scholarly journals Study on Evolution Characteristics of Regenerated Roof Structure in Downward Mining of Bifurcated Coal Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Ru Hu ◽  
Jiwen Wu ◽  
WenBao Shi ◽  
Xiaorong Zhai ◽  
Kai Huang
Keyword(s):  
Rock Mass ◽  
Theoretical Analysis ◽  
Coal Seam ◽  
Fractured Rock ◽  
Structural Evolution ◽  
Fractured Rock Mass ◽  
Roof Structure ◽  
Evolution Characteristics ◽  
Seam Mining ◽  
Similar Simulation

In recent years, the structural evolution characteristics of the regenerated roof of the lower coal seam have become a research hotspot when the bifurcation coal seam is mined downward. In this paper, taking the bifurcation coal seam of Xutuan Coal Mine in China as an example, the structural evolution characteristics of regenerated roof under the influence of mining in bifurcation coal seam are comprehensively studied by theoretical analysis, field measurement, and indoor similar simulation experiment. The stress transfer law in the floor after mining in the upper coal seam is also analyzed. The results show the overburden structure and stress field change caused by upper coal seam mining. The caving and fracture zones are formed in the roof, the average height of the caving zone is 8.28 m, and the one of the fracture zone is 34.91 m. The results of the field test verify the accuracy of theoretical analysis and similar simulation test results. According to the relative size of the depth of the strong failure zone of the coal seam floor and the coal seam spacing, the rock mass structure of the regenerated roof of lower coal seam is divided into three types: fractured rock mass + scattered rock mass (I), fractured rock mass + scattered rock mass + fractured rock mass (II), and fractured rock mass + bulk rock mass + fractured rock mass + layered rock mass (III), and the stability of the three types of regenerated roof structure is evaluated: III > II > I. The research in this paper can provide a theoretical basis for determining the target area of broken roof control under the mining conditions of bifurcation coal seam and provide guidance for the selection of the location and parameters of the grouting borehole for roof reinforcement.

scholarly journals Evolution Characteristics of Overburden Strata Structure for Ultra-Thick Coal Seam Multi-Layer Mining in Xinjiang East Junggar Basin

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 332 ◽  
Author(s):  
Xufeng Wang ◽  
Dongdong Qin ◽  
Dongsheng Zhang ◽  
Weiming Guan ◽  
Mengtang Xu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Coal Seam ◽  
Junggar Basin ◽  
Structure Evolution ◽  
Thick Coal Seam ◽  
Roof Structure ◽  
Gravity Load ◽  
Evolution Characteristics ◽  
Fracturing Process ◽  
Overburden Strata

The efficient and safe extraction of ultra-thick coal seam in the Xinjiang East Junggar Basin has been a major focus in the future of mining in China. This paper systematically studied the overburden strata fracturing process and the structure evolution characteristics based on a typical ultra-thick coal seam condition in Xinjiang, using both physical and numerical modeling studies. The interactions between shields and the roof strata were also examined, from the perspective of ground support. The results indicated that roof structure was mainly in the form of voussoir beam at the early mining stage, where overburden stability was affected by the rock mass properties and mining parameters. The support load mainly included top coal and immediate roof gravity load and the load caused by main roof rotary consolidation. As a result of mining disturbance and strata movement, the overlying strata re-fractured in the later mining stage. The roof structure changed from beam to arch gradually and propagates upwards with the increase of multi-layer mining times. The support load was mainly the gravity load of the friable rock mass within compression arch. The results will provide a guideline for the improvement of roof stability under similar mining conditions in Xinjiang.

Study of the geometrical size effect of a fractured rock mass based on the modified blockiness evaluation method

2018 ◽  
Vol 11 (11) ◽  
Author(s):  
Qingfa Chen ◽  
Tingchang Yin ◽  
Wenjing Niu ◽  
Wenshi Zheng ◽  
Junguang Liu
Keyword(s):  
Rock Mass ◽  
Size Effect ◽  
Evaluation Method ◽  
Fractured Rock ◽  
Fractured Rock Mass ◽  
Geometrical Size

Application of Borehole Camera Technology in Fractured Rock Mass Investigation of a Submarine Tunnel

2019 ◽  
Vol 83 (sp1) ◽  
pp. 609 ◽  
Author(s):  
Zengqiang Han ◽  
Chuanying Wang ◽  
Sheng Hu ◽  
Yiteng Wang
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fractured Rock Mass ◽  
Borehole Camera

scholarly journals A methodology of re-generating a representative element volume of fractured rock mass

2020 ◽  
Vol 71 (4) ◽  
pp. 347-358
Author(s):  
DANG Hong-Lam ◽  
THINH Phi Hong
Keyword(s):  
Rock Mass ◽  
Fractured Rock ◽  
Fracture Network ◽  
Hydraulic Calculation ◽  
Fractured Rock Mass ◽  
Fracture Characteristics ◽  
Mechanical Calculation ◽  
Representative Element ◽  
Representative Element Volume ◽  
Actual Fracture

In simulation of fractured rock mass such as mechanical calculation, hydraulic calculation or coupled hydro-mechanical calculation, the representative element volume of fractured rock mass in the simulating code is very important and give the success of simulation works. The difficulties of how to make a representative element volume are come from the numerous fractures distributed in different orientation, length, location of the actual fracture network. Based on study of fracture characteristics of some fractured sites in the world, the paper presented some main items concerning to the fracture properties. A methodology of re-generating a representative element volume of fractured rock mass by DEAL.II code was presented in this paper. Finally, some applications were introduced to highlight the performance as well as efficiency of this methodology.

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