Liquefaction Behavior of Toyoura Sand Under Cyclic Strain Controlled Triaxial Testing Available to Purchase

To investigate the possibility of using conventional strain controlled triaxial testing apparatus for liquefaction determination of sands. The effects of repeated monotonic loading and unloading over a range of densities and at various strain amplitudes are shown to be linked with the cyclic behavior in a cyclic stress controlled triaxial testing program, using a unique loading apparatus and control program. Various parameters such as excess pore pressure developed during monotonic loading and the apparent maximum strength of the sample are shown to correlate to the cyclic resistance determined by a suite of cyclic triaxial tests. A comparison between strain-controlled cyclic triaxial testing and stress-controlled cyclic triaxial testing shows similar results in the critical 10-cycle region. Strain-controlled testing more closely reflects the available data and may lead to reduced costs in performing liquefaction resistance assessments. Introduction Numerous research efforts in the past have linked the monotonic loading behavior of soil with the cyclic behavior (Castro and Poulos(1977), Vaid and Chern (1983, 1985), Vaid and Thomas(1994)). The critical stress ratio (CSR) and the phase transformation state have both been shown to directly bear on the cyclic loading behavior. It is well understood that a deposit of contractive sand that is stressed beyond the critical stress ratio moves into a region of decreasing stiffness and experiences rapid strain development. Predicting the cyclic stress ratio that will induce a sample to pass through this critical stress ratio in a given number of loading cycles by means of a suite of cyclic triaxial tests is the typical approach for major engineering works. Samples that move past the CSR will then either develop true liquefaction, limited liquefaction or strain hardening (Vaid and Chern (1983) depending on the relationship between the various factors Involved.