应力因素下的岩盐卸荷扩容试验研究

Test study of unloading capacity expansion characteristics of salt rock under stress factors

通过开展围压卸载试验,研究不同三轴应力状态下围压卸载对岩盐试件扩容特征的影响,以及扩容与卸载形式之间的关系。研究发现,(1)围压卸载时岩盐的体积扩容量与偏应力存在较为明显的对数关系;(2)卸载的初始围压对岩盐的扩容影响几乎不存在;轴压增大能够促进岩盐的扩容,使加速扩容点前移,且加速扩容点对应的偏应力与轴压的增加呈线性关系;(3)岩盐的膨胀系数(即横向应变与纵向变形的比值)随着偏应力的增大,呈现先线性增加后指数增加的趋势。

Through the confining pressure unloading experiments,the dilatation characteristics of salt rock under different triaxial stress states unloading pressure,and the relationship between dilatation and unloading method are researched.The results show that:(1) There is a logarithmic relationship between volumetric expansion of capacity and deviatoric stress during unloading confining tests.(2) Initial confining pressure value hardly effects the dilation of salt rock.The growth of axial pressure can promote the dilation,and make the accelerated-expansion-point appear forward.Meanwhile,the corresponding deviatoric stress linearly increases with the axial pressure.(3) With the increase of deviatoric stress,the expansion coefficient of salt rock(ratio of lateral strain to longitudinal deformation) will increase linearly at the beginning;and then exponentially.