Quasi-static method for dynamic safety coefficient of homogeneous pure clay slope under earthquake action

Abstract

The invention provides a quasi-static method for a dynamic safety coefficient of a homogeneous pure clay slope under an earthquake action, and the method is characterized in that the method comprises the following steps: deducing a pure clay normal stress and shear stress expression with an internal friction angle of zero, and substituting the pure clay normal stress and shear stress expression into a stress balance differential equation set containing an earthquake action coefficient; employing trigonometric transformation, deriving two groups of characteristic line differential equations of a slip line field under the action of an earthquake according to a characteristic line method, and solving the differential equations by adopting a finite difference method to obtain the slip line field under the action of the earthquake and a slope surface curve (a dynamic limit slope surface curve for short) under a dynamic limit state; giving active, transitional and passive area boundary conditions under the earthquake action; and finally, calculating a dynamic safety coefficient by adopting a concept of a strength reduction method, namely reducing the cohesive force, judging the dynamic stability of the homogeneous pure clay slope under the earthquake action according to positive and negative ordinate values of an intersection point of a dynamic limit slope curve and an ordinate axis, and judging that the slope is in a dynamic limit state when the ordinate value of the intersection point is zero; wherein at the moment, the reduction coefficient is the pure clay slope power safety coefficient.

Description

technical field [0001] The invention belongs to the field of slope stability evaluation, in particular to a quasi-static method for the dynamic safety factor of a homogeneous pure clay slope under earthquake action. Background technique [0002] When the internal friction angle of the cohesive soil medium that constitutes the slope is approximately equal to zero, the clay strength is mainly cohesive force, which is called pure clay. At present, there are two main methods for analyzing the dynamic stability of pure clay slopes under earthquakes: one is the limit equilibrium strip quasi-static method. The assumptions of the direction of the slices and the force between the soil strips will affect the calculation results. At the same time, it is necessary to use trial calculation or optimization methods to obtain the critical slip surface. Different critical slip surfaces will cause differences in the calculation results or only obtain a local optimal solution; Another method ...

AI Technical Summary

Problems solved by technology

At present, there are two main methods for analyzing the dynamic stability of pure clay slopes under earthquakes: one is the limit equilibrium strip quasi-static method. The assumptions of the direction of the slices and the force between the soil strips will affect the calculation results. At the same time, it is necessary to use trial calculation or optimization methods to obtain the critical slip surface. Different critical slip surfaces will cause differences in the calculation results or only obtain a local optimal solution; Another method is the concept of strength reduction combined with dynamic numerical analysis methods (such as dynamic finite element method). This method does not need to assume or search the critical slip surface to directly obtain the dynamic safety factor, but the dynamic instability criterion, that is, how Judging that the slope is in the limit state under earthquake is a key issue. At present, the main methods of dynamic instability criterion are: (1) Calculation non-convergence criterion. The complexity of the dynamic numerical analysis model will affect the calculation convergence, so that the dynamic limit There are errors in the determination of the state; (2) the displacement mutation criterion, sometimes the inflection point of the displacement curve of the dynamic feature point is not obvious, which requires human subjective judgment, and there will be human subjective factors in the selection of the feature point position; (3) the plastic zone penetration criterion It is generally believed that it is only a necessary but not sufficient condition for slope dynamic instability and failure.

Images