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为获得压实膨胀土在湿度与密度变化范围内的抗剪强度全貌,采用非饱和直剪试验测定38种湿度与密度组合状态下荆门弱膨胀土的抗剪强度,获得了湿度从风干到饱和、密度在孔隙比0.539~1.089范围内的抗剪强度的分布规律。结果表明,(1)剪切过程中试样大多呈应变软化,仅在低密度与高湿度组合下产生应变强化。高密度与低湿度组合下易出现“应力跌落”。相同密度下,随湿度增大,土体塑性变形能力增强。相同湿度下,随密度降低,土体塑性变形能力增强;(2)非饱和抗剪强度与总黏聚力均随湿度增加先增大后减小而呈现出显著的“山峰效应”;(3)非饱和抗剪强度、总黏聚力、总内摩擦角均随密度减小而显著降低,呈现出显著的“密度效应”。
In order to obtain the whole shear strength of compacted expansive soil in the range of humidity and density, the shear strength of Jingmen weak expansive soil under 38 combinations of humidity and density was measured by non-saturated direct shear test, and the humidity from air-dried to saturated , The density in the porosity ratio of 0.539 ~ 1.089 range of shear strength distribution. The results show that: (1) Most of the specimens are strain softened during shearing, which results in strain hardening only under the combination of low density and high humidity. High density and low humidity combination prone to “stress drop ”. With the same density, with the increase of humidity, soil plastic deformation ability. Under the same humidity, with the decrease of density, soil plastic deformation capacity is enhanced; (2) Unsaturated shear strength and total cohesion increase first and then decrease with the increase of humidity, showing a significant “peak effect”; (3) Unsaturated shear strength, total cohesion and total internal friction angle all decreased significantly with decreasing density, showing a significant “density effect”.