scholarly journals Analysis on Subsidence Law of Bedrock and Ultrathick Loose Layer Caused by Coal Mining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Weiping Shi ◽  
Kaixin Li ◽  
Shengwen Yu ◽  
Cunzhi Zhang ◽  
Jingkai Li
Keyword(s):  
Coal Mining ◽  
Ground Subsidence ◽  
Simulation Test ◽  
Working Face ◽  
Similar Materials ◽  
Bedrock Surface ◽  
The Law ◽  
Similar Simulation Test ◽  
Theory Calculation ◽  
Loose Layer

In the process of coal mining, when the buried depth is large and the loose layer is thick, the ground subsidence tends to be abnormal, thus causing great damage to the surface ecological environment. In order to reveal the mechanism of mining ground subsidence under ultrathick loose layer, taking 1305 working face of a mine as the background, the law of mining ground subsidence under ultrathick loose layer was analyzed through field measurement. The law of bedrock subsidence is analyzed by similar simulation test, and the role of ultrathick loose layer in bedrock subsidence is quantitatively analyzed. The hydrophobic settlement model of ultrathick loose layer is established by settlement theory calculation, and the law of ground subsidence caused by hydrophobic of ultrathick loose layer is analyzed. The results show that the ground subsidence is mainly composed of bedrock subsidence and hydrophobic settlement of ultrathick loose layer. The maximum ground subsidence measured in the field is 4.201 m, the bedrock surface subsidence obtained by the simulation test of similar materials is 3.552 m, and the subsidence of ultrathick loose layer obtained by hydrophobic settlement analysis is 0.58 m. Adding the subsidence of bedrock surface and the subsidence of ultrathick loose layer, the ground subsidence is 4.132 m. It is in good agreement with the total ground subsidence measured in the field, which verifies the rationality that the ground subsidence mainly includes bedrock subsidence and hydrophobic settlement of ultrathick loose layer.

scholarly journals Study on the Law of Earth’s Surface Movement on Ultra-long Working Face

2021 ◽  
Author(s):  
Rui Peng ◽  
Fang Meiling ◽  
Ren Ruile ◽  
Zhu Jianming ◽  
Qifeng Zhao ◽  
...  
Keyword(s):  
Coal Mining ◽  
Simulation Software ◽  
Coal Bed ◽  
Length Effect ◽  
Surface Movement ◽  
Working Face ◽  
Face Length ◽  
The Face ◽  
The Law ◽  
Rock Strata

Abstract The problem of stoping on ultra-long working face is one of challenges for making coal mining safe and efficient. The strong mining effect of surrounding rock induced by long working face mining causes a number of coal or rock dynamic disasters to safe and efficient coal mining. For the purpose of in-depth study of the law of earth’s surface movement on ultra-long working face, this paper, with FLAC3D (numerical simulation software) used to build a numerical model of ultra-long working face, analyzes the law of roof-to-floor strata behaviors in coal bed during mining, and studies the weakening of roof-to-floor parameters in coal bed, bearing pressure and the law of roof caving and rock strata movement; Analyzes the face length effect resulted from the difference in face lengths. It has been recognized that the sphere of influence of bearing pressure changes from small to large and then to small, and changes in distribution of arch bottom and arch height at the plastic failure zone are further intensified over advancing of the working face, moreover, the movement of rock strata is subject to the cumulative influence of the advancing direction of the working face and the face length effect. The above-mentioned research results can serve as a theoretical basis for practical engineering.

Strata Behaviors of Fully-Mechanized Sublevel Caving Face Based on Similar Simulation Test

2013 ◽  
Vol 734-737 ◽  
pp. 638-643
Author(s):  
Hua Wen Lv
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Test Model ◽  
Simulation Test ◽  
Slow Increase ◽  
Working Face ◽  
Sublevel Caving ◽  
Pressure Peak ◽  
Similar Simulation Test ◽  
Similar Simulation

in view of research situations of the fully mechanized sublevel caving, the similar simulation test model for fully mechanized sublevel caving was presented. During the top-coal caving process, variation of top-coal subsidence and abutment pressure were measured. Consequently, the ground pressure behavior of fully mechanized sublevel caving was analyzed. The following conclusions can be reached: (1) top coal subsidence experiences the process of slow increase, trend to aggressive and sharp increase; (2) undulate change as well as decay after reaching the peak of abutment pressure is appeared with the advance of working face, strata behaviors of main roof displays smoothly; (3) on account of cushion above hydraulic support, influence of dynamic load during periodic weighting such as rock burst can be eased and abutment pressure peak moves forward, consequently, strata behaviors in the working face presents smoothly.

Research on Ground Subsidence Law Using FEM for Comprehensive Mechanized Caving Coal Mining under Railway

2012 ◽  
Vol 178-181 ◽  
pp. 1479-1483
Author(s):  
Yang Wang ◽  
Qing Yuan Li
Keyword(s):  
Coal Mining ◽  
Horizontal Displacement ◽  
Coal Industry ◽  
Deformation Monitoring ◽  
In Situ Monitoring ◽  
Ground Subsidence ◽  
Nonlinear Fem ◽  
Term Operation ◽  
Fem Method ◽  
Working Face

With the project of mining 701 Working Face of Baojianshan Coalmine of Jingyuan Coal Industry Group undermine special railway as a background, the authors predict ground subsidence law caused by routine comprehensive mechanized caving coal mining method and back filling method with elastic-plastic nonlinear FEM method. By different exploitation methods, development law of horizontal displacement, vertical displacement, shift angle of strata during mining is given. According to predication by FEM method, the maximum vertical settlement of subsidence area near railway subgrade is 7cm, which is caused by mining 701 Working Face. The in-situ monitoring results were essentially identical with the FEM predication value, this indicates that FEM predication is reliable. The rehabilitation technical measure of railway bed and deformation monitoring scheme of railway during long-term operation are advised.

The Adaptation Analysis of the Fully Mechanized Coal Mining Face of Huopu Mine’s Third Soft Coal Seam

2014 ◽  
Vol 1049-1050 ◽  
pp. 335-338 ◽  
Author(s):  
Fa Quan Liu ◽  
Xue Wen Geng ◽  
Yong Che ◽  
Xiang Cui
Keyword(s):  
Coal Seam ◽  
Coal Mining ◽  
Geological Condition ◽  
Soft Coal ◽  
Working Face ◽  
Mining Face ◽  
Soft Coal Seam ◽  
Working Resistance

To get the maximum coal in front of the working face of the 17# coal seam, we installed a longer beam which is 1.2m in length in the leading end of the original working face supports ZF3000/17/28, and know that working face supports’ setting load and working resistance are lower .We changed the original supports with shield supports ZY3800/15/33 that are adaptable in the geological condition and got the favorable affection.

La Ley Maldita: The Law for the Permanent Defense of Democracy

2019 ◽  
pp. 98-125
Author(s):  
James Lockhart
Keyword(s):  
Cold War ◽  
United Nations ◽  
Coal Mining ◽  
Communist Party ◽  
Soviet Bloc ◽  
The United Nations ◽  
The Law ◽  
The 1950S ◽  
Mining Regions

This chapter explains Chileans' contributions to the origins of the larger Cold War from 1947 into the 1950s. It incorporates the González administration's conflicts with Chilean Communists and the Soviet bloc, from events in Santiago and Chile's coal mining regions to those in Prague, Bogotá, and the United Nations, into the unfolding global conflict, thus reframing the passing of the Law for the Permanent Defense of Democracy, which banned the Chilean Communist Party.

scholarly journals A Mechanical Model of the Overlying Rock Masses in Undersea Coal Mining and a Stress-Seepage Coupling Numerical Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Jie Fang ◽  
Lei Tian ◽  
Yanyan Cai ◽  
Zhiguo Cao ◽  
Jinhao Wen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Coal Mining ◽  
Water Inrush ◽  
Mining Area ◽  
Analysis Model ◽  
Fractured Zones ◽  
Working Face ◽  
Seam Mining ◽  
Overlying Strata

The water inrush of a working face is the main hidden danger to the safe mining of underwater coal seams. It is known that the development of water-flowing fractured zones in overlying strata is the basic path which causes water inrushes in working faces. In the engineering background of the underwater mining in the Longkou Mining Area, the analysis model and judgment method of crack propagation were created on the basis of the Mohr–Coulomb criterion. Fish language was used to couple the extension model into the FLAC3d software, in order to simulate the mining process of the underwater coal seam, as well as to analyze the initiation evolutionary characteristics and seepage laws of the fractured zones in the overlying strata during the advancing processes of the working face. The results showed that, during the coal seam mining process, the mining fractured zones which had been caused by the compression-shear and tension-shear were mainly concentrated in the overlying strata of the working face. Also, the open-off cut and mining working face were the key sections of the water inrush in the rock mass. The condition of the water disaster was the formation of a water inrush channel. The possible water inrush channels in underwater coal mining are mainly composed of water-flowing fractured zones which are formed during the excavation processes. The numerical simulation results were validated through the practical engineering of field observations on the height of water-flowing fractured zone, which displayed a favorable adaptability.

scholarly journals Extraction of Irregularly Shaped Coal Mining Area Induced Ground Subsidence Prediction Based on Probability Integral Method

2020 ◽  
Vol 10 (18) ◽  
pp. 6623
Author(s):  
Xianfeng Tan ◽  
Bingzhong Song ◽  
Huaizhi Bo ◽  
Yunwei Li ◽  
Meng Wang ◽  
...  
Keyword(s):  
Coal Mining ◽  
Integral Method ◽  
Mesh Size ◽  
Mining Area ◽  
Ground Subsidence ◽  
Data Set ◽  
Coal Mining Area ◽  
Subsidence Prediction ◽  
Probability Integral Method ◽  
Probability Integral

Underground coal mining-induced ground subsidence (or major ground vertical settlement) is a major concern to the mining industry, government and people affected. Based on the probability integral method, this paper presents a new ground subsidence prediction method for predicting irregularly shaped coal mining area extraction-induced ground subsidence. Firstly, the Delaunay triangulation method is used to divide the irregularly shaped mining area into a series of triangular extraction elements. Then, the extraction elements within the calculation area are selected. Finally, the Monte Carlo method is used to calculate extraction element-induced ground subsidence. The proposed method was tested by two experimental data sets: the simulation data set and direct leveling-based subsidence observations. The simulation results show that the prediction error of the proposed method is proportional to mesh size and inversely proportional to the amount of generated random points within the auxiliary domain. In addition, when the mesh size is smaller than 0.5 times the minimum deviation of the inflection point of the mining area, and the amount of random points within an auxiliary domain is greater than 800 times the area of the extraction element, the difference between the proposed method-based subsidence predictions and the traditional probability integral method-based subsidence predictions is marginal. The measurement results show that the root-mean-square error of the proposed method-based subsidence predictions is smaller than 3 cm, the average of absolute deviations of the proposed method-based subsidence predictions is 2.49 cm, and the maximum absolute deviation is 4.05 cm, which is equal to 0.75% of the maximum direct leveling-based subsidence observation.

Chapter 11 Coal mining subsidence in the UK

2020 ◽  
Vol 29 (1) ◽  
pp. 291-309 ◽  
Author(s):  
Laurance Donnelly
Keyword(s):  
Coal Mining ◽  
Longwall Mining ◽  
Ground Surface ◽  
Mining Subsidence ◽  
Ground Movement ◽  
Working Face ◽  
Mine Roadway ◽  
Coal Mining Subsidence ◽  
The Uk

AbstractOne of the geohazards associated with coal mining is subsidence. Coal was originally extracted where it outcropped, then mining became progressively deeper via shallow workings including bell pits, which later developed into room-and-pillar workings. By the middle of the 1900s, coal was mined in larger open pits and underground by longwall mining methods. The mining of coal can often result in the subsidence of the ground surface. Generally, there are two main types of subsidence associated with coal mining. The first is the generation of crown holes caused by the collapse of mine entries and mine roadway intersections and the consolidation of shallow voids. The second is where longwall mining encourages the roof to fail to relieve the strains on the working face and this generates a subsidence trough. The ground movement migrates upwards and outwards from the seam being mined and ultimately causes the subsidence and deformation of the ground surface. Methods are available to predict mining subsidence so that existing or proposed structures and land developments may be safeguarded. Ground investigative methods and geotechnical engineering options are also available for sites that have been or may be adversely affected by coal mining subsidence.

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