurry pipes are respectively connected to the inner grouting pipe and the slurry barrel, and the slurry barrel is connected to the air compressor, and the grouting pressure is controlled by the pressure gauge to dynamically adjust the grouting process; the particle image velocimetry PIV can observe the slurry seepage and diffusion process on the side wall of the test model box to realize the visualization of the slurry seepage and diffusion process during the grouting process.

[0033] Compared with the prior art, the present invention has the following technical effects:

[0034] (1) The present invention can carry out the simulation of directional grouting penetration in the goaf.

[0035] (2) The present invention adopts the internal and external double-pipe grouting technology, which can achieve multiple groutings and specifically fill the formation defects at different positions and depths. At the same time, the outer pipe (perforated steel pipe) serves as a skeleton, having both the functions of support and slurry guiding, and can effectively realize the grouting reinforcement under complex geological conditions such as sandy cobble layers, fractured and extremely fractured rock masses, soft soil layers, and karst caves.

[0036] (3) The method of the present invention is convenient for the prototype sampling of the rock mass after the slurry penetration for reinforcement, and the original mechanical properties can be detected, and even microscopic tests can be carried out.

[0037] (4) The experiment of the present invention can obtain the law of slurry penetration and diffusion under high penetration pressure.

[0038] (5) The experiment of the present invention can observe the morphology of slurry penetration and diffusion. Description of the Drawings

[0039] Figure 1 It is a schematic diagram of the directional grouting test device for the goaf.

[0040] Figure 2 It is a curve graph showing the relationship between the volume of slurry occupying the pores in the fractured rock mass (slurry ratio) and the grouting time under different grouting pressures.

[0041] The meanings of the various reference numerals in the figure are as follows:

[0042] 1. Test model box, 2. Bedrock, 3. Mineral to be mined, 4. Area to be reinforced, 5. Earth pressure gauge, 6. Water pressure gauge, 7. Pressure gauge data acquisition line, 8. Data acquisition instrument, 9. Surface directional bedding grouting perforated steel pipe, 10. Surface directional grouting perforated steel pipe, 11. Inner grouting pipe, 12. Grout delivery pipe, 13. Grout bucket, 14. Pressure gauge, 15. Air compressor, 16. Particle Image Velocimetry PIV. Detailed Embodiment

[0043] The following are the specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and any equivalent transformation based on the technical solution of the present application falls within the protection scope of the present invention.

[0044] Embodiment:

[0045] This embodiment provides a directional grouting visualization test method for a goaf, including the following steps:

[0046] Step 1, building the bedrock: Build the bedrock in the test model box with gypsum, bricks and mortar. The inclination angle of the bedrock is the same as that of the mineral layer to be mined and the area to be reinforced. Specifically, it is formed by building with gypsum, bricks and mortar to make the bedrock have sufficient strength and not deform. At the same time, design the inclination angle of the bedrock according to the actual geological conditions, and the inclination angle is the same as that of the mineral layer and the area to be reinforced to simulate the grouting effect under different inclined formation conditions.

[0047] Step 2, laying the minerals to be mined: Use silt as the laying material and lay silt layer by layer on the bedrock. After scraping the surface of each layer of filling, lay the next layer. Its water content should be appropriate to be able to level the top surface smoothly without obvious air holes. Specifically, design the strike, dip, and dip angle of the mineral layer according to the actual engineering geological conditions to meet the needs of the actual project. The laying material uses silt with a certain water content, and the thickness of each layer of filling is 2 cm. After scraping the surface, lay the next layer. The water content should be appropriate to be able to level the top surface smoothly without obvious air holes. At the same time, different water contents can reflect the groundwater and water-bearing conditions of the mineral layer to achieve the grouting effect under different groundwater conditions;

[0048] Step 3, filling the area to be reinforced: Precast test blocks in advance with cement, sand, and water in a certain ratio. The size of the test blocks is considered according to the actual geological conditions to simulate structures such as rock mass fractures and joints. After the test blocks are cured, lay them in layers at a certain angle on the minerals to be mined according to the actual engineering geological conditions to simulate layered rock masses. When the strata of the area to be reinforced overlying the mined minerals are uneven, different ratios of materials such as cement, sand, and water can be used to layer and divide the area to simulate complex strata;

[0049] Step 4, burying earth pressure gauges and water pressure gauges: According to the actual engineering situation, bury multiple earth pressure gauges and water pressure gauges respectively at certain intervals in the area to be reinforced, and connect them to a data acquisition instrument through the pressure gauge data acquisition line to monitor the changes in earth pressure and water pressure during the test, and realize the visualization of the internal earth and water pressure changes during the grouting process;

[0050] Step 5, burying grouting perforated pipes: Bury steel perforated pipes in the middle and upper parts of the model respectively, including ground directional bedding grouting steel perforated pipes and non-bedding ground directional grouting steel perforated pipes to compare and analyze the grouting effects of the two. The angle between the vertical grouting pipe of the ground directional bedding grouting steel perforated pipe and the bedding grouting pipe along the direction of the area to be reinforced should not be too small. If it is too small, the slurry will be blocked at the corner, affecting the grouting effect. If the angle is too large, it cannot be effectively injected into the area to be reinforced. This angle should be determined comprehensively in combination with the actual engineering situation and the slurry consistency, and generally should be controlled at 120° - 160°;

[0051] Step 6, arranging internal grouting pipes: The internal grouting pipes pass through the reserved holes at the bottom of the steel perforated pipes to ensure that the slurry diffuses to the surrounding soil layers through the outer pipe holes. The internal grouting pipes are fixed to the steel perforated pipes to avoid displacement during grouting. The use of the internal and external double-pipe grouting technology can achieve multiple groutings and targeted filling of stratum defects at different positions and depths. It can effectively realize the grouting reinforcement under complex geological conditions such as sandy gravel layers, fractured and extremely fractured rock masses, soft soil layers, and karst caves. The internal grouting pipes are PVC pipes used to directly transport the slurry to the target area;

[0052] Step 7, Connect the grouting system: Connect the slurry delivery pipe to the inner grouting pipe and the slurry bucket respectively, connect the slurry bucket to the air compressor, and control the grouting pressure through the pressure gauge to dynamically adjust the grouting process;

[0053] Step 8, Set up the Particle Image Velocimetry (PIV): Observe the slurry seepage and diffusion process on the side wall of the test model box through the Particle Image Velocimetry, and realize the visualization of the slurry seepage and diffusion process during the grouting process through PIV monitoring;

[0054] Step 9, During the test, use the earth pressure gauge and water pressure gauge to monitor and obtain the slurry internal seepage and diffusion process and the stress state of the rock and soil mass;

[0055] Step 10, Calculate the total amount of slurry flowing into the model through the scale outside the slurry bucket, and combine the results of Steps 7 to 9 to obtain the relationship between the slurry penetration pressure - total slurry amount - penetration distance;

[0056] Step 11, After grouting for a period of time, when the slurry penetration area has been formed and stabilized, the air compressor and the slurry delivery pipe can be closed; Use geotechnical tools to take undisturbed samples of the grouting penetration and reinforcement area, and then conduct mechanical property tests such as direct shear and microscopic tests such as scanning electron microscopy to analyze the slurry penetration and reinforcement effects;

[0057] Step 12, Combining the results of Steps 7 to 11 can obtain the relationship between the grouting pressure - penetration distance - mechanical properties.

[0058] The present invention also provides a directional grouting test device for a goaf, and this device is used for the above-mentioned directional grouting visualization test method for a goaf; as Figure 1 shown, this device includes parts such as a test model box, a data acquisition system, a grouting system, and a monitoring system, specifically including a test model box 1, bedrock 2, minerals to be mined 3, and areas to be reinforced 4 laid in sequence from bottom to top in the test model box 1, earth pressure gauges 5 and water pressure gauges 6 arranged in the area to be reinforced 4, pressure gauge data acquisition lines 7, data acquisition instruments 8, ground directional bedding grouting steel pipes 9, non-bedding ground directional grouting steel pipes 10, inner grouting pipes 11, slurry delivery pipes 12, slurry buckets 13, pressure gauges 14, air compressors 15, and Particle Image Velocimetry (PIV) 16.

[0059] The test model box 1 is made of transparent tempered glass, and the joints of the test model box 1 are sealed with waterproof and high-strength sealant to ensure the sealing during the test process.

[0060] There are multiple steel pipes for both the ground directional bedding grouting steel pipes 9 and the ground directional grouting steel pipes 10, and seamless 304 stainless steel pipes are used. The pipe body is drilled with grouting holes, the hole diameter is about 5 mm, and the holes are arranged in a plum blossom shape or symmetrically to enhance the slurry diffusion ability.

[0061] The ground directional layer grouting steel flower pipe 9 is formed by connecting a vertical grouting pipe with a layer grouting pipe. The layer grouting pipe is along the direction of the area to be reinforced, and the angle between the vertical grouting pipe and the layer grouting pipe is 120° to 160°.

[0062] The steel flower pipe is used as a skeleton, which has both support and slurry guiding functions, and is pre-buried to the designed depth and fixed. The grouting inner pipe 11 passes through the reserved hole at the bottom of the steel flower pipe to ensure that the slurry diffuses to the surrounding soil layer through the outer pipe holes, and the grouting inner pipe is fixed to the steel flower pipe.

[0063] The test device has good air tightness and water tightness.

[0064] The slurry delivery pipe 12 is connected to the grouting inner pipe 11 and the slurry barrel 13 respectively, the slurry barrel 13 is connected to the air compressor 15, and the grouting pressure is controlled by the pressure gauge 14 to dynamically adjust the grouting process; the particle imaging velocimeter PIV16 can observe the slurry seepage and diffusion process on the side wall of the test model box to realize the visualization of the slurry seepage and diffusion process during the grouting process.

[0065] The embodiment of the present invention uses a test device to carry out a ground directional near-horizontal layer grouting penetration test:

[0066] The grouting pressures were 40 kPa, 50 kPa and 60 kPa respectively. The pressure changes inside the model and the slurry penetration process were observed by soil pressure gauge, water pressure gauge and PIV during the test. The relationship curve between the slurry volume in the fractured rock mass (slurry ratio) and the grouting time under different grouting pressures was further obtained. Figure 2 .

[0067] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0068] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0069] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A directional grouting visualization test method for gob areas, characterized in that, It includes the following steps: Step 1, building the bedrock: Use gypsum, bricks and mortar to build the bedrock in the test model box. The inclination angle of the bedrock is the same as that of the mineral layer to be mined and the area to be reinforced; Step 2, laying the mineral to be mined: Use silt as the laying material and lay the silt layer by layer on the bedrock. After scraping the surface of each layer of filling, lay the next layer. Its moisture content should be such that the top surface can be smoothed without obvious air holes; Step 3, filling the area to be reinforced: Precast test blocks using cement, sand and water. The size of the test blocks is considered according to the actual geological conditions to simulate rock mass fractures and joint structures; After the test blocks are cured, lay them in layers on the mineral to be mined according to the actual engineering geological conditions to simulate layered rock masses; Step 4, burying earth pressure gauges and water pressure gauges: According to the actual engineering situation, bury earth pressure gauges and water pressure gauges respectively in the area to be reinforced, and connect them to the data acquisition instrument through the pressure gauge data acquisition line to monitor the changes of earth pressure and water pressure during the test, so as to realize the visualization of the internal earth and water pressure changes during the grouting process; Step 5, burying grouting perforated pipes: Bury steel perforated pipes in the middle and upper parts of the model respectively, including ground directional bedding grouting perforated pipes and non-bedding ground directional grouting perforated pipes; Step 6, arranging the inner grouting pipes: The inner grouting pipes pass through the reserved holes at the bottom of the steel perforated pipes to ensure that the grout diffuses to the surrounding soil layers through the holes in the outer pipes; The inner grouting pipes are fixed to the steel perforated pipes to avoid displacement during grouting; Step 7, connecting the grouting system: Connect the slurry delivery pipes to the inner grouting pipes and the slurry bucket respectively, connect the slurry bucket and the air compressor, and control the grouting pressure through the pressure gauge to dynamically adjust the grouting process; Step 8, setting up the Particle Image Velocimetry (PIV): Observe the slurry seepage and diffusion process on the side wall of the test model box through the Particle Image Velocimetry, and realize the visualization of the slurry seepage and diffusion process during the grouting process through PIV monitoring; Step 9, during the test, use the earth pressure gauges and water pressure gauges to monitor the slurry internal seepage and diffusion process and the stress state of the rock and soil mass; Step 10, calculate the total amount of slurry flowing into the model through the external scale of the slurry bucket, and combine the results of steps 7 to 9 to obtain the relationship between the slurry penetration pressure - the total amount of slurry - the penetration distance; Step 11, after grouting, turn off the air compressor and the slurry delivery pipes; Take undisturbed samples of the grouting penetration and reinforcement area, and then conduct mechanical property tests and microscopic tests to analyze the slurry penetration and reinforcement effects; Step 12, combining the results of steps 7 to 11 can obtain the relationship between the grouting pressure - the penetration distance - the mechanical properties; 2. The directional grouting visualization test method for gob areas according to claim 1, characterized in that In step 2, design the strike, dip and dip angle of the mineral layer to be mined according to the actual engineering geological conditions to meet the needs of the actual project.

3. The directional grouting visualization test method for gob areas according to claim 1, characterized in that In step 2, the thickness of each layer of the laying material is 2 cm.

4. The directional grouting visualization test method for gob areas according to claim 1, wherein In step 3, when the strata of the area to be reinforced overlying the mined minerals are uneven, use different ratios of cement, sand and water materials to simulate complex strata in layers and regions.

5. The directional grouting visualization test method for gob areas according to claim 1, characterized in that In step 5, the included angle between the vertical grouting pipe and the bedding grouting pipe of the ground directional bedding grouting perforated pipe is 120° - 160°.

6. The directional grouting visualization test method for gob areas according to claim 1, wherein In step 6, the inner grouting pipe is a PVC pipe, which is used to directly transport the slurry to the target area.

7. A directional grouting test device for a goaf, characterized in that, This device is used for the directional grouting visualization test method for goafs described in claim 1; the device includes a test model box, bedrock, minerals to be mined, and areas to be reinforced laid in sequence from bottom to top in the test model box, earth pressure gauges and water pressure gauges arranged in the areas to be reinforced, pressure gauge data acquisition lines, a data acquisition instrument, ground directional bedding grouting steel pipes, non-bedding ground directional grouting steel pipes, inner grouting pipes, slurry delivery pipes, slurry barrels, pressure gauges, air compressors, and a particle image velocimetry (PIV).

8. The directional grouting test device for gob areas according to claim 7, characterized in that, The test model box is made of transparent tempered glass, and waterproof high-strength sealant is used at the joints of the test model box to ensure the sealing during the test process.

9. The directional grouting test device for a gob area according to claim 7, wherein The steel pipes of the ground directional bedding grouting steel pipes and the ground directional grouting steel pipes are both seamless 304 stainless steel pipes, and grouting holes are drilled on the pipe body, and the holes are arranged in a plum blossom shape or symmetrically to enhance the slurry diffusion ability; The inner grouting pipe passes through the reserved hole at the bottom of the steel pipe to ensure that the slurry diffuses to the surrounding soil layers through the holes of the outer pipe, and the inner grouting pipe is fixed to the steel pipe.

10. The directional grouting test device for gob areas according to claim 7, characterized in that, The slurry delivery pipes are respectively connected to the inner grouting pipe and the slurry barrel, and the slurry barrel is connected to the air compressor. The grouting pressure is controlled by the pressure gauge to dynamically adjust the grouting process; the particle image velocimetry (PIV) can observe the slurry seepage and diffusion process on the side wall of the test model box to realize the visualization of the slurry seepage and diffusion process during the grouting process.

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