Physical Modeling of Floor Failure Above Confined Water: A Case Study in China

2021 ◽  
Author(s):  
Wenmiao WANG ◽  
Yong YUAN ◽  
Zhongshun CHEN ◽  
Cheng ZHU
Keyword(s):  
Coal Mining ◽  
Water Pressure ◽  
Water Diversion ◽  
Confined Water ◽  
Failure Characteristics ◽  
Water Loading ◽  
Working Face ◽  
Floor Failure ◽  
Loading System ◽  
Coal Wall

Abstract Coal mining in areas with deep confined water is very dangerous; to ensure safety, it is necessary to clarify the damage characteristics of the working face floor. To directly reflect the failure characteristics of the working face floor under the coupled effects of mining stress and confined water pressure, this study takes the II633 working face of the Hengyuan coal mine in the Huaibei mining area as the engineering background. With the use of a self-designed monitoring system for confined water diversion and a similar material simulation experimental method, the mining stress distribution patterns, the deformation and failure characteristics of the overburden, and the diversion characteristics of the confined water in the working face floor are studied. The combined use of a confined water loading system and a confined water lifting system can directly reproduce the floor confined water lifting characteristics affected by floor failure during coal mining. The results show that the floor undergoes three stages of deformation in the horizontal direction: premining stress concentration compression (10-15 m ahead of the working face), postmining floor pressure relief expansion, and roof collapse stress recovery (the distance of the lagging working face is 15-20 m). In the vertical direction, a soft rock layer blocks the continuous transfer of mining stress to deeper layers and produces an important cushioning effect. In the process of coal mining, shear cracks easily develop in the coal wall in front of and behind the working face. After the coal seam is excavated, the length of the fractures that develop in the model is 27 cm. The confined water loading system can visually reproduce the hydraulic characteristics of the confined water during the mining process; that is, the confined water easily bursts at the front and back ends of the coal wall in the goaf. The error, as determined by comparison between the field measurement and the theoretical calculation results, is only 0.617 m, verifying the reliability of the similar simulation method.

scholarly journals Comprehensive Measurement of the Deformation and Failure of Floor Rocks: A Case Study of the Xinglongzhuang Coal Mine

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Hao Liu ◽  
Pu Wang ◽  
Weihe Zhang ◽  
Qiang Liu ◽  
Lijun Su
Keyword(s):  
Coal Mine ◽  
Abutment Pressure ◽  
Three Dimensional ◽  
Strain Sensing ◽  
Floor Rock ◽  
Deformation And Failure ◽  
Working Face ◽  
Floor Failure ◽  
Coal Wall ◽  
Different Depths

The isolated island panel 10304 of the Xinglongzhuang coal mine was used as the research subject to study the deformation and damage characteristics of the coal seam floor. The damage of the floor was studied using the borehole strain sensing method and borehole imaging technology, and FLAC3D was used to study the influence of abutment pressure on floor failure. The result shows that the floor under the superimposed area which is affected by lateral and advanced abutment pressure is damaged firstly, and the maximum depth reaches 26 m, other areas of the working face about 23 m. The degree of deformation and failure of floor rock at different depths is decreased. The deformation damage increases with the advancement of the working face until a certain distance at the same depth. The hole image can clearly show the influence range of the abutment pressure in front of the coal wall and influence the degree of the advancement and lag by means of the strain increment curve for each sensor probe and the images from different drilled positions. On the basis that the results of simulation and field measurement are consistent, the results can reflect the three-dimensional failure characteristics of the whole island working face floor in the process of coal mining more comprehensively and accurately; moreover, they also can provide important information for mine flood prevention and ecological environment protection.

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 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.

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 A case study of floor failure characteristics under fully mechanised caving mining conditions in extra-thick coal seams

2020 ◽  
Vol 17 (5) ◽  
pp. 813-826
Author(s):  
Pingsong Zhang ◽  
Yuanchao Ou ◽  
Binyang Sun ◽  
Chang Liu
Keyword(s):  
Stress Distribution ◽  
Western China ◽  
Monitoring Method ◽  
Thick Coal Seam ◽  
Failure Characteristics ◽  
Engineering Research ◽  
Object A ◽  
Working Face ◽  
Floor Failure ◽  
Inclined Boreholes

Abstract To determine the failure characteristics and evolution regularity of the floor strata during fully mechanised top-coal cave mining in typical deep and extra-thick seams in western China, the 61303 working face of an Ordos mine was selected as the engineering research object. A comprehensive monitoring method combining a BOTDR (Brillouin Optical Time-Domain Reflection) distributed fiber strain test and a borehole resistivity CT (Computerised Tomography) test was adopted. The results show that floor stress distribution of the deep-buried and extra-thick coal seam is significantly affected by the different depths of rock lithology. At the interface of the rock strata with a large difference in the elastic modulus, phenomena such as the asynchronism of strata movement and obvious differences in failure easily occur. The failure depth of the floor strata in the 61303 working face is approximately 15.90 m, and the influence depth of the floor disturbance is approximately 32.70 m. Under the influence of the mining pressure, floor stress distribution and crack evolution have obvious spatial and temporal effects. In different inclined boreholes, the data captured by the cable have different values and the fracture locations of the cable also differ. Compared with a single borehole, multiple boreholes with different inclinations, directions and locations can provide more comprehensive and reliable data trends. The knowledge obtained by this monitoring can provide reference information for the study of floor damage under similar conditions and the formulation of technical measures such as those that prevent mine water disasters.

scholarly journals Simulated Experiment of Water-Sand Inrush across Overlying Strata Fissures Caused by Mining

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Guibin Zhang ◽  
Hailong Wang ◽  
Shenglei Yan ◽  
Chuanyang Jia ◽  
Xiaoyuan Song
Keyword(s):  
Water Pressure ◽  
Test System ◽  
Mine Safety ◽  
Water Yield ◽  
Support Pressure ◽  
Confined Water ◽  
Working Face ◽  
Unconsolidated Sand ◽  
Seam Mining ◽  
Overlying Strata

In western region of China, the water-sand inrush across overlying strata fissures caused by mining threatens the mine safety production seriously. In order to study the development of water-sand inrush across overlying strata fissures caused by mining, a simulated test system consisted of load support bracket, laboratory module, confined water module, coal seam mining simulator, storage tank, and control system is developed. The combination of coal bearing strata in the south of Shendong mining area is looked on as the engineering background, and a series of new nonhydrophilic composite materials with lower intensity are developed to simulate the coal measure strata. The excavation of physical model can reproduce the whole process of water-sand inrush across overlying strata fissures caused by mining to the life. Under the action of mining and water pressure, after the fourth excavation, the mining-induced vertical fractures of overlying strata pass through the entire bedrock and connect the unconsolidated sand bed, which serves as pathways between the unconsolidated sand bed and working face, triggering water-sand inrush. The water pump suddenly accelerates, and the water yield suddenly increases to the extreme value of 150 L/h. The water pressure rapidly drops to 0 MPa, and a small amount of colored sand enters into the fractures of overlying strata and flows out with the water. The distribution of support pressure around the working face can be divided into 4 areas obviously, that is, the original stress area, the stress-concentrated area, the stress-released area, and the stress restoration area. Test results show that the system is stable and reliable, which have important significance for studying the formation mechanism of water-sand inrush across overlying strata fissures further.

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.

The Effect of Coal-Mining on the Bottom Floor Stress and Floor Failure Law

2012 ◽  
Vol 170-173 ◽  
pp. 106-109
Author(s):  
Zhao Ning Gao
Keyword(s):  
Stress Concentration ◽  
Coal Mining ◽  
Coal Mine ◽  
Additional Stress ◽  
Stress Recovery ◽  
Evolution Law ◽  
Working Face ◽  
Floor Failure ◽  
Group Evolution ◽  
The Difference

According to the geology condition of 1028 face in Suntuan Coal Mine of Huaibei Mining Group, evolution law of stress and displacement of water-resisting floor along with working face ad-vancement was studied. The results show that the stress and the displacement of the floor change dynamically , the displacement in the front and back of working face ,and the difference of displacement result from stress concentration before mining ,relief pressure after mining , superpo-sition effect of additive stress caused by the additional stress in stress recovery . The measures to re-duce the coal floor damage were proposed.

Analysis Floor Failure Characteristics of 7122 Working Face in the Qinan Coal Mine Based on the Plasticity Theory

2013 ◽  
Vol 275-277 ◽  
pp. 999-1002 ◽  
Author(s):  
Lei Han ◽  
Xiang Rui Meng
Keyword(s):  
Coal Mine ◽  
Plasticity Theory ◽  
Horizontal Distance ◽  
Feature Maps ◽  
Key Strata ◽  
Working Face ◽  
Floor Failure ◽  
Coal Wall ◽  
Damage Depth ◽  
Failure Depth

In order to study the floor damage depth of 7122 working face in the Qinan Coal Mine, we used Key strata theory and elastic-plastic theory to analyze the activities mechanisms and characteristics of the surrounding rock. By theoretical calculation obtained floor strata failure depth 8.79m of 7122 Face Mining; The horizontal distance of from the greatest floor damage depth to the coal wall is about 5.71m; The goaf floor failure distance is about 25.44m. Combined with the results of plasticity theory, we had drawn floor damage feature maps of 7122 working face in Qinan Coal Mine.

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