基于应力修正的土体抗剪强度影响因素分析

为探究地基土体在附加应力作用下抗剪强度的变化规律，对传统剪切试验方法进行了改进。通过气压式全自动固结仪预先对试样施加多组精确的附加应力（超出原状土体上覆土重的荷载）后进行快剪试验，以淤泥质粉质黏土与粉土夹粉砂两类土体为研究对象，分析结构与状态的变化对抗剪强度指标值的影响；从受剪土体与剪切盒各层面受力与沉降关系出发，融入剪切面积动态表达式，推导出剪切正应力的修正公式，代入试验计算抗剪强度参数值。结果表明:两类土体受附加应力的影响存在明显的差异，淤泥质粉质黏土以黏聚力变化为主，粉土夹粉砂则体现在内摩擦角上；含水量及孔隙比的改变与土体抗剪强度参数值的变化之间存在反相关关系。

An analysis of the factors affecting shear strength parameters of soils based on stress correction

In order to simulate the strength changes of foundation caused by different building load, the traditional method of shear test is improved. Accurate additional force (beyond the capacity of force of soil covered above the undisturbed soil) is imposed on the sample in advance by using the automatic pressure consolidometer, and consolidated quick shear tests are carried out. Two kinds of unsaturated undisturbed soils are selected as study objects (one is mucky silt and the other is silt with silty sand) to analyze the influence on shear strength indexes according to the changes of their structures and states. Beginning with the relationship between stress and settlement of shear soil and shear box, this article employs the equation to calculate the dynamic shear area to derive the correction formula of shear normal stress, which is used to calculate the shear strength indexes. The results show that different types of soil have different properties. The changes in shear strength of the mucky silt are mainly in terms of cohesiveness. For the silt and silty sand, the angle of internal friction is the main factor. Water content and void ratio have the inverse relationship with the shear strength indexes.