氯盐-干湿循环耦合作用下水泥土的力学性能

Mechanical Properties of Cement Soil Subject to Coupling Effect of Chloride Salt Solution and Dry-Wet Cycles

为研究氯盐干湿循环耦合作用下水泥土的力学性能,针对纤维改良水泥黏土进行无侧限抗压强度、超声波检测、扫描电镜(SEM)及X射线衍射(XRD)试验,分析了水泥土质量损失率、相对波速、峰值应力、残余应力、变形模量的变化规律和微观结构特征.结果表明:随着氯盐质量浓度和干湿循环次数的增加,水泥土的内部微观结构更加疏松,质量损失率增大,纵波波速下降;在氯盐干湿循环耦合作用下,水泥土的应力应变曲线存在压密阶段、弹塑性阶段、破坏阶段和残余阶段;水泥土的峰值应力和残余应力均符合指数函数下降规律,在清水、4.5、18.0、30.0 g/L NaCl溶液中经历28次干湿循环后,水泥土的峰值应力、残余应力和变形模量分别下降48.79%、57.71%和49.33%,52.63%、48.76%和54.37%,56.88%、59.70%和57.50%,57.89%、57.71%和65.67%,水泥土破坏后的残余应力为峰值应力的20%~40%.

In order to study the mechanical properties of cement soil subjected to the coupling effect of chloride salt solution and dry-wet cycles,unconfined compression test,ultrasonic test,scanning electron microscope(SEM)test and X-ray diffraction(XRD)test were performed.The change rules of mass loss rate,relative wave velocity,peak stress,residual stress,deformation modulus and microstructure characteristics of cement soil were investigated.The results show that with increasing chloride salt concentration and the number of dry-wet cycles,the internal microstructure of cement soil becomes more loose,and the mass loss rate increases,but the P-wave velocity decreases.The stress-strain curve of cement soil subjected to the coupling effect of chloride salt and dry-wet cycles can be divided into compaction phase,elastic-plastic phase,failure phase and residual phase.The peak stress and residual stress of cement soil comply with the exponential decline law.Compared with those before the wet-dry cycle,the peak stress,residual stress and deformation modulus subjected to 28 wet-dry cycles in water,4.5,18.0,30.0 g/L NaCl solutions decrease by 48.79%,57.71%and 49.33%,52.63%,48.76%and 54.37%,56.88%,59.70%and 57.5%,57.89%,57.71%and 65.67%,respectively.And the residual stress is 20%40%of the peak stress.