RESEARCH ON DEVIATORIC STRESS VARIATION LAWS FOR DEEP FROZEN CLAY AT DIFFERENT TEMPERATURE GRADIENTS
RESEARCH ON DEVIATORIC STRESS VARIATION LAWS FOR DEEP FROZEN CLAY AT DIFFERENT TEMPERATURE GRADIENTS
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发表时间：
2009
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通讯作者：
Lin Shengsheng
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作者：
Lin Shengsheng
采用K0固结前冻结法，在4种温度梯度下对深冻粘土进行了三轴加载和卸载试验，研究了加载和卸载过程中偏应力的衰减规律及偏应力的增加速率。结果表明：不同温度梯度下的偏应力增加速率与均匀温度场下的偏应力增加速率相似，可以用修正的Duncan-Chang双曲模型拟合；温度梯度对偏应力的影响大于温度梯度对偏应力的影响。在加载和卸载过程的初始阶段，最明显的规律是偏应力的增加速率和衰减程度都随温度梯度而减弱。在相同的轴向变形下，偏应力的衰减规律可以用衰减因子A来描述；A与温度梯度的关系与广义双曲模型吻合较好。卸载过程增强了深冻黏土初始阶段偏应力增加速率在加载和卸载过程中的衰减趋势；随着温度梯度的增大，卸载过程对随偏应力幅值衰减速率的影响明显大于加载过程。如果不考虑非均匀温度场和冻结壁卸载路径的影响，深层冻结黏土的强度会被高估。
The loading and unloading triaxial tests were carried out on the deep frozen clay at four temperature gradients using the method of freezing before K0 consolidation,and attenuation law for deviatoric stress as well as deviatoric stress increasing rates in the process of loading and unloading was investigated. The results show that the increasing rate of deviatoric stress at different temperature gradients is similar to that in the homogeneous temperature fields,which can be fitted by modified Duncan-Chang hyperbolic model. However,the influence of temperature gradients on the deviatoric stress is larger than that of the temperature. The most obvious regularity observed in the initial stage of loading and unloading process is that both increasing rates of deviatoric stress and attenuation degree are weakened by the temperature gradients. The attenuation law for deviatoric stress under the same axial deformation can be described by the attenuation factor A;and the relationship between A and temperature gradients agrees well with that of the generalized hyperbolic model. The unloading process enhances the attenuation trend of deviatoric stress increasing rates for deep frozen clay at the initial stage both in loading and unloading processes;and the influence of unloading process on the attenuation rates along with the amplitude of the deviatoric stress is obviously larger than that of the loading process as the temperature gradients increase. The strength of deep frozen clay would be overestimated if the effects of non-homogeneous temperature fields and unloading path for the frozen walls are neglected.