基质吸力对非饱和重塑黄土抗剪强度的贡献  

CONTRIBUTION OF MATRIC SUCTION TO SHEAR STRENGTH OF UNSATURATED REMOULDED LOESS SOILS

作　　者：闫亚景[1] 文宝萍[1] 计博勋[1] 

机构地区：[1]中国地质大学(北京)水资源与环境学院,北京100083

出　　处：《工程地质学报》2011年第6期865-874,共10页Journal of Engineering Geology

基　　金：国家自然科学基金项目(40872182)资助

摘　　要：非饱和土抗剪强度随饱和度降低、基质吸力增大而提高。然而,不同类型非饱和土中,基质吸力对抗剪强度的贡献却显著不同。本文通过室内试验,探讨了基质吸力对非饱和重塑黄土抗剪强度贡献的基本特征。研究结果表明,非饱和重塑黄土抗剪强度随着基质吸力的增大,表现为非线性的和明显的4个阶段性增、降和逐渐稳定特征,且分段特征值与土-水特征曲线完全一致。基质吸力5kPa、60kPa、170kPa分别是这4个阶段的临界值。其中,当基质吸力60kPa时,非饱和重塑黄土抗剪强度出现峰值。非饱和黄土表观黏聚力随基质吸力变化特点与抗剪强度基本一致,但表观内摩擦角呈现阶段性增大趋势。表观黏聚力对基质吸力的敏感程度显著大于表观内摩擦角。非饱和重塑黄土抗剪强度变化特点显示其抗剪强度参数φb值为一个非常量数值。Shear strength of unsaturated soil increases as its matric suction increases and the degree of saturation decreases.However,effect of matric suction to shear strength can be greatly different for different types of unsaturated soils.In this paper,the relationship between matric suction and shear strength of the unsaturated remoulded loess soil is examined with experimental approach.It is found that as matric suction increases,the soil shear strength varies nonlinearly.The variation has clear four stages： increasing,decreasing and keeping relatively constant.Particularly,the four stages can be identified based on the correlations between matric suction and shear strength,consistent with those shown on the soil—water characteristic curve.Matric suction of 5 kPa,60 kPa,170 kPa are critical values for the four stages.Notably,shear strength of the soils attain their peak values at matric suction of 60 kPa.Variation of apparent cohesions of the soils with matric suction shows the same trend as those of shear strengths,whereas variation of apparent internal friction angles of the soils increases stage by stage.It is also found that shear strength parameter φb of the unsaturated loess soil is not a constant.

关 键 词：非饱和重塑黄土 基质吸力临界值 抗剪强度 非饱和土抗剪强度参数 

分 类 号：P642.131[天文地球—工程地质学]