|M.Sc Student||Lloyd Noam|
|Subject||Peudo Static Characterization of Slopes Subjected|
to Higher Accelerationthan than the Critical One
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Assaf Klar|
|Full Thesis text|
Common geotechnical earthquake engineering design approaches utilize acceleration levels to evaluate slope failure triggering and resulting permanent displacements, using pseudostatic stability analyses together with the Newmark method. These approaches assume a single sliding mechanism and do not take into account the possibility of multiple (increased in size) mechanisms due to higher accelerations than the critical one.
This thesis presents a “quasi-dynamic” analysis framework which aims to overcome some of the limitations of the classical methods and allows evaluation of the effect of higher acceleration (beyond the critical one) on the mechanism and the volume of the slide. The suggested framework combines concepts from pseudo-static analysis together with plastic flow, such that the developed mechanisms are restricted from transferring greater stresses than their yield values (and by that preventing factor of safety lower than 1.0). The approach may be said to be quasi-dynamic in which the failing mass continues to accelerate under the unbalanced forces (beyond the critical one), while the remaining stable body is static, until an additional, new mechanism develops.
The approach is applied to slopes characterized by ideal elastic-plastic material to demonstrate that in certain conditions an increase in the acceleration level, by itself, may alter the failure mechanism. However, In order to demonstrate that the resulting response of slopes subjected to high acceleration levels is not limited to the current framework, but in fact illustrates the actual response of slopes subjected to strong ground motion, a complete dynamic simulation is presented. Thus, it is postulated that despite its simplified nature, the quasi-dynamic procedure may be at least considered as a reliable, first approximation framework to evaluate slopes response to high acceleration levels.