Numerical simulation on undrained cylic triaxial test of soft marine clay considering end restrictions of soil specimen

Abstract

Soft marine clay is subjected to long-term cyclic loads such as waves or seismic loadings in marine environment. Numerous cyclic traixial tests have been conducted to investigate the dynamic behaviors of soft marine clay. However, due to the limitation of laboratory triaxial test, such as end restraints caused by friction between the loading caps, pedestal and the specimen, a perfect cyclic triaxial test is impossible in reality. In this study, taking two extreme boundary conditions into consideration, based on the “Cyclic Mobility (CM) Model”, an elastoplastic constitutive model and a soil-water coupled finite element-finite difference (FE-FD) code named as DBLEAVES, a series of numerical simulations on cyclic triaxial tests of soft marine clay are conducted. The influence of those factors such as, cyclic stress ratio (CSR), loading frequency and confining pressure are also discussed in detail. The results show that the CM Model can describe the mechanical behavior of clay under cyclic loading accurately. End restrictions have high influence on the cyclic response of clay by creating strain localization areas and extreme pore water pressure zone. This paper makes clear the significant influence of boundary conditions on the cyclic triaxial test results.