scholarly journals Research on Mechanisms and Control Measures of Surrounding Rock Disaster in Large Section Roadway with Top Coal under the Influence of Tectonic Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Yang Yu ◽  
Jianfei Lu ◽  
Dingchao Chen ◽  
Yuxin Pan ◽  
Xiangqian Zhao ◽  
...  
Keyword(s):  
Damage Mechanics ◽  
Tectonic Stress ◽  
Surrounding Rock ◽  
Control Measures ◽  
Shanxi Province ◽  
Stress Effect ◽  
Large Section ◽  
Thick Coal Seam ◽  
Surrounding Rock Control ◽  
Seam Mining

Based on the research background of large section roadway with top coal (LSRTC) in thick coal seam mining in Wangzhuang Coal Mine, Shanxi Province, China, catastrophe characteristics of the surrounding rock of the LSRTC were investigated and summarized. Based on the principle of damage mechanics, the critical size discriminant of the LSRTC was deduced, and the induction mechanism of section size effect and tectonic stress effect on the roadway surrounding rock disaster was revealed. Accordingly, the roadway surrounding rock control principle with the basic idea of “stabilizing and controlling top coal, reconstructing the coal wall, and limiting floor heave” was put forward, and the roadway surrounding rock stability control countermeasures with the core technology of “strong pressure support for roof + grouting reinforcement for two sides + bolt barrier for floor angle” were developed, which solved the surrounding rock control problem of the LSRTC under the action of tectonic stress and provided a useful reference for the difficult problem of roadway surrounding rock control under similar conditions.

scholarly journals Study on Rib Sloughage Prevention Based on Geological Structure Exploration and Deep Borehole Grouting in Front Abutment Zones

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Cheng Wang ◽  
Zuqiang Xiong ◽  
Chun Wang ◽  
Yuli Wang ◽  
Yaohui Zhang
Keyword(s):  
Coal Seam ◽  
Tectonic Stress ◽  
Geological Structure ◽  
Longwall Face ◽  
Mine Safety ◽  
Shanxi Province ◽  
Thick Coal Seam ◽  
Plastic Failure ◽  
Mining Conditions ◽  
Roof Strata

This research presents the grouting method of preventing rib sloughage which severely impacts mine safety and longwall retreat speed in thick coal seam with numerical simulation and laboratory tests. Based on the analysis of the plastic failure mode of five types of coal seam, roof strata ahead of the longwall face, and fractures developed in the coal seam, the following results are drawn, the range and degree of plastic failure generated in the coal seam and roof strata ahead of the longwall face gradually decreased as the coal mass strength increased; the grouting boreholes are essentially laid out within the coal rib instead of the roof. For a particular case of a coal mine in Shanxi province, a novel cement-based material was grouted, which fulfilled the reinforcement requirements under the tectonic stress regions and front abutment zones. Besides, the grouting borehole construction requested predrilled boreholes, full borehole intubation, lengthened hole sealing, and multiple-step drilling and grouting. This study can provide a theoretical framework of a design overview and practical basis for similar mining conditions in other coalfields.

scholarly journals Roadway Surrounding Rock under Multi-Coal-Seam Mining: Deviatoric Stress Evolution and Control Technology

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Dongdong Chen ◽  
En Wang ◽  
Shengrong Xie ◽  
Fulian He ◽  
Long Wang ◽  
...  
Keyword(s):  
Plastic Zone ◽  
Coal Seam ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Deviatoric Stress ◽  
Mine Pressure ◽  
Coal Face ◽  
Surrounding Rock Control ◽  
Seam Mining ◽  
Peak Value

Multi-coal-seam mining creates surrounding rock control difficulties, because the mining of a coal face in one seam can affect coal faces in another. We examine the effects of multi-coal-seam mining on the evolution of the deviatoric stress distribution and plastic zone in the roadway surrounding rock. In particular, we use numerical simulation, theoretical calculation, drilling detection, and mine pressure observation to study the distribution and evolution characteristics of deviatoric stress on Tailgate 8709 in No. 11 coal seam in Jinhuagong mine when the N8707 and N8709 coal faces in No. 7-4 coal seam and the N8707 and N8709 coal faces in No. 11 coal seam are mined. The evolution laws of deviatoric stress and the plastic zone of roadway surrounding rock in the advance and behind sections of the coal face are studied, and a corresponding control technology is proposed. The results show that the peak value of deviatoric stress increases with the advance of the coal face, and the positions of the peak value of deviatoric stress and the plastic zone become deeper. The deflection angle of the peak stress after mining at each coal face and the characteristics of the peak zone of deviatoric stress and the plastic zone of the roadway surrounding rock under the disturbance of multi-coal-seam mining are determined. In conclusion, the damage range in the roadway roof in the solid-coal side and coal pillar is large and must be controlled. A combined support technology based on high-strength and high pretension anchor cables and truss anchor cables is proposed; long anchor cables are used to strengthen the support of the roadway roof in the solid-coal side and coal pillar. The accuracy of the calculated plastic zone range and the reliability of the combined support technology are verified through drilling detection and mine pressure observation on site. This research can provide a point of reference for roadway surrounding rock control under similar conditions.

scholarly journals Support design of main retracement passage in fully mechanised coal mining face based on numerical simulation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yalong Li ◽  
Mohanad Ahmed Almalki ◽  
Cheng Li
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Surrounding Rock ◽  
Control Measures ◽  
Coal Face ◽  
Support Design ◽  
Working Face ◽  
Surrounding Rock Control ◽  
Mining Face ◽  
Mining Pressure

Abstract For the comprehensive mechanised coal mining technology, the support design of the main withdrawal passage in the working face is an important link to achieve high yield and efficiency. Due to the impact of mining, the roof movement of the withdrawal passage is obvious, the displacement of the coal body will increase significantly, and it is easy to cause roof caving and serious lamination problems, and even lead to collapse accidents, which will affect the normal production of the mine. In this paper, the mining pressure development law of the main withdrawal passage support under the influence of dynamic pressure is designed, the most favourable roof failure form of the withdrawal passage is determined, and the action mechanism and applicable conditions of different mining pressure control measures are studied. The pressure appearance and stress distribution in the final mining stage of fully mechanised coal face are studied by numerical simulation. The deformation and failure characteristics and control measures of roof overburden in the last mining stage of fully mechanised coal face are analysed theoretically. Due to the fact that periodic pressure should be avoided as far as possible after the full-mechanised mining face is connected with the retracement passage, some auxiliary measures such as mining height control and forced roof blasting are put forward on this basis. The relative parameters of the main supporting forms are calculated. The main retracement of a fully mechanised working face in a coal mine channel is put forward to spread the surrounding rock grouting reinforcement, reinforcing roof, and help support and improve the bolt anchoring force, the main design retracement retracement channels in the channel near the return air along the trough for supporting reinforcing surrounding rock control optimisation measures, such as through the numerical simulation analysis, the optimisation measures for coal mine fully mechanised working face of surrounding rock is feasible. Numerical simulation results also show that the surrounding rock control of fully mechanised working face of coal mine design improvements, its main retreat channel under the roof subsidence, cribbing shrank significantly lower, and closer, to better control the deformation of surrounding rock, achieved significant effect, to ensure the safety of coal mine main retracement channel of fully mechanised working face support.

scholarly journals Failure Analysis and Control Measures of Deep Roadway with Composite Roof: A Case Study

2021 ◽  
Author(s):  
Yongliang LI ◽  
Renshu Yang ◽  
Shizheng Fang ◽  
Hai Lin ◽  
Shaojie Lu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Mechanical Response ◽  
Surrounding Rock ◽  
Control Measures ◽  
Shanxi Province ◽  
Efficient Production ◽  
Stable Layer ◽  
Failure Characteristics ◽  
Geological Conditions ◽  
Unstable Layer

Abstract There is great variation in the lithology and lamination thickness of composite roof in coal-measure strata; thus, the roof is prone to delamination and falling, and it is difficult to control the surrounding rock when developing roadway in such rock strata. In deep mining, the stress environment of surrounding rock is complex, and the mechanical response of the rock mass is different from that of the shallow rock mass. For composite-roof roadway excavated in deep rock mass, the key to safe and efficient production of the mine is ensuring the stability of the roadway. The present paper obtains typical failure characteristics and deformation and failure mechanisms of composite-roof roadway with a buried depth of 650 m at Zhaozhuang Coal Mine (Shanxi Province, China). On the basis of determining a reasonable cross-section shape of the roadway and according to the failure characteristics of the composite roof in different regions, the roof is divided into an unstable layer, metastable layer, and stable layer. The controlled unstable layer and metastable layer are regarded as a small structure while the stable layer is regarded as a large structure. A superimposed coupling support technology of large and small structures with a multi-level prestressed bearing arch formed by strong rock bolts and highly prestressed cable bolts is put forward. The support technology provides good application results in the field. The study thus provides theoretical support and technical guidance for ground control under similar geological conditions.

scholarly journals Study on Surrounding Rock Deformation Mechanism and Control of Roadway with Large Section and Extra-Thick Top Coal

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yuliang Yang ◽  
Xiaobin Li ◽  
Pengfei Li
Keyword(s):  
Support System ◽  
Deformation Mechanism ◽  
Shear Failure ◽  
High Strength ◽  
Surrounding Rock ◽  
Shanxi Province ◽  
Large Section ◽  
Anchor Cable ◽  
Geological Conditions ◽  
And Control

In order to solve the problem of safe and rapid excavation and support of roadway with large section and extra-thick top coal under complex geological conditions, the deformation mechanism and control of roadway are analyzed by means of field investigation, numerical simulation, theoretical analysis, and field practice, taking the 2203 transportation roadway of a mine in Shanxi Province as the engineering background. The results show the following: (1) the concentration of normal tensile stress in the middle of large-span roadway roof and end shear stress is significant, which may easily lead to the separation of roof and the extrusion deformation of surrounding rock; (2) the surface shear failure depth of the roadway side is large, and the insufficient length of the bolt, the small density of the protective side, and the insufficient support strength are easy to cause the bulge and splitting of the coal wall; (3) roof joints and fractures are developed, and the dirt band of different thickness occurs, so it is easy for the roof separation and the anchor solids to cut down along the weak surface of the dirt band; (4) the geological structure produces horizontal movement of surrounding rock, which easily leads to poor supporting effect of roadway roof and material deformation and failure. Finally, a safe and economic comprehensive support system of “high-strength, high-resistance, and high-prestressed anchor cable support system + high-strength support of the two sides roadway + U-shaped anchor cable combined truss” is proposed, and the control mechanism is explained and applied successfully in the field.

Numerical Analysis of Influencing Factors of Stability in Thick Coal Seam Mining Roadway

2012 ◽  
Vol 256-259 ◽  
pp. 1453-1457
Author(s):  
Zhi Hua Li ◽  
Xin Zhu Hua ◽  
Ke Yang ◽  
Ruo Jun Zhu ◽  
De Sheng Zhou
Keyword(s):  
Coal Seam ◽  
Abutment Pressure ◽  
Surrounding Rock ◽  
Rock Body ◽  
Thick Coal Seam ◽  
Mining Depth ◽  
Working Face ◽  
Face Length ◽  
Seam Mining ◽  
Mining Height

The FLAC-3D software was used to study the surrounding rock displacement and the side abutment pressure distribution laws about roadway in thick coal seam. Based on this model, through change the mining height, working face length and mining depth, the differences of roadway underground pressure characteristics were analyzed between thick coal seam working face and normal working face. The results indicate that: ①the displacement of roadway surrounding rock increases with the increase of mining depth and mining height, the closer to the coal wall the larger of the increase range of roadway displacement. ②the peak of side abutment pressure increases with the increase of mining depth and mining height, the peak district of the stress will move toward the inner department of rock body. ③ the effect of working face length on the roadway displacement and the side abutment pressure is very feeble.

scholarly journals Analysis of Failure Mechanism of Roadway Surrounding Rock under Thick Coal Seam Strong Mining Disturbance

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Fuzhou Qi ◽  
Dangwei Yang ◽  
Yuguo Zhang ◽  
Yuxi Hao
Keyword(s):  
Coal Seam ◽  
Failure Mechanism ◽  
Strain Energy ◽  
Central Area ◽  
Surrounding Rock ◽  
Thick Coal Seam ◽  
Mining Disturbance ◽  
The Stability ◽  
Seam Mining ◽  
Basic Roof

Severe dynamic disturbance in extrathick coal seam mining has become one of the main factors threatening the stability of roadway surrounding rock. In this article, the #6 thick coal seam of Buliangou mine in Inner Mongolia, China, is taken as the engineering background. A mechanical model of the roadway roof structure is established to obtain an analytic formula of the key block subsidence. A three-dimensional discrete element model is established and used to verify the field measurement results. The fracture characteristics of the main roof above the F6104 transport roadway and the deformation and damage evolution law of the surrounding rock during thick coal seam mining are analyzed. The results show that because of the long-term breaking and falling of the roof rocks during extrathick coal seam mining, the F6104 transport roadway will undergo two severe mining disturbances at the locations of 10∼30 m and 50∼70 m ahead of the F6103 working face. During the two disturbance periods, the roadway roof displacement settles to 300∼350 mm and 750∼800 mm, and the deformation of the solid coal wall reaches 650∼700 mm and 1350∼1450 mm, respectively. The energy change curve of the total length of the fractured key roof is obtained, and when mining at 50 m, the basic roof is close to its tensile strength, and the strain energy can reach the peak value of 5.2 × 10 4  kJ, which easily leads to rock burst. The plastic damage zones on both sides of the roadway develop to the roof central area and eventually coalesce, and the deformation of the surrounding rock is obvious. When mining at 50∼70 m, the basic roof breaks and unloads, and elastic strain energy of 3.57 × 10 4  kJ is instantaneously released. These two dynamic disturbances are the main reasons for the instability of the roadway surrounding rock. The results clarify that the failure mechanism investigation of roadways in thick coal seam mining conditions can be effectively applied to control the stability of the roadway surrounding rock under strong mining disturbance.

Study on Coal Pillar Width and Surrounding Rock Control of Gob-Side Entry in Extra-thick Coal Seam

2020 ◽  
Vol 38 (6) ◽  
pp. 6855-6868
Author(s):  
Xiaobin Li ◽  
Yongqiang Zhao ◽  
Wenrui He ◽  
Liang Li ◽  
Fulian He
Keyword(s):  
Coal Seam ◽  
Coal Pillar ◽  
Surrounding Rock ◽  
Pillar Width ◽  
Thick Coal Seam ◽  
Surrounding Rock Control

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

scholarly journals Study on instability failure mode and monitoring early warning standard of surrounding rock in fully weathered argillaceous sandstone section of large section tunnel

2019 ◽  
Vol 136 ◽  
pp. 04023
Author(s):  
Ming Zhao ◽  
Ke Li ◽  
Hong Yan Guo ◽  
KaiCheng Hua
Keyword(s):  
Limit State ◽  
Stable State ◽  
Simulation Software ◽  
Surrounding Rock ◽  
Large Section ◽  
Rock Stability ◽  
Geological Conditions ◽  
Construction Step ◽  
The Face ◽  
The Stability

Based on the special geological conditions of a tunnel in Qingyuan section of Huizhou-Zhanzhou Expressway, FLAC3d numerical simulation software is used to simulate the rheological properties and instability of surrounding rock in large-section fully weathered sandstone section, and the stability and loss of surrounding rock are analyzed. The deformation of the dome and the face at steady state is analyzed. It is found that: 1) when the surrounding rock is in a stable state, the deformation curve of the dome is smooth. When the surrounding rock of the face is unstable, the front of the face appears ahead. Deformation should be first strengthened on the surrounding rock in front of the face. 2) The arched foot is an important part of the instability of the surrounding rock. In order to prevent the expansion of the collapsed part, the arched part should be reinforced. 3) In order to obtain the limit state of surrounding rock stability, the strength of surrounding rock is reduced, and the strength reduction coefficient corresponding to the displacement sudden point is taken as the safety factor of rock stability around the hole, and the stability safety coefficients of surrounding rock of each construction step are greater than 1.2. 4) The dynamic standard values of deformation control in the whole construction stage are obtained by analyzing the deformation curves of each data monitoring point with time in the corresponding time period of each construction step.

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