Grouting method for fracture zone in karst strata

Abstract

The present invention provides a grouting method for a fracture zone in a karst formation. The method comprises: conducting a tracer test on a first branch borehole arranged in a fracture zone in a karst formation to obtain a diffusion range of a tracer, and determining a hole spacing in the fracture zone based on the diffusion range; determining the branch transverse positions of second branch boreholes based on the transverse extension of the fracture zone and the hole spacing; determining the branch longitudinal positions of the second branch boreholes corresponding to each branch transverse position based on the top positions of aquifers in the karst formation on both sides of the fracture zone; arranging second branch boreholes in the fracture zone based on each branch transverse position and the branch longitudinal position corresponding to each branch transverse position, and grouting the second branch boreholes. The present invention achieves effective regional management of the fracture zone, reducing the number of boreholes and grouting fluid consumption.

Description

Technical Field

[0001] The invention relates to the technical field of mine water hazard prevention and control, and in particular to a grouting method for a karst stratum fracture zone. Background Art

[0002] When karst confined aquifers exist in the coal seam floor, water inrush accidents are likely to occur in fault zones. Karst fault zones are characterized by uneven distribution, large extensions, well-developed fissures, and difficulty in sealing. As water storage spaces and water channels, karst fault zones are key geological elements in controlling water hazards. Their exploration and management are one of the challenges in coal mine water hazard prevention and control.

[0003] Accurate detection and effective management of fault zones in coal mining areas are crucial for preventing water inrush from mines. Fault zones are formed by crustal movement, and their distribution across regions has a certain regularity. However, within mining areas, the distribution of these fractured zones, such as faults, is often uncertain and hidden, making their precise detection and management a highly technical challenge.

[0004] Exploration of fault zones, such as faults, is typically conducted using geophysical and drilling methods. The typical approach is to first delineate geological structures, such as faults, using surface 3D seismic or downhole channel wave geophysical methods. During underground tunnel construction, drilling is then used to verify suspected structural areas to determine parameters such as the fault's location and occurrence, and to analyze its size and water conductivity. Once the fault zone's location and parameters are determined, grouting drill holes are constructed in the water-conducting fault zone. Through drilling, small areas of water-conducting fissures are grout-sealed to control water damage.

[0005] Grouting drilling holes for fault zones are generally arranged in groups of single holes. The number of drilling holes is large, the engineering workload is large, and the grouting drilling holes cover a small area, which can only form local governance and cannot form effective regional governance. Summary of the Invention

[0006] The present invention provides a grouting method for a karst stratum fracture zone, which is used to solve the defect in the prior art that fracture zone grouting requires a large number of drillings and can only form local treatment, thereby reducing the amount of drilling and forming effective regional treatment of the fracture zone.

[0007] The present invention provides a grouting method for a karst stratum fracture zone, comprising:

[0008] Conducting a tracer test on the first branch borehole arranged in the fault zone of the karst formation to obtain the diffusion range of the tracer, and determining the hole spacing in the fault zone based on the diffusion range;

[0009] Determining the branch lateral position of the second branch drill hole according to the lateral distribution length of the fault zone and the hole spacing;

[0010] Determining the longitudinal position of the second branch borehole corresponding to each branch transverse position according to the top position of the aquifer in the karst strata on both sides of the fault zone;

[0011] Arrange a second branch borehole on the fault zone according to each branch transverse position and the branch longitudinal position corresponding to each branch transverse position, and perform grouting on the second branch borehole.

[0012] According to a grouting method for a karst stratum fracture zone provided by the present invention, the first branch borehole has three branches;

[0013] The tracer test is conducted on the first branch borehole arranged in the fault zone of the karst formation to obtain the diffusion range of the tracer, including:

[0014] Arranging an intermediate branch of the first branch borehole, and injecting a tracer into the intermediate branch;

[0015] Drilling two branches on both sides of the first branch borehole, and taking samples to test whether the tracer exists in the boreholes of the two branches;

[0016] The diffusion range of the tracer is determined based on the sampling test results.

[0017] According to a grouting method for a karst stratum fracture zone provided by the present invention, determining the diffusion range of the tracer based on the sampling test results includes:

[0018] If the tracer is present in the borehole of one of the two side branches and not in the borehole of the other side branch, the diffusion range of the tracer is the lateral distance between the one side branch and the middle branch;

[0019] If the tracer exists in the boreholes of the two side branches, the diffusion range of the tracer is the lateral distance between the two side branches and the middle branch.

[0020] According to a grouting method for a karst stratum fracture zone provided by the present invention, determining the hole spacing in the fracture zone according to the diffusion range includes:

[0021] If the diffusion range of the tracer is the lateral distance between the one side branch and the middle branch, the lateral distance between the one side branch and the middle branch is used as the hole spacing;

[0022] If the diffusion range of the tracer is the lateral distance between the two side branches and the middle branch, the maximum value of the lateral distances between the two side branches and the middle branch is used as the hole spacing.

[0023] According to a grouting method for a fault zone in a karst stratum provided by the present invention, determining the branch lateral position of the second branch drill hole according to the lateral distribution length of the fault zone and the hole spacing includes:

[0024] Divide the horizontal spread length by the hole spacing, round down, and add 1 to obtain the number of branch horizontal projections of the second branch drill hole;

[0025] The branch transverse positions of the second branch drill holes are determined according to the number of branch transverse projections and the hole spacing of the second branch drill holes.

[0026] According to a grouting method for a karst stratum fracture zone provided by the present invention, determining the branch longitudinal position of the second branch drill hole corresponding to each branch transverse position according to the top position of the aquifer in the karst stratum on both sides of the fracture zone, comprising:

[0027] If the top position of the aquifer in the karst stratum on one side of the fault zone is lower than the top position of the aquifer in the karst stratum on the other side of the fault zone, the bottom branch longitudinal position corresponding to each branch transverse position is determined according to the top position of the aquifer on one side of the fault zone, and the top branch longitudinal position corresponding to each branch transverse position is determined according to the top position of the aquifer on the other side of the fault zone, and the intermediate branch longitudinal position is determined between the bottom branch longitudinal position and the top branch longitudinal position.

[0028] According to a grouting method for a karst stratum fracture zone provided by the present invention, grouting into the second branch borehole comprises:

[0029] Using a grouting pump to inject slurry with a first preset concentration into the bottom branch located at the longitudinal position of the bottom branch in the second branch borehole, and stopping for a second preset time after each grouting for a first preset time, until the pressure of the grouting pump is greater than a first preset threshold;

[0030] Slurry with a second preset concentration is injected into the bottom branch until the grouting pressure of the grouting pump is greater than a second preset threshold; the first preset concentration is greater than the second preset concentration, and the first preset threshold is less than the second preset threshold.

[0031] According to a grouting method for a karst stratum fracture zone provided by the present invention, grouting into the second branch borehole comprises:

[0032] using a grouting pump to inject slurry having a third preset concentration into the top branch located at the longitudinal position of the top branch in the second branch borehole, and stopping for a fourth preset time after each grouting for a third preset time, until the pressure of the grouting pump is greater than a third preset threshold value; the third preset concentration is less than the first preset concentration, and the third preset threshold value is greater than the first preset threshold value;

[0033] Slurry with a fourth preset concentration is injected into the top-level branch, and a permeability test is performed until the grouting pressure of the grouting pump is greater than a fourth preset threshold and the formation permeability of the top-level branch is less than a fifth preset threshold; the fourth preset concentration is less than the third preset concentration, and the fourth preset threshold is greater than the third preset threshold.

[0034] According to a grouting method for a karst stratum fracture zone provided by the present invention, grouting into the second branch borehole comprises:

[0035] Use a grouting pump to grout the middle branch segments located at the longitudinal position of the middle branch in the second branch borehole, injecting slurry with a concentration of the fifth preset concentration until the grouting pressure of the grouting pump is greater than the sixth preset threshold and the formation permeability of the middle branch is less than the seventh preset threshold; the fifth preset concentration is less than the third preset concentration, and the sixth preset threshold is greater than the fourth preset threshold.

[0036] According to a grouting method for a fracture zone in a karst formation provided by the present invention, a tracer test is performed on a first branch borehole arranged in a fracture zone in the karst formation to obtain a diffusion range of a tracer, comprising:

[0037] Determining a suspected area of ​​the fault zone based on geophysical methods;

[0038] Conduct tracer tests on the first branch boreholes arranged in the suspected area of ​​the fault zone of the karst formation to obtain the diffusion range of the tracer;

[0039] The step of drilling a hole into the second branch and performing grouting comprises:

[0040] Determining the area where the fault zone is located based on the second branch drilling;

[0041] Grouting is performed into the second branch drill hole in the area where the fault zone is located.

[0042] The grouting method for a karst stratum fracture zone provided by the present invention determines the hole spacing by conducting a tracer test on directional drilling in the fracture zone, determines the planar distribution of branch drill holes based on the hole spacing, and determines the vertical distribution of branch drill holes based on the top position of the aquifer in the karst stratum on both sides of the fracture zone, thereby achieving effective regional management of the fracture zone and reducing the number of drill holes and grouting fluid consumption. 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 This is one of the flow diagrams of the grouting method for the karst stratum fracture zone provided by the present invention;

[0045] Figure 2 It is a schematic projection diagram of the first branch borehole on the cross section of the karst stratum in the grouting method for the karst stratum fracture zone provided by the present invention;

[0046] Figure 3 It is a schematic diagram of the arrangement of the second branch borehole on the plane of the fracture zone in the karst stratum fracture zone grouting method provided by the present invention;

[0047] Figure 4 This is a schematic diagram of the vertical layered arrangement of the second branch boreholes in the fracture zone of the karst stratum in the grouting method provided by the present invention;

[0048] Figure 5 This is the second flow diagram of the grouting method for the karst stratum fracture zone provided by the present invention. DETAILED DESCRIPTION

[0049] 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.

[0050] The following combination Figure 1 A grouting method for a fracture zone in a karst formation according to the present invention includes: step 101, performing a tracer test on a first branch borehole arranged in a fracture zone in a karst formation to obtain a diffusion range of a tracer, and determining a hole spacing in the fracture zone based on the diffusion range;

[0051] The first branch borehole is used to explore the diffusion range of the grouting liquid in the fracture zone area. Optionally, the first branch borehole includes a main trunk and multiple branches, each branch connected to the main trunk and passing through the longitudinal section of the fracture zone. This embodiment is not limited to the number of branches.

[0052] Inject a tracer into one branch of the first branch borehole. Sampling is then performed to detect the presence of tracer in other branches, thereby determining the tracer's diffusion range. The diffusion range is then used to determine the appropriate hole spacing for fault zone remediation. For example, the tracer's diffusion range can be used directly as the hole spacing.

[0053] Step 102: determining the lateral position of the second branch drill hole according to the lateral length of the fault zone and the hole spacing;

[0054] The transverse extension length of the fault zone is the axial length of the transverse interface of the fault zone. The transverse position of the second branch borehole is the projection position of the branch of the second branch borehole on the cross section.

[0055] Optionally, the transverse spread length is divided into multiple equal segments according to the hole spacing, and branch projections of the second branch borehole passing through the fault zone are made through the segmentation points of the transverse spread length, thereby determining the branch transverse positions of the second branch boreholes.

[0056] Step 103, determining the branch longitudinal position of the second branch borehole corresponding to each branch transverse position according to the top position of the aquifer in the karst strata on both sides of the fault zone;

[0057] The longitudinal position of the branch is the projected position of the branch of the second branch drill hole on the longitudinal section, reflecting the depth of the branch.

[0058] Because fault zones, such as faults, develop vertically deep, the tops of the aquifers on either side of the fault zone are located at different positions. Based on these different top positions of the aquifers on both sides of the fault zone, a layered perforation method is used to treat the upper part of the karst aquifer.

[0059] Step 104 : Arrange a second branch drill hole in the fault zone according to each branch transverse position and the branch longitudinal position corresponding to each branch transverse position, and perform grouting in the second branch drill hole.

[0060] The branch transverse position and branch lateral position correspond to the projected position of the branch on the cross section and longitudinal section. A branch position of a second branch borehole can be determined based on a branch transverse position and a branch longitudinal position. A second branch borehole is arranged based on the branch position of the second branch borehole, and grouting is injected into the arranged second branch borehole to achieve fault zone remediation.

[0061] This embodiment determines the hole spacing by conducting tracer tests on directional drilling in the fault zone, determines the planar distribution of branch boreholes based on the hole spacing, and determines the vertical distribution of branch boreholes based on the top position of the aquifer in the karst strata on both sides of the fault zone, thereby achieving effective regional management of the fault zone and reducing the number of boreholes and grouting fluid consumption.

[0062] Based on the above embodiments, Figure 2As shown, in this embodiment, the first branch borehole has three branches;

[0063] Arrange a set of three-branch first-branch boreholes in the fault zone area. Figure 2 The projection of the first branch borehole on the cross section of the karst stratum. Branches ①, ②, and ③ of the first branch borehole can be located on the same cross section or on different cross sections.

[0064] The method of performing a tracer test on a first branch borehole arranged in a fault zone of a karst formation to obtain a diffusion range of a tracer includes: arranging an intermediate branch of the first branch borehole and injecting a tracer into the intermediate branch;

[0065] When arranging branches ①, ② and ③ of the first branch borehole, the construction sequence is as follows: first the middle branch hole and then the two sides branch holes. The branch hole spacing R of the second branch borehole is determined by trial grouting.

[0066] First construct the middle branch ① and conduct a grouting test, using the grouting slurry as a tracer.

[0067] Drilling two branches on both sides of the first branch borehole, and taking samples to test whether the tracer exists in the boreholes of the two branches;

[0068] Through the branches on both sides of the subsequent construction, namely, drilling holes ② and ③, samples are taken to test whether there is slurry component in drilling holes ② and ③.

[0069] The diffusion range of the tracer is determined based on the sampling test results.

[0070] The tracer diffusion range in branch ① is determined by testing for the presence of slurry in boreholes ② and ③. The horizontal spacing between ① and ③, as well as the horizontal spacing between ① and ②, is set empirically. The tracer diffusion range can only be determined if slurry is present in at least one of boreholes ② and ③. If slurry is absent in both boreholes ② and ③, the horizontal spacing is too large. Reduce the horizontal spacing between ②, ③, and ①.

[0071] In this embodiment, a tracer test is performed using the first branch borehole to determine the slurry diffusion range, thereby determining the hole spacing for remediating the fault zone. This reduces the number of drill holes and grouting fluid consumption while ensuring effective remediation of the fault zone.

[0072] Based on the above embodiment, the present embodiment determines the diffusion range of the tracer according to the sampling test results, including: if the tracer exists in the borehole of one branch of the two side branches and does not exist in the borehole of the other side branch, then the diffusion range of the tracer is the lateral distance between the one side branch and the middle branch;

[0073] Figure 2In the figure, if there is a tracer in the ② branch borehole and no tracer in the ③ branch borehole, the slurry diffusion range is the horizontal distance R1 between ① and ②.

[0074] If there is no tracer in the ② branch borehole and there is a tracer in the ③ branch borehole, the slurry diffusion range is the horizontal distance R2 between ① and ③.

[0075] If the tracer exists in the boreholes of the two side branches, the diffusion range of the tracer is the lateral distance between the two side branches and the middle branch.

[0076] If tracers are present in both branch boreholes ② and ③, the slurry diffusion range includes two parts, R1 and R2.

[0077] Based on the above embodiment, the method of determining the hole spacing for the fault zone according to the diffusion range in this embodiment includes: if the diffusion range of the tracer is the lateral distance between the one side branch and the middle branch, then using the lateral distance between the one side branch and the middle branch as the hole spacing;

[0078] If there is a tracer in only one of the ② and ③ branches, the corresponding R1 or R2 is used as the hole spacing.

[0079] If the diffusion range of the tracer is the lateral distance between the two side branches and the middle branch, the maximum value of the lateral distances between the two side branches and the middle branch is used as the hole spacing.

[0080] If tracers are present in both branches ② and ③, the hole spacing is Max(R1,R2).

[0081] Based on the above embodiments, Figure 3 As shown, in this embodiment, determining the branch transverse position of the second branch drill hole according to the transverse extension length of the fault zone and the hole spacing includes: dividing the transverse extension length by the hole spacing, rounding down, and adding 1 to obtain the number of branch transverse projections of the second branch drill hole;

[0082] According to the horizontal distribution length L of the fault zone and the determined branch hole spacing R, [L / R]+1 branch boreholes are designed to form a fault zone management area and realize the plane design plan of the karst fault zone.

[0083] The branch transverse positions of the second branch drill holes are determined according to the number of branch transverse projections and the hole spacing of the second branch drill holes.

[0084] Figure 3The cross section of the fault zone is shown in Figure 1. The branches of the second branch borehole pass through the longitudinal section of the fault zone. The lateral position of the branches of the third branch borehole is determined based on the number of branch projections and the hole spacing. Figure 3 shown.

[0085] On the basis of the above embodiments, the branch longitudinal position of the second branch borehole corresponding to each branch transverse position is determined according to the top position of the aquifer in the karst strata on both sides of the fault zone in this embodiment, including: if the top position of the aquifer in the karst stratum on one side of the fault zone is lower than the top position of the aquifer in the karst stratum on the other side of the fault zone, then the bottom branch longitudinal position corresponding to each branch transverse position is determined according to the top position of the aquifer on one side of the fault zone, the top branch longitudinal position corresponding to each branch transverse position is determined according to the top position of the aquifer on the other side of the fault zone, and the intermediate branch longitudinal position is determined between the bottom branch longitudinal position and the top branch longitudinal position.

[0086] Figure 4 This is a schematic diagram of the vertical layered arrangement of the second branch boreholes in the fault zone. The top of the karst aquifer on the left side of the fault zone is lower than the top of the karst aquifer on the right side of the fault zone.

[0087] First, the top of the karst aquifer below the fracture zone cuts through the karst stratum is used as the longitudinal location of the bottom branch. Bottom branch ① is constructed and grouting is injected into the bottom branch. This serves to build a bottom and form a water-blocking plug at the bottom of the reinforced area. Second, the top branch ② is constructed and grouting is injected into the top branch. This serves to seal the top. The diffusion of the grout connects the top of the fracture zone with the aquifer, inhibiting excessive upward diffusion of the grout. Finally, an intermediate branch ③ is constructed between bottom branch ① and top branch ②. This serves to reinforce the middle of the fracture zone after grouting has been completed at both the top and bottom branches, ensuring that the grouting fills the fractures as fully as possible and ensures a good grouting effect in the fracture zone. One or more intermediate branches can be constructed.

[0088] This embodiment arranges multiple layers of directional holes in the vertical direction to form a multi-form layered efficient grouting and plugging method for water-conducting channels such as bottoming, capping and middle reinforcement, thereby improving the management effect and efficiency of the fault zone and reducing the amount of grouting and drilling.

[0089] Based on the above embodiment, the grouting into the second branch borehole in this embodiment includes: using a grouting pump to inject slurry with a first preset concentration into the bottom branch located at the longitudinal position of the bottom branch in the second branch borehole, and stopping for a second preset time after each grouting for a first preset time, until the pressure of the grouting pump is greater than a first preset threshold value;

[0090] In this embodiment, time-controlled grouting is performed on the bottom branch of the fault zone, using a high-density thick slurry (1.5 to 1.6 kg / L) and low-pressure (0 to 3 MPa) grouting process.

[0091] The purpose of the bottom branch is to build a bottom and reduce the diffusion of slurry into the deep part of the fault zone to form a blockage. The key to the success of bottom building lies in the time-controlled grouting process.

[0092] The time-controlled grouting process refers to the use of a thick slurry with a first preset concentration (1.5 to 1.6 kg / L) after the directional hole is constructed to the fracture zone, and the grouting is stopped for 1 to 2 hours every 3 to 8 hours, alternating back and forth until the grouting pump pressure is greater than 3 MPa.

[0093] Slurry with a second preset concentration is injected into the bottom branch until the grouting pressure of the grouting pump is greater than a second preset threshold; the first preset concentration is greater than the second preset concentration, and the first preset threshold is less than the second preset threshold.

[0094] Then gradually reduce the slurry density to 1.3kg / L until the grouting pump displacement reaches 200L / h and the grouting pressure is greater than 10MPa, then the bottom is successfully built.

[0095] Based on the above embodiment, the grouting into the second branch borehole in this embodiment includes: using a grouting pump to inject slurry with a third preset concentration into the top branch located at the longitudinal position of the top branch in the second branch borehole, and stopping for a fourth preset time after each grouting for a third preset time until the pressure of the grouting pump is greater than a third preset threshold; the third preset concentration is less than the first preset concentration, and the third preset threshold is greater than the first preset threshold;

[0096] In this embodiment, time-controlled grouting and permeability testing are performed on the branch holes in the top layer of the fault zone using a medium-density (1.3 to 1.4 kg / L) slurry and a medium-high-pressure (8 to 12 MPa) grouting process.

[0097] The purpose of the top branch is to seal the cracks at the top of the fault zone and transform the top aquifer. After drilling to the fault zone, the time-controlled grouting process is used.

[0098] The slurry concentration is medium density (1.3 to 1.4 kg / L). Stop grouting for 1 to 2 hours every 3 to 8 hours, and repeat this process alternately until the grouting pump pressure is greater than 8 MPa.

[0099] Slurry with a fourth preset concentration is injected into the top-level branch, and a permeability test is performed until the grouting pressure of the grouting pump is greater than a fourth preset threshold and the formation permeability of the top-level branch is less than a fifth preset threshold; the fourth preset concentration is less than the third preset concentration, and the fourth preset threshold is greater than the third preset threshold.

[0100] After the time-controlled grouting stage is completed, the permeability test grouting stage begins. In this stage, the slurry density is 1.2kg / L. When the grouting pump displacement is 200L / h and the grouting pressure is greater than 12MPa, the formation permeability K is tested. When K<10 -5 m / d, the capping is successful.

[0101] Based on the above embodiment, the grouting into the second branch borehole in this embodiment includes: using a grouting pump to grout the middle branch segmented at the longitudinal position of the middle branch in the second branch borehole, injecting slurry with a concentration of the fifth preset concentration until the grouting pressure of the grouting pump is greater than the sixth preset threshold and the formation permeability of the middle branch is less than the seventh preset threshold; the fifth preset concentration is less than the third preset concentration, and the sixth preset threshold is greater than the fourth preset threshold.

[0102] In this embodiment, permeability test grouting is performed on the reinforced branch holes in the middle of the fault zone, using a medium-low density slurry (1.1 to 1.2 kg / L) and a high pressure (12 to 15 MPa) grouting process.

[0103] The purpose of the intermediate reinforcement branch is high-pressure, high-intensity grouting, which involves injecting as much slurry as possible to enrich the ground. After the base and capping branches are grouted, all medium and large fissures in the fault zone are sealed. Smaller fissures require grouting using a high-pressure, thin-slurry injection process.

[0104] The branch was divided into several sections with a length of 100m, and the formation permeability test and high-pressure grouting were carried out separately. Here, each grouting section (100m) mainly adopts medium-low density slurry (1.1 to 1.2kg / L) high-pressure (12 to 15MPa) grouting technology, and K<10 -5 m / d, move on to the next grouting section until the branch construction is completed.

[0105] After the construction of the bottom, top and middle reinforcement branches is completed, the permeability test of the karst fracture zone is carried out. When the overall permeability K is less than 10-5m / d, the regional layered time-controlled grouting operation of the karst fracture zone is completed. The complete flow chart is as follows Figure 5 shown.

[0106] This embodiment forms a systematic regional layered time-controlled and efficient grouting process for the ground karst fault zone, which solves the problems of small area, low efficiency, long cycle, low safety, and large consumption of grouting materials in underground fault zone management. After the fault zone is managed according to this embodiment, the safety of coal mining on pressurized water bodies in the geological fault zone area of ​​the coal mine can be guaranteed.

[0107] Based on the above embodiments, the tracer test is performed on the first branch borehole arranged in the fault zone of the karst formation to obtain the diffusion range of the tracer, including: determining a suspected area of ​​the fault zone based on a geophysical prospecting method; performing the tracer test on the first branch borehole arranged in the suspected area of ​​the fault zone of the karst formation to obtain the diffusion range of the tracer;

[0108] The grouting into the second branch drill hole includes: determining the area where the fault zone is located according to the second branch drill hole; and grouting into the second branch drill hole in the area where the fault zone is located.

[0109] This embodiment only requires using existing geophysical methods to determine the suspected area of ​​the fault zone in advance. The arranged branch boreholes are also used to verify the fault zone, and grouting is performed on the branch boreholes verified to be the fault zone, realizing integrated and efficient exploration and injection.

[0110] 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 grouting method for a karst stratum fracture zone, characterized in that: include: Conducting a tracer test on the first branch borehole arranged in the fault zone of the karst formation to obtain the diffusion range of the tracer, and determining the hole spacing in the fault zone based on the diffusion range; Determining the branch lateral position of the second branch drill hole according to the lateral distribution length of the fault zone and the hole spacing; Determining the longitudinal position of the second branch borehole corresponding to each branch transverse position according to the top position of the aquifer in the karst strata on both sides of the fault zone; Arranging a second branch borehole on the fault zone according to each branch transverse position and a branch longitudinal position corresponding to each branch transverse position, and performing grouting on the second branch borehole; The first branch borehole has three branches; The tracer test is conducted on the first branch borehole arranged in the fault zone of the karst formation to obtain the diffusion range of the tracer, including: Arranging an intermediate branch of the first branch borehole, and injecting a tracer into the intermediate branch; Drilling two branches on both sides of the first branch borehole, and taking samples to test whether the tracer exists in the boreholes of the two branches; determining the diffusion range of the tracer according to the sampling test results; The step of determining the lateral position of the second branch drill hole according to the lateral length of the fault zone and the hole spacing includes: Divide the horizontal spread length by the hole spacing, round down, and add 1 to obtain the number of branch horizontal projections of the second branch drill hole; determining the branch transverse position of the second branch drill hole according to the number of branch transverse projections and the hole spacing of the second branch drill hole; The step of determining the longitudinal position of the second branch borehole corresponding to each branch transverse position according to the top position of the aquifer in the karst strata on both sides of the fault zone comprises: If the top position of the aquifer in the karst stratum on one side of the fault zone is lower than the top position of the aquifer in the karst stratum on the other side of the fault zone, the bottom branch longitudinal position corresponding to each branch transverse position is determined according to the top position of the aquifer on one side of the fault zone, and the top branch longitudinal position corresponding to each branch transverse position is determined according to the top position of the aquifer on the other side of the fault zone, and the intermediate branch longitudinal position is determined between the bottom branch longitudinal position and the top branch longitudinal position.

2. The grouting method for a fracture zone in a karst formation according to claim 1, characterized in that: Determining the diffusion range of the tracer based on the sampling test results includes: If the tracer exists in the borehole of one of the two side branches and does not exist in the borehole of the other side branch, the diffusion range of the tracer is the lateral distance between the one side branch and the middle branch; If the tracer exists in the boreholes of the two side branches, the diffusion range of the tracer is the lateral distance between the two side branches and the middle branch.

3. The grouting method for a fracture zone in a karst formation according to claim 2, characterized in that: The step of determining the hole spacing for the fracture zone according to the diffusion range includes: If the diffusion range of the tracer is the lateral distance between the one side branch and the middle branch, the lateral distance between the one side branch and the middle branch is used as the hole spacing; If the diffusion range of the tracer is the lateral distance between the two side branches and the middle branch, the maximum value of the lateral distances between the two side branches and the middle branch is used as the hole spacing.

4. The grouting method for a fracture zone in a karst formation according to claim 1, characterized in that: The step of drilling a hole into the second branch and performing grouting comprises: Using a grouting pump to inject slurry with a first preset concentration into the bottom branch located at the longitudinal position of the bottom branch in the second branch borehole, and stopping for a second preset time after each grouting for a first preset time, until the pressure of the grouting pump is greater than a first preset threshold; Slurry with a second preset concentration is injected into the bottom branch until the grouting pressure of the grouting pump is greater than a second preset threshold; the first preset concentration is greater than the second preset concentration, and the first preset threshold is less than the second preset threshold.

5. The grouting method for a fracture zone in a karst formation according to claim 4, characterized in that: The step of drilling a hole into the second branch and performing grouting comprises: using a grouting pump to inject slurry having a third preset concentration into the top branch located at the longitudinal position of the top branch in the second branch borehole, and stopping for a fourth preset time after each grouting for a third preset time, until the pressure of the grouting pump is greater than a third preset threshold value; the third preset concentration is less than the first preset concentration, and the third preset threshold value is greater than the first preset threshold value; Slurry with a fourth preset concentration is injected into the top-level branch, and a permeability test is performed until the grouting pressure of the grouting pump is greater than a fourth preset threshold and the formation permeability of the top-level branch is less than a fifth preset threshold; the fourth preset concentration is less than the third preset concentration, and the fourth preset threshold is greater than the third preset threshold.

6. The grouting method for a fracture zone in a karst formation according to claim 5, characterized in that: The step of drilling a hole into the second branch and performing grouting comprises: Use a grouting pump to grout the middle branch segments located at the longitudinal position of the middle branch in the second branch borehole, injecting slurry with a concentration of the fifth preset concentration until the grouting pressure of the grouting pump is greater than the sixth preset threshold and the formation permeability of the middle branch is less than the seventh preset threshold; the fifth preset concentration is less than the third preset concentration, and the sixth preset threshold is greater than the fourth preset threshold.

7. The grouting method for a karst stratum fracture zone according to any one of claims 1 to 6, characterized in that: The tracer test is conducted on the first branch borehole arranged in the fault zone of the karst formation to obtain the diffusion range of the tracer, including: Determining a suspected area of ​​the fault zone based on geophysical methods; Conduct tracer tests on the first branch boreholes arranged in the suspected area of ​​the fault zone of the karst formation to obtain the diffusion range of the tracer; The step of drilling a hole into the second branch and performing grouting comprises: Determining the area where the fault zone is located based on the second branch drilling; Grouting is performed into the second branch drill hole in the area where the fault zone is located.

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