In order to obtain the earth pressure coefficient at rest (K0) at higher consolidation pressures during secondary compression, a series of K0 tests for saturated reconstituted clay were conducted. The results indicate that the measured K0 in secondary compression can be described by equations related to internal friction angle, secondary compression coefficient, compression index, recompression index, and sediment time. Effects of consolidation pressures and sediment time on K0 during secondary compression can be attributed to cementation (part of cohesion) increase and internal friction angle decrease. Cementation increase leads to nonlinear variation for K0 and internal friction angle decrease results in increase of K0. K0 computed by equations associated with internal friction angle is overestimated at apparent lower consolidation pressures with different sediment time, which agrees with the measured values well at apparent higher consolidation pressures.
A series of triaxial compression tests for frozen clay were performed by K0DCGF (freezing with non-uniform temperature under loading after K0 consolidation) method and GFC (freezing with non-uniform temperature without experiencing K0 consolidation) method at various confining pressures and thermal gradients. The experimental results indicate that the triaxial compression strength for frozen clay in K0DCGF test increases with the increase of confining pressure, but it decreases as the confining pressure increases further in GFC test. In other words, the compression strength for frozen clay with identical confining pressure decreases with the increase in thermal gradient both in K0DCGF test and GFC test. The strength of frozen clay in K0DCGF test is dependent of pore ice strength, soil particle strength and interaction between soil skeleton and pore ice. The decrease of water content and distance between soil particles leads to the decrease of pore size and the increase of contact area between particles in K0DCGF test, which further results in a higher compression strength than that in GFC test. The compression strength for frozen clay with thermal gradient can be descried by strength for frozen clay with a uniform temperature identical to the temperature at the height of specimen where the maximum tensile stress appears.
