Experimental study on floor failure of coal mining above confined water

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Baoliang Zhang ◽  
Zhaobo Meng
Keyword(s):  
Experimental Study ◽  
Coal Mining ◽  
Confined Water ◽  
Floor Failure

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.

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 Experimental Study of Gangue Layer Weakening with Deep-Hole Presplitting Blasting

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jianchi Hao ◽  
Lifeng Ren ◽  
Hu Wen ◽  
Duo Zhang
Keyword(s):  
Experimental Study ◽  
Coal Seam ◽  
Coal Mining ◽  
Hard Rock ◽  
Blast Hole ◽  
Normal Operation ◽  
Deep Hole ◽  
Coal Seams ◽  
Layer 4 ◽  
Similar Simulation

Advances in coal mining technology and an increase in coal output are resulting in increasingly challenging conditions being encountered at coal seams. This is particularly so at thin coal seams, where a large number of hard rock layers known as gangue are often present, which seriously affect the normal operation of the shearer and reduce coal output. Therefore, the effective weakening of hard gangue layers in a coal seam is crucial to ensure that the shearer operates effectively and that coal output is maximized. In this paper, the weakening effect of deep-hole presplitting blasting technology on the hard gangue layer in a coal seam is studied via a similar simulation. Four test schemes are designed: (1) A blasting hole spacing of 200 mm with the holes offset vertically. (2) A blast hole spacing of 300 mm with the holes offset vertically. (3) A blast hole spacing of 200 mm with the holes parallel to the gangue layer. (4) A blasting hole spacing of 200 mm with the holes offset vertically and initiation of interval blasting. The effect of the different blasting hole spacings and arrangements and different detonation methods on the weakening of coal seam clamping by gangue is studied, and the best configuration is identified. This improves the effect of weakening the coal gangue layer by deep-hole presplitting blasting.

An experimental study on the effect of confined water on resistance and propulsion of an inland waterway ship

2018 ◽  
Vol 167 ◽  
pp. 11-22 ◽  
Author(s):  
Philipp Mucha ◽  
Ould el Moctar ◽  
Thorsten Dettmann ◽  
Matthias Tenzer
Keyword(s):  
Experimental Study ◽  
Confined Water ◽  
Inland Waterway

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.

Microseismic Monitoring and Numerical Simulation Research of Floor Failure Depth in Extra-Thick Coal Seam

2014 ◽  
Vol 881-883 ◽  
pp. 1799-1804 ◽  
Author(s):  
Ai Ping Cheng ◽  
Yong Tao Gao ◽  
Chao Liu ◽  
Jin Fei Chai
Keyword(s):  
Numerical Analysis ◽  
Coal Mining ◽  
Microseismic Monitoring ◽  
Floor Rock ◽  
Thick Coal Seam ◽  
Floor Failure ◽  
Mining Disturbance ◽  
Microseismic Events ◽  
Mining Face ◽  
Failure Depth

Based on the condition of fully mechanized caving face in one mine, two methods of microseismic monitoring and numerical analysis were combined to study the evolution characteristics and development law of floor failure depth in extra-thick coal seam. Microseismic monitoring results show that the number of microseismic events partly reflects the influence of mining disturbance in the roof and floor rock mass. The distribution of microseismic events are intensive near the coal mining face, which show the floor rock mass is seriously damaged during the coal mining. The greatest floor failure depth estimated from mine microseismic monitoring is 31 meters. Numerical analysis indicate that the rock stress around the mine stope is redistributed during the coal mining, due to the effect of mining disturbance. The abutment pressure increases in front of the coal mining face and the stress reduces in the mined areas. The concentration and release of the stress makes contribution to the destroy of the floor rock. The maximum floor failure depth is up to 28 meters calculated from numerical simulation. The consistency of microseismic monitoring results and numerical analysis improve that it is effective and reliable to obtain floor failure depth and considerably possible to predict the water inrush using microseismic monitoring technology with its inherent ability to remotely monitor the progressive failure caused by mining. The research results have great popularization and application values for the similar mine.

scholarly journals Evolution Analysis of Microseismic Events before and after Mining through Large-Scale Weak Zone with High Confined Water

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jing Jia ◽  
Xianjie Hao ◽  
Guanghui Zhao ◽  
Yubao Li ◽  
Xiaoyu Chuai ◽  
...  
Keyword(s):  
Energy Level ◽  
Coal Mining ◽  
Large Scale ◽  
Confined Aquifer ◽  
Confined Water ◽  
Weak Zone ◽  
Joint Influence ◽  
Before And After ◽  
Microseismic Events ◽  
The Difference

The existence of large-scale weak zone will have a great adverse impact on coal mining in high confined aquifer. Taking the Wutongzhuang Coal Mine which is threatened by high-pressure water as an example, this paper studies the difference between the microseismic events before and after mining and analyzes the influence of the large size weak zone on the coal mining on the confined aquifer. The research results show that the microseismic characteristics of the large soft weak belt are small number of events, the spatial distribution of events is concentrated, and the energy level is large. The amplitude of microseismic events is higher, and the proportion of large events in microseismic events is larger than that of small events; the characteristics of microseismic events caused by mining face mining are that the number of events is more, the distribution of events is loose, the distribution of roof and floor is more, the energy level is less, the amplitude is smaller, and the proportion of small and medium events in microseismic events is larger than that of large events. Due to the joint influence of large-scale weak zone of floor and mining, the floor in the middle area of working face is affected by mining, the number of microseismic events in each aquifer increases suddenly, the karst fissures between the aquifers are further developed, and there is a trend of transfixion. Therefore, measures such as floor grouting should be taken to reinforce the large-scale weak zone before mining.

Deterministic Method of Floor Rock Permeability Tensor of Mining over Confined Water and Application in Numerical Simulation

2012 ◽  
Vol 204-208 ◽  
pp. 4840-4844
Author(s):  
Wei Tao Liu ◽  
Jian Jun Shen ◽  
Yun Juan Liu
Keyword(s):  
Coal Mining ◽  
Fractured Rock ◽  
Water Inrush ◽  
Water Injection ◽  
Correction Method ◽  
Permeability Tensor ◽  
Imaging Method ◽  
Confined Water ◽  
Rock Permeability ◽  
Floor Rock

Based on equivalent continuum media theory of fractured rock mass, the author got the permeability tensor of floor strata in some mine according to core logging method, drilling imaging method and boring water injection method, and determined the floor rock permeability tensor using correction method. The author simulated the floor inrush problem by coupling fluid-solid theory and anisotropic flow model with FLAC3D software. The result shows that, the destroyed depth of floor and the confined water rising height are all slight when the coal mining workface is 150m apart from the fault, but they increase obviously when the coal mining workface is 30m apart from the fault, and are extremely easy to get through and casue water inrush through fault.

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