Papers by Author: Wei Shen Zhu

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Authors: Wei Shen Zhu, Jian Hua Liu, Shu Cai Li
Abstract: A brief description is given to the visco-plastic constitutive model of 3-D FLAC software and some treating methods for the numerical analysis. The excavation steps and the exerting time of excavation loads are determined in the light of the real construction process. The rockmass mechanical parameters are determined according to back analysis of in-situ measured displacement data. The analysis results of displacement and stability of the opening complex surrounding rocks in the construction process and in a long period of time after excavation completion are given.
Authors: Xiao Jing Li, Wei Min Yang, Wei Shen Zhu, Shu Cai Li, Ai Hua Sun
Abstract: The jointed rock mass distributed in the nature widely and its mechanical characteristic influenced the stability of the rock engineering badly. The cracks propagated and coalesced each other and macroscopic failure happened. Bolts were a kind of effective reinforcement instrument and they could prevent the cracks from propagating. However, the anchoring mechanism of bolts was not realized clearly and their reinforcement could not be reflected effectively in the numerical simulation yet. Based on the damage mechanics, a constitutive relation and damage equation of anchored jointed rock mass were presented in this paper. With a project application, the model was proved to be feasible one.
Authors: Wei Shen Zhu, Shu Cai Li, R.H.C. Wong, K.T. Chau, Jian Xu
Authors: Dun Fu Zhang, Wei Shen Zhu, Shu Cai Li
Abstract: By use of complex variable theory, formulae for tangential stress on ellipse edge are derived. Sub-crack point, opening angle and maximal tangential stress on ellipse edge are studied under uniaxial compression, biaxial compression, or uniaxial compression and crack water pressure separately. Based on the maximal tension stress criterion, formulas of maximal tangential stress and critical load are presented. The results show that sub-crack point, opening angle, maximal tangential stress and critical load are varied with different aspect ratio and different inclined angle. Meanwhile, the most dangerous inclined angle is obtained.
Authors: Ning Liu, Wei Shen Zhu, Xiao Jing Li
Abstract: Considering the time effect of surrounding rock and the long time stability of the underground caverns after being excavated, a method on the finite element viscoelastic displacement based on Kelvin model. The recursion formula is obtained by the displacement analytic solution of Kelvin model. It can be used to predict the viscoelastic displacement development fast and accurately. Finally this method is employed into a project, and the calculated values by this method agree well with the measured values. Prove that the method is effective.
Authors: Song Yu, Wei Shen Zhu, Hao Zhou, Dun Fu Zhang
Abstract: Based on a shear test for jointed rock sample conducted by former study, a numerical improved method DDARF is carried out to simulate the shear test. The simulation result of shear fracture phenomenon show high compatibility with the model test. Different fracture phenomenon and peak strength value of shear testing are explored in the condition of different colinnear and ladder echelon arrangement of cracks.
Authors: Y.S.H. Guo, R.H.C. Wong, K.T. Chau, Wei Shen Zhu, Shu Cai Li
Abstract: A number of instability problems in rock engineering projects are caused by crack propagation. However, crack growth mechanisms from 3-dimentional flaw are not fully understood, in particular for 3-D flaw case with varied dipping angle. This study focuses on 3-D surface flaw using real rock specimens containing a flaw with varied inclination angle α from axial loading and dipping angle γ from specimen surface under uniaxial compression. Acoustic emission technique was used for tracing the initiation and growth of micro-cracks inside of specimen. It was found that crack growth process is affected by the dipping angle γ of the 3-D flaw. When dipping angle γ ≠ 90º, the thickness of rock above the flaw plane is thinner than that of below the flaw plane. As a result, compressive crack and wing crack initiated easily from the thinner flaw tips. And, the normalized stress for crack initiation σi /σc, AE events and the AE energy for crack growth decreases with the dipping angle γ. However, for γ = 90º, the thickness of rock above and below of the flaw tips is the same, it was observed that anti-wing crack (crack growth direction opposite to wing crack) initiated first at a certain place away from the flaw tips, then wing crack and compressive crack emerged at the late stage. For this case, the stress σi /σc, AE events and the AE energy for crack initiation and propagation are at a high value. Thus, for rock mass contains flaws geometry with small dipping angle, some problems of crack propagation may be induced easily during excavation.
Authors: Shuai Guo, Wei Shen Zhu, Yong Li, Chao Jia
Abstract: Referring to the previous shearing model tests on intermittence jointed rock mass, DDARF method was adopted to conduct the corresponding numerical simulation. It could be concluded from the cracking failure phenomena that the results of the numerical simulation and the tests were in good agreement. Then the intermittence joints were arranged as en echelon and different cracking failure phenomena, peak shear strengths and strain-stress relationships were also obtained.
Authors: Wei Shen Zhu, Yong Li, Min Yong, Q.B. Zhang, Shu Cai Li
Abstract: Geomechanics modeling has played important role in geotechnical engineering. In order to investigate on the stability of underground caverns at great depth, a large-scale geomechanics model test system was designed and manufactured. The system mainly consisted of a steel structural frame and a hydraulic loading control system, which can apply active loading on six sides with a true three-dimensional stress state. Newly developed combinational ball sliding walls were installed on each of the major loading surfaces, which were significantly reduced the friction due to model deformation. The system has apparent technical advantages such as high stiffness, great stability, and flexibility of assembly, and easy adjustment of its dimensions.
Authors: Qiang Yong Zhang, Wei Shen Zhu, Yong Li, X.H. Guo
Abstract: Geomechanics model test can simulate the real excavation process of geotechnical engineering and the mechanics deformation properties of the rockmass prototype on the condition of meeting the similar principles. In order to conducting geomechanics model test, similar material which can meet similar mechanical properties must be used. It is only after conducting a massive mechanics experiments that a new-type similar materials called iron crystal sand is developed in this paper. This material consists of iron ore powder, blanc fix, quartz sand, gypsum powder and rosin alcohol solution which are evenly mixed in certain proportion and pressed together. The iron ore powder, blanc fix and quartz sand among them are main materials. The rosin alcohol solution is the cementing agent and gypsum powder the regulator. The material mechanics experiments show that this material has following outstanding characteristics: high volume-weight, wide variable mechanical parameters, stable performance, low price, quick drying, simple processing and innocuity. It can simulate most rockmass material from soft to hard ones and can be widely used in geomechanics model tests in fields of energy sources, transportation, water conservancy and mining.
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