人工冻土蠕变试验及损伤经验模型分析

Study on Creep Test and Empirical Damage Model of Artificial Frozen Soils

在冻结法施工中,掌握冻土的蠕变特性对评价冻结壁的稳定性至关重要。文章通过对山西某矿粘土层进行不同冻结温度下单轴抗压及蠕变试验,得到蠕变随冻结温度、加载应力变化的规律。在分析Kachanov损伤理论模型及人工冻土蠕变经验模型特性的基础上,建立人工冻土理论-经验蠕变模型。通过对比分析建立模型计算值与人工冻结粘土蠕变试验结果,模型计算曲线与试验数据曲线拟合度较高,两者均反映了初始弹性变形、应变加速度逐渐减小至加速度为零的过程;若试样发生破坏,曲线则会在应变加速度为零的基础上继续加速上升。该模型能够反映深部人工冻土的各阶段蠕变特性,能为指导冻结法施工提供科学依据。

It is important to understand the creep characteristics of frozen soils to evaluate the stability of frozen walls during freezing construction.The uniaxial compressive and creep tests are conducted on the clay stratum of a mine in Shanxi province under different freezing temperatures,and the law of creep varying with freezing temperature and loading stress is obtained.Based on an analysis of the characteristics of Kachanov’s theoretical damage model and empirical creep model of artificial frozen soils,a theoretical-empirical creep model of artificial frozen soils is established.Through a comparative analysis on the calculated values of the model and the creep test results of artificially frozen clay,it is found that the curve of model calculations and the curve of experimental data fit very well,and both the curves show the process of initial elastic deformation,gradual decrease of strain acceleration and zero acceleration;the established model reflects the creep characteristics of deep artificial frozen soils in different stages.