Coal mine caving zone actual measurement method based on dichotomy

Abstract

The invention provides a coal mine caving zone actual measurement method based on a dichotomy, which comprises the following steps: S1, predicting a caving zone height interval, and setting an initial range; s2, selecting a drilling position in the height interval by adopting a dichotomy method, collecting a rock core sample and analyzing the crushing degree; s3, updating the upper limit or the lower limit of the caving zone height interval based on the rock core crushing degree; s4, in combination with an elastic mechanical model and micro-seismic data, performing fracture judgment on a key layer exposed by drilling, and dynamically adjusting an upper limit or a lower limit of a caving zone height interval; and S5, repeating the steps S2-S3 until the interval precision meets the requirement, and determining the final caving zone height. According to the method, the caving zone development height is efficiently and accurately determined in a mode of combining staged drilling observation and key layer mechanical analysis, and a scientific basis is provided for coal mining process optimization and safe production.

Description

Technical Field

[0001] The present invention mainly relates to the technical field related to coal mining safety, specifically a coal mine collapse zone measurement method based on dichotomy, which aims to efficiently and accurately determine the development height of the collapse zone by combining phased drilling observation with key layer mechanical analysis, so as to provide a scientific basis for coal mining process optimization and safe production. Background Art

[0002] Traditional methods for determining the height of coal mine collapse zones mainly rely on empirical formulas or single testing methods, such as theoretical calculations based on mining height and rock expansion coefficient, or direct observation through geological drilling. However, such methods have the following defects:

[0003] Large error range: The empirical formula does not fully consider the influence of the mechanical properties of the key layers and the overburden structure, resulting in a large deviation between the predicted results and the actual results;

[0004] High cost and low efficiency: The traditional drilling method requires dense deployment of points and has poor adaptability to complex geological conditions. Insufficient data integration: The existing technology does not effectively combine dynamic data such as microseismic monitoring and key layer fracture determination, making it difficult to achieve multi-source information fusion analysis. Summary of the invention

[0005] In order to solve the shortcomings of the current technology, the present invention combines the existing technology and, starting from practical application, provides a coal mine collapse zone measurement method based on dichotomy. By reducing the drilling range in stages and combining dynamic judgment of key layers, the measurement accuracy and efficiency are significantly improved.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention combines the dichotomy method with the mechanical analysis of the key layer, and gradually approaches the upper boundary of the collapse zone through iterative drilling observation and rock formation state determination. The specific method is as follows:

[0008] A method for measuring coal mine collapse zone based on dichotomy method comprises the following steps:

[0009] S1. Predict the height interval of the collapse zone and set the initial range;

[0010] S2, using the dichotomy method to select the drilling location within the height interval, collect core samples and analyze the degree of fragmentation;

[0011] S3. Based on the degree of core fragmentation, update the upper or lower limit of the collapse zone height interval;

[0012] S4. Combine elastic mechanics model with microseismic data to determine the fracture of key layers revealed by drilling, and dynamically adjust the upper or lower limit of the collapse zone height range;

[0013] S5. Repeat steps S2-S3 until the interval accuracy meets the requirements and determine the final collapse zone height.

[0014] Furthermore, in step S1, geological drilling data and mining parameters of the target mining area are collected to preliminarily estimate the height range of the collapse zone, including mining parameters such as coal seam thickness, rock expansion coefficient, etc.

[0015] Further, in step S2, drilling is performed at the midpoint of the interval each time, and the midpoint of the interval is expressed as follows:

[0016] h3=(h1+h2) / 2

[0017] Among them, h3 is the midpoint of the interval, h1 is the lower limit of the interval, and h2 is the upper limit of the interval.

[0018] Furthermore, in step S3, core samples are collected and the degree of crushing is analyzed. If the rock layer at h3 is broken and loose and is determined to be a collapse zone feature, the upper limit of the interval h2=h3 is adjusted. If the rock layer is intact and belongs to a fracture zone or a curved zone, the lower limit of the interval h1=h3 is adjusted.

[0019] Further, in step S4, the critical overhang length a of the key layer exposed by drilling is calculated using an elastic thin plate mechanics model, and the formula is:

[0020]

[0021] In the formula, h is the thickness of the key layer, R is the tensile strength, q is the bearing load, and λ is the influence coefficient of the working face advancement speed;

[0022] Combined with microseismic monitoring data, verify whether the key layer is broken: if the overhang length exceeds the critical value a, it is judged as a fracture and included in the collapse zone.

[0023] Further, in step S5, when the difference between the upper limit and the lower limit of the collapse zone height interval is less than the set threshold, it is determined that the interval requirement is met.

[0024] Beneficial effects of the present invention:

[0025] 1. Improved accuracy: Integrate drilling observation, key layer mechanical analysis and microseismic monitoring data to improve the reliability of judgment. Through iterative judgment, the error is controlled within 1m, which is better than the traditional method (error range 5-10m).

[0026] 2. Cost reduction: By drilling holes in stages, ineffective points can be reduced, construction costs can be reduced, the number of holes drilled can be reduced by more than 50%, and the construction period can be shortened by 30%.

[0027] 3. Adaptive adjustment mechanism: Dynamically correct the drilling position and judgment threshold according to real-time data to adapt to complex geological conditions.

[0028] 4. Enhanced safety: Dynamic monitoring and key layer analysis effectively prevent roof accidents and ensure the safety of underground operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attached Figure 1 It is a schematic diagram of the process structure of the present invention.

[0030] Attached Figure 2 It is a schematic diagram of the key layer determination process in the present invention.

[0031] Attached Figure 3 Schematic diagram of the overburden layer structure. DETAILED DESCRIPTION

[0032] The present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the application.

[0033] The embodiment of the present invention provides a method for measuring coal mine collapse zone based on dichotomy. The method mainly includes the following steps.

[0034] Step 1: Initial Range Prediction

[0035] The geological drilling data and mining parameters (such as coal seam thickness, rock expansion coefficient, etc.) of the target mining area were collected, and the preliminarily estimated height range of the collapse zone was h1 and h2, where h1 is the lower limit and h2 is the upper limit.

[0036] Step 2: Dichotomy Drilling Layout

[0037] Drill a hole at the midpoint of the interval h3 = (h1 + h2) / 2, collect core samples and analyze the degree of fragmentation.

[0038] Step 3: Interval Update

[0039] based on Figure 3 From the shown overburden stratification structure, if the rock layer at h3 is broken and loose (characteristic of a collapse zone), the upper limit h2 is adjusted to h3; if the rock layer is complete (a fracture zone or a curved zone), the lower limit h1 is adjusted to h3.

[0040] Step 4: Dynamic determination of critical layer fracture

[0041] For the key layer exposed by drilling, the elastic thin plate mechanics model is used to calculate its overhang critical length a, and the formula is:

[0042]

[0043] Where h is the thickness of the key layer, R is the tensile strength, q is the bearing load, and λ is the influence coefficient of the working face advancement speed.

[0044] Combined with microseismic monitoring data, verify whether the key layer is broken: if the monitored overhang length exceeds the critical value a, it is judged as a fracture and included in the collapse zone.

[0045] Step 5: Iterate convergence and output results, repeat steps 2 to 4 until the interval accuracy meets the requirements (such as |h2-h1|≤1m), and the final collapse zone height is h2.

[0046] Finally, a height distribution map of the collapse zone is generated, and the safe mining areas are marked.

[0047] The following is a specific example to further illustrate the actual measurement method of the present application.

[0048] Take the mining of thick coal seams in a coal mine as an example:

[0049] 1. Initial prediction: Based on the mining height of 3.5m and the expansion coefficient of 1.3, the initial estimate of the collapse zone height range h1~h2 is 4.5~16m;

[0050] 2. First drilling: Drill at h3 = 10.25m, find that the rock layer is broken, adjust the upper limit h2 = 10.25m;

[0051] 3. Secondary drilling: Drill at h3 = 7.375m, the rock layer is intact, and the lower limit h1 is adjusted to 7.375m;

[0052] 4. Determination of key layer: Combined with microseismic data, the key layer fracture at h = 8.2m was verified, and the actual height of the collapse zone was determined to be 8.2m ± 0.5m;

[0053] 5. Application of results: Optimize the selection of hydraulic supports to ensure that the support strength of the top plate of the working face matches the characteristics of the collapse zone, and apply the collapse zone measurement in the "two-zone" or "three-zone" measurement report.

[0054] This embodiment combines phased drilling observation with key layer mechanical analysis to efficiently and accurately determine the development height of the collapse zone, providing a scientific basis for coal mining process optimization and safe production.

Claims

1. A method for measuring coal mine collapse zone based on dichotomy, characterized in that: The steps include: S1. Predict the height interval of the collapse zone and set the initial range; S2, using the dichotomy method to select the drilling location within the height interval, collect core samples and analyze the degree of fragmentation; S3. Based on the degree of core fragmentation, update the upper or lower limit of the collapse zone height interval; S4. Combine elastic mechanics model with microseismic data to determine the fracture of key layers revealed by drilling, and dynamically adjust the upper or lower limit of the collapse zone height range; S5. Repeat steps S2-S3 until the interval accuracy meets the requirements and determine the final collapse zone height.

2. The coal mine collapse zone measurement method based on dichotomy according to claim 1 is characterized in that: In step S1, geological drilling data and mining parameters of the target mining area are collected to preliminarily estimate the height range of the collapse zone.

3. The coal mine collapse zone measurement method based on dichotomy according to claim 1 is characterized in that: In step S2, drilling is performed at the midpoint of the interval each time, and the midpoint of the interval is expressed as follows: h3=(h1+h2) / 2 Among them, h3 is the midpoint of the interval, h1 is the lower limit of the interval, and h2 is the upper limit of the interval.

4. The coal mine collapse zone measurement method based on dichotomy according to claim 1 is characterized in that: In step S3, core samples are collected and the degree of crushing is analyzed. If the rock layer at h3 is broken and loose and is determined to be a collapse zone, the upper limit of the interval h2=h3 is adjusted. If the rock layer is intact and belongs to a fracture zone or a bending zone, the lower limit of the interval h1=h3 is adjusted.

5. The coal mine collapse zone measurement method based on dichotomy according to claim 1 is characterized in that: In step S4, the critical overhang length a of the key layer exposed by drilling is calculated using an elastic thin plate mechanics model, and the formula is: In the formula, h is the thickness of the key layer, R is the tensile strength, q is the bearing load, and λ is the influence coefficient of the working face advancement speed; Combined with microseismic monitoring data, verify whether the key layer is broken: if the overhang length exceeds the critical value a, it is judged as a fracture and included in the collapse zone.

6. The coal mine collapse zone measurement method based on dichotomy according to claim 1 is characterized in that: In step S5, when the difference between the upper limit and the lower limit of the collapse zone height interval is less than the set threshold, it is determined that the interval requirement is met.

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