scholarly journals Effect of Crack Propagation on Mining-Induced Delayer Water Inrush Hazard of Hidden Fault

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yanhui Du ◽  
Weitao Liu ◽  
Xiangxi Meng ◽  
Lifu Pang ◽  
Mengke Han
Keyword(s):  
Shear Stress ◽  
Coal Seam ◽  
Water Inrush ◽  
Hydraulic Pressure ◽  
Failure Zone ◽  
Stress Release ◽  
Working Face ◽  
Floor Failure ◽  
Seam Mining ◽  
Hidden Fault

Hidden faults in deep coal seam floor threaten the exploitation of coal resources. Under the influence of mining and water confined in the floor, the cemented filler in the hidden fault will be eroded by water flow, in order to investigate the fracture characteristics and water inrush risk of hidden faults in floors above confined aquifer. Using the 27305 working face as geological background, the influence of the seepage scouring filler on the mechanism of water inrush from hidden faults was assessed by developing a stress-seepage coupling model and employing the finite difference method to simulate the seepage process of hidden faults under the combined action of high ground stress and high confined water. The evolution of seepage, shear stress, and plastic zone was also assessed. The influence of the hydraulic pressure of the aquifer and the thickness of a waterproof rock floor on the formation of the water inrush pathway was analyzed. Results indicate that (1) under the influence of mining, the hidden fault experienced the change process of stress stability, stress concentration, and stress release. The shear stress increases first and then decreases. The compressive stress decreases gradually due to stress release. (2) Water inrush disaster will not occur immediately when the working face is above the hidden fault. The delayed water inrush occurs in the mined-out area when the working face advances to 160 m, the floor failure zone is connected with the hidden fault failure zone, and the delayed water inrush channel is formed. (3) With the mining advances, the water pressure of aquifer is the same. The larger-angle fault leads to the thinner thickness of floor aquifer. The greater the influence of hidden fault on coal seam mining, the higher the danger of water inrush.

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 Discussion on Advanced Seepage Reduction Characteristics of Working Face under Seepage-Damage Coupling

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Feisheng Feng ◽  
Jiqiang Zhang ◽  
Zhen Yang ◽  
Dongdong Pang ◽  
Jing Zhang
Keyword(s):  
Stress Field ◽  
Coal Seam ◽  
Water Inrush ◽  
Seepage Flow ◽  
Mechanics Model ◽  
Working Face ◽  
Management Modes ◽  
Reduction Characteristics ◽  
Seam Mining ◽  
Two Sectors

The water burst of roof on working face has been one of the significant geotechnical engineering problems that needs to be urgently resolved. The coupling effects of seepage and damage on the amount and intensity of water inrush from the roof are critically important. In this paper, the seepage-damage coupling mathematical model of the aquifer in the working face is studied, and the seepage-damage coupling mechanics model at different stages of the aquifer is established. Under the coupling of permeability and damage, the water-soil characteristics of the aquifer in the 101163 working face of Mindong were numerically simulated by establishing the constitutive relation between vertical stress and permeability coefficient. The numerical results show that the stress concentration factor of the mining stress field gradually increases with the coal seam mining. The water-flowing fractured zone of the overburden is close to the communication of the quaternary aquifer. When the coal seam is excavated 250–300 m. Three free surfaces appear in the groundwater pressure field, and a large falling funnel is formed to establish a deep flow S-well well flow model. The research on the mining stress field and seepage field is carried out in combination with the Jakob formula. It is found that two sectors with reduced permeability of the fan surface are formed in front of the work. The variation law of the apocalyptic permeability infiltration under different mining distances, different coal seam thicknesses, different water pressures, and different roof management modes is studied systematically. The research indicates that the seepage flow under the condition of seepage infiltration of the lower aquifer should be between 50% and 100% of the traditional calculation method. The research results can help to deepen the understanding of the process of water inrush under the coupling of stress and seepage.

scholarly journals Investigation on Failure Characteristics of Coal Seam Floor in Paste Filling Working Face

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qingliang Chang ◽  
Xingjie Yao ◽  
Chongliang Yuan ◽  
Qiang Leng ◽  
Hao Wu
Keyword(s):  
Theoretical Model ◽  
Coal Seam ◽  
Water Inrush ◽  
Failure Behavior ◽  
Term Strength ◽  
Failure Characteristics ◽  
Working Face ◽  
Floor Failure ◽  
Failure Depth

Water inrush disasters are extremely prone to occur if the coal seam floor contains a confined aquifer. To find out the failure behavior of coal seam floor of paste filling working face, a beam-based theoretical model for the floor aquifuge was built, and then, the water inrush risk was evaluated based on the thickness of floor aquifuge. Next, the floor failure characteristics of the paste filling face was numerically studied and the effects of the filling interval and long-term strength of the filling body on the floor failure depth, stress and displacement distributions, and plastic zone were explored. The results showed that the theoretical model for evaluating the safety of the floor of the paste filling face based on the empty roof distance is proved to be consistent with that of the empirical formula judged based on the assumption that the paste filling working face was regarded as a cut hole with a certain width. The filling interval has a significant effect on the stress concentration of the surrounding rock, failure depth of floor, and roof-floor convergence. The smaller the filling interval is, the smaller their values are. When the filling rate is 98%, the long-term strength of the filling body is 5 MPa, and the floor failure depth is not more than 4 m. In contrast, the strength of the filling body has no obvious influence on the floor failure depth, but it has a certain impact on the roof-floor convergence. From the perspective of reducing floor failure depth, there is no need to increase the long-term strength of backfill, but it is necessary to increase the early strength of backfill so as to reduce the width of the equivalent roadway.

Study on Coal Seam Mining Face Floor Failure under Imbalance High Water Pressure

2014 ◽  
Vol 919-921 ◽  
pp. 758-761 ◽  
Author(s):  
Chun Jie Song ◽  
Cheng Fan ◽  
Li Song
Keyword(s):  
Coal Seam ◽  
Water Pressure ◽  
Water Inrush ◽  
Simulation Software ◽  
Pressurized Water ◽  
Coal Deformation ◽  
Floor Failure ◽  
Mining Face ◽  
Seam Mining ◽  
Fluidstructure Interaction

According to the seam floor aquifer inhomogeneity,in order to analysis the coal deformation and failure law in pressurized water ,this paper established mechanical model of nonuniform pressure and fluidstructure interaction models,using numerical simulation software FLAC3D analysis fluidstructure interaction water inrush regularity .Analyzing the extent of damage from the coal seam floor, the stress and displacement when working face promote different distances, this paper carried out the basic rules of mining face water inrush. This study shows that by monitoring the position of bottom water inrush occurs easily, analyzing the influence of pore pressure by the mining ,it can be accurately analysis the risk of water inrush and play an important role in guiding prevention and control of water inrush.

scholarly journals Research on Characteristic Recognition and Dangerous Prevention While Mining through Collapse Column of Pansan Minefield,China

2021 ◽  
Author(s):  
Haitao Xu ◽  
hui yang ◽  
Wenbin Sun ◽  
Lingjun Kong ◽  
Peng Zhang
Keyword(s):  
Coal Seam ◽  
Water Inrush ◽  
Coal Pillar ◽  
Simulation Software ◽  
Coal Seams ◽  
Transient Electromagnetic ◽  
Working Face ◽  
Electromagnetic Detection ◽  
Floor Failure ◽  
Collapse Column

Abstract In order to find out the characteristics of geological isomer exposed in the mining process of 12318 working face in Pansan Mine and grasp its influence law on subsequent coal seams mining, the isomer was firstly determined as the collapse column by means of 3D seismic, transient electromagnetic detection, SYT detection and other methods, and its development characteristics, conductivity and water enrichment were identified.Then FLAC3D numerical simulation software was used to analyze the characteristics of vertical stress and plastic failure zone in different coal seams during mining.Finally, by comparing the ultimate failure depth of floor and the thickness of waterproof layer in the process of each coal seam directly pushing through the collapse column, the risk of water inrush and the prevention are analyzed.The results show that the exposed geological isomer is characterized by weak water-rich collapse column.Under the influence of the mining of the previous coal seam and the activation of the collapse column, the subsequent coal seam is in the low stress area before mining, which increases the floor failure and causes the activation of the collapse column more easily during mining.Coal 5# and 4# can be directly pushed through the collapse column, and coal pillar of sufficient width should be left for coal 1# to prevent the collapse column from activating water inrush.

scholarly journals Experimental study on the control effect of ground stress on the damage of coal seam mining floor

2019 ◽  
Vol 79 ◽  
pp. 02012
Author(s):  
Gan Tian ◽  
Weiyue Hu
Keyword(s):  
Experimental Study ◽  
Coal Seam ◽  
Water Inrush ◽  
In Situ Stress ◽  
Mine Pressure ◽  
Control Effect ◽  
Distribution Rule ◽  
Floor Failure ◽  
Ground Stress ◽  
Seam Mining

In order to study on mechanism of in-situ stress control on the coal floor damage during deep coal seam mining, the internal relationship among ground stress, mine pressure and floor water inrush was analyzed base on the increasing distribution rule of ground stress with the increasing depth of stratum. It is shown that the stress on the deep coal seam has obvious control effect on the depth of the floor damage and failure through the experimental study and the statistical analysis of the measured data of the mining damage depth of the coal seam floor. And the calculation formula for the depth of the floor failure in the deep seam mining was put forward.

Research on Automatic Detection Technology for Coal Seam Floor Failure Features

2011 ◽  
Vol 467-469 ◽  
pp. 1870-1875 ◽  
Author(s):  
Guang Ming Zhao ◽  
Xiang Rui Meng
Keyword(s):  
Coal Seam ◽  
Water Inrush ◽  
Damage Zone ◽  
Detection Technology ◽  
Floor Failure ◽  
Industry Practice ◽  
Iteration Model ◽  
Forward Calculation ◽  
Mining Coal ◽  
The Impact

By the impact of coal mining, coal floor will produce distortion and damage, and make the damage zone which may result in water inrush from the floor of coal seam. CT technology with DC electricity is used to analyze two-dimensional point source current field by employing the forward calculation, inverse iteration, model correction and other methods. On the basis, inverted resistivity image of the detecting zone is obtained, which can help to determine damage law and damage depth of coal seam floor. And then the possibility of water inrush from the coal floor is analyzed. Industry practice shows that the research results are credible and can play an important guiding role in the controlling of water inrush.

scholarly journals Exploration and application of directional long boreholes in coal measure strata

2021 ◽  
Vol 261 ◽  
pp. 03003
Author(s):  
Qin Ke ◽  
Peng Dong ◽  
Duan Huijun
Keyword(s):  
Coal Seam ◽  
Water Inrush ◽  
Critical Value ◽  
Coal Measure ◽  
Bottom Plate ◽  
Drain Water ◽  
Safe Water ◽  
Working Face ◽  
Water Hazard ◽  
Insulation Thickness

two roadways in adjacent working face of Baode Mine may have the risk of water inrush at the same time, so it is necessary to construct long borehole to cover the roadway excavation. On the basis of the hydrogeological conditions of the mine, the safe water insulation thickness and water inrush coefficient of coal seam No .8 are calculated. The results show that the water inrush coefficient is 0.035-0.037 MPa/m, which is less than the critical value 0.06 MPa/m and the bottom plate has no sudden water hazard. In the construction of No .10 coal seam, the directional long borehole is used to detect whether there is a hidden structure communicating with the floor limestone and to drain water. The test shows that there is no effluent phenomenon in the borehole, which proves that there is no hidden structure in No .10 coal seam.

scholarly journals Research on Control of Rib Spalling Disaster in the Three-Soft Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Feng Cui ◽  
Tinghui Zhang ◽  
Xiaoqiang Cheng
Keyword(s):  
Coal Seam ◽  
Field Experiments ◽  
Simulation Experiment ◽  
Current Status ◽  
Soft Coal ◽  
Grouting Pressure ◽  
Working Face ◽  
Coal Wall ◽  
Soft Coal Seam ◽  
Seam Mining

Rib spalling disaster at the coal mining faces severely restricted the safe and efficient output of coal resources. In order to solve this problem, based on the analysis of the current status of rib spalling in the three-soft coal seam 1508 Working Face of Heyang Coal Mine, a mechanical model of sliding-type rib spalling was established and the main influencing factors that affect rib spalling are given. The mechanism of grouting technology to prevent and control rib spalling has been theoretically analyzed. A similarity simulation experiment is used to analyze the change law of roof stress under the condition of three-soft coal seam mining. The optimal grouting pressure is determined by a numerical simulation experiment. And, silicate-modified polymer grouting reinforcement materials (SMPGMs) are used in field experiments. After twice grouting operations in the 1508 Working Face, the coal wall was changed from the original soft and extremely easy rib spalling to a straight coal wall and the amount of rib spalling has been reduced by 57.45% and 48.43, respectively. And, the mining height has increased by 0.16 m and 0.23 m, respectively. The experimental results show that the rib spalling disaster of the three-soft coal seam has been effectively controlled.

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