冻结重塑黏土损伤特性及影响因素分析

Damage properties and influence factors of remolded frozen clay

基于连续损伤力学理论及冻土横观各向同性损伤变量的计算方法，利用冻土常规三轴剪切试验，系统分析了不同温度、含水率和围压条件下冻结重塑黏土的损伤特性。研究结果表明：①不同试验条件下冻结重塑黏土损伤演化曲线规律一致，前期增长比较快速，后期变化相对平缓，且最大轴向损伤变量D1max般介于0．6～0．8之间：②温度对冻结重塑黏土损伤特性影响较明显，降低温度可以明显强化冻土结构，减少冻土结构的损伤及延缓冻土损伤的发展，而含水率和围压对其影响不明显；③割线模量可以较好地表征冻土在加载过程中裂缝的发展特点和结构的损伤演化规律，损伤初始点轴向应变和割线模量与温度之间存在较好的线性增长关系，且冻结重塑黏土损伤应变门槛值晶一般介于0．3％～0．7％，对应的割线模量一般介于200-550MPa。

Based on the theories of the continuum damage mechanics and the methods for transversely isotropic damage variables, the damage properties of remolded frozen clay are systematically analyzed under different temperatures, moisture contents and confining pressures by using the conventional triaxial shear tests. The research results show that： （1） the damage evolution behaviors of the remolded frozen clay under different test conditions are consistent, that is, the early stage has rapid growth and the later stage has gentle change and the maximum interaxial damage variable D~,~ generally ranges from 0.6 to 0.8; （2） the freezing temperature has obvious effect on the damage properties of the remolded frozen clay, and lowering the temperature may strengthen the structure obviously so as to reduce its structural damage and to delay its damage evolution; and （3） the secant modulus can well represent the development characteristics of cracks and the damage evolution behaviors of the remolded frozen clay during the loading procedure, and the relationship between the axial strain and the secant modulus of the damage threshold and temperature rises linearly, the damage strain threshold E0 generally ranges from 0.3% to 0.7% and the corresponding secant moduli generally range from 200 MPa to 550 MPa.