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Hao J.,Xinjiang Agricultural University | Shi K.-B.,Xinjiang Agricultural University | Wang X.-L.,Xinjiang Agricultural University | Bai X.-J.,Gezhouba Xinjiang Engineering Co. | Chen G.-M.,Gezhouba Xinjiang Engineering Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2016

The rating of rockburst is fuzzy and uncertainty, though the cloud model of rough set theory has a unique advantage to dealing with fuzzy and uncertainty problem. A new cloud model for evaluating rockburst grade is proposed on the basis of the rough set of fuzzy C-means (FCM) algorithm. Some main evaluation factors of rockburst are chosen in this study, such as uniaxial compressive strength σc, the maximum tangential stress σθ, tensile strength θt and elastic energy index Wet. According to the criteria of rockburst classification, each evaluation factor is calculated by using the characteristics of cloud number of different rockburst levels. The rough set theory based on FCM algorithm is employed to analyze each factor attributed in the forty samples of rockburst engineering in China and internationally, and then the weight of each evaluation factor is calculated. The comprehensive degrees of certainty of the samples for evaluation are calculated by the positive normal cloud generator, and the level of rockburst is finally specified by the maximum certainty degree. The results show that the evaluated results agree well with the practical records, which implies that the proposed procedure is of feasibility and reliability, and is a new idea for rockburst prediction. © 2016, Academia Sinica. All right reserved.


Hao J.,Xinjiang Agricultural University | Shi K.-B.,Xinjiang Agricultural University | Chen G.-M.,Gezhouba Xinjiang Engineering Co. | Bai X.-J.,Gezhouba Xinjiang Engineering Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

This paper provides the reliable theoretic guidance for parameters selection of surrounding rock stability analysis in Bulungl-Gongur hydropower station underground cavern. The grey relation analysis of deformation sensitivity method is proposed based on probability distribution model of surrounding rock mechanical parameters, while the spatial variability of parameters and the shortcomings of conventional sensitivity analysis are considered. Three-dimensional discrete element calculation program is used. This method regards density, elastic modulus, Poisson's ratio, cohesion, internal friction angle and joints internal friction angle as factor array. The vault crown settlement is specified as the target array. The influence of each factor changing in defined domain on the vault crown settlement is analyzed. The results show that the density is the most sensitive influential factor among all the factors. The subordinate sensitive influential factors are the elastic modulus, cohesion and Poisson's ratio. The internal friction angle and joints internal friction angle are the minimum sensitive influential factors. Finally, comparison of results between conventional sensitivity analysis and the proposed method is made. The results indicate that except density, internal friction angle and joints internal friction angle are consistent, the sensitivity of the rest parameters are not consistent. Therefore, this method could evaluate those parameters more accurately and reasonably based on considering the probability distribution of rock mechanical parameters. ©, 2015, Academia Sinica. All right reserved.


Hao J.,Xinjiang Agricultural University | Shi K.,Xinjiang Agricultural University | Chen G.,Gezhouba Xinjiang Engineering Co. | Bai X.,Gezhouba Xinjiang Engineering Co.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2014

The key block theory assumes that the rock masses are crossed over completely by structural planes, which is in conflicting with the fact that the lengths of traces of structural planes are finite, leading to the overestimation of the number of key blocks and the underestimation of the safety factor in calculations. The edge lengths of key blocks and the actual lengths of traces were thus computed according to the stereo-analytical method of block theory. The key block probability was redefined as absolute key block probability, relative key block probability and non-key block probability according to the probability theory of traces of structural planes. Calculations on the example of an equilateral triangular pyramid showed that when the ratio of length of trace to edge was larger than 100, the absolute key block probability was nearly 1.0 and structural planes could be considered to cross through rock mass in this case. If the ratio of length of trace to edge was equal to 1.5, the relative key block probability reached 0.75 and if the ratio of length of trace to edge was greater than 7.5, the non-key block probability was close to 0. The safety factor of the underground cavern at Bulungl-Gongur hydropower station was 3.145 according to the stability analysis of key block theory and was 4.591-5.233 based on the absolute key block probability, increased 46.0%-66.4%.

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