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冻土的变形和强度受温度、水分及压力的影响甚为显著。通过对-6℃的冻结粉质黏土在初始含水率为12.5%~20%范围内进行一系列的三轴试验,分析初始含水状态对冻土变形和强度的影响规律。研究发现,当初始含水率较低时,随着围压的增大,冻结粉质黏土相继出现应变软化和应变硬化特征;当初始含水率大于16%时,其应力-应变关系主要呈现出应变软化特征;随着初始含水率的增大,初始切线模量随围压从线性缓慢增大逐渐过渡为抛物线形的分布。同时,根据包络线定理,建立非线性摩尔-库仑强度准则,用以描述初始含水率为12.5%、14%和16%的冻结粉质黏土强度随围压变化的非线性;当初始含水率为18%和20%时,其强度可用线性摩尔-库仑强度准则描述。
The deformation and strength of frozen soil are greatly affected by temperature, moisture and pressure. A series of triaxial tests were carried out on the frozen silty clay at -6 ℃ in the initial moisture range of 12.5% ~ 20% to analyze the effect of initial water content on the deformation and strength of frozen soil. The results show that when the initial moisture content is low, the strain-softening and strain-hardening characteristics of frozen silty clay occur with the increase of confining pressure. When the initial moisture content is more than 16%, the stress-strain relationship of the frozen silty clay mainly shows strain Softening characteristics. With the increase of initial water content, the initial tangent modulus gradually changes from parabolic linear to parabolic with the increase of confining pressure. At the same time, according to the envelope theorem, a nonlinear Moore-Coulomb strength criterion is established to describe the non-linearity of the intensity of frozen silty clay with the initial pressure of 12.5%, 14% and 16% Is 18% and 20%, the intensity can be described by the linear molar-Coulomb strength criterion.