scholarly journals Method to Calculate Mining-Induced Fracture Based on the Movement and Deformation of Overburden Strata

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Guo-sheng Xu ◽  
Hui-gui Li ◽  
De-hai Li ◽  
Yan-bin Zhang
Keyword(s):  
Coal Seam ◽  
Burial Depth ◽  
Empirical Methods ◽  
Fractured Zone ◽  
Strata Movement ◽  
Probability Integral Method ◽  
Movement And Deformation ◽  
Probability Integral ◽  
Seam Mining ◽  
Overburden Strata

Mining-induced fracture of overburden strata is intimately related to underground water disasters in coal mining. In this work, we develop an analytical model that uses the probability integral method to calculate the subsidence of the subsurface and the overburden strata. In the developed model, according to the failure characteristics of the mining-induced strata, the horizontal deformation of the strata is expressed by the tensile rate of the elastic plate’s neutral plane to reflect the degree of fracture initiation and expansion. The distribution of the water-flowing fractured zone (WFZ) in the overburden strata is calculated by substituting the probability integral function of overburden strata movement into the equation of layer tensile rate. The panel 31071 in Peigou coal mine is taken as a case study, and the height of the water-flowing fractured zone (HWFZ) is determined by the proposed method. Conventional empirical methods and the proposed method are used to predict HWFZ in panels with mining schemes, and the results show that the model is particularly advantageous for inclined coal seam mining where the inclined mining size gradually increases and the coal seam burial depth gradually decreases. In such kind of situations, the overburden strata movement and deformation intensify and the mining fracture develops further with the progress of mining, a feature considered poorly by conventional empirical methods but well represented in the proposed method.

The Influence of Different Fault Throws to the Height of Water-Flowing Fractured Zone

2014 ◽  
Vol 1073-1076 ◽  
pp. 2088-2091 ◽  
Author(s):  
Zhen Li Fan
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Simulation Analysis ◽  
Fractured Zone ◽  
Seam Mining ◽  
Fault Displacement

For fault displacement on the influence of the water flowing fractured zone, using the methods of numerical simulation analysis, the research simulated the coal seam mining of mid-hard superincumbent stratum. Through the simulations of the influence to water flowing fractured zone of different fault displacements, the study concluded that: with the increase of fault throw, the increase of the height of water flowing fractured zone is not big, in general, the increase value is bigger 2.44 ~ 7.32% than no fault existence in the coal seam mining.

scholarly journals Height of the Fractured Zone in Coal Mining under Extra-Thick Coal Seam Geological Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Dequan Sun ◽  
Xiaoyan Li ◽  
Zhijie Zhu ◽  
Yang Li ◽  
Fang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Process Analysis ◽  
Failure Process ◽  
Analysis Method ◽  
Coal Seams ◽  
Fractured Zone ◽  
Seam Mining ◽  
Borehole Televiewer ◽  
Overlying Strata

The height of the fractured zone caused by coal mining is extremely significant for safely mining under water, water conservation, and gas treatment. At present, the common prediction methods of overburden fractured zone height are only applicable to thin and medium-thick coal seams, not suitable for thick and extra-thick coal seams. In order to determine the overburden fractured zone distribution characteristics of extra-thick seam mining, failure process analysis method of overlying strata was proposed based on key strata theory. This method was applied to 15 m coal seam of Tongxin coal mine, and fractured zone height was determined to be 174 m for 8100 panel. EH4 electromagnetic image system and borehole televiewer survey were also conducted to verify the theory results. The distribution of the electrical conductivity showed that the failure height was 150–170 m. Observation through the borehole televiewer showed that the fractured zone height was 171 m. The results of the two field test methods showed that the fractured zone height was 150–171 m, and it was consistent with the theory calculation results. Therefore, this failure process analysis method of overlying strata can be safely used for other coal mines.

Study on Mountainous Shallow-Buried Coal Seam Mining Working Face Strata Behaviors and Overlying Strata Movement Features

2011 ◽  
Vol 121-126 ◽  
pp. 2911-2916
Author(s):  
Guo Lei Liu ◽  
Ke Gong Fan ◽  
Tong Qiang Xiao
Keyword(s):  
Coal Seam ◽  
Horizontal Displacement ◽  
Simulation Software ◽  
High Rate ◽  
Strata Movement ◽  
Working Face ◽  
Element Simulation ◽  
Valve Opening ◽  
Seam Mining ◽  
Overlying Strata

Through testing the mountainous shallow-buried coal seam mining working face strata behaviors in Faer mine field, it got the strata behaviors: it was of large roof pressure, high rate of safety valve opening in hydraulic support, and even some supports crushed or took separation between top beams and tail beams. Traditional method of calculating supports’ resistance can not be applied to mountainous shallow-buried coal seam mining working face. With the discrete element simulation software UDEC it analyzed the strata movement feature, and got that the overlying strata took collapse and horizontal displacement after mountainous shallow-buried coal seam mined, and the strata movement feature was different between reverse slope mining and positive slope mining.

scholarly journals Comprehensive Study of Strata Movement Behavior in Mining a Longwall Top Coal Caving Panel of a Composite Coal Seam with Partings

2020 ◽  
Vol 10 (15) ◽  
pp. 5311
Author(s):  
Hongtao Liu ◽  
Linfeng Guo ◽  
Guangming Cao ◽  
Xidong Zhao ◽  
Pengfei Wang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Coal Seam ◽  
Physical Modeling ◽  
Image Correlation ◽  
Thick Coal Seam ◽  
Fractured Zone ◽  
Strata Movement ◽  
Longwall Panel ◽  
Longwall Top Coal Caving ◽  
Comprehensive Study

Strata movement due to extraction of a longwall panel is of great significance both in terms of environment and ground control. Thick coal seam extraction is expected to severely disturb the overburden, which is critical. Most studies use only one or two methods to investigate strata movement that are not thorough or comprehensive. This paper presents a detailed comprehensive case study of strata movement in extraction of a longwall top coal caving panel of a composite coal seam with partings in the Baozigou Coal Mine. The caved zone and fractured zone development were captured through physical modeling by incorporating the digital image correlation method (DICM), universal distinct element code (UDEC) numerical modeling, and field observation with the method of high-pressure water injection. The result of the physical modeling is 90 m. The numerical modeling result is 84 m. Field data show that the fractured zone is 81 m. Therefore, it demonstrates that the results from different methods are consistent, which indicates that the results from this comprehensive study are reliable and scientific.

scholarly journals Formation Mechanism and the Height of the Water-Conducting Fractured Zone Induced by Middle Deep Coal Seam Mining in a Sandy Region: A Case Study from the Xiaobaodang Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaoshen Xie ◽  
Enke Hou ◽  
Shuangming Wang ◽  
Xueyang Sun ◽  
Pengfei Hou ◽  
...  
Keyword(s):  
Coal Seam ◽  
Formation Mechanism ◽  
Coal Mine ◽  
Field Measurements ◽  
Development Stage ◽  
Mine Safety ◽  
Maximum Height ◽  
Fractured Zone ◽  
Seam Mining

The height of the water-conducting fractured zone (WCFZ) is a basic parameter related to water protection in coal mines and is also crucial for aquifer protection and mine safety. In order to accurately detect the height and shape and reveal the formation mechanism of the WCFZ, which is caused by middle-deep coal seam mining in a sandy region, the 112201 coalface at the 1# coal mine of Xiaobaodang was taken as a case study. Filed measurements including fluid leakage, borehole TV, and similar simulation were adopted to analyze the regularity of the WCFZ in this area. The detection results of field measurements showed that the maximum height of the WCFZ was 177.07 m in a borehole near the open-off cut, and the ratio of the height of the water-conducting fractured zone divided by the mining thickness was 30.53. The WCFZ acquired an inward-convergent saddle shape, which was inclined to the goaf. The saddle bridge was located at the boundary of the goaf, and the saddle ridge was located at the center of the goaf. Also, through analyzing the results of similar simulations, we found that, in the process of mining, separation cracks and the beam structure were the main forms of overburden disturbance transmitting upward and ahead of mining, respectively. The main cause of the increase in height of the WCFZ was the connection of the separation cracks and vertical cracks caused by fractures of beam structures. The development of the WCFZ was divided into five stages: incubation stage, development stage, rapidly increasing stage, slowly increasing stage, and stable stage. Moreover, the duration of each stage was related to the lithology and mining technology. This research can provide significant theoretical insights for the prediction of the WCFZ, enabling the prevention of water hazards on mine roofs and assisting with water resources protection.

Prediction of Groundwater Inrush into Coal Mines from Aquifers Overlying the First Coal Seam in Eastern Ningxia Coalfield, China

2014 ◽  
Vol 1073-1076 ◽  
pp. 1634-1640
Author(s):  
En Ke Hou ◽  
Jie Feng ◽  
Fan Yang ◽  
Yan Jing Zhang
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Water Flow ◽  
Mining Area ◽  
Observation Data ◽  
Groundwater Inrush ◽  
Fractured Zone ◽  
Mining Areas ◽  
Seam Mining ◽  
Runoff Discharge

In the region where Eastern Ningxia coalfield locates, with the fragile eco-environment and the relative short water resources, it is significant to make clear the influence of coal mining on the groundwater in this region. According to analyses of water-filling factors for the 21 mine fields in the 7 mining areas and 1 independent mine field of Eastern Ningxia coalfield. Firstly, this paper selects the formula in the regulations on the preserving of the coal pillar and coal mining under buildings, water, rail and main shafts (regulations for short) and the Standard on the Exploration of Hydrogeology and Engineering-Geology in the Mining Area (GB12719-91) (standard for short) to calculate the height of water-flow fractured zone in the first coal seam mining, and compares the analysis results of the above formula to the observation data of 3 working faces, and determine the estimated method on the height of water-flow fractured zone, and then use “three maps-two predictions” method to complete the criterion of aquifer water-enrichment and inbreak in safety of the first coal seam. Finally, analyzing the influence of coal mining on the direction of groundwater and recharge-runoff-discharge conditions, the final comprehensive division program on the risk of the groundwater inrush is presented. The research results served as the general guidelines for the mine operations.

scholarly journals Influencing Factors’ Analysis of Disturbance Degree of Key Stratum Based on the Response Surface Method

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yang Li ◽  
Nan Wang ◽  
Yuqi Ren ◽  
Xiangji Ou ◽  
Yikun Liu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Response Surface ◽  
Response Surface Method ◽  
Interlayer Spacing ◽  
Burial Depth ◽  
Key Stratum ◽  
Surface Method ◽  
Calculation Results ◽  
Seam Mining ◽  
Mining Height

The key stratum controls the activities of the overlying strata or the whole strata up to the surface, which is one of the important research objects in the coal seam mining. Based on the analysis of several geological factors affecting on the key stratum, the definition of “disturbance degree of key stratum” (KSDD) was proposed. And, the KSDD is quantified by the value among 0 to 10. Through the response surface method, experiments of three factors (mining height, buried depth, and interlayer spacing) with three different lithology types (soft, medium, and hard) between key stratum and coal seam are signed. And, the KSDD of each scheme is calculated by the developed calculation system. The response surface regression models of KSDD with three lithology types are established. And, the single influence and interactive influences of the three factors on the KSDD with different lithology types are studied. The results show that the following. (1) Mining height and buried depth are positively correlated with the value of KSDD, and the interlayer spacing is negatively correlated with KSDD. However, when the value of interlayer spacing exceeds 30 m, the change of the KSDD tends to be gentle. (2) The value of KSDD is not only affected by a single factor but also affected by the interaction of various factors. With the increase of burial depth, the decrease of interlayer spacing and the impact of mining height on key stratum are more severe. (3) The influence order of each factor on KSDD is as follows: the interlayer spacing > mining height > buried depth. (4) Although the three factors interact with each other, the three factors decrease with the increase of the lithology proportional coefficient. According to the above research results, based on the calculation results of KSDD on five mines, the variation laws of KSDD with actual situation are analysed. And, the calculation results further verify the above experimental rules, which provide a certain reference and theoretical basis for the design of backfilling parameters and the management of the roof.

scholarly journals Study on Deformation and Failure Characteristics of Weak Cemented Roof in Shallow and Extra Thick Coal Seam Mining

2021 ◽  
Author(s):  
Chang Liu ◽  
Pingsong Zhang ◽  
Duoxi Yao ◽  
Yuancaho Ou ◽  
Yutong Tian
Keyword(s):  
Coal Seam ◽  
Apparent Resistivity ◽  
Maximum Height ◽  
Geoelectric Field ◽  
Electrical Method ◽  
Deformation And Failure ◽  
Fractured Zone ◽  
Working Face ◽  
Seam Mining ◽  
Loose Layer

Abstract Detecting the development height of water flowing fractured zone in the roof of coal seam is of great significance for the roof safety of working face with developed sandstone and thick loose layer. This paper analyzes the influence of the induced polarization effect of electrode on the traditional single-mode parallel electrical method. In order to avoid this interference, the dual-mode parallel electrical method is applied to monitor the roof deformation and failure of a coal mine in Ordos Basin. The monitoring results show that: under the influence of mining, the change of geoelectric field of coal seam roof is dynamic, the apparent resistivity of initial mining fracture is high, the apparent resistivity of surrounding rock water filling mining fracture is low, and the apparent resistivity of fracture water flowing to goaf is high again. According to the characteristics of geoelectric field, the maximum height of water flowing fracture zone is 122 M; The average mining coal thickness of the working face is 11 m, and the fracture / mining thickness ratio is 11.1. The results of plastic zone show that the maximum height of water flowing fractured zone above the working face is 122 m, which is consistent with the test results. The vertical stress response characteristics of roof monitoring points are zonal. Under the influence of mining, the loose layer near the surface above the working face is cracked. The edge type ground fissures exist for a long time, and there are a series of geological problems such as soil erosion, ground subsidence.

scholarly journals Quantitative Evaluation for the Threat Degree of a Thermal Reservoir to Deep Coal Mining

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Yun Chen ◽  
Xinyi Wang ◽  
Yanqi Zhao ◽  
Haolin Shi ◽  
Xiaoman Liu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Fuzzy Variable ◽  
Thermal Storage ◽  
Burial Depth ◽  
Eastern Region ◽  
Analytic Hierarchy ◽  
Water Abundance ◽  
Total Study Area ◽  
Seam Mining

Taking the Suiqi coalfield located in North China as the object, where the coal seam burial depth is more than 1100 m, the water abundance of the roof pore thermal storage aquifer is better than average, the ground temperature is abnormally high, and hydrogeological data are relatively lacking, this paper selects and determines eight index factors that influence the mining of the coalfield. Based on the analytic hierarchy process (AHP), the index factor weight is defined, and then, the threat degree of the roof thermal storage aquifer to the coal mining is quantitatively evaluated and divided by using the fuzzy variable set theory. The evaluation results show that the threat degree of the roof in the eastern region is generally greater than that in the western region and that the closer it is to the coal seam outcrop line, the higher the threat degree is; near the boreholes, in the areas Qs1,Qs5, Qs8, Sx1, Tk5, Zc4, and Zc7, which are close to the hidden outcrop line of the coal seam, the classification characteristic value of the threat degree is greater than 3.5, which is in the high-threat zone for disasters caused by roof thermal storage aquifers during coal seam mining. The area above the medium-threat zone accounts for 71.82% of the total study area, indicating that deep coal mining is affected by multiple factors and that roof water and heat disasters are more likely to occur.

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