Study on Loading Rate Dependence of the Coal Failure Process Based on Uniaxial Compression Test

2020 ◽  
Vol 177 (10) ◽  
pp. 4925-4941 ◽  
Author(s):  
Weijing Xiao ◽  
Dongming Zhang ◽  
Ying Cai ◽  
Yapei Chu
2017 ◽  
Vol 14 (3) ◽  
pp. 200-207 ◽  
Author(s):  
Feng Luo ◽  
Guodong Li ◽  
Hao Zhang

Purpose The purpose of this paper is to obtain the mechanical behavior and damage mechanism of the coal and rock near the stope under the stress state and stress paths of the surrounding rock with the dynamic mining. Design/methodology/approach Through the three-axial compression test and the uniaxial compression test by meso experiment device, the mechanical behavior and fracture evolution process of coal and rock were studied, and the acoustic emission (AE) characteristics under uniaxial compression of the coal and rock were contrasted. Findings Under the three-axial compression, the strength of coal and rock enhance significantly by confining pressure. The volume of outburst coal shows obvious stages: compression is followed by expansion. The coal first appear to undergo compaction under vertical stress due to volume decrease, but with the development of micro- and macro-cracks, the specimens appeared to expand; under the uniaxial compression, through the comparison of stress–strain relationship and the crack propagation process, stress drop and fracture of coal have obvious correlation. The destruction of coal was gradual due to the slow and steady accumulation of internal damage. Due to the influence of the end effect, the specimens show the “conjugate double shear failure”. The failure process of the coal and rock and the characteristics of the AEs have a corresponding relationship: the failure causes a large number of AE events. Before the events peak, there was an initial stage, calm growth stage and explosive growth stage. There were some differences between the rock and coal in the characteristics of the AE. Originality/value These research studies are conducted to provide guidance on the basis of mine disaster prevention and control.


2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhixi Liu ◽  
Guangming Zhao ◽  
Xiangrui Meng ◽  
Ruofei Zhang ◽  
Dong Chunliang ◽  
...  

To investigate the energy evolution characteristics of sandstone under static-quasi-dynamic loading rates (1.0 × 10−3, 5.0 × 10−3, 1.0 × 10−2, 5.0 × 10−2, and 1.0 × 10−1 mm/s), the uniaxial compression tests, the uniaxial cyclic loading-unloading tests, and the uniaxial incrementally cyclic loading-unloading tests were conducted under five different loading rates. Through analysis of the elastic energy of the uniaxial cyclic loading-unloading test and the uniaxial incremental cyclic loading-unloading test, show that the impact of the loading rate and the cycle numbers on the elastic energy is less. Hence, we can deem that when the loads of the uniaxial incremental cyclic loading-unloading test and the uniaxial compression test are equal, the elastic energy of the two also equals. The energy in the uniaxial compression tests analyzed by the uniaxial incrementally cyclic loading-unloading test show that elastic energy increased linearly when the input energy increased under different loading rates. Through the linear energy storage law and the uniaxial incremental cyclic loading and unloading test, it is possible to analyze the energy in the uniaxial compression test at any loading rates. The results show that the greater the loading rate, the greater the peak elastic energy and peak input energy. But when the load is equal, the greater the loading rate, the smaller the input energy and elastic energy. Compared with traditional methods, the new energy analysis method is accurate and simple. Meanwhile, based on energy dissipation, the damage of rock during uniaxial compression tests was studied.


2011 ◽  
Vol 396-398 ◽  
pp. 217-220
Author(s):  
Bing Xie ◽  
Jin Jun Guo ◽  
Xiang Xia

Numerical specimens with ramdom joints is established by particle flow code PFC2D and uniaxial compression tests are conducted under three different loading rate. Studies have shown that strength of uniaxial compression are all increased with the loading rate no matter what specimen is complete or with random joints. The sensitivity of changes of uniaxial compressive strength of specimen with random joints decreases with increasing of the loading rate.


2019 ◽  
Vol 7 (6) ◽  
pp. 415
Author(s):  
Wu Zhichou ◽  
Zhang Ning ◽  
Wang Jiabo ◽  
Wang Shuo

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Man Lei ◽  
Fa-ning Dang ◽  
Haibin Xue ◽  
Mingming He

In order to study the mechanical properties of granite at the micro- and nanoscale, the load-displacement curve, residual indentation information, and component information of the quartz, feldspar, and mica in granite were obtained using a nanoindentation test, a scanning electron microscope (SEM), and X-ray diffraction (XRD). The elastic modulus and the hardness of each component of the granite were obtained through statistical analysis. Treating rock as a composite material, the relation between the macro- and microscopic mechanical properties of rock was established through the theory of micromechanical homogenization. The transition from micromechanical parameters to macromechanical parameters was realized. The equivalent elastic modulus and Poisson’s ratio of the granite were obtained by the Self-consistent method, the Dilute method, and the Mori-Tanaka method. Compared with the elastic modulus and the Poisson ratio of granites measured by a uniaxial compression test and the available data, the applicability of the three methods were analyzed. The results show that the elastic modulus and hardness of the quartz in the granite is the largest, the feldspar is the second, the mica is the smallest. The main mineral contents in granite were analyzed using the semiquantitative method by XRD and the rock slice identification test. The elastic modulus and the Poisson ratio of granite calculated by three linear homogenization methods are consistent with those of the uniaxial compression test. After comparing the calculation results of the three methods, it is found that the Mori-Tanaka method is more suitable for studying the mechanical properties of rock materials. This method has an important theoretical significance and practical value for studying the quantitative relationship between macro- and micromechanical indexes of brittle materials. The research results provide a new method and an important reference for studying the macro-, micro-, and nanomechanical properties of rock.


2017 ◽  
Vol 37 (5) ◽  
pp. 973-986 ◽  
Author(s):  
Michael Mazurana ◽  
Renato Levien ◽  
Lucas Zulpo ◽  
Gabrielle M. Passos ◽  
Hyran S. Kerpen

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