四川理县小歧村冰碛物角砾土抗剪强度特性研究

Study on shear strength properties of moraine breccia soil at Xiaoqi Village of Lixian County

在岷江上游的干暖河谷地区分布有众多高陡且持续变形的大型冰碛物堆积体,现场调查研究发现,该类冰碛物具有极强的水敏性。利用室内力学强度试验和SWCC试验,对不同含水率下冰碛物的水敏特征进行了研究。结果表明：冰碛物土体中黏粒含量低（17%）,遇水易崩解,加之土体的大颗粒性,使得土体凝聚力、内摩擦角均随其饱和度增加而减小,其中内摩擦角可减小到最初的1/3左右,凝聚力减小到最初的1/8左右;当其饱和度介于10%-70%时,土体水敏性表现尤其明显。根据物质组分特征,利用MATLAB编程,确定了凝聚力偏移量的修正公式,并建立了Mohr-Coulomb准则修正模型。该模型能较好反映该类角砾土的力学特性,对该类土力学特性的研究有参考价值。

There are plenty of huge high and steep moraine deposits that are in continuous deformation in the dry and warm val- ley area of the upper Minjiang River, and severe water sensitivity are discovered for these moraine material. In the indoor me- chanical strength test and SWCC test, the water sensitivity characteristics of the moraine material under different water content were analyzed. The results showed that the moraine soil with low clay content（ 17% ） is prone to disintegration when encountering water ; moreover, because of larger soil particle, the soil cohesion and internal friction angle all decrease with the increase of sat- uration, in which, the internal angle can reduce to about 1/3 of the initial value, the cohesion can reduce to about 1/8 ; when the saturation is in the scope of 10% -70/% , the water sensitivity is especially obvious. Using MATLAB program, the modification formula of cohesion offset and modification model of Mohr - Coulomb criterion are established, which can well reflect the mechan- ical characteristics of the breccia soil and has reference value for the research on the mechanical characteristics of this kind of soil.