A lignite mining roof wind oxidation zone classified grouting reinforcement method

Abstract

The application discloses a lignite mining roof wind oxidation zone classified grouting reinforcement method, and relates to the technical field of coal mining. The method comprises the following steps: obtaining the average wind oxidation zone thickness, water inflow and average natural gamma value of each pressure step distance segment on the overlying surface of the lignite mining working face to be mined; determining a set number of drilling points on the lignite mining working face according to the average wind oxidation zone thickness, water inflow and average natural gamma value of each pressure step distance segment; obtaining the drilling loss amount of each drilling point; determining the functional relationship between the drilling loss amount and the average wind oxidation zone thickness, water inflow and average natural gamma value based on the data of each drilling point; determining the drilling loss amount of each pressure step distance segment according to the functional relationship; dividing the drilling loss amount of each pressure step distance segment into a plurality of grade grout consumption areas; and adopting different grouting processes for grouting reinforcement on each grade grout consumption area. The application can reduce roof accidents, reduce grout loss, and additionally simply reduce grouting cost.

Description

Technical Field

[0001] This application relates to the field of coal mining technology, and in particular to a method for classifying and grouting the roof oxidation zone in lignite mining. Background Technology

[0002] When mining shallow lignite resources, the weathering and fracturing of the roof of the solid mineral deposit is often caused by the cutting action of the terrain. This fractured roof makes it difficult to form good support conditions, creating safety hazards. Currently, grouting is mainly used to reinforce weathered roofs, but this method has the following problems: (1) Weathering is affected by a variety of factors and is uneven. It is difficult to identify before the lignite mining face is formed, which makes it difficult to select grouting technology and to accurately reinforce it.

[0003] (2) Traditionally, a uniform grouting method is used. Due to the uniformity of this method, there is a problem of poor applicability.

[0004] (3) Grouting in the wind oxidation zone often results in grout leakage and cross-contamination under fractured conditions. Under the condition of severe wind oxidation zone development, the existing grouting process is ineffective. Summary of the Invention

[0005] The purpose of this application is to provide a method for classifying and reinforcing the wind oxidation zone of the roof in lignite mining, which can reduce roof accidents, reduce grout leakage, and also simply reduce grouting costs.

[0006] To achieve the above objectives, this application provides the following solution: This application provides a method for classifying and grouting reinforcement of the wind oxidation zone in lignite mining roof, including: Obtain the pressure step distance of the lignite mining face to be mined; Obtain the average thickness of the wind-oxidized zone over the pressure step segment corresponding to each pressure step; During the tunnel excavation of lignite mining face, the water inflow and average natural gamma value are obtained for each pressure step. Based on the average thickness of the aeolian oxidation zone, water inflow, and average natural gamma value corresponding to each pressure step, a set number of boreholes are determined on the lignite mining face. Conduct exploratory drilling at each drilling point and record the drilling leakage at each drilling point; Based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value of the corresponding pressure step distance for each borehole point, the functional relationship between borehole leakage and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value is determined. The borehole leakage rate for each pressure step segment is determined based on the aforementioned functional relationship; The drilling leakage of each pressure step is divided into multiple levels of slurry-absorbing areas according to preset rules; Different grouting processes were used to reinforce the grouting areas of different grades.

[0007] Optionally, a set number of boreholes are determined on the lignite mining face based on the average thickness of the aeolian oxidation zone, water inflow, and average natural gamma value corresponding to each pressure step, specifically including: The pressure step segment corresponding to the maximum value among the average wind oxidation zone thicknesses is determined as the first pressure step segment, the pressure step segment corresponding to the maximum value among the various inflow rates is determined as the second pressure step segment, and the pressure step segment corresponding to the minimum value among the average natural gamma values ​​is determined as the third pressure step segment. A set number of boreholes are selected on the lignite mining face. Among the set number of boreholes, at least one is implemented in the first pressure step section, at least one is implemented in the second pressure step section, and at least one is implemented in the third pressure step section.

[0008] Optionally, the set quantity is 5.

[0009] Optionally, exploratory drilling is performed at each drilling point, specifically including: When drilling exploratory boreholes at each borehole point, the borehole diameter of each exploratory borehole is less than or equal to 91 mm, each exploratory borehole exposes the entire thickness of the aeolian oxide zone, and the borehole inclination of each exploratory borehole is less than 3°.

[0010] Optionally, the borehole leakage in each pressure step section is divided into multiple levels of slurry ingestion zones according to preset rules, specifically including: The drilling leakage of each pressure step is divided into three levels of slurry-absorbing areas according to preset rules; For each pressure step segment: If the borehole leakage is less than or equal to the inflow, then the pressure step section is a low slurry intake area. If the borehole leakage is greater than the water inflow, but less than the preset leakage, then the pressure step section is a medium slurry intake area. If the borehole leakage is greater than the water inflow, and the borehole leakage is greater than or equal to the preset leakage, then the pressure step section is a high slurry intake area.

[0011] Optionally, the preset leakage rate is 150 L / min.

[0012] Optionally, different grouting processes can be used to reinforce grouting areas of different grouting levels, specifically including: For the low grout absorption area, grouting is carried out with a water pressure greater than 2MPa, and the injected grout is made of cement and water in a mass ratio of 0.5:1 to 1:1. For the medium grouting area, during grouting, first drill holes with a diameter greater than or equal to 133 mm, then seal the holes with quick-setting cement, and then perform secondary perforation with a diameter less than or equal to 91 mm; wherein, the sealing thickness is greater than 1 meter, and the injected grout is made of cement and water in a mass ratio of 1:1 to 2:1. For the high grout-absorbing area, a horizontal jet grouting machine is used to mix and reinforce the top slab with cement; the injected grout is made of cement and water in a mass ratio of 1:1 to 2:1.

[0013] Optionally, the average thickness of the aeolian oxide zone overlying each pressure step segment is obtained, specifically including: Before mining the lignite face, three-dimensional seismic exploration was used to determine the average thickness of the aeolian oxide zone overlying each pressure step.

[0014] Optionally, during the excavation of roadways in lignite mining faces, the water inflow and average natural gamma value for each pressure step are obtained, specifically including: During the excavation of roadways in lignite mining faces, the water inflow volume of each pressure step is recorded; During the tunneling of lignite mining face roadways, a 1-meter borehole is drilled for each pressure step, and natural gamma logging is performed on the 1-meter borehole to obtain the average natural gamma value for each pressure step.

[0015] Optionally, based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value of the corresponding pressure step section at each borehole point, the functional relationship between the borehole leakage and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value is determined, specifically including: Based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value of the corresponding pressure step distance for each borehole point, a multivariate linear statistical method is used to determine the functional relationship between borehole leakage and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value.

[0016] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides a method for grouting reinforcement of the aeolian oxidation zone in lignite mining, based on the borehole leakage at each borehole point and the average aeolian oxidation zone thickness, water inflow, and average natural gamma value of the corresponding pressure step section. The method determines the functional relationship between borehole leakage and these factors. Based on this functional relationship, the borehole leakage for each pressure step section is determined. The borehole leakage for each pressure step section is then divided into multiple grouting zones according to a preset rule. Different grouting processes are used to reinforce each grouting zone at each level. By grouting multiple grouting zones at different levels, various grouting reinforcement technologies are implemented for areas with different degrees of aeolian oxidation zone development. This makes grouting more precise, reduces roof accidents, minimizes unnecessary grouting, and reduces grout leakage. Furthermore, using a functional relationship to determine the borehole leakage for each pressure step section reduces the number of exploratory boreholes, shortens the construction period, is simple to implement, and lowers grouting costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating a method for classifying and grouting the roof oxidation zone in lignite mining, as provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] This application considers that the degree of development of the aeolian oxidation zone is affected by various geological factors, and therefore often exhibits heterogeneity. The aeolian oxidation zone exposed in a lignite mining face is under different conditions, and the grouting reinforcement should be different accordingly. Otherwise, in areas where the aeolian oxidation zone is not developed, low-pressure grouting will have a limited reinforcement range, while in moderately developed areas, using a high water-cement ratio will result in a large amount of grout leakage and runoff. In highly developed areas, conventional grouting is difficult to withstand pressure and grout leakage is difficult to seal.

[0022] In one exemplary embodiment, this application provides a method for classifying and grouting the wind oxidation zone of the roof in lignite mining, such as... Figure 1 As shown, the method for classifying and reinforcing the wind oxidation zone of the roof in lignite mining includes steps 101-109.

[0023] Step 101: Obtain the pressure step distance of the lignite mining face to be mined.

[0024] Step 102: Obtain the average thickness of the wind-oxidized zone overlying each pressure step segment.

[0025] Step 103: During the tunnel excavation of the lignite mining face, obtain the water inflow and average natural gamma value for each pressure step.

[0026] Step 104: Determine the set number of boreholes on the lignite mining face based on the average thickness of the aeolian oxidation zone, water inflow, and average natural gamma value corresponding to each pressure step distance.

[0027] Step 105: Conduct exploratory drilling at each drilling point and record the drilling leakage at each drilling point.

[0028] Step 106: Based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the water inflow, and the average natural gamma value of the pressure step section corresponding to each borehole point, determine the functional relationship between the borehole leakage and the average thickness of the aeolian oxide zone, the water inflow, and the average natural gamma value.

[0029] Step 107: Determine the borehole leakage for each pressure step segment based on the aforementioned functional relationship.

[0030] Step 108: Divide the drilling leakage of each pressure step into multiple levels of slurry-absorbing areas according to preset rules.

[0031] Step 109: Use different grouting processes to reinforce the grouting areas of different grades.

[0032] This application achieves multiple grouting reinforcement technologies for areas with different degrees of wind oxidation development by grouting in multiple grouting zones. This makes grouting more precise, reduces roof accidents, reduces unnecessary grouting, and reduces grout leakage. At the same time, it uses a functional relationship to determine the amount of borehole leakage in each pressure step, which reduces the number of exploratory boreholes, shortens the construction period, is simple to implement, and reduces grouting costs.

[0033] In an exemplary embodiment, step 101 specifically includes: obtaining the mining face distance through numerical simulation technology before mining the lignite mining face.

[0034] In an exemplary embodiment, step 102 specifically includes: before mining the lignite mining face, using three-dimensional seismic exploration to determine the average thickness of the aeolian oxide zone overlying each pressure step segment.

[0035] In an exemplary embodiment, step 103 specifically includes: recording the water inflow at each pressure step during lignite mining face roadway excavation. During lignite mining face roadway excavation, a 1-meter borehole is drilled at each pressure step, and natural gamma logging is performed on the 1-meter borehole to obtain the average natural gamma value for each pressure step.

[0036] In an exemplary embodiment, step 104 specifically includes: determining the pressure step segment corresponding to the maximum value among the average wind oxidation zone thicknesses as the first pressure step segment, determining the pressure step segment corresponding to the maximum value among the inflow rates as the second pressure step segment, and determining the pressure step segment corresponding to the minimum value among the average natural gamma values ​​as the third pressure step segment.

[0037] A set number of boreholes are selected on the lignite mining face. Among the set number of boreholes, at least one is implemented in the first pressure step section, at least one is implemented in the second pressure step section, and at least one is implemented in the third pressure step section.

[0038] In one exemplary embodiment, the set quantity is 5.

[0039] In an exemplary embodiment, probing drilling is performed on each borehole point, specifically including: when probing drilling is performed on each borehole point, the borehole diameter of each probing borehole is less than or equal to 91 mm, each probing borehole exposes the entire thickness of the aeolian oxide zone, and the borehole inclination of each probing borehole is less than 3°.

[0040] In an exemplary embodiment, step 106 specifically includes: based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value of the pressure step segment corresponding to each borehole point, a multivariate linear statistical method is used to determine the functional relationship between the borehole leakage Y and the average aeolian oxide zone thickness X1, the inflow rate X2, and the average natural gamma value X3.

[0041] The functional relationship is expressed as: .

[0042] Where a, b, and c are all regression coefficients.

[0043] The functional relationship is used to predict the borehole leakage for each pressure step segment.

[0044] In an exemplary embodiment, step 108 specifically includes: dividing the drilling leakage of each pressure step into three levels of slurry-absorbing areas according to a preset rule.

[0045] For each pressure step segment: If the borehole leakage is less than or equal to the inflow, then the pressure step section is a low slurry intake area. If the borehole leakage is greater than the water inflow, but less than the preset leakage, then the pressure step section is a medium slurry intake area. If the borehole leakage is greater than the water inflow, and the borehole leakage is greater than or equal to the preset leakage, then the pressure step section is a high slurry intake area.

[0046] In one exemplary embodiment, the preset leakage rate is 150 L / min.

[0047] In one exemplary embodiment, step 109 specifically includes the following:

[0048] 1) For the low grouting area, grouting is carried out with a water pressure greater than 2MPa. The grout is made of cement and water in a mass ratio of 0.5:1 to 1:1.

[0049] 2) For the medium grouting area, when grouting, first drill holes with a diameter greater than or equal to 133 mm, then inject quick-setting cement to seal the holes, and then use holes with a diameter less than or equal to 91 mm for secondary penetration; wherein, the sealing thickness is greater than 1 meter, and the injected grout is made of cement and water in a mass ratio of 1:1 to 2:1.

[0050] 3) For the high grouting area, a horizontal jet grouting machine is used to mix and reinforce the top slab with cement; the injected grout is made of cement and water in a mass ratio of 1:1 to 2:1.

[0051] After classifying and reinforcing each pressure step section with grouting, the mineral resources within the mining face are extracted.

[0052] The beneficial effects of this application are as follows: 1) It significantly reduces the number of exploratory boreholes, shortens the construction period, and is simple and easy to implement; 2) Grouting conditions at the mining face can be obtained through simple observation and testing, making grouting more accurate and reducing unnecessary grouting; 3) It reduces grout leakage and runoff during the grouting process, resulting in less grouting work and greater economy; 4) It proposes various grouting reinforcement technologies for areas with different degrees of wind oxidation development, making the methods more adaptable.

[0053] This application proposes a method for classifying and reinforcing the wind oxidation zone of the roof in lignite mining. The method is developed through two aspects: first, the assessment of the development of the wind oxidation zone (different degrees of grout absorption); and second, the selection of grouting techniques under different wind oxidation zone development conditions.

[0054] Firstly, the degree of grout absorption in boreholes is greatly influenced by geological conditions. Exposing large areas through drilling is time-consuming and expensive. This application characterizes the geological conditions of the grouting area, i.e., the borehole leakage Y, using three factors: grout layer thickness (X1, where other conditions are the same, a thicker grout layer results in a larger grout volume), tunnel water inflow (X2, where other conditions are the same, a larger water inflow results in a larger grout volume), and natural gamma logging (X3, where a higher content of clay or other materials that are difficult to grout results in a higher natural gamma value). By establishing these relationships, more accurate working face conditions can be obtained while reducing the number of boreholes required.

[0055] Secondly, the grouting principle under different conditions can be divided into three aspects. (1) The selection of grouting technology under different wind oxidation zones is firstly based on the pressure step distance as a unit, because one pressure step is the breakage of a masonry beam, and whether a good support structure can be formed is the key. (2) The classification of different grouting zone levels is first based on the relationship between borehole leakage Y and water inflow X2. When Y is less than or equal to X2, it indicates that the connectivity of weathering fissures is poor, and it is not easy for grout to run or cross-flow. Conversely, it is easy for it to happen. Secondly, the degree of grout running also varies. When it is greater than 150L / min, it indicates that the general single pump flow (when the borehole diameter is less than 91mm) is completely lost, while when it is less than 150L / min, it indicates that the general single pump flow will not be completely lost. This classification takes into account both the connectivity of fissures and the general grouting capacity. (3) Grouting process selection under different types: In low grout-absorbing areas, it indicates that natural weathering is not strong, and the grout is difficult to inject, with a limited diffusion range. At this time, higher water pressure is needed to expand the cracks and inject more grout. There is no need to worry about grout leakage. In medium grout-absorbing areas, it indicates that grout leakage has occurred, but it can be reinforced by traditional processes. At this time, a cement cover to prevent grout leakage is needed. In order to prevent grout leakage, the water-cement ratio should be reduced. In high grout-absorbing areas, grout leakage has occurred, and the existing pumping capacity is insufficient to form a cement cover. At this time, jet grouting technology is used to directly mix the severely broken roof slab with cement to generate a recycled roof slab, which effectively reduces grout leakage.

[0056] In one exemplary embodiment, a mine is in the shallow development stage of lignite mining. Due to the crisscrossing gullies and the fracturing of the overlying aeolian oxide zone during the mining of solid ore deposits, numerous roof collapses occurred during the initial mining face. To reinforce the aeolian oxide zone, grouting reinforcement measures were implemented. However, significant grout leakage occurred at the start of grouting, and roof problems persisted in some areas even after grouting. To address this issue, a categorized grouting method was adopted, with the specific steps as follows: Step 1: Before mining the lignite face, the step distance of the mining face is determined by conventional numerical simulation technology, which ranges from 15 meters to 25 meters.

[0057] Step 2: Before mining the lignite face, three-dimensional seismic surveys were conducted on each pressure step section to determine the average thickness of the overlying aeolian oxide zone, which ranged from X1 to 43 meters.

[0058] Step 3: During the tunnel excavation at the lignite mining face, record the water inflow rate X2 = 0.5m for each pressure step. 3 / h~15.6m 3 / h.

[0059] Step 4: During the tunneling of the lignite mining face, a simple 1-meter borehole is drilled for each pressure step. Natural gamma logging is performed on the recommended boreholes to obtain the average natural gamma value of each pressure step, X3 = 19 API ~ 96 API.

[0060] Step 5: Select 5 points on the lignite mining face for exploratory drilling. One of the selected boreholes is drilled at X1=43 meters, corresponding to the third cycle of pressure application, and another is drilled at X2=15.6 meters. 3 / h, for the 6th cycle of pressure section, one is implemented at X3=19APId, for the 10th cycle of pressure section. All probing boreholes have a diameter of 91mm. Probing boreholes should expose the entire thickness of the aeolian oxide zone. Probing boreholes are vertically upward boreholes with an inclination of less than 3°.

[0061] Step Six: Record the borehole leakage rate Y = 18L / min ~ 182L / min for the exploratory borehole implemented in Step Five.

[0062] Step 7: Based on the values ​​obtained in Steps 2-4 and Step 6, use the multivariate linear statistical method to determine the functional relationship between Y and X1, X2, and X3, i.e., Y = 3.2X1 + 4.2X2 - 0.5X3.

[0063] Step 8: Using the functional relationship determined in Step 7, predict the borehole leakage rate Y = 10.5 L / min ~ 182 L / min for each pressure step.

[0064] Step Nine: Divide the borehole leakage rate into three levels: Y less than or equal to X2 is the low slurry intake area; Y greater than X2 but less than 150 L / min is the medium slurry intake area; and Y greater than X2 and greater than or equal to 150 L / min is the high slurry intake area. The low slurry intake area has 10 pressure-receiving sections, the medium slurry intake area has 25 pressure-receiving sections, and the high slurry intake area has 5 pressure-receiving sections.

[0065] Step 10: For the three grouting zones identified in Step 9, different grouting processes are adopted for each zone.

[0066] In areas with low grout absorption, grouting is carried out using a water pressure of 2.5 MPa. The grout is made of cement and water in a mass ratio of 1:1.

[0067] In areas with moderate grout intake, 133mm diameter holes are first drilled during grouting. After drilling, quick-setting cement is injected to seal the holes, followed by secondary penetration using 91mm smaller diameter holes. The sealing thickness is 1.5 meters. The injected grout is composed of cement and water at a mass ratio of 2:1.

[0068] In areas with high grout intake, a horizontal jet grouting machine is used to directly mix and reinforce the roof slab with cement. The injected grout is made of cement and water at a mass ratio of 2:1.

[0069] Step 11: After classifying and reinforcing each pressure step section with grouting, the mineral resources in the mining face are then extracted.

[0070] Compared with traditional grouting reinforcement technology, no roof slab accidents occurred after adopting this technology, and the phenomena of grout leakage and cross-contamination were reduced by more than 76%, while the cost was lower.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for classifying and grouting the wind oxidation zone of the roof in lignite mining, characterized in that, The classified grouting reinforcement method for the wind oxidation zone of the roof in lignite mining includes: Obtain the pressure step distance of the lignite mining face to be mined; Obtain the average thickness of the wind-oxidized zone over the pressure step segment corresponding to each pressure step; During the tunnel excavation of lignite mining face, the water inflow and average natural gamma value are obtained for each pressure step. Based on the average thickness of the aeolian oxidation zone, water inflow, and average natural gamma value corresponding to each pressure step, a set number of boreholes are determined on the lignite mining face. Conduct exploratory drilling at each drilling point and record the drilling leakage at each drilling point; Based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value of the corresponding pressure step distance for each borehole point, the functional relationship between borehole leakage and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value is determined. The borehole leakage rate for each pressure step segment is determined based on the aforementioned functional relationship; The drilling leakage of each pressure step is divided into multiple levels of slurry-absorbing areas according to preset rules; Different grouting processes were used to reinforce the grouting areas of different grades.

2. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, Based on the average thickness of the aeolian oxidation zone, water inflow, and average natural gamma value corresponding to each pressure step, a set number of boreholes are determined on the lignite mining face, specifically including: The pressure step segment corresponding to the maximum value among the average wind oxidation zone thicknesses is determined as the first pressure step segment, the pressure step segment corresponding to the maximum value among the average water inflows is determined as the second pressure step segment, and the pressure step segment corresponding to the minimum value among the average natural gamma values ​​is determined as the third pressure step segment. A set number of boreholes are selected on the lignite mining face. Among the set number of boreholes, at least one is implemented in the first pressure step section, at least one is implemented in the second pressure step section, and at least one is implemented in the third pressure step section.

3. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, The set quantity is 5.

4. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, Detection drilling was conducted at each drilling point, specifically including: When drilling exploratory boreholes at each borehole point, the borehole diameter of each exploratory borehole is less than or equal to 91 mm, each exploratory borehole exposes the entire thickness of the aeolian oxide zone, and the borehole inclination of each exploratory borehole is less than 3°.

5. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, The borehole leakage in each pressure step is divided into multiple levels of slurry ingestion zones according to preset rules, specifically including: The drilling leakage of each pressure step is divided into three levels of slurry-absorbing areas according to preset rules; For each pressure step segment: If the borehole leakage is less than or equal to the inflow, then the pressure step section is a low slurry intake area. If the borehole leakage is greater than the water inflow, but less than the preset leakage, then the pressure step section is a medium slurry intake area. If the borehole leakage is greater than the water inflow, and the borehole leakage is greater than or equal to the preset leakage, then the pressure step section is a high slurry intake area.

6. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 5, characterized in that, The preset leakage rate is 150 L / min.

7. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 5, characterized in that, Different grouting techniques are used to reinforce grouting areas of different grouting levels, specifically including: For the low grout absorption area, grouting is carried out with a water pressure greater than 2MPa, and the injected grout is made of cement and water in a mass ratio of 0.5:1 to 1:

1. For the medium grouting area, during grouting, first drill holes with a diameter greater than or equal to 133 mm, then seal the holes with quick-setting cement, and then perform secondary perforation with a diameter less than or equal to 91 mm; wherein, the sealing thickness is greater than 1 meter, and the injected grout is made of cement and water in a mass ratio of 1:1 to 2:

1. For the high grout-absorbing area, a horizontal rotary jet grouting machine is used to mix and reinforce the top slab with cement; the injected grout is made of cement and water in a mass ratio of 1:1 to 2:

1.

8. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, Obtain the average thickness of the aeolian oxide zone overlying each pressure step segment, specifically including: Before mining the lignite face, three-dimensional seismic exploration was used to determine the average thickness of the aeolian oxide zone overlying each pressure step.

9. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, During the excavation of roadways in lignite mining faces, the water inflow and average natural gamma value are obtained for each pressure step, specifically including: During the excavation of roadways in lignite mining faces, the water inflow volume is recorded for each pressure step. During the tunneling of lignite mining face roadways, a 1-meter borehole is drilled for each pressure step, and natural gamma logging is performed on the 1-meter borehole to obtain the average natural gamma value for each pressure step.

10. The method for classifying and grouting the roof oxidation zone in lignite mining according to claim 1, characterized in that, Based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, water inflow, and average natural gamma value of the corresponding pressure step section at each borehole point, the functional relationship between borehole leakage and the average aeolian oxide zone thickness, water inflow, and average natural gamma value is determined, specifically including: Based on the borehole leakage at each borehole point and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value of the corresponding pressure step distance for each borehole point, a multivariate linear statistical method is used to determine the functional relationship between borehole leakage and the average thickness of the aeolian oxide zone, the inflow rate, and the average natural gamma value.

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