路用土石混合料的剪切特性试验研究

Experimental Research on Shear Behavior of Soil-rock Mixture for Road Construction

路用土石混合料是一种不同于土和岩石的高度非均质材料。混合材料的变形和剪切强度参数主要受含石率、块石形状和土体性质的影响。通过现场取样，综合考虑三个因素的影响，开展室内大型直剪试验。研究结果表明：应力应变关系曲线表现出三个阶段；碎石与土组成的混合料抗剪强度大于同等混合比例的卵石与土组成的混合料；含石率为40％～60％时，混合料抗剪强度较好；粘土与块石的混合料含石率较低时，低围压下表现为剪胀，高围压下表现为剪缩，含石率较高时，低围压和高围压均表现为剪胀；砂土与块石的混合料在低围压和高围压下均表现为剪胀。为快速评测现场土石混合料的粘聚力和内摩擦角，本文还提出了一种实用、简便的估算方法。

Soil-rock mixture is a heterogeneous discontinuous body different from soil and rock. Rock content, rock shape ~ soil properties are three important factors that can influence the mixture ＇ s deformation and parameter of shear strength. This paper uses the on-site sampling, to totally consider these three factors and carry out indoor large direct shear tests. The results show that the shear stress-strain curve can be divided into three stages; the shear strength of gravel with soil mixture is larger than the pebble with soil mixture on the same mix ratio condition; when the rock content is between 40% -60% , the shear strength of the mixture is better; when the rock content is low, clay-rock mixture specimens show dilation under low confining pressure and show compression under high confining pressure, when the rock content is high, the mixtures show dilation in both low confining pressure and high confining pressure conditions; the sand-rock mixtures show dilation in both low confining pressure and high confining pressure conditions. What ＇ s more, the paper puts forward a simple method to estimate the cohesion and friction of the on-site soil-rock mixture.