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昔格达组是西南地区第四纪的一套静水河湖相沉积地层,岩石矿物成分复杂,粘土岩具有遇水软化、强度随含水率升高而降低的特点。本文以西昌昔格达组粘土岩在不同含水率下的剪切试验为基础,从多角度就含水率对该区粘土岩抗剪强度的影响程度及影响机理进行了分析。试验发现,随着含水率的增加,粘土岩抗剪强度明显降低,含水率对粘土岩粘聚力及内摩擦角的影响具有明显的停滞性。粘土岩的SEM矿物形貌特征分析表明,在粘土岩片架结构中,抗剪强度主要由“团聚体”的三个强度分量共同产生,随着含水量的增加,各分量均呈下降趋势,最终导致“团聚体”破坏,使粘土岩抗剪强度降低。
The Xigeda Formation is a set of Quaternary sedimentary strata of the Jingshui River in the southwestern China. The composition of rock minerals is complex. The clay rock has the characteristics of softening with water and decreasing strength with increasing water cut. Based on the shear tests of clay rock of Xigeda Formation in Xichang at different water cut-off rates, the influence of moisture content on the shear strength of clay rock in this area is analyzed in this paper. The experimental results show that with the increase of water content, the shear strength of clay rock decreases obviously, and the influence of water content on the cohesion and internal friction angle of clay rock has obvious stagnation. The analysis of the SEM mineralogical characteristics of clay rocks shows that the shear strength is mainly produced by the three intensity components of “agglomerate ” in the clay rock frame structure, and the components decrease with the increase of water content , Eventually leading to “agglomeration ” destruction, the clay rock shear strength decreased.