广吸力范围内一种改进的非饱和土抗剪强度模型

An improved shear strength model of unsaturated soils over a wide suction range

不同类型的非饱和土在自然界中广泛存在。由于不同类型土的颗粒级配和矿物组成成分的不同,其强度特性存在较大的差异。为了建立一种适用于不同类型非饱和土的强度预测统一模型,本研究系统地分析了土体类型对非饱和土强度演化趋势的影响,在综合考虑两种常用模型优越性的基础上,提出了一种改进的非饱和土抗剪强度模型,同时,利用现有常用的强度模型,对不同类型土在广吸力范围内的强度特性进行了预测,并对拟合结果进行了对比分析。研究结果表明:(1)在广吸力范围内,不同类型土的强度演化规律可分为两类,山峰型和增长稳定型;(2)改进模型可以较为准确地预测不同类型土在广吸力范围内的强度特性;(3)明确了改进模型中各参数的物理意义,并初步给出了改进模型在应用于不同类型土时各参数取值的建议范围。

Different types of unsaturated soils are widespread in nature.Due to the differences in grain size and mineral composition,the shear strength characteristics of the unsaturated soils are significantly different over a wide suction range.In order to establish a unified model for predicting the shear strength of different soil types over a wide suction range,a systematic investigation was carried out to examine the effect of soil type on the shear strength of unsaturated soils.An improved shear strength model is proposed based on the advantages of two traditional equations.The proposed model is verified by comparing the published experimental data and the predicted results of the proposed and the existing equations.The conclusions are as follows:(1)the shear strength for different types of soils over a wide suction range can be roughly classified into two types:peak type and steady growth type;(2)the proposed model demonstrates good agreement between the predicted and measured shear strength results over a wide suction range;(3)the physical meaning and the recommended values of the model parameters for different soil types are given.