砒砂岩重塑土强度和应力-应变曲线试验研究

Experiment study on strength and stress-strain curve characteristics of Pisha-sandstone remolded soil

以内蒙古鄂尔多斯市南部准格尔旗作为研究区域,以当地紫红色砒砂岩重塑土为研究对象,使用TSZ-6A全自动静三轴仪,在常温下进行不同冻融循环次数、不同围压下的三轴剪切试验来分析砒砂岩的变形情况.研究结果表明:在每个冻融循环次数的不同围压下,砒砂岩重塑土试样的应力-应变曲线都呈现出应变硬化的特性,并且从应力-应变曲线分布上,大致都经历了3个阶段:近似完全弹性阶段、应变硬化阶段、屈服阶段.为了定量地分析了不同冻融循环次数下砒砂岩的强度参数,引入强度参数劣化系数KC和KΦ,通过劣化系数曲线拟合得出强度参数劣化趋势函数.通过比较不同冻融循环次数下,砒砂岩重塑土峰值强度与残余强度的大小关系,分析了砒砂岩重塑土的应力-应变曲线软、硬化特性,并引入系数Kq来更直观地分析砒砂岩的变形情况.

The research area of this research project was Zhungeer Banner in the southern part of Erdos,Inner Mongolia,with the local reddish purple sandstone remolded soil as the research object.This test was conducted under different numbers of freeze-thaw cycle and different confining pressures by using TSZ-6 A full automatic static triaxial apparatus. The results show that in each of the freeze-thaw cycles under different confining pressures. Pisha-sandstone remolded soil stress-strain curve presents the characteristics of the strain hardening. Stress-strain curve roughly experiences three stages with the increase of axial strain including nearly completer elastic range,strain hardening stage and Yielding stage. In order to quantitatively analyze the strength parameters of Pisha-sandstone under different freeze-thaw cycles,the strength parameter degradation coefficients KCand KΦwere introduced,and the degradation trend function of strength parameters were obtained by fitting the degradation coefficient curve. Then the hardening properties and softening properties of stress-strain curve of Pisha-sandstone remolded soil were analyzed after comparing the relationship between Pisha-sandstone peak strength and residual strength under different numbers of freeze-thaw cycles. Kqwas utilized to analyze the deformation of Pisha-sandstone directly.