基于广义吸力的非饱和土强度理论

Strength Theory of Unsaturated Soil Based on Generalized Suction

基于非饱和土的剪切强度是由于可变吸力和表观凝聚力折减之后构成,其可变吸力对强度的贡献不仅取决于吸力的大小,还取决于土粒接触点处孔隙水面积,是粒间作用力和作用面积动态变化的结果。分析结果表明:表观凝聚力对强度的贡献与饱和度的变化路径相关,随着饱和度的增加,表观凝聚力对强度的贡献逐渐减小,当土体达到饱和时,表观凝聚力对土体强度的贡献变为零。如果饱和度是减小,表观凝聚力对强度的贡献保持不变或稍有增加,直到饱和度为零的时候,表观凝聚力对强度的贡献达到最大值。因此,从广义吸力的理论出发,根据两者对强度的贡献,可以建立更为合理的非饱和土强度理论。

Shear strength of unsaturated soil is made up of reduction of variable suction and apparent cohesion.The contribution of variable suction to the shear strength depends not only on the size of suction,but also on the pore water area of the contact point,which is dynamic action of particle force and the pore water area.The analysis result shows that（1） The contribution of apparent cohesion to shear strength varies with the change of saturation.As the saturation increases,the contribution of apparent cohesion to the soil decreases gradually.When the soil is saturated,the contribution of apparent cohesion to the soil reaches zero.（2） While as the saturation decreases,the contribution of apparent cohesion to the soil remains constant or increases a little.When the soil saturation is zero,the contribution of apparent cohesion to the soil reached the maximum.So based on the generalized suction theory and the contribution of variable suction and apparent cohesion,a rational theory could be established for the shear strengths of unsaturated soil.