A constitutive model with double yielding surfaces for silty sand after freeze-thaw cycles
CHANG Dan1,LIU Jiankun1,LI Xu1,2
(1. School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;2. Transportation Industry Laboratory of Highway Construction and Maintenance Technology in Permafrost Regions-Qinghai Research Observation Base,Qinghai Research Institute of Transportation,Xining,Qinghai 810000,China)
Abstract:Based on the consolidated drained triaxial test on silty sand after freeze-thaw cycles,a constitutive model with double yielding surfaces was established by introducing the residual ratio of shear modulus and the numbers of freeze-thaw cycles. The experimental results showed that the stress-strain relationships exhibited strain hardening properties while the volumetric strain appeared shear contraction during the shearing process. The elastic shear modulus increased with the confining pressure but decreased firstly and then increased with the numbers of freeze-thaw cycles. The shear modulus dropped about 36% compared with the unfrozen silty sand. The shear yielding surface was expressed as a linear function cross the origin,while the volumetric one was represented as an elliptic curve. The shear and volumetric hardening parameters were related to the plastic strain and the numbers of freeze-thaw cycles and the non-associated flow rule was adopted. The proposed constitutive model with double yielding surfaces was verified by comparing the modeling results with the triaxial test results. The stress-strain curves predicted by the proposed model agreed well with the experimental results for both the unfrozen silty sand and the samples experiencing freeze-thaw cycles.
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