scholarly journals Failure Behavior and Damage Characteristics of Coal at Different Depths under Triaxial Unloading Based on Acoustic Emission

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4451
Author(s):  
Anlin Zhang ◽  
Ru Zhang ◽  
Mingzhong Gao ◽  
Zetian Zhang ◽  
Zheqiang Jia ◽  
...  

The depth effect of coal mechanical behavior seriously affects the safety and efficiency of deep coal mining. To explore the differences in failure behavior and damage characteristics of coal masses at different depths during the coal mining process, based on the consideration of in situ stress environment, physical properties, and mining disturbance of coal seams, triaxial unloading experiments with acoustic emission (AE) monitoring were conducted on coal samples at four different depths taken from the Pingdingshan coal mine area. The results showed that the AE activity of deep coal was more concentrated, and the cumulative AE energy of coal increased with increasing depth. The cumulative AE energy of the 1050-m coal sample was 69 times that of the 300-m coal sample. The b value representing the microcrack scale decreased with increasing depth, and the rupture degree of deep coal increased. The cracking mode of coal was classified and the failure behavior was analyzed. The cumulative tensile crack percentage of coal increased with increasing depth, and the tensile–shear composite failure occurred in the 300-m coal sample, whereas significant tensile failure occurred in the 1050-m coal sample. In addition, the damage evolution process of coal was divided into three stages, and the characteristic stress of coal was obtained. The ratio of crack initiation stress (σci) to peak stress (σc) increased with increasing depth, and the damage evolution process of deep coal was more rapid. The research results can provide useful guidance for disaster prevention and evaluation of surrounding rock stability during deep coal resource mining in the Pingdingshan coal mine area.

2013 ◽  
Vol 448-453 ◽  
pp. 823-829
Author(s):  
Hao Wang

By conducting field investigation and tests, such as groundwater pumping test and rock mechanics test, and building numerical models to simulate damage of coal mining to aquifers, it was proved that coal mining in some coal mine area caused impacts to groundwater environment, including impact on water cycle, the structure of aquifers, and groundwater flow field, as a result of which some water supply sources in coal mine area become unavailable. In addition, a couple of solutions are presented to mitigate the impacts.


2018 ◽  
Vol 35 ◽  
pp. 01005 ◽  
Author(s):  
Van Thinh Nguyen ◽  
Waldemar Mijał ◽  
Vu Chi Dang ◽  
Thi Tuyet Mai Nguyen

Methane hazard has always been considered for underground coal mining as it can lead to methane explosion. In Quang Ninh province, several coal mines such as Mạo Khe coal mine, Khe Cham coal mine, especially Duong Huy mine that have high methane content. Experimental data to examine contents of methane bearing coal seams at different depths are not similar in Duong coal mine. In order to ensure safety, this report has been undertaken to determine a pattern of changing methane contents of coal seams at different exploitation depths in Duong Huy underground coal mine.


2013 ◽  
Vol 316-317 ◽  
pp. 1112-1117 ◽  
Author(s):  
Ai Jun Shao ◽  
Yuan Huang ◽  
Qing Xin Meng

This paper presents the numerical simulation of groundwater flow and the prediction of drainage in the No.5 mine of the Feng-feng coal mine area, using the data from a water invasion. First of all, we build a mathematical model of groundwater flow according to the hydrogeological conditions. Then, the model is verified by the water invasion data. The measured and simulated water level fit well during the model verification. At last, the mine drainage was predicted using the established model. The results indicated that the coal mining below -100m would result in a large amount of drainage and relative high cost.


2020 ◽  
Vol 30 (1) ◽  
pp. 145-159
Author(s):  
Yong Tian ◽  
Rangang Yu ◽  
Yin Zhang ◽  
Xinbo Zhao

The study of rock damage evolution is of great significance in the field of underground engineering. In this paper, the damage development of deep formation rock was quantitatively evaluated by acoustic emission (AE) test. The Young’s modulus of the test rock specimens under ideal intact state was obtained by assuming a linear relationship between the AE rate parameter and the damage variation based on the rate process theory. Through the multi-stage cyclic loading test, the damage parameters corresponding to the peak stress of the previous stage were calculated by using the tangent modulus at the initial moment. The results showed that there was abrupt transition stage of damage development with the linear increase of stress. The damage parameter curves of rock specimens during loading process were obtained by using the method of cumulative AE energy, and the development trend of the curves was analyzed simply by combining the concepts of crack initiation stress and crack damage stress. Comparing the two methods of obtaining damage parameters by using cyclic loading test and cumulative AE energy, the results of them were highly consistent except for some deviation in the initial and final stages.


2020 ◽  
Vol 53 (5) ◽  
pp. 2063-2076 ◽  
Author(s):  
Zheqiang Jia ◽  
Heping Xie ◽  
Ru Zhang ◽  
Cunbao Li ◽  
Man Wang ◽  
...  

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