Numerical studies of seismically induced slope deformation using smoothed particle hydrodynamics method.

摘要

There has been growing interest in improving current procedures for estimating seismically-induced deformations of natural and man-made slopes due to recently frequent earthquake events and the resulted damaged to infrastructure systems. The aim of this study is to develop a numerical model to effectively and reliably assess seismically-induced slope deformations that typically involve large deformations and complex soil constitutive behaviors. A numerical model based on the meshfree Smoothed Particle Hydrodynamics (SPH) method has been developed by implementing various advanced constitutive models into the SPH formulations. The developed model is validated by two readily available and well-documented experiments: axisymmetric collapses of granular columns and model slope tests on a shaking table. For the former, the non-dilatant Drucker-Prager (D-P) constitutive relationship with perfect plasticity is used. The developed model precisely reproduces the experimentally-observed three regimes of flow patterns based on the initial aspect ratio of the granular column. In addition to the flow patterns, the simulated final deposit height and run-out distance along with the non-deformed region after the collapse of granular columns are in excellent agreement with experimental data in the literature. For the latter, a constitutive model that combines the strain-softening viscoplasticity and Modified Kondner and Zelasko (MKZ) rule is implemented and utilized to account for the effects of wave propagation in the sliding mass, cyclic nonlinear behavior of soil, and progressive reduction in shear strength during sliding, which are not explicitly considered in various Newmark-type analyses widely used in the current research and practice in geotechnical earthquake engineering. The initiation of slope failure and subsequent progressive development of the sliding surface are successfully captured by the developed SPH model. A localized shear band along the failure surface and a bulge near the toe of the model slope are observed in the simulations, showing a good agreement with the experimental observations. The simulated failure mode, displacement time histories, and acceleration response spectra at several monitor locations along the model slope also agree well with the experimental recordings.;Based on the validated SPH model, a parametric study is followed to investigate the effects of spatial parameters including both particle spacing and smooth length on the accuracy of SPH simulations. The parametric study also investigates the effects of material strength and shear modulus along with boundary conditions on the seismically-induced slope deformations, providing insights into the mechanisms of earthquake-induced slope deformations. It is thus suggested that the proposed SPH model is an effective tool for assessing the seismic performance of soil slopes. It may be also used to advance the computational capability of modeling geotechnical engineering phenomena involving large deformations.