Mechanism of evolution of stress–structure controlled collapse of surrounding rock in caverns: A case study from the Baihetan hydropower station in China

2016 ◽  
Vol 51 ◽  
pp. 56-67 ◽  
Author(s):  
Ya-Xun Xiao ◽  
Xia-Ting Feng ◽  
Guang-Liang Feng ◽  
Hua-Ji Liu ◽  
Quan Jiang ◽  
...  
Keyword(s):  
Surrounding Rock ◽  
Hydropower Station ◽  
Baihetan Hydropower Station

Geo-Stress Direction Evaluation Method Based on Numerical Simulation

2014 ◽  
Vol 580-583 ◽  
pp. 2011-2014
Author(s):  
Su Chao Xu ◽  
C Y. Jin
Keyword(s):  
Numerical Simulation ◽  
Evaluation Method ◽  
Maximum Shear Stress ◽  
Local Stress ◽  
Surrounding Rock ◽  
Hydropower Station ◽  
Local Stress Concentration ◽  
Stress Direction ◽  
Baihetan Hydropower Station

The phenomenon of spalling at Baihetan Hydropower Station is influenced by such factors as the stress redistribution in surrounding rock, the local stress concentration and also poor properties of disturbed belt. In this paper, a series of numerical simulation were carried out and some beneficial conclusions were gained as follows: 1) the ratio of maximum shear stress and uniaxial compressive strength is more rational in the prediction of spalling and can give confident explanation for “V” shape pits; 2) the in-situ geo-stress direction is in accordance with NNE and NE.

scholarly journals Rock Mass Classification for Columnar Jointed Basalt: A Case Study of Baihetan Hydropower Station

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Shiyue Zhang ◽  
Mingjie He ◽  
Jinjian Gu ◽  
Zhihao Cui ◽  
Jian Wang ◽  
...  
Keyword(s):  
Rock Mass ◽  
Classification Scheme ◽  
Jointed Rock ◽  
Rock Mass Classification ◽  
Classification Systems ◽  
Hydropower Station ◽  
Columnar Jointed Basalt ◽  
Baihetan Hydropower Station ◽  
Mass Classification

Rock mass classification is important in preliminary design of geotechnical engineering projects. Using the columnar jointed basalt at the foundation of Baihetan Hydropower Station as an example, this paper presents a classification scheme of the columnar jointed rock. Unlike many common rock masses, an obvious characteristic of columnar jointed rock is that it is discontinuous in geometry while continuous in mechanics. Due to the inapplicability of existing rock mass classification systems, a classification scheme, combined with rock mass integrity, weak plane tightness, and permeability, is proposed. The new classification system has five grades with quantitative factors, which takes into account the features of columnar joints. As an easy-to-use scheme and case study, it would be helpful as a reference in the rock mass classification of similar problems.

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 Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

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