砂卵石土是一种特殊性质粗粒土,其强度变形特性是工程界重点关注的问题之一。针对某工程砂卵石土地基系统开展三轴剪切试验、界面剪切试验及流变试验等综合研究其强度变形特性,选取合适的力学模型描述砂卵石土的应力-应变关系并整理相应模型参数。试验结果表明:砂卵石土非饱和样的抗剪强度指标明显大于饱和样,在低围压下砂卵石土饱和样和非饱和样分别呈现出剪缩特性和剪胀特性,而在高围压下则均表现出明显的剪缩特性;砂卵石土与混凝土面板间的接触面剪应力与剪切位移基本呈双曲线关系,抗剪强度随法向应力的增大线性增大;在双对数坐标系下砂卵石土流变变形随着时间线性增长,基于试验规律提出了砂卵石土11参数流变模型,该模型可较好地反映砂卵石土的流变特性。研究成果为砂卵石土强度变形特性研究及地基沉降分析提供理论支撑。

Sandy pebble soil is a special coarse-grained soil whose strength and deformation characteristics are one of the key concerns in engineering field. The comprehensive mechanical properties of sandy pebble soil were examined via triaxial shear test,interfacial shear test and rheological test,and appropriate constitutive relationships were selected to describe the stress-strain relationships of sandy pebble soil. In addition,the corresponding model parameters were summarized. Tests results reveal that the shear strength of unsaturated sand pebble soil was remarkably larger than that of saturated samples. Under low confining pressure,unsaturated samples and saturated samples displayed shear shrinkage characteristics and dilatancy characteristics,respectively,while under high confining pressure,obvious shear shrinkage characteristics could both be observed. The shear stress and displacement on the interface between sandy pebble soil and concrete face show a good hyperbola relationship,and the shear strength and normal stress show a good linear relationship. The relationship between rheological deformation and time of sandy pebble soil is linear in logarithmic coordinates. A rheological model of sandy pebble soil with eleven parameters was proposed to better reflect the rheological properties of sandy pebble soil. The research results provide theoretical support for the research of strength and deformation characteristics and settlement prediction of sandy pebble soil foundation.