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针对低含水率砂土边坡失稳过程中的应力应变场演变过程和水分迁移规律,采用离心模型试验与数值模拟相结合的方法进行研究。此外,分析了低含水率砂土似黏聚力的产生原因,提出了其计算方法,并阐明了低含水量非饱和砂土抗剪强度出现峰值效应的机理。研究表明:各模型均呈浅表层崩塌,对应的失稳破坏离心加速度值分别为24.6g,44.3g和40.0g。随着离心加速度增加,应力梯度增大,剪应变从靠近坡脚处向坡顶逐步发展,最终在坡体内形成了塑性贯通的滑裂面,边坡发生滑动失稳。离心试验后水分明显向坡体深处转移,浅部含水量在残余含水量附近波动。当土水特征曲线拟合参数与基质吸力二者满足一定关系式时,低含水率砂土的似黏聚力将出现极大值。
Aiming at the stress-strain field evolution process and water migration in the process of instability of low water cut sand slope, the centrifugal model test and numerical simulation are combined to study the process. In addition, the cause of sand-like cohesion of low water cut was analyzed, the calculation method was put forward, and the mechanism of peak effect of shear strength of unsaturated sands was clarified. The results show that all the models show shallow surface collapse with corresponding values of centrifugal acceleration of 24.6 g, 44.3 g and 40.0 g respectively. As the centrifugal acceleration increases, the stress gradient increases, and the shear strain gradually develops from near the slope foot to the top of the slope. Finally, a plastic-through sliding surface is formed in the slope body, and the slope slip instability occurs. After centrifugation, the water obviously migrated to the deep slope, and the shallow water content fluctuated around the residual water content. When both the soil water characteristic curve fitting parameters and the substrate suction satisfy a certain relationship, the maximum cohesion of the low moisture sand will appear.