干湿循环作用下红黏土无侧限抗压强度与电阻率关系研究

Relationship between unconfined compressive strength and electrical resistivity of red clay under dry and wet cycles

为了探索快速准确评价红黏土在单轴载荷作用下的力学行为的新型手段,以桂林红黏土为研究对象,在室内开展干湿循环作用下红黏土的无侧限抗压强度试验,并采用二相电极法同步测定土体电阻率的变化过程,得到不同干湿循环次数下红黏土应力应变电阻率同步变化曲线,进一步分析干湿循环作用对无侧限抗压强度、初始电阻率、破坏电阻率的影响,最后探讨出无侧限抗压强度与初始电阻率、破坏电阻率之间的定量关系。试验结果表明:干湿循环作用使红黏土产生不可逆的体积收缩和结构破坏,且这种作用效应主要发生在前2次干湿循环;0~5次干湿循环作用下红黏土的应力应变电阻率同步变化曲线呈现出相反变化趋势且临界点较吻合,应力应变曲线先陡升后下降,与之对应的电阻率应变关系曲线先陡降后上升;红黏土无侧限抗压强度、初始电阻率、破坏电阻率均随干湿循环次数的增加而减小,且无侧限抗压强度和初始电阻率的衰减主要发生在前2次干湿循环;不同干湿循环次数下的红黏土的无侧限抗压强度与初始电阻率、破坏电阻率均呈现出良好的正向指数关系。

In order to find a new method for quick and accurate evaluation of the mechanical behavior of red clay under uniaxial loading,the stress-strain-electrical resistivity test for Guilin red clay is carried out under different dry and wet cycles during the whole process of unconfined compressive strength test.The stress-strain-resistivity curve of red clay under different dry and wet cycles is obtained.Meanwhile,the effect of dry and wet cycles on unconfined compressive strength,initial resistivity and damage resistivity is analyzed.Finally,the quantitative relationship between unconfined compressive strength,initial resistivity and destructive resistivity is discussed.The experimental results indicate that dry and wet circulation causes irreversible volume shrinkage and structural damage of red clay,and this effect mainly occurs in the first two dry and wet cycles.The synchronous curves of stress-strain-resistivity under different dry and wet cycles show good matching.The stress-strain curve first rises sharply and then falls,and the corresponding resistivity-strain relationship curve decrease steeply and then rises.The unconfined compressive strength,initial resistivity,damage resistivity decrease with the increase of the number of dry and wet cycles,and the attenuation of unconfined compressive strength and initial resistivity mainly occurs in the first two wet and dry cycles.The unconfined compressive strength of red clay under different dry and wet cycles has a good positive exponential relationship with initial resistivity and damage resistivity.