scholarly journals The Assessment and Evolution of Water-Conducting Rules under the Influence of Mining-Induced Stress

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Feisheng Feng ◽  
Suping Peng ◽  
Wenfeng Du ◽  
Yunlan He ◽  
Shan Chong
Keyword(s):  
Water Inrush ◽  
Loading Path ◽  
External Loading ◽  
Shear Stresses ◽  
Confined Water ◽  
Rock Stratum ◽  
Permeability Characteristics ◽  
Working Face ◽  
Compression And Expansion ◽  
Set Up

It is important to study the mechanism of water inrush on a seam floor by exploring the rules of permeability variations during rock deformation on the seam floor and in the course of fracturing as well as their responses to characteristics of the macromechanical environment such as mine ground pressure, engineering geology, and fluid mechanics. First, through the analysis of bearing pressure changes in the process of exploiting the working face, a mechanical model for the seam floor above the confined water is established. Based on the graphic data-processing software Mathcad, the computational process and methods for assessing the vertical, horizontal, and shear stresses are provided together with the corresponding variation curve of the rock stratum 5 m below the floor, covering the entire process from a position 120 m away from the working face to a position 280 m behind it. Second, the permeability coefficients of different lithologies are measured in the laboratory. For rock stratum 5 m below the floor, the corresponding external loading path is set up according to its actual stress. The actual dynamic stress environment of the rocks is simulated, and their permeability characteristics are studied. In addition, based on data fitting, the permeability coefficient variations in the mining process are determined for a rock stratum 5 m below the floor. Finally, in accordance with the permeability variation law of the floor of the working face, the seam floor is divided into six areas, namely, the compression and expansion zone, the bed separation and expansion zone, the pressure relief zone, the compression zone, the stable recovery zone, and the stability zone. Thus, the water-resisting performance of the floor can be expressed more objectively.

On-Site Monitoring of Floor Failure Depth with High Confined Water and Mining Risk Assessment

2013 ◽  
Vol 716 ◽  
pp. 693-698
Author(s):  
Shu Xin Liu ◽  
Chang Wu Liu ◽  
Ya Ming Kang ◽  
Duo Yang
Keyword(s):  
Water Inrush ◽  
Ground Subsidence ◽  
Confined Water ◽  
Mining Technology ◽  
Working Face ◽  
Site Monitoring ◽  
Floor Failure ◽  
Depth Analysis ◽  
Face Length ◽  
Failure Depth

About under-group coal seams mining with the threat of high-pressure ordovician water, conventional mining technology by draining depressurization usually causes environmental issues such as soil erosion and ground subsidence etc.,By using grouting reinforcement technology, this paper changes floor direct charge layer into relatively separatedwater layer in the coal seam and achieves the goals of sealing the water inrush channel, moreover, on the basis of coal floor failure depth analysis and monitoring, the paper evaluates risk of water-inrush from seam floor when face length increases, On this basis, puts forward a reasonable working face length and mining technology, and has abtained good economic and social benefits in practice.

scholarly journals Control of Water Inrush from Longwall Floor Aquifers Using a Division Paste Backfilling Method

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Qingliang Chang ◽  
Xingjie Yao ◽  
Shiguo Ge ◽  
Ying Xu ◽  
Yuantian Sun
Keyword(s):  
Water Inrush ◽  
Water Injection ◽  
Field Measurements ◽  
Mining Method ◽  
Confined Water ◽  
Working Face ◽  
Floor Failure ◽  
Site Water ◽  
Failure Depth ◽  
Theoretical Analyses

Aiming at the problem of the safety mining problems of longwall paste filling working face under buildings on high confined water in the Daizhuang Coal Mine, the paste filling mining method was used. A series of theoretical analyses, numerical simulations, and field measurements were applied. The results showed that when the filling interval of the working face increases from 1.2 m to 3.6 m, no significant change is found in the depth of the perforated plastic zone of the floor strata. According to the types of water-conducting cracks in the floor strata of the working face 11607, the floor strata are divided into the floor intact area, the structure developed area, and the floor weak area. Based on that, the measures for preventing and controlling the floor failure in the paste filling working face are proposed. Furthermore, the failure depth of the floor of the test working face was detected by the on-site water injection method, and the results showed that the maximum failure depth of the floor of the test working face was about 3 m.

scholarly journals Experimental Study on Lateral Permeability Evolution of Sandstone under Seepage-Damage Coupling

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Dongdong Pang ◽  
Feisheng Feng ◽  
Guanghui Jiang ◽  
Dongjing Xu ◽  
Xiaohan Wang
Keyword(s):  
Coal Mining ◽  
Coupling Effect ◽  
Water Inrush ◽  
Stress Change ◽  
Loading Path ◽  
Small Range ◽  
Working Face ◽  
Pore Evolution ◽  
Mining Front ◽  
Permeability Experiment

To analyze the internal pore evolution law of aquifer rock in a coal mining front under the coupling effect of stress and seepage and the influence on the water inrush performance of the working face, research on the working face was conducted to improve the RTR-1000 high-temperature and high-pressure rock triaxial mechanical testing system, using hollow cylindrical and complete sandstone samples and by considering the stress change law in the actual mining process as the reference loading path. At the initial stage of loading, the permeability of sandstone demonstrates a rapid downward trend within a small range of stress change, with a decline rate of 50%. At lower permeabilities, the fluctuation is small; the plastic and failure stages are transient, and the relationship curve between the horizontal permeability and the axial confining pressure of sandstone is divided into compaction, multiple fluctuations, surrender, and failure. In several stages, the sandstone lateral permeability experiment under the coupling effect of stress and seepage demonstrates that the permeability of the aquifer in the coal mining front is significantly reduced after the original rock stress is disturbed by mining, suggesting that the water inrush calculation of the traditional water-flowing fractured zone and caving zone aquifer rock permeability experiment is inaccurate. Further research can deepen the stress and seepage coupling evolution process under the action of working face water inrush.

The Analysis of the Coal Floor Water Inrush Effected by the Fault

2014 ◽  
Vol 535 ◽  
pp. 626-630
Author(s):  
Yun Xun Zhang ◽  
She Rong Hu ◽  
Ji Chao Peng ◽  
Xue Qing Zhang
Keyword(s):  
Water Pressure ◽  
Water Inrush ◽  
Bottom Layer ◽  
Geological Structure ◽  
Mine Pressure ◽  
Confined Water ◽  
Working Face ◽  
The Face ◽  
Pressure Water ◽  
Floor Water Inrush

Water inrush from coal floor is some kind of complex geology and mining phenomenon. It is the confined water underlying the coal seams breaking the barrier of the bottom layer, and the water runs into the face of mine in emergencies or delayed, causing natural disasters like discharge increases or flooding. According to the previous studies on water inrush, the water inrush is a joint result of geological structure, water pressure, mine pressure, water-resisting floor and mining of working face. The thesis focuses on the influence of geological fault on the water-inrush from coal floor and analyses the controlling effects of fault property and non-water conducted fault activation of water in order to provide a reference or significance for the analysis of water-inrushs genesis mechanism.

scholarly journals Stability Analysis and Reasonable Layout of Floor Drainage Roadway above Confined Water and under Mining Influence

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaofei Guo ◽  
Yongen Li ◽  
Guangdong Zhou ◽  
Zengji He ◽  
Haoran Yu ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Water Inrush ◽  
Coal Pillar ◽  
Middle Part ◽  
Surrounding Rock ◽  
Confined Water ◽  
Working Face ◽  
Stress Environment ◽  
And Control ◽  
Sandy Mudstone

The surrounding rock failure range of floor drainage roadway under the mining influence and its effect on the aquiclude are the key to determine the aquiclude thickness of the floor. This paper studied the distribution characteristics of the surrounding rock plastic zone by the numerical simulation when the floor drainage roadway was located at different positions under the working face and determined the rational position. Results show that (1) when the floor drainage roadway is staggered inward, the floor surrounding rock is prone to appear the butterfly plastic zone under single work face mining. And the butterfly plastic zone increases sharply after being affected by secondary mining of adjacent working face. (2) When the floor drainage roadway is staggered outward, the floor surrounding rock plastic zone extends gently affected by a single working face. And the depth of the plastic zone has no obvious change after being affected by secondary mining of adjacent working face. (3) According to the risk of water inrush, the three layout schemes can be ranked as follows: stagger   inward   25   m > stagger   inward   80   m > stagger   outward   15   m . (4) Considering the floor stress environment, gas extraction efficiency, and water prevention and control, the reasonable location of floor drainage roadway below the No. 11060 working face of Zhaogu No. 2 Coal Mine was finally determined. It was arranged in the sandy mudstone layer on the upper part of L9 limestone under the middle part of coal pillar and was drived along the seam floor.

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 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.

Effect of poisson's ratio strains in adherends on stresses of an idealized lap joint

1973 ◽  
Vol 8 (2) ◽  
pp. 134-139 ◽  
Author(s):  
R D Adams ◽  
N A Peppiatt
Keyword(s):  
Shear Stress ◽  
Poisson’S Ratio ◽  
Longitudinal Shear ◽  
Poisson's Ratio ◽  
Shear Stresses ◽  
Lap Joint ◽  
Stress Concentrations ◽  
Maximum Value ◽  
Set Up ◽  
Transverse Stresses

Poisson's ratio strains in the adherends of a simple adhesive lap joint induce transverse stresses both in the adhesive and in the adherends. Two simultaneous second-order partial-differential equations were set up to describe the normal stresses along and across an adherend and were solved both by an approximate analytical method and a finite-difference technique: the two solutions agreed closely. The adhesive shear stresses can then be obtained by differentiating these solutions. The transverse shear stress has a maximum value for metals of about one-third of the maximum longitudinal shear stress, and this occurs at the corners of the lap, thus making the corners the most highly stressed parts of the adhesive. Bonding adherends of dissimilar stiffness was shown to produce greater stress concentrations in the adhesive than when similar adherends are used.

Robot Controlled Rotary Peen Forming by Laser-Assisted Distance Control

2015 ◽  
Vol 651-653 ◽  
pp. 1084-1089 ◽  
Author(s):  
Markus Gottschalk ◽  
Markus Bambach ◽  
Gerhard Hirt
Keyword(s):  
Machine Design ◽  
Shear Stresses ◽  
Structural Components ◽  
Principal Stresses ◽  
Aircraft Fuselage ◽  
Innovative Process ◽  
Distance Control ◽  
Peen Forming ◽  
Set Up ◽  
Intrusion Depth

Surface curvature radii required for aircraft fuselage as well as structural components can be produced by peen forming processes. The innovative process idea of Rotary Peen Forming is a modification of the well-known Shot Peen Forming. Here, the impactors are flexibly connected to a rotating hub and thus moving on circular trajectories. As a consequence, there is no need to pressurize and recirculate the shots, as it is essential in Shot Peen Forming. Using a six axes robot, the rotating hub can be guided flexibly. The resulting machine design is more compact compared to traditional Shot Peen Forming.However, in Rotary Peen Forming not only principal stresses but also shear stresses are caused in the deformation zone which has a fundamental influence on the curvature. In order to generate defined curvatures on the workpiece, the capability to precisely adjust the intrusion depth of the impactors is essential.In this paper, a laser-assisted distance control for the Robot Controlled Rotary Peen Forming is introduced. By means of a point laser, the set-up allows for a distance control to adjust and keep a determined intrusion depth. This way, the machine design provides a mechanism to readjust the intrusion depth of the impactors while the desired curvature is formed during the process by the introduced plastic strains at the specimen’s surface. Using the distance control, the resulting curvature is two to four times bigger compared to experiments without a readjustment of the intrusion depth.

scholarly journals Size effect of Water-flowing fracture Zone height based on FLAC3D

2020 ◽  
Vol 194 ◽  
pp. 01011
Author(s):  
Chao Zheng ◽  
Lan Yu ◽  
Ning Sun ◽  
Hualong Zhou ◽  
Jiangyi He
Keyword(s):  
Size Effect ◽  
Coal Mine ◽  
Fracture Zone ◽  
Average Distance ◽  
Water Inrush ◽  
Water Diversion ◽  
Effect Of Water ◽  
Face Width ◽  
Working Face ◽  
Simulation Results

The loss of water resources caused by mining fissures is a key factor restricting the green development of coal resources in western mining areas. in order to analyze the influence of mining thickness and face width on the development height of water diversion fracture zone, based on the characteristics of overburden in Xinzhuang Coal Mine, the finite difference software FLAC3D is used to simulate and analyze the size effect of water diversion fracture zone height. The simulation results show that the height of the water diversion fracture zone is positively correlated with the increase of mining thickness and working face width. When the mining thickness is 9m and the width of the working face is 240m, the height of the water diversion fracture zone is 115m, and the average distance between the coal layer 8 of Xinzhuang Coal Mine and the bottom of the Cretaceous aquifer is 106.9m, which may cause water inrush in the mine. Therefore, according to the simulation results and referring to the mining size of part of the mine face in the attached Binchang mining area, it is suggested that the mining thickness of Xinzhuang Coal Mine is about 10m and the width of the working face is not more than 200m.

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