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Liu J.-P.,Northeastern University China | Li Y.-H.,Northeastern University China | Xu S.-D.,Northeastern University China | Xu S.,Northeastern University China | And 2 more authors.
Engineering Fracture Mechanics | Year: 2015

Acoustic Emission (AE) technique and moment tensor (MT) analysis were both applied to study the spatial-temporal evolution of micro-cracks of coarse-grained granite samples, containing a circular opening, which were subjected to uniaxial compression. The results show that AE locations are in agreement with the macroscopic fractures, observed on the surface of the granite specimens after the end of the experiments. Shear cracks are dominant as the ratio is more than 40% of the total number of events, tension cracks are fewer, since they accounted for more than 30% of the total events, and mixed-mode cracks represent a minimum proportion. © 2015 Elsevier Ltd. Source

Wang H.,CAS Wuhan Institute of Rock and Soil Mechanics | Li X.,CAS Wuhan Institute of Rock and Soil Mechanics | Mi Z.,Mining Company | Bai J.,Mining Company | Wang S.,Northern Engineering and Technology Corporation
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

Based on the investigation, test and numerical analysis of the mine dumps, it is believed that the key of disaccord between results from the 2D-LEM and reality is system spatial effect under the interaction of base and dump body. The spatial clamp effect of convex and divergent effect of concave are explained, as well as essential relationship between height and radius of curvature which should be abided by 2D or 3D stability analysis is given on the basis of field test, theoretical analysis and physical model. Furthermore, the safe class, evaluation criterion and technical route which takes the factor of stability as major and also considers stress, displacement fields and plastic region distribution is established, under the principle that the deformation and partial failure are allowable. Source

Li X.,CAS Wuhan Institute of Rock and Soil Mechanics | Ren W.,CAS Wuhan Institute of Rock and Soil Mechanics | Wang S.,Northern Engineering and Technology Corporation | Wang H.,CAS Wuhan Institute of Rock and Soil Mechanics | Cui Y.,CAS Wuhan Institute of Rock and Soil Mechanics
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

There are some controversies on the selection of stability calculation methods when preparing for the new specification of waste dump. We evaluate the accuracy and applicability of 7 limit equilibrium methods by using the difference percentage and standard deviation of safety factors in waste dump slope stability analysis. Combined with previous research, the application of limit equilibrium method in waste dump slope analysis is described. Ordinary method has a poor accuracy. The accuracy is larger than 30% and the standard deviation is large when dealing with ground water problem. Its calculation result can be used as a lower limit. Bishop method has an accuracy of 3.7% and good standard deviation, although only satisfying moment equilibrium. For the simple algorithm, it is recommended as a basic method. The correct values can be obtained from methods satisfying force and moment equilibrium, which applies to a variety of conditions. Source

Kang Y.-M.,Northeastern University China | Zhao S.-Y.,Northern Engineering and Technology Corporation | Wang T.-T.,Northeastern University China | Liu S.-Z.,Northeastern University China
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2015

Based on the characteristics of acoustic emission(AE) signals of rock, decomposition, de-noising and reconstruction for the acoustic emission signals were conducted through wavelet packet transform. It is found that the signal denoised by the wavelet packet transform (WPT) method has a higher signal-to-noise ratio (SNR) and a lower distortion than those by other methods based on wavelet transform (WT) methods and the WPT method shows the overall superiority. ©, 2015, Northeastern University. All right reserved. Source

Li Y.-G.,Northeastern University China | Kong X.-N.,Northern Engineering and Technology Corporation | Gao Y.-Y.,Northeastern University China
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

Considering that the bolt looseness induces the variation of dynamic parameters of joint of bolt connection, a detection method was proposed based on vibration signals of two connected parts. The probability densities of the two signals were calcuated, the probability density curves were processed by a mesh to obtain probability matrixes, and were the probability matrixes were transformed by using principal component analysis (PCA) method. After PCA, two projection matrixes of the probability matrixes were merged to one matrix. To this matrix, PCA and projection were implemented again. According to the peculiarity of bolt looseness, tow detection modes are designed based on the proposed method. The mode 1 carries out training work using foregone samples to generate projection points of each looseness condition employing the proposed method, then in detection, Euclidean distance between projection point and each foregone projection point was used as estimation criterion. The mode 2 directly detects looseness condition by using proposed method based on the signals of tight bolt connection condition and field measurement, and a criterion for judging bolt looseness was designed. The experimental verification shows that the proposed method can distinguish different looseness conditions, and the detection mode 2 is easy and simple to be handled without foregone fault samples. ©, 2015, Chinese Vibration Engineering Society. All right reserved. Source

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