冻融循环对鄂尔多斯砒砂岩重塑土样力学性能影响

为了分析内蒙古南部鄂尔多斯市准格尔旗砒砂岩重塑土的力学性能,采用TSZ-6A全自动静三轴仪,在常温下进行不同冻融循环次数的三轴压缩试验,研究冻融对砒砂岩重塑土力学性能的影响.在不同冻融循环次数(0~7次)和不同围压(50~300 kPa)条件下,得到了砒砂岩抗剪强度、内摩擦角和黏聚力、弹性模量的变化规律.结果表明:在相同的冻融循环次数下,随着围压的增大,抗剪强度峰值呈线性增长.在相同的冻融循环次数下,砒砂岩黏聚力均随含水率增大而减小,内摩擦角随着含水率的增加呈现上下波动,因此冻融循环对抗剪强度的影响主要表现在对黏聚力的影响.在饱和含水率之前,弹性模量基本保持不变,含水率和冻融对其弹塑性的影响可以不考虑.达到饱和含水率后,偏应力-应变曲线不再存在直线段,砒砂岩弹性消失,全面进入塑性阶段.此研究可以为鄂尔多斯砒砂岩冻融侵蚀的破坏机理研究以及治理提供基础依据.

Effects of freeze-thaw cycles on mechanical properties of Ordos remolded Pisha-sandstone soil

To analyze the mechanical properties of remodeled Pisha-sandstone in southern Ordos city of Inner Mongolia Jungar Banner, the effect of freeze-thaw on mechanical properties of the remodeled Pisha-sandstone soil was studied by using the TSZ-6A full-automatic static triaxial apparatus, at room temperature for different freeze-thaw cycles of triaxial compression test. Under the condition of different freezing and thawing cycles(0-7 times)and different confining pressure(50-300 kPa), the changing laws of Pisha-sandstone shear strength, angle of internal friction and cohesion, and the modulus of elasticity were obtained. The results indicate that in the same freeze-thaw cycle index, with the increase of confining pressure, the peak of shear strength shows linear growth. In the same freeze-thaw cycle index, the effect of freezing and thawing cycle on the shear strength is mainly manifested in the cohesion of influence, for which the cohesion of Pisha-sandstone decreases with the increasing moisture content, and internal friction angle fluctuates with the increasing of moisture content. Before the saturated moisture content, the elastic modulus basically remains the same, so the moisture content and freeze-thaw on its plasticity need not be considered. After the saturated moisture content, the linear segment of partial stress-strain curve no longer exists, and Pisha-sandstone elasticity disappears, and fully enters the plastic stage. This study provides a basis for Ordos Pisha-sandstone damage mechanism and control of freeze-thaw erosion.