Study on Local Yielding Effect and Energy Evolution Law of Deep Roadway

Author(s):  
Zhijia Wang ◽  
Wenlong Wu ◽  
Feiyue Sun ◽  
Weidong Sun ◽  
Pengfei Li
Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Chun Wang ◽  
Mei-zhi Xie ◽  
Zu-qiang Xiong ◽  
Cheng Wang ◽  
Lu-ping Cheng

Based on the complex engineering environment in deep rock engineering, preloaded high axial pressure, unloading of axial pressure, and impact loading were used to simulate high in situ stress, unloading of excavation, and blasting disturbance, respectively; the experimental study on frequent impact disturbances under unloading of high static load was carried out, which aimed at revealing the energy evolution law of rock. First, the equations of elastic property, plastic energy, and incident energy in the impact process are discussed by theoretical analysis. Then, it is found by further investigation that dynamic stress-strain curve and envelope curve of rock are with the same change tendency. The initial stage was short straight stage, and then linear stage appeared and was less influenced by unloading rate. The plastic energy, the ratio of reflected energy to incident energy, and the energy consumption per unit volume of rock increase during impact. The higher the preloaded axial pressure is, the greater the ratio of reflected energy to incident energy is, the smaller the ratio of transmitted energy to incident energy and the average energy dissipation per unit volume of rock are. When the unloading rate increased, the elastic energy generated by impact gradually increased, the plasticity gradually weakened, the ratio of transmitted energy to incident energy increased, and the ratio of reflection energy to incident energy decreased.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ying Xu ◽  
Xiekang Zhou ◽  
Weimei Gong

Because top coal is not stable, a roadway with thick top coal often appears to mine pressure problems, such as bolt failure, cable breakage, and roof caving. In particular, these problems are more serious in rockburst mines. Based on a cable breakage case of No. 3 roadway in Xingcun coal mine, the paper analyzed the stress and elastic energy evolution law of surrounding rock and stress state of cable in the 3# roadway by means of the numerical simulation method. Thus, the cable breakage mechanism of the roadway with thick top coal in rockburst mine was revealed. Then, because surrounding rock grouting can reduce the stress concentration of surrounding rock and cable, surrounding rock grouting technology was proposed as control technology of cable breakage. Finally, parameters of surrounding rock grouting were designed and applied in the No. 3 roadway. The field results showed that surrounding rock grouting technology can be one of the solutions for cable breakage of roadway with thick top coal in rockburst mine. The research results of this paper can provide certain theoretical and practical value for mine pressure control of roadway.


2020 ◽  
Vol 24 (6 Part B) ◽  
pp. 4001-4009
Author(s):  
Peng Hou ◽  
Lin Gao ◽  
Yan Xing ◽  
Zhao-Peng Zhang

In geothermal energy exploration, the reservoir rock is always subjected to thermal cycles and its physical properties will be seriously affected. In this paper, the changes of the internal structure of the sandstone after the thermal cycle are firstly evaluated by ultrasonic tests. Then, uniaxial compression tests are conducted on the treated specimens. The effects of the thermal cycling on mechanical properties and energy evolution law of the sandstone are analyzed. The results show that the density, P-wave velocity and mechanical properties of the sandstone reduced with the increase in the thermal cycle, especially in the high temperature cycle. The increase of the temperature in the thermal cycle can increase the influence of the thermal cycle on the energy evolution law.


2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Yun-liang Tan ◽  
Wei-yao Guo ◽  
Qing-heng Gu ◽  
Tong-bin Zhao ◽  
Feng-hai Yu ◽  
...  

In order to research the influence of homogeneity on the rockburst tendency and on AE characteristics of coal-rock combination body, uniaxial compressive tests of inhomogeneous coal-rock combination bodies obeyed by the Weibull distribution were simulated using particle flow code (PFC2D). Macromechanical properties, energy evolution law, and AE characteristics were analyzed. The results show that (1) the elastic modulus homogeneitymEhas an exponential relation with macroscopic modulusE, and the bonding strength homogeneitymσhas an exponential relation with uniaxial compressive strengthσc; (2) the rockburst tendency of the coal-rock combination body will increase with the increase ofmEormσ, andmσis the leading factor influencing this tendency; and (3) both the change law of AE hits and lasting time in different periods of AE characteristics are influenced bymσ, butmEjust influences the lasting time. The more inhomogeneous the coal-rock combination body is, the shorter the lasting time in booming period of AE characteristics will be. This phenomenon can be used to predict the rockburst tendency of the coal-rock combination body.


Author(s):  
Elena Benvenuti ◽  
Nicola Orlando

AbstractWe propose a formulation for tracking general crack paths in elastodamaging materials without mesh adaptivity and broadening of the damage band. The idea is to treat in a unified way both the damaging process and the development of displacement discontinuities by means of the regularized finite element method. With respect to previous authors’ contributions, a novel damage evolution law and an original crack tracking framework are proposed. We face the issue of mesh objectivity through several two-dimensional tests, obtaining smooth crack paths and reliable structural results.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2108
Author(s):  
Guanlin Liu ◽  
Youliang Chen ◽  
Xi Du ◽  
Peng Xiao ◽  
Shaoming Liao ◽  
...  

The cracking of rock mass under compression is the main factor causing structural failure. Therefore, it is very crucial to establish a rock damage evolution model to investigate the crack development process and reveal the failure and instability mechanism of rock under load. In this study, four different strength types of rock samples from hard to weak were selected, and the Voronoi method was used to perform and analyze uniaxial compression tests and the fracture process. The change characteristics of the number, angle, and length of cracks in the process of rock failure and instability were obtained. Three laws of crack development, damage evolution, and energy evolution were analyzed. The main conclusions are as follows. (1) The rock’s initial damage is mainly caused by tensile cracks, and the rapid growth of shear cracks after exceeding the damage threshold indicates that the rock is about to be a failure. The development of micro-cracks is mainly concentrated on the diagonal of the rock sample and gradually expands to the middle along the two ends of the diagonal. (2) The identification point of failure precursor information in Acoustic Emission (AE) can effectively provide a safety warning for the development of rock fracture. (3) The uniaxial compression damage constitutive equation of the rock sample with the crack length as the parameter is established, which can better reflect the damage evolution characteristics of the rock sample. (4) Tensile crack requires low energy consumption and energy dispersion is not concentrated. The damage is not apparent. Shear cracks are concentrated and consume a large amount of energy, resulting in strong damage and making it easy to form macro-cracks.


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