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研究目的:非饱和黏性土的压缩特性是路基工程、基础工程、地下工程以及边坡工程设计计算的重要参数。为研究基质吸力对非饱和土一维压缩特性的影响,本文以合肥地区非饱和黏性地基土为研究对象,进行基质吸力为常数、净竖向应力逐级增大的一维压缩试验。研究结论:(1)一维压缩变形下,不同基质吸力的e-lgp曲线均可以看作以净竖向应力300 k Pa为分界点的两条直线段;(2)压缩指数随基质吸力的变化关系符合Barcelona模型;压缩指数和切线压缩系数随基质吸力的增大呈指数衰减的变化规律;(3)为反映吸力对土体一维压缩变形的贡献,提出吸力切线压缩系数的概念,得到吸力切线压缩系数与净竖向应力之间呈现指数关系;(4)该成果可为研究黏性地基土的非饱和工程特性提供理论参考。
Research purposes: The compressibility of unsaturated clay is an important parameter in roadbed engineering, foundation engineering, underground engineering and slope engineering design and calculation. In order to study the effect of substrate suction on the one-dimensional compressional characteristics of unsaturated soils, a one-dimensional compressive test was conducted in which the substrate suction was constant and the net vertical stress was increased step by step based on the unsaturated viscous subsoil in Hefei. The conclusions are as follows: (1) Under one-dimensional compressive deformation, the e-lgp curves of different substrate suction can be regarded as two straight line segments with the net vertical stress of 300 k Pa as the cut-off point. (2) (3) In order to reflect the contribution of suction to the one-dimensional compression deformation of soil, the concept of suction tangent compression coefficient was proposed, and the relationship between compression coefficient and tangential compression coefficient was exponentially decayed with the increase of substrate suction. (4) The result can provide theoretical reference for studying unsaturated engineering characteristics of viscous soil.