An experimental investigation on the secondary compression of unsaturated GMZ01 bentonite
Résumé
The secondary compression behavior of compacted GMZ01 bentonite was experimentally investigated by conducting a series of suction-controlled high-pressure oedometer tests. GMZ01 bentonite powder was first exposed to suction controlled conditions at 110 MPa and then statically compacted to a dry density of 1.70 g/cm(3). Then, the compacted samples were hydrated to designed suctions using the vapor equilibrium technique and finally submitted to multi-staged loading oedometer tests. Corresponding results were presented in terms of stress-strain-time curves. Based on the test results, the incremental compression index C-c(*) and secondary compression index C-alpha were defined. Relationships between C-alpha(*),C-alpha, vertical stress and suction were analyzed. It is observed that both C-c(*) and C-alpha increase linearly with increasing vertical stress, which is different from the convex relationship reported by other researchers in saturated soils. Moreover, C-c(*) and C-alpha also increase with decreasing suction. The relationship between C-c(*) and C-alpha is linear in the considered stress range and the slope of this linear relationship (C-alpha/C-c(*)) increases with decreasing suction. Finally, a logarithm function is established between C-alpha(*)/C-c(*) and suction s, which represents the coupling of suction, creep and stress of GMZ01 bentonite.