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Wang W.,Shijiazhuang University | Wang W.,CAS Wuhan Institute of Rock and Soil Mechanics | Wang Q.,Shijiazhuang University | Wang Q.,Nuclear Industry of China Geotechnical Engineering Co. | And 3 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014

Numerical simulations of initial dynamic extension of microcracks of mode I under shock wave loading of blasting using ABAQUS embedded with a numerical module of dummy nodes and a load subroutine of air wedge was carried out to investigate the blasting-enhanced permeability of low-permeability sandstone with uranium deposits (BEPUD). The numerical results indicated that the longer duration of rise time of shock waves, the more microcracks were activated in rocks. High peak pressure of shock wave led to high release rate of dynamic energy at crack tips. The excessive or insufficient peak pressures of shock wave were not conducive for the initial dynamic extension of microcracks and fully consumption of explosive energy. In virtue of the comparison of results from the static and the dynamic numerical analysis under explosive gas load, more crack growth in the dynamic analysis was found than in quasi-static analysis. The dynamic analysis explained better the phenomenon of the movement of crack instability. Source


Sun L.-C.,Nuclear Industry of China Geotechnical Engineering Co. | Zhang H.-P.,Nuclear Industry of China Geotechnical Engineering Co. | Zhou N.-Q.,Tongji University
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

Random-fuzzy statistical method can be used to reflect the space variation of geotechnical parameters. The method for determining the weight coefficient is discussed. Especially, the significance of "reference point" is studied. The results show that when the reference point limitlessly approaches the core point, the corresponding maximum membership degree is just the desired correct result. Based on the principle of random-fuzzy statistical method, an iterative calculation procedure is proposed to calculate the objective function. To analyze the geotechnical parameters in a certain nuclear power plant project, the curves of membership degree of each rock sample against reference point, as well as the procedure curves of reference point approaching core point, are obtained. The results show that the exponential function well expresses the function of membership degree. The distribution of membership degrees of samples exhibits normal distribution of narrow region. Therefore, the random-fuzzy statistical method is consistent with the practice; and then it is better than the conventional random method. Source


Sun L.,Nuclear Industry of China Geotechnical Engineering Co. | Wang H.,Nuclear Industry of China Geotechnical Engineering Co. | Zhou N.,Tongji University | Ning B.,Nuclear Industry of China Geotechnical Engineering Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

The method of back analysis targeted on factor of safety and failure probability is introduced on the basis of reliability theory. According to the limit state function of wedge failure, Monte Carlo method is applied to back analysis of wedge failure of foundation pit slope in a nuclear power engineering. The limit state of failure slope is represented by failure probability. It is found that the back analysis method targeted on failure probability is more proper and reasonable than that targeted on critical factor of safety, for the latter has some deficiencies. Combined with case study, the effects of variation factor of cohesion and internal friction angle, truncated location, and correlation coefficient on the results of back analysis are discussed. The results show that the shear strength of structural surface obtained by back analysis is more realistic, and it can guide engineering practices. Source

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