scholarly journals Rockburst Precursors and the Dynamic Failure Mechanism of the Deep Tunnel: A Review

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7548
Author(s):  
Yulong Chen ◽  
Junwen Zhang ◽  
Jiahao Zhang ◽  
Bin Xu ◽  
Luji Zhang ◽  
...  
Keyword(s):  
Failure Mechanism ◽  
Dynamic Instability ◽  
Rapid Development ◽  
Prediction Method ◽  
Surrounding Rock ◽  
Deep Tunnel ◽  
Dynamic Failure ◽  
Failure Characteristics ◽  
Underground Caverns ◽  
The Stability

With the rapid development of underground caverns in the fields of hydraulic engineering, mining, railway and highway, the frequency, and intensity of rockburst and dynamic instability have gradually increased, which has become a bottleneck restricting the safe construction of deep caverns. This paper presents a review of the current understanding of rockburst precursors and the dynamic failure mechanism of the deep tunnel. Emphasis is placed on the stability of the surrounding rock of the deep tunnel, the rockburst prediction method, and the dynamic failure characteristics of the surrounding rock of the deep tunnel. Throughout the presentation, the current overall gaps in understanding rockburst precursors and the dynamic failure mechanism of deep tunnels are identified in an attempt to stimulate further research in these promising directions by the research community.

scholarly journals Influence of Discontinuities on Rock Failure under Blasting at Shuangjiangkou Hydropower Station

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Xi Zhao ◽  
Bangbiao Wu ◽  
Liyuan Yu ◽  
Tieshuan Zhao ◽  
Zhonghua Hu
Keyword(s):  
Impact Resistance ◽  
Surrounding Rock ◽  
Hydropower Station ◽  
Dynamic Tests ◽  
Support Design ◽  
Failure Characteristics ◽  
Underground Caverns ◽  
Geological Conditions ◽  
The Stability ◽  
Surrounding Rock Deformation

The underground caverns of Shuangjiangkou hydropower station are under complex geological conditions. During excavation, the stability of the tunnels is severely affected by problems, such as blasting impact and excavation unloading, resulting in abnormal deformation at different locations. On the basis of on-site measurement, the characteristics of rocks at the main powerhouse and the main transformer room are compared through dynamic tests, and a numerical model is established using discrete element method (DEM) to analyze the special influence of fault SPD9-f1 on the deformation after excavation. It is revealed that the surrounding rock of the main powerhouse has stronger impact resistance than that of the main transformer room and that the existence of fault SPD9-f1 accounts for the abnormal deformation. In this study, the failure characteristics and mechanism of surrounding rock deformation controlled by stress and fault are revealed, providing important references for the subsequent excavation and support design of underground projects.

Study on the Stability of Underground Constructions with Different Locations in Alpine and Gorge Region

2010 ◽  
Vol 163-167 ◽  
pp. 3320-3323
Author(s):  
Min Yong ◽  
Wei Shen Zhu ◽  
Da Jun Yu ◽  
Li Ge Wang
Keyword(s):  
Slope Angle ◽  
Great Influence ◽  
Vertical Component ◽  
Surrounding Rock ◽  
Underground Structures ◽  
Underground Caverns ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Underground Constructions ◽  
Selection Of

The reasonable selection of a location for underground structures has a great influence on the stability of surrounding rock masses, especially when the construction is built in the alpine and gorge regions. In general, the higher and steeper the mountains are, the more significant the effect is. In this paper, numerical analysis was carried out to study the stress distribution characters in the mountain with different slope angles of 30 °, 45 ° and 60 °. The results show that, the initial vertical component of stress field can not be directly determined by the buried depth when the slope angle is greater than 30 °. Meanwhile, numerical results indicate that is unfavorable for the structural stability when the underground caverns are constructed in the stress concentration areas of mountains with high slope angle. Moreover, some conclusions and recommendations were proposed for the design of underground constructions.

scholarly journals A Case Study on Large Deformation Failure Mechanism of Coal given Chamber and Invention of a New Wall-Mounted Coal Bunker in Xiashijie Coal Mine with Soft, Swelling Floor Rock

2017 ◽  
Author(s):  
Xingkai Wang ◽  
Wenbing Xie ◽  
Shengguo Jing ◽  
Jianbiao Bai ◽  
Zhili Su
Keyword(s):  
Failure Mechanism ◽  
Coal Mine ◽  
Numerical Models ◽  
Surrounding Rock ◽  
Engineering Practice ◽  
Floor Rock ◽  
Geological Conditions ◽  
Floor Heave ◽  
The Stability ◽  
Bearing Structure

Serious damage caused by floor heave in the coal given chamber of a vertical coal bunker is one of the challenges faced in underground coal mines. Engineering practice shows that it is more difficult to maintain the coal given chamber (CGC) than a roadway. More importantly, repairing the CGC during mining practice will pose major safety risks and reduce production. Based on the case of the serious collapse that occurred in the bearing structure of the CGC at the lower part of the 214# coal bunker in Xiashijie mine, China, this work analysed (i) the main factors influencing floor heave and (ii) the failure mechanism of the load-bearing structure in the CGC using FLAC2D numerical models and expansion experiment. The analysis results indicate that: the floor heave, caused mainly by mine water, is the basic reason leading to the instability and repeated failure of the CGC in the 214# coal bunker. Then a new coal bunker, without building the CGC, is proposed and put into practice to replace the 214# coal bunker. The FLAC3D software program is adopted to establish the numerical model of the wall-mounted coal bunker (WMCB), and the stability of the rock surrounding the WMCB is simulated and analysed. The results show that: (1) the rock surrounding the sandstone segment is basically stable. (2) The surrounding rock in the coal seam segment, which moves into the inside of the bunker, is the main zone of deformation for the entire rock mass surrounding the bunker. Then the surrounding rock is controlled effectively by means of high-strength bolt–cable combined supporting technology. According to the geological conditions of the WMCB, the self-bearing system, which includes (i) H-steel beams, (ii) H-steel brackets, and (iii) self-locking anchor cables, is established and serves as a substitute for the CGC to transfer the whole weight of the bunker to stable surrounding rock. The stability of the new coal bunker has been verified by field testing, and the coal mine has gained economic benefit to a value of 158.026174 million RMB over three years. The new WMCB thus made production more effective and can provide helpful references for construction of vertical bunkers under similar geological conditions.

scholarly journals Failure Mechanism for Surrounding Rock of Deep Circular Roadway in Coal Mine Based on Mining-Induced Plastic Zone

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yue Yuan ◽  
Weijun Wang ◽  
Shuqing Li ◽  
Yongjian Zhu
Keyword(s):  
Plastic Zone ◽  
Failure Mechanism ◽  
Coal Mine ◽  
Surrounding Rock ◽  
Deformation And Failure ◽  
Uniformity Coefficient ◽  
Shape Coefficient ◽  
The Stability ◽  
The Relationship

In order to reveal the failure mechanism of the deep roadway under mining-induced pressure in coal mine, the boundary equations for the plastic zone around the deep roadway were deduced, and then the evolution laws for morphology of the plastic zone and the relationship between the morphological indexes and the stability of surrounding rock were discussed. The results show that, for the deep roadway, the effect of mining on the plastic zone is more sensitive than that on the shallow one. Even if the changes of mining influence are small, they may also cause extremely serious plastic failure of surrounding rock masses, leading to the sudden instability of the roadway. When the plastic wings of the plastic zone are approximately perpendicular to the roof, floor, or sidewall, the large deformation and failure of the deep roadway are very likely to occur. Compared with the index of the uniformity coefficient, the irregular shape coefficient can be used to better characterize the differences in the plastic zone morphology. Finally, a case study was provided to apply the principles for the formation and extension of a butterfly-shaped plastic zone.

Application of Stereographic Projection in the Search of Key Block of Surrounding Rock Mass for Underground Powerhouse

2010 ◽  
Vol 44-47 ◽  
pp. 1189-1192
Author(s):  
Zhong Chang Wang
Keyword(s):  
Rock Mass ◽  
Stereographic Projection ◽  
Side Wall ◽  
Surrounding Rock ◽  
Main Role ◽  
Measuring Point ◽  
Underground Powerhouse ◽  
Underground Caverns ◽  
Key Block ◽  
The Stability

The rose diagram of joint is generalized by grouping the attitude of disclosed discontinuous faces in detecting cavern and measuring point coordinate. The search of movable and key blocks of surrounding rock mass for underground powerhouse is implemented, the combinations of discontinuous faces and sliding faces, the location and the parameter of stability of movable and key blocks are obtained by used of the method of stereographic projection and vector analysis of the block theory. It is shown that the numbers of movable and key blocks in the location of downriver right side wall and vault are larger than those in other location owing to numerous discontinuous faces, and the faults of F34 and F33 play a main role in the stability of movable and key blocks. The guidance for excavation and reinforce of underground caverns is provided.

Construction Technology of Cangyuan Tunnel of LanYu Railway

2012 ◽  
Vol 256-259 ◽  
pp. 1291-1295
Author(s):  
Su Qi ◽  
Ye Zhang ◽  
Shu Hao Liu ◽  
Nian Liu
Keyword(s):  
Debris Flow ◽  
Rapid Development ◽  
Surrounding Rock ◽  
Construction Technology ◽  
Road Tunnel ◽  
Step Method ◽  
Geological Conditions ◽  
Construction Experience ◽  
Pass Through ◽  
The Stability

The phenomenon of railway and road tunnel passing through the debris flow gully is more and more prevalent, for the rapid development of the construction of railways and highways. At present, the construction experience of tunnels passing through the debris flow gully is not rich enough, so the study on this part is necessary. The engineering geological conditions of Cangyuan Tunnel are complex and the construction of which is difficult. The three-step seven-step method, tunnel surface grouting and tunnel root piles reinforcement basis are used to ensure the stability of the tunnel surrounding rock, based on the characteristics of Cangyuan Tunnel which passes through the debris flow gully. The deformation is controlled within the specification range, which indicates that the construction effect of Cangyuan Tunnel is good. These construction measures solve the construction problems of tunnels which pass through the debris flow gully and ensure project quality and duration, therefore, these construction measures can be used in similar projects.

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.

scholarly journals Earthquake Dynamic Failure Mechanism of Dangerous Rock Based on Dynamics and PFC3D

2021 ◽  
Vol 9 ◽  
Author(s):  
Yun Tian ◽  
Yong Wu ◽  
Hongtao Li ◽  
Bangzheng Ren ◽  
Hao Wang
Keyword(s):  
Failure Mechanism ◽  
Failure Mode ◽  
Calculation Method ◽  
Rock Block ◽  
Particle Flow ◽  
Dynamic Failure ◽  
Seismic Acceleration ◽  
Stability Coefficient ◽  
Time Frequency ◽  
The Stability

The dynamic failure mechanism of horizontally layered dangerous rock during earthquakes is complex and only few studies have addressed the combination of particle flow code (PFC) meso-level failure mechanism and mechanical analysis. Based on fracture mechanics and material mechanics we establish a calculation method for the interlayer load and stability coefficient of horizontal layered dangerous rock during strong earthquakes. The method was applied for calculating the stability of a horizontally layered dangerous slope along a highway in the Sichuan Province (China) during earthquakes as a case study. Using a 3D particle flow simulation technology, a PFC3D model of horizontal layered dangerous rock was established. Its dynamic stability, failure mode and Hilbert-Huang 3D time-frequency characteristics are analyzed, and the results of the simulation are largely consistent with the time of the dangerous rock failure as estimated by our new calculation method. Our study documents that as the seismic acceleration gradually increases, the stability coefficient of the rock block fluctuates more violently and the stability coefficient gradually decreases. The stability coefficient of the rock block decreases fastest between 5 and 6 s and the reduction in the stability coefficient is between 0.12 and 0.25. Before the seismic acceleration reaches the maximum, the dangerous rock blocks on the two main controlling structures collapse and get destroyed. 25 s after the earthquake, the failure mode of the dangerous rock is collapse-slip-rotation. We show that earthquakes with frequencies of 0–10 and 250 Hz have the strongest destructive effect on the stability of the horizontally layered dangerous rocks.

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