Shear strength degradation characteristics of expansive soil during#br#
freeze-thaw process considering moisture migration
LI Yanlong1，2，WANG Zili2
(1. School of Civil Engineering，Xuchang College，Xuchang，Henan 461000，China；
2. Yellow River Institute of Hydraulic Research，Yellow River Conservancy Commission，Zhengzhou，Henan 450003，China)
Abstract：The shear strength of soil would be deteriorated by moisture migration and the accompanying phenomenon during freeze-thaw process. For the prevention and treatment of freeze-thaw diseases in expansive soil engineering，it is necessary to ascertain the degradation effect of moisture migration on the shear strength of expansive soil. By simulating real freeze-thaw boundary conditions，the moisture migration experiments of expansive soil under the axial freezing and bidirectional thawing action were carried out，and direct shear tests were conducted. The moisture field，temperature field and vertical deformation of expansive soil were monitored during the test. The research results show that the moisture migration quantity is influenced by the freezing temperature gradient，and that the expansive soil during freezing-thawing shows frost heave and thawing settlement characteristics and the thawing settlement is slightly larger than the frost heave. The variation of the shear strength has a high consistency with the water content redistribution along the depth direction. For specific performance，the shear strength of frozen soil attenuates when the water content increases，while the shear strength of unfrozen soil increases mildly with decreasing the water content. The variations of shear strength indexes and moisture field redistribution also show a high consistency along the depth direction. Specifically，shear strength indexes decrease when the water content increases. The attenuation degree of the cohesive force is significantly greater than that of the internal friction angle. The decrease of the cohesive force is the main reason of freeze-thaw deterioration the shear strength for expansive soil.
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2019, Vol. 38 
