土体内外摩擦及摩擦强度试验研究

TESTING STUDY ON INTERNAL AND EXTERNAL FRICTION AND FRICTIONAL STRENGTH OF SOILS

分析了摩擦的机理及土的摩擦强度,通过一系列的试验,分析了土体之间及土体与混凝土之间的外摩擦以及土体内摩擦随含水量的变化规律。试验结果表明:(1)影响土体外摩擦的主要因素有土体的颗粒组成、含水量、孔隙水溶液成分的化学性质和垂直接触面的压应力4个因素;(2)土体表观和本征内摩擦系数均随含水量增大而减小,但表观内摩擦系数受含水量的影响比本征内摩擦系数要大;(3)土中粒间吸力(尤其是可变结构吸力)对土体的摩擦影响很大;(4)土体裂隙面的外摩擦强度与土体的内摩擦强度随含水量的变化规律完全不同。土的外摩擦(系数)与土的内摩擦(系数)的区别主要在于:土体的外摩擦(系数)属于表观摩擦(系数),它包含了与水溶液化学性质及饱和状态相关的广义吸力等各种粘聚力的贡献。而土体的内摩擦(系数)属于本征摩擦(系数),广义吸力等各种粘聚力主要归入土体抗剪强度的粘聚力。土体抗剪强度组成部分的内摩擦与粘聚力存在关联作用。

Friction mechanism and frictional strength of soils are analyzed in this paper. Through a series of experiments,the external friction between soils or between soil and concrete and the internal friction of soils are studied. The results show that (1) the primary factors influencing external friction of soils include the grain com- position of soils,the water content,the chemical properties of the pore water and the vertical load on soils,(2) the apparent and intrinsic internal friction factors reduce as the water content in soils increases,and the influence of the water content on the former is larger than that on the latter,(3) the suctions between grains (especially the variable structure suctions) in soils can exert a tremendous influence on the friction of soils,and (4) the influence of water content on external friction strength between structure surfaces is different from the influence on internal friction strength of soils. The distinguish between internal friction (factors) and external friction (factors) of soil is mainly that the formers belong to apparent ones,comprising the contribution of coherences such as generalized suctions that are relative to chemical character of aqueous solution and saturation state,and the latters belong to intrinsic ones,comprising the contribution of coherences such as generalized suctions of shear strength. The coherence and internal friction,which constitute the compressive strength of soil mass,are correlative.