Undrained behaviour of Changi sand in triaxial and plane-strain compression

Abstract

The results of an experimental study of the undrained behaviour of Changi sand under axisymmetric and plane-strain conditions are presented. K 0 consolidated undrained plane-strain tests and K 0 or isotropically consolidated triaxial tests on very loose and medium dense specimens were conducted. The undrained behaviour of sand at very loose and medium dense states under plane-strain conditions was characterised and compared with that under axisymmetric conditions. It was observed that the undrained behaviour of very loose and medium dense sand under plane strain is similar to that under axisymmetric conditions. However, because of the formation of shear bands in plane-strain tests, the post-peak behaviour of medium dense sand in plane strain is different from that in triaxial tests. It was also established that an instability line for plane-strain conditions can be defined in a way similar to that for axisymmetric conditions. Using the state parameter, a unified relationship between the normalised slope of instability line and the state parameters can be established for both axisymmetric and plane-strain conditions. Using this relationship, the instability conditions established under axisymmetric conditions can be used for plane-strain conditions.

The strength and deformation behaviour of a residual soil in Singapore

“…The failure envelope was also compared between different type of tests with principal stress rotation, e,g., in CK 0 UC, CK 0 UE and CK 0 UDSS tests (see Figure 5.38). It is observed that the CK 0 UPS test gives the highest failure envelope, which is consistent with previous studies, such as Ladd & Lambe (1963), Ladd et al, (1980), Wanatowski & Chu (2008) and Mayne et al (2009).…”

“…As seen from Figure 5.38, the CK 0 UPS tests gave the highest failure envelope, i.e., CK 0 UPS tests gave the highest undrained shear strength (c u ) at the same stress level. This is consistent with many other previous studies (Ladd & Lambe, 1963;Ladd et al, 1980;Wanatowski & Chu, 2008;Mayne et al, 2009).…”

“…This is consistent with the study carried out on intact residual soil of Bukit Timah granite, which presented in Chapter 5. It is also consistent with many other previous studies (Ladd & Lambe, 1963;Ladd et al, 1980;Wanatowski & Chu, 2008;Mayne et al, 2009). Strength anisotropy was again observed in terms of c u /σ 1 ′ 0 .…”

Influence of Loading History and Boundary Conditions on Parameters of Soil Constitutive Models

“…This was proved, e.g., by the results of experiments carried out on Todi Clay, presented in the above mentioned work of Burland [7]. As far as the influence of boundary conditions on the shape of failure surface and parameters describing it is considered, Jefferies and Shuttle [36] and Wanatowski and Chu [79,80] in their studies of noncohesive soils proved that the aforementioned parameter M takes smaller values in plain strain compression than in triaxial conditions. This means that M value is affected by the intermediate principal stress.…”

Enhancing Constitutive Models for Soils: Adding the Capability to Model Nonlinear Small Strain in Shear

“…Wanatowski and Chu's [30] investigation on the undrained behaviour of Changi sand shows a continuous Advances in Civil Engineering strain-hardening behaviour for the medium-dense sand, which results in effective stress path approaching a constant stress ratio (asymptotic behaviour). Similar behaviour is also reported by other researchers and in different conditions [31][32][33][34].…”