Discontinuous deformation analysis of the kinematics of landslides.

摘要

Discontinuous Deformation Analysis (Shi, 1988, 1993) is used to investigate the kinematics of landslides. DDA is based on dynamic equilibrium and considers both friction and the kinematics of motion of individual blocks. It is well suited for stability analysis of geologic media, particularly jointed rock masses.; In order to facilitate slope stability analysis using DDA, several enhancements were added as a part of this research to increase the accuracy of the results. The displacement function was modified to allow a more accurate representation of rigid body rotations; plane strain boundary conditions and a gravity turn-on routine were also implemented. Validation was performed to verify the accuracy of the DDA results, particularly calculation of displacements and velocities, demonstrating that the method is capable of modeling kinematics and time dependent behavior of discontinuous media.; DDA analyses of slopes with compound failure surfaces indicate that kinematics has a major influence on their stability. Limit equilibrium methods may produce overly conservative results because they do not account for kinematics. However, this effect is less pronounced for curved failure surfaces.; The most significant aspect of the DDA method is that actual movement can be modeled; consequently, predictions can be made regarding block velocities and whether the blocks will accelerate or decelerate. Such predictions are of obvious practical significance in the analysis of field problems. Two case studies are presented to illustrate the strengths of DDA in the analysis of field problems. Analyses of the Vaiont landslide in northern Italy indicate that the velocity of sliding is very much a function of the kinematics of the landslide mass deformation. The results show that the computed slide mass velocity increases with increasing degree of discretization without even considering such phenomena as displacement-dependent strength parameters and/or pore pressure generation. Analysis of a large toppling failure located in northern California shows that the stable slope configuration can be predicted analyticaily, provided a realistic distribution of joint properties is assumed. Overall, the results of the analyses presented here show that DDA provides a viable and powerful alternative to the limit equilibrium methods currently in use.