Entity

Time filter

Source Type


Wei W.,Wuhan University | Jiang Q.-H.,Wuhan University | Jiang Q.-H.,State Key Laboratory of Water Resources and Hydropower Engineering | Zhou C.-B.,Wuhan University | Zhou C.-B.,State Key Laboratory of Water Resources and Hydropower Engineering
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The dynamic relaxation algorithm is used to solve quasi-static problems in numerical manifold method (NMM). However, the mechanism of energy dissipation of NMM is unclear. In this paper, the viscous-type and self-adaptive dampings are adopted to absorb the kinetic energy caused by the oscillation of system. The equilibrium equations containing damping term are derived by minimizing the total potential energy. A new algorithm for simulation of sequential excavation in rock masses is proposed. The excavation faces are considered as the special kind of discontinuity, and the phased excavation process is simulated through setting contact states of excavation faces according to excavation sequences. The convergence criterion including displacement and acceleration criteria are defined to determine whether the system reaches new equilibrium or not. The numerical results show that the improved NMM has good convergence performance and that the results from NMM agree with those from UDEC and analytical solutions. Source


Wei W.,Wuhan University | Wei W.,State Key Laboratory of Water Resources and Hydropower Engineering | Jiang Q.,Wuhan University | Jiang Q.,State Key Laboratory of Water Resources and Hydropower Engineering | And 2 more authors.
Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics | Year: 2014

The large deformation of structure calculated by original numerical manifold method (NMM) is cumulated by small deformation calculated in each time step. However, when the structure undergoes large deformation and large rotation, the calculation strategy used in original NMM will lead to calculation error. In order to solve this problem, in this study, combining the interpolation function of NMM, the Numerical Manifold Method based on finite deformation theory is deduced from integral weak form of the momentum conservation equation and the stress boundary conditions. The comparison between the iteration schemes of original NMM and improved NMM points out the sources of error calculated by original NMM for the large deformation problem. Finally, examples of large deformation cantilever and rotation block are employed to exam the improved NMM. The numerical result shows that the improved NMM handles the problem involving in large deformation and large rotation very well. The result calculated by the improved NMM eliminates the errors caused by rotation of structure and is coincide with the analytical solution and Abaqus numerical solution very well. Source


Wei W.,Wuhan University | Wei W.,State Key Laboratory of Water Resources and Hydropower Engineering | Lu R.L.,Wuhan University | Lu R.L.,State Key Laboratory of Water Resources and Hydropower Engineering | And 2 more authors.
Rock Characterisation, Modelling and Engineering Design Methods - Proceedings of the 3rd ISRM SINOROCK 2013 Symposium | Year: 2013

The dynamics relaxation algorithm is used to solve quasi-static problem in Numerical Manifold Method (NMM). However, the mechanism of energy dissipation of NMM is unclear. In this study, the viscous-type damping is adopted to absorb the kinetic energy caused by the oscillation of system. The equilibrium equations containing damping term are derived by minimizing the total potential energy. In order to improve the calculation efficiencies of NMM, convergence criterion including displacement and acceleration criterion are defined to determine whether the system reach new equilibrium. The example of strip foundation settlement is calculated to demonstrate the capability of the NMM with new extensions. The numerical results show that the improved NMM has high accuracy and good convergence performance. © 2013 Taylor & Francis Group. Source


Ye Z.,State Key Laboratory of Water Resources and Hydropower Engineering | Ye Z.,Aramco Research Center | Liu H.-H.,Aramco Research Center | Jiang Q.,State Key Laboratory of Water Resources and Hydropower Engineering | And 3 more authors.
Advances in Water Resources | Year: 2015

A systematic numerical method has been presented to investigate the constitutive relationships between two-phase flow properties of horizontal fractures and aperture distributions. Based on fractal geometry, single rough-walled fractures are generated numerically by modified successive random addition (SRA) method and then aperture distributions with truncated Gaussian distribution are formed by shear displacement between lower and upper surfaces. (The truncated Gaussian distribution is used to describe aperture evolution under different normal stresses.) According to the assumption of two-dimensional porous media and local parallel plate model, invasion percolation approach is employed to model the two-phase flow displacement (imbibition) in generated horizontal fractures, in which capillary forces are dominant over viscous and gravity forces. For truncated Gaussian distributions, constitutive relationships from numerical simulation are compared to closed-form relationships and a good agreement is obtained. The simulation results indicate strong phase interference with the sum of two phase relative permeability values being less than one in the intermediate saturations. It is found that fracture properties related to residual saturations depend on spatial correlation of aperture distributions. Based on the simulation results, we proposed an empirical relationship between the fracture residual-saturation-rated parameters and the corresponding aperture distributions. © 2014 Elsevier Ltd. All rights reserved. Source


Ye Z.,Wuhan University | Ye Z.,State Key Laboratory of Water Resources and Hydropower Engineering | Jiang Q.,Wuhan University | Jiang Q.,State Key Laboratory of Water Resources and Hydropower Engineering | And 3 more authors.
Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics | Year: 2013

To solve non-steady seepage flow problems with free surface in fractured rock masses, Darcy's law is extended to the entire domain. A parabolic variational inequality (PVI) formulation, in which a Signorini's type of boundary condition enforced on the potential seepage surface, is established for transforming the flux condition on the potential seepage surface into natural boundary conditions, and then proved to be equivalent to the partial differential equation (PDE) formulation, and then the difficulty in solving this problem is reduced. Finite element numerical solution of the PVI formulation is proposed, and the validity of the numerical approach is verified by comparison of theoretical and calculated results for cross fracture model. Finally, the proposed approach is applied for non-steady seepage flow behaviors in a complex fractured rock slope, and the calculation results validate the reliability and robustness of this method well. Source

Discover hidden collaborations