Collapse behavior of sand

Abstract

Loose cohesionless materials can collapse during either static or dynamic loading, resulting in a rapid buildup of pore pressure and associated reduction in shear resistance. As the cohesionless material collapses, it rapidly looses resistance until the acting shear stress decreases to the available residual or steady-state strength. Specially designed stress-path testing has been performed on sand to investigate this collapse process. Results from this test program and previously published data show that a state boundary can be defined when a cohesionless material moves from peak to steady state along a constant void ratio stress path regardless of whether it is loaded drained or undrained. Further, it is demonstrated that the state boundary represents a surface in the effective mean normal stress–deviator stress–void ratio space. Hence, flow slides and liquefaction can be initiated when the stress path followed during either drained or undrained loading attempts to cross this state boundary surface. Key wordy : sand, collapse, liquefaction, stress path, state boundary, triaxial test.

Effect of triaxial specimen size on engineering design and analysis

“…We observed that the void ratio of these samples deviated by less than ±0.6 % (±0.005) from the average void ratio of the specimen. This is consistent with the void ratio variations of undercompacted moisttamped specimens found by Sasitharan (1994).…”

Evaluation of Babolsar Sand Behaviour by Using Static Triaxial Tests and Comparison with Case History

“…Chern (1983) [16], Kramer and Seed (1988) [17], Vasquez-Herrera and Dobry (1989) [18], Lade (1992) [19], (1993) [20], Ishihara (1993) [21], Konrad (1993) [22], Sasitharan et al (1993) [23], (1994) [24] and among others) identified similar yield conditions and proposed various names for these conditions. The collapse line is considered as a limit state boundary between the stable and the unstable states of soil undrained behaviour.…”

Factors affecting pre-failure instability of sand under plane-strain conditions

“…For example, during water infiltration, a soil element in a slope may follow a CSD stress path, as suggested by Brand (1981). Along this stress path, a soil element may become unstable under fully drained conditions (Sasitharan et al, 1993;Skopek et al, 1994;Anderson & Riemer, 1995;Anderson & Sitar, 1995;Chu et al, 2003;Leong, 2004;Loke, 2004;Wanatowski, 2005;Wanatowski et al, 2010).…”

“…Therefore, as suggested by Brand (1981) when investigating the failure mechanisms of a slope, the stress-strain behaviour of the soil along stress paths that simulate water infiltration should be studied. Such stress paths may be idealised as paths with constant shear stress, but decreasing mean effective stress, or the so-called constant shear drained (CSD) tests performed under constant deviatoric stress (Brand, 1981;Sasitharan et al, 1993;Skopek et al, 1994;Anderson & Riemer, 1995;Anderson & Sitar, 1995;Chu et al, 2003;Orense et al, 2004;Daouadji et al, 2010).…”

“…Several experimental studies on pre-failure instability behaviour of sand have been reported in the past (Sasitharan et al, 1993;Skopek et al, 1994;Chu & Leong, 2001;Chu et al, 2003;Orense et al, 2004;Sento et al, 2004;Daouadji et al, 2010). However, all the above cited studies were carried out under axisymmetric conditions.…”