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灰绿色、红色泥岩在干旱或半干旱气候条件下形成,富含黏土矿物,遇水后物理力学性质发生显著变化,对工程建设的安全有重要影响,对其物理力学特性开展研究在地质灾害防治和工程设计施工中都具有重要意义。不同泥岩具有不同的物理力学性质,为进一步研究其差异,对甘肃省天水秦州区西河乡灰绿色泥岩以及天水花南村滑坡(310国道K1428+200段)滑带处红色泥岩进行了基本土工试验、矿物成分分析、易溶盐成分分析以及高含水率下的直接剪切试验。研究发现灰绿色泥岩级配更好,且含有较多的黏土矿物,而红色泥岩则含有较多的石英及原生矿物,二者的黏土矿物都以伊利石为主,高岭石次之,蒙脱石含量较少。2种泥岩遇水后都溶解出较多的Na~+,K~+,3HCO-以及少量的Ca~(2+),使土体颗粒水膜增厚,带电分子间的引力减弱,黏结力降低,并使矿物更易遭受破坏,灰绿色泥岩溶于水后的易溶盐总量相对较多。在高含水率情况下,2种泥岩的抗剪强度参数都随含水率及干密度发生变化,灰绿色泥岩的抗剪性能明显优于红色泥岩。当含水率达到25%时,红色泥岩抗剪强度较绿色泥岩显著降低,含水率超过30%后,二者都基本丧失抗剪能力。
Gray-green and red mudstone formed in arid or semi-arid climatic conditions, rich in clay minerals, significant changes in the physical and mechanical properties after encountering water have an important impact on the safety of the project construction. The study of its physical and mechanical properties is of great importance in the prevention and control of geological hazards And engineering design and construction are of great significance. Different mudstones have different physical and mechanical properties. To further study their differences, basic geotechnical tests were conducted on the red mudstone of Xihe Township, Qinzhou District, Tianshui, Gansu Province and the red mudstone at the slippery zone of Huaxiancun Landslide of Tianshui (State Highway K1428 + 200) , Mineral composition analysis, soluble salt composition analysis and direct shear test at high water cut. The study found that gray-green mudstone graded better, and contains more clay minerals, and red mudstone contains more quartz and primary minerals, both of the clay minerals are illite-based, followed by kaolinite Less trimmings content. The two kinds of mudstone dissolve more Na ~ +, K ~ +, 3HCO- and a small amount of Ca ~ (2+) after the water metamorphic, make the water film of soil particles thicker, the gravitation between charged molecules weakened, and the cohesive force Reduce and make the mineral more vulnerable to damage, gray-green mudstone dissolved in water after the relatively large amount of soluble salt. At high water cut, the shear strength parameters of two kinds of mudstone all change with the moisture content and dry density, and the shear resistance of gray-green mudstone is obviously better than red mudstone. When the moisture content reaches 25%, the shear strength of the red mudstone is significantly lower than that of the green mudstone. After the moisture content exceeds 30%, both of them have almost lost their shear resistance.