基于土水特征曲线的非饱和土强度预测

摘要

The soil-water characteristic curve reflects the relationship between suction and water content or satu-ration in unsaturated soil, the theory of soil water characteristic curve is designed in many aspects of unsaturated soil,such as seepage,strength,diffusion and so on. On the basis of previous studies,the microscopic mechanism of hysteresis effect of soil-water characteristic curve was analyzed,thinking that the negative pressure produced by suction corresponds to the positive stress increment produced between soil particles. The volumetric water content was introduced into the shear strength increment formula. The strength of unsaturated soil is divided into the strength of soil saturated state and the strength increment caused by matrix suction. The strength prediction formula of unsaturated soil was proposed,and the formula is modified by defining the effective saturation. The experimental results show that the proposed strength prediction formula is matched with the actual situation,the proposed formula has certain applicability. The contribution of matrix suction was systematically analyzed to the strength of unsaturat-ed soils.%土水特征曲线反映了非饱和土体中的基质吸力与含水量,或者饱和度之间的关系,在非饱和土的渗流、强度、扩散等诸多方面的研究都会涉及土水特征曲线的相关理论.在前人研究的基础上,分析了土水特征曲线产生滞回效应的微观机理,将基质吸力产生的负压力对应于土颗粒间所产生正应力的增量,将体积含水量引入抗剪强度增量公式.认为非饱和土的强度分为土体处在饱和状态时的强度以及由于基质吸力所引起的强度增量两个部分,提出了非饱和土的强度预测公式;并通过定义等效含水率对公式进行修正.通过选取的四种材料参数对所提出的公式进行验证,结果表明强度预测公式与实际情况吻合良好,所提公式具有一定的适用性.在此基础上较为系统地分析了基质吸力对非饱和土体强度的贡献.