scholarly journals The Principle of Invariant Stress of the Surrounding Rock of the Hole under the Condition of Equal Pressure in the Deep Rock Mass

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiangye Wu ◽  
Jingya Wang ◽  
Jingang Li ◽  
Jianwei Li ◽  
Tao Xu ◽  
...  
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Surrounding Rock ◽  
Small Scale ◽  
Depth Range ◽  
Central Idea ◽  
Deep Rock Mass ◽  
Study Results ◽  
Deep Rock ◽  
Stress Influence

Based on the hydrostatic pressure theory of initial stress state of rock mass, combined with Saint-Venant’s principle central idea, the principle of invariant stress of surrounding rock mass of the hole under the condition of equal pressure in deep rock mass is put forward. Numerical simulation is used to study the properties of surrounding rock and section shape of different holes, the depth of the plastic zone, the range of stress influence, and the relationship between them. The study results showed the following. (1) In the current mining depth range, it is difficult to reach the limit of 5 times the hole radius under the condition of invariant pressure of deep rock mass, and it has a significant impact on the near field and relatively small impact on the far field, reflecting the localization effect of the stress influence range. (2) The increase of stress influence range mainly moves outward with the increase of plastic zone range, and its growth slope is low and tends to be horizontal, and the increase amount is negligible. (3) When the failure range of the plastic zone of the hole is small, the influence range of the stress does not change itself, which reflects the stress invariability of the small-scale failure of the surrounding rock of the hole. The research results verify the principle of stress invariability of the surrounding rock of the hole under the condition of equal pressure of the deep rock mass, which is consistent with Saint-Venant’s central idea.

Numerical Study on Zonal Disintegration of Deep Rock Mass Using Three-Dimensional Bonded Block Model

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Qingteng Tang ◽  
Wenbing Xie ◽  
Xingkai Wang ◽  
Zhili Su ◽  
Jinhai Xu
Keyword(s):  
Rock Mass ◽  
Fracture Zone ◽  
Numerical Study ◽  
Confining Pressure ◽  
Surrounding Rock ◽  
Zonal Disintegration ◽  
Block Model ◽  
Deep Rock Mass ◽  
Damaged Zone ◽  
Deep Rock

Zonal disintegration, a phenomenon of fractured zones and intact zones distributed alternately in deep rock mass, is different from the excavation-damaged zone of shallow rock mass. In this study, bonded block model of 3DEC was employed to study the fracture mode and origination condition of zonal disintegration. Initiation, propagation, and coalescence progress of fracture around the roadway boundary under different triaxial stress conditions are elaborated. Numerical simulation demonstrated that zonal disintegration may occur when the direction of maximum principal stress is parallel to the roadway axis. It is interesting to find that the fracture around the roadway boundary traced the line of a spiral line, while slip-line fractures distributed apart from the roadway boundary. The extent of the alternate fracture zone decreased as the confining pressure increased, and alternate fracture zone was no longer in existence when the confining pressure reaches a certain value. Effects of roadway shape on zonal disintegration were also studied, and the results indicated that the curvature of the fracture track line tends to be equal to the roadway boundary in shallow surrounding rock of the roadway, while the fractures in deep surrounding rock seems unaffected by the roadway shape. Those findings are of great significance to support design of deep underground openings.

Research on Support Technique for Excavation Process of Deep Rock Mass

2013 ◽  
Vol 438-439 ◽  
pp. 1249-1252
Author(s):  
Hong Xiao Wu ◽  
Song Lin Yue ◽  
Cun Cheng Shi ◽  
Xiao Hu ◽  
Cheng Chu ◽  
...  
Keyword(s):  
Rock Mass ◽  
High Strength ◽  
Surrounding Rock ◽  
Support Program ◽  
Tunnel Excavation ◽  
Deep Rock Mass ◽  
Rock Stability ◽  
Excavation Process ◽  
Deep Rock ◽  
Fracturing Mechanism

In the deep rock mass surrounding, rock burst, large deformation, zonal fracturing and phenomena like these may occur in the tunnel excavation process. When zonal fracturing happens, it is essential to reconsider the types of support, the boundary of support and the approach of tunnel excavation. In this paper, the control theory about the surrounding rock stability under high pre-existing stresses was researched, and the efficient support form which was the combination of high strength anchor bar and anchor cable was ascertained to be adaptive to deep tunnel excavation. According to the deformation and zonal fracturing mechanism of the surrounding rock, a comprehensive support program that combined intensive short anchor bars and long anchor cables was established, and the numerical simulation was carried out to verify the feasibility of the support form.

Analysis on Surrounding Rock Mass Plastic Zone of Deep Underground Chamber Based on Hoek-Brown Criterion

2013 ◽  
Vol 838-841 ◽  
pp. 741-746 ◽  
Author(s):  
Nan Yin
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Analytical Method ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Number Of Factors ◽  
Deep Rock ◽  
Deep Underground ◽  
Underground Chamber

Generalized Hoek-Brown criterion is indicated as a dimensionless quantity, on this basis, elastic-plastic analytical method of circular underground chamber is presented based on generalized Hoek-Brown criterion in uniform stress field. Take into account a number of factors such as deep rock mass quality, rock strength, etc, surrounding rock mass plastic zone of deep underground chamber is analyzed by the analytical method. The results show that taking measures to improve the quality of rock mass can effectively control surrounding rock mass plastic zone for soft rock underground chamber, however, taking measures to improve the quality of rock mass can not appreciably control surrounding rock mass plastic zone for hard rock underground chamber.

scholarly journals An Improved Stress and Strain Increment Approaches for Circular Tunnel in Strain-Softening Surrounding Rock Considering Seepage Force

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Ling Wang ◽  
Jin-feng Zou ◽  
Yu-ming Sheng
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Radial Displacement ◽  
Axisymmetric Problem ◽  
Strain Softening ◽  
Strain Increment ◽  
Surrounding Rock ◽  
Stress And Strain ◽  
Seepage Force ◽  
Circular Tunnel

Considering the effect of seepage force, a dimensionless approach was introduced to improve the stress and strain increment approach on the stresses and radial displacement around a circular tunnel excavated in a strain-softening generalized Hoek–Brown or Mohr–Coulomb rock mass. The circular tunnel can be simplified as axisymmetric problem, and the plastic zone was divided into a finite number of concentric rings which satisfy the equilibrium and compatibility equations. Increments of stresses and strains for each ring were obtained by solving the equilibrium and compatibility equations. Then, the stresses and displacements in softening zone can be calculated. The correctness and reliability of the proposed approach were performed by the existing solutions.

Microseism Induced by Transient Release of In Situ Stress During Deep Rock Mass Excavation by Blasting

2012 ◽  
Vol 46 (4) ◽  
pp. 859-875 ◽  
Author(s):  
Jianhua Yang ◽  
Wenbo Lu ◽  
Ming Chen ◽  
Peng Yan ◽  
Chuangbing Zhou
Keyword(s):  
Rock Mass ◽  
In Situ Stress ◽  
Deep Rock Mass ◽  
Deep Rock

Simulation on THM Coupling Process of Deep Rock Roadway with Aquifer in Coalmine

2013 ◽  
Vol 671-674 ◽  
pp. 1131-1134
Author(s):  
Jian Guo Yang ◽  
Li Chuan Chen ◽  
Hong Liang Liao ◽  
Fan Yang
Keyword(s):  
Rock Mass ◽  
Pore Pressure ◽  
Surrounding Rock ◽  
Stress Fields ◽  
Important Process ◽  
Governing Equations ◽  
Coupling Process ◽  
Deep Rock ◽  
Rock Roadway

THM coupling is an important process in engineering rock mass. In order to study the mechanism of THM coupling in surrounding rock of deep rock roadway in coalmine, the interactions between THM fields were analyzed, and the governing equations of THM coupling were given. Finally, a model of rock roadway with aquifer is simulated, and the distribution of pore pressure as well as the thermal and stress fields were obtained after some steps of calculation.

scholarly journals Research on the Reasonable Strengthening Time and Stability of Excavation Unloading Surrounding Rock of High-Stress Rock Mass

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Wensong Xu ◽  
Wentao Xu ◽  
Yunhai Cheng
Keyword(s):  
Rock Mass ◽  
Plastic Zone ◽  
Failure Process ◽  
High Stress ◽  
Stable State ◽  
Surrounding Rock ◽  
Triaxial Tests ◽  
Uniaxial Compression Test ◽  
True Triaxial ◽  
True Triaxial Tests

This study is aimed at better understanding the deformation and failure mechanism of surrounding rock during excavation unloading of a high-stress rock mass and determining the reasonable reinforcement time for the surrounding rock. To fulfill this aim, true triaxial tests were carried out on different loading and unloading paths during the unilateral unloading of a high-stress rock mass. The variational condition for minimization of plastic complementary energy is obtained, the optimal reinforcement time is determined, and the range of the plastic zone in the surrounding rock reinforced by anchor mesh-cable-grouting is compared and analyzed. The results are as follows: (1) Based on the Mohr-Coulomb yield criterion and the deformation reinforcement theory of surrounding rock, the stable state with the minimum reinforcement force is obtained. (2) After the true triaxial tests on the unilateral unloading of the third principal stress were carried out under different confining pressures, loading continued to be performed. Compared with rock failure without confining pressure, in the conventional uniaxial compression test, the failure of samples is dominated by composite splitting-shear failure; the unilateral unloading stress-concentration failure is a progressive failure process of splitting into plates followed by cutting into blocks and then the ejection of blocks and pieces. (3) The relationship between the time steps of the surrounding rock stability and the excavation distance is obtained. The supporting time can be divided into four stages: presupport stage, bolt reinforcement stage, anchor cable reinforcement stage, and grouting reinforcement stage. (4) In the range of within 5 m behind the tunneling face, the plastic zone of the surrounding rock with support is reduced by 7 m as compared with that with no support. In the range of over 5 m behind the tunneling face, the plastic zone of the roadway floor with support is reduced by 2.6 m as compared with that without support, and the deformation is reduced by 90%. These results can serve as a reference for controlling the behavior of surrounding rock during excavation unloading of high-stress rock masses.

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