不同加载速率下冻结黏土的强度及破坏特性

Strength and failure properties of frozen clay under varying loading rates

冻土在不同加载速率下的强度和变形特性,是改进冻土机械开挖方法和设备所需的重要参数。通过对冻结黏土进行单轴压缩试验,研究了不同温度和加载速率条件下冻结黏土的强度特性、模量特性和破坏特性。通过分析试验,得到以下结论:(1)冻结黏土的抗压强度和起始屈服应力均随温度的降低和加载速率的增大而增大,且起始屈服应力与抗压强度有很好的线性关系。(2)温度和加载速率对起始屈服模量和切线模量影响很大,不同温度条件下切线模量与加载速率存在对数函数关系。(3)在不同温度条件下,破坏应变和破坏时间均随加载速率的增大而减小。(4)在较大加载速率条件下,温度对冻结黏土的破坏应变和破坏时间影响不明显。

The strength properties of frozen soils under varying loading rates are the important parameters for improving the mechanical excavation methods and equipments. The strength, modulus and failure properties of frozen clay are studied through a series of uniaxial compressive tests conducted on remolded frozen clay samples. From the test results, it is concluded that （1） The compressive strength and the initial yield stress increase with the decreasing temperature and the increasing loading rate, and there exists a good linear relationship between the failure strength and the initial yield stress. （2） The initial yield modulus and the tangent modulus are sensitive to the temperature and loading rates, and there is a logarithmic function relationship between the tangent modulus and the loading rates under different temperatures. （3） The failure strain and damage time decrease with the increase of loading rates under different temperatures. （4） The effects of temperature on the failure strain and damage time are not evident at large loading rates.