Unified Description of the Mechanical Properties of Typical Marine Soil and Its Application

Yongqiang Li,Liping Jing,Gang Wang,Xinjun Cheng,Lei Zhang

doi:10.1155/2017/3892193

Abstract

This study employed a modified elastoplastic constitutive model that can systematically describe the monotonic and cyclic mechanical behaviors of typical marine soils combining the subloading, normal, and superloading yield surfaces, in the seismic response analysis of three-dimensional (3D) marine site. New evolution equations for stress-induced anisotropy development and the change in the overconsolidation of soils were proposed. This model can describe the unified behaviour of unsaturated soil and saturated soil using independent state variables and can uniquely describe the multiple mechanical properties of soils under general stress states, without changing the parameter values using the transform stress method. An effective stress-based, fully coupled, explicit finite element–finite difference method was established based on this model and three-phase field theory. A finite deformation analysis was presented by introducing the Green-Naghdi rate tensor. The simulation and analysis indicated that the proposed method was sufficient for simulating the seismic disaster process of 3D marine sites. The results suggested that the ground motion intensity would increase due to the local uneven complex topography and site effect and also provided the temporal and spatial distribution of landslide and collapse at the specific location of the marine site.

Highlights

The seismic safety of marine sites in strong earthquake is receiving increased attention because of the potential serious hazard of earthquakes to offshore engineering
In the seismic response analysis of 3D marine sites, one of the key points is to build a constitutive model that can suitably describe the mechanical properties of marine soils; in particular, a reasonable description of the dynamic characteristics of marine soils is the most important task
The effects of water pressure and the pore water pressure cannot be neglected in the seismic response analysis of marine site

Summary

Introduction

The seismic safety of marine sites in strong earthquake is receiving increased attention because of the potential serious hazard of earthquakes to offshore engineering. In the seismic response analysis of 3D marine sites, one of the key points is to build a constitutive model that can suitably describe the mechanical properties of marine soils; in particular, a reasonable description of the dynamic characteristics of marine soils is the most important task. Zhang et al [3] introduced a new approach to describe the stress-induced anisotropy They noted that the change in density is influenced by plastic stretching and elastic unloading and stress-induced anisotropy. Based on their model, the mechanical behaviour of soil subjected to different loadings under different drainage conditions was simulated. The above constitutive models are all based on the Cam-Clay

Objectives

Results

Conclusion