Huang L.-X.,CAS Wuhan Institute of Rock and Soil Mechanics
Yantu Lixue/Rock and Soil Mechanics | Year: 2011
In rock dynamics, one of typical types of loading is impact loading, which can induce the strain rate up to 1 × 10 -1-1 × 10 4 s -1. Impact loading can be generated by a dynamic machine, Hopkinson bar testing equipment and blasting, and is used to investigate the dynamic behavior of rock. When rock is subjected to dynamical loading, inertial effect will become significant. Hence the objective of rock dynamics is to investigate the propagation and dissipation of stress waves in rock, the interaction between the stress waves and the joints of rocks, the reflection, diffraction and injection of the stress waves in layered materials. Initial study of rock dynamics in China could be traced back to the early sixties of last century, when the dynamic effect of blasting on the slope stability of Daye Iron Mine was investigated. Comprehensive research for such a subject started in 1965, when State Commission of Science & Technology and National Defense Commission of Science & Technology approved to establish the defense engineering research group, and launched "construction and research for protective engineering" as a key national research program. Through such events, China built up the foundation for its rock dynamics study. In 1987, the Commission of Rock Dynamics, a sub-committee of Chinese Society of Rock Mechanics and Engineering was founded; and this event became the milestone of the further development of rock dynamics. Members of the commission came from universities and research institutions of water conservancy, hydropower, energy, mining, coal, petroleum, railway transportation etc. Organized by the commission, the "National Conference for Rock Dynamics" has been held every two years, making a great contribution to the advancement of rock dynamics research. This paper will introduce the development and new achievements of rock dynamics in China recent 10 years; and it can be divided into two parts, i.e. the past achievements and the future development trends.
Zheng H.,CAS Wuhan Institute of Rock and Soil Mechanics
Engineering Geology | Year: 2012
In the stability analysis of landslides based on limit equilibrium methods, the "rigorous" methods that satisfy complete equilibrium conditions are more reliable and are preferred. For two-dimensional analyses, the rigorous methods of slices are becoming mature in both theory and practice. However, the attempts to realize their three-dimensional rigorous counterparts have not yet been realized. Introducing the Morgenstern-Price (M-P) assumption on the internal forces of the slip body, this study presents the three-dimensional version of the M-P method, which is rigorous and applicable to failure surfaces of complex shape. In the formulation, meanwhile, the volume integrals over the slip body are transformed into the boundary integrals, rendering column-partitioning unnecessary. The methodology developed in this study can be utilized to extend those two-dimensional rigorous methods of slices to their three-dimensional rigorous versions. © 2012 Elsevier B.V.
Zheng H.,Beijing University of Technology |
Xu D.,CAS Wuhan Institute of Rock and Soil Mechanics
International Journal for Numerical Methods in Engineering | Year: 2014
Aiming to solve, in a unified way, continuous and discontinuous problems in geotechnical engineering, the numerical manifold method introduces two covers, namely, the mathematical cover and the physical cover. In order to reach the goal, some issues in the simulation of crack propagation have to be solved, among which are the four issues to be treated in this study: (1) to reduce the rank deficiency induced by high degree polynomials as local approximation, a new variational principle is formulated, which suppresses the gradient-dependent DOFs; (2) to evaluate the integrals with singularity of 1/r, a new numerical quadrature scheme is developed, which is simpler but more efficient than the existing Duffy transformation; (3) to analyze kinked cracks, a sign convention for argument in the polar system at the crack tip is specified, which leads to more accurate results in a simpler way than the existing mapping technique; and (4) to demonstrate the mesh independency of numerical manifold method in handling strong singularity, a mesh deployment scheme is advised, which can reproduce all singular locations of the crack with regard to the mesh. Corresponding to the four issues, typical examples are given to demonstrate the effectiveness of the proposed schemes. © 2014 John Wiley & Sons, Ltd.
Li J.C.,CAS Wuhan Institute of Rock and Soil Mechanics
Geophysical Journal International | Year: 2013
Studying wave propagation across joints is crucial in geophysics, mining and underground construction. Limited analyses are available for oblique incidence across non-linear joints. In this paper, the time-domain recursive method (TDRM) proposed by Li et al. is extended to analyse wave propagation across a set of non-linear joints. The Barton-Bandis model (B-B model) and the Coulomb-slip model are adopted to describe the non-linear normal and shear properties of the joints, respectively. With the displacement discontinuity model and the time shifting function, the wave propagation equation is established for incident longitudinal-(P-) or transverse-(S-)wave across the joints with arbitrary impinging angles. Comparison between the results from the TDRM and the existing methods is carried out for two specific cases to verify the derived wave propagation equation. The effects of some parameters, such as the incident angle, the joint spacing, the amplitude of incidence and the joint maximum allowable normal closure, on wave propagation are discussed. ©The Author 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.
Fan H.,Northwest University, China |
Kong L.,CAS Wuhan Institute of Rock and Soil Mechanics
Canadian Geotechnical Journal | Year: 2013
As indicated by the theory of a clay-water-electrolyte system, the dispersive mechanism of cohesive soil involves three aspects: low clay content, high sodium ion percentage, and strongly alkaline pH. Accordingly, an empirical equation was established with an associated procedure and criteria proposed for evaluating the dispersivity of cohesive soil. The equation consists of four soil physical and chemical indicators: liquid limit (WL), clay content (PC), sodium percentage in the pore water (PS), and pH. The equation is F = 4 - 0.01(2WL + PC - PS) + 0.1 pH, where F is the soil dispersivity value. Compared with the evaluation based on laboratory tests, the empirical equation had higher accuracy for the evaluation of the dispersivity of cohesive soil, and was thus conducive to greater engineering safety. This indicates that the proposed empirical equation is applicable for evaluating the dispersivity of cohesive soil in general engineering.