膨胀性泥岩抗剪强度与含水率相关性机理

为探讨膨胀性红层泥岩在不同含水率状态下抗剪强度的变化规律,分别对不同含水率的重塑样、黏土单矿物样、配土样进行直剪试验.依据抗剪强度参数值的变化规律及微结构特征对其相关性进行分析,得出以下结论:①重塑泥岩黏聚力随含水率的增加,呈先增大后减小的趋势;内摩擦角随含水率的增加呈非线性递减的趋势.②蒙脱石随含水率增加,抗剪强度呈先增大后减小的趋势,含水率在22％附近出现抗剪强度峰值;伊利石和绿泥石在含水率分别为18％和19％时,黏聚力出现峰值,而两类黏土矿物的内摩擦角受水的影响相对较小.③蒙脱石含量在30.42％时,基本体现该类矿物的抗剪特征;绿泥石含量达到18.3％时,对试样内摩擦角的主控作用相对较强.④孔隙数量越多,膨胀性相对减弱;结构越密实,胶结度越好,其黏聚力值相对增大.

Correlation Research between Shear strength and Moisture content ofSwelling Mudstone

In order to study the variation of shear strength of swelling red mudstone at different water content in different ages, direct shear tests were conducted on remodeled soil samples, clay single mineral samples and soil samples with different water content. According to the variation law of shear strength parameter and the microstructure characteristics, the correlation is analyzed and the following conclusions are obtained: (1) With the increase of water content, the cohesive force of the remodeled mudstone shows a trend of increasing first and then decreasing; the internal friction angle decreases non-linearly as the water content increases. (2) Montmorillonite increases with the water content , The shear strength increased first and then decreased, with a shear strength peak around 22% moisture content; At the moisture content of 18% and 19%, illite and chlorite have peak cohesion, while the internal friction angle of the two types of clay minerals is relatively less affected by water. (3) When the montmorillonite content is 30.42%, it basically reflects the shear characteristics of this type of mineral; when the chlorite content reaches 18.3%, the main control effect on the internal friction angle of the sample is relatively strong. (4) The larger the number of pores, the relatively weak the expansion; the denser the structure, the better the degree of cementation, and its cohesion value will increase relatively.