Abstract
At present, there is no clear understanding of the influence of differences in soil mineral composition, particle size grading, and hydraulic paths on the shear strength of unsaturated soil, and the related strength models are not applicable. The shear strength characteristics of different saturation specimens under different hydraulic paths were studied on two granite weathered soils. The experimental results show that the shear strength index of the prepared specimen is “arched” with the increase of saturation, and the dehydration specimen decreases linearly with the saturation. As considering the cementation of free oxides in soils and the interaction among soil particles at different saturations, it is assumed that there are three different contact modes among soil particles: direct contact, meniscus contact, and cement contact. The difference in contact modes will reflect the different laws of shear strength. A shear strength model capable of distinguishing between the capillary effect and the adsorptive effect was established. The model predicted and verified the shear strength data of granite weathered soil under different hydraulic paths well, and then theoretically explained the evolution law of the shear strength of granite weathering soil under the change of saturation.
Highlights
Shear strength is the ultimate ability of soil to resist shear force, which is one of the most important indexes of soil mechanical properties
It is challenging to control suction in mechanical tests in high suction range accurately, and the vapor flow technique or the osmotic suction techniques have been adopted to control the high suction of specimens [10,11,12,13]
Most existing shear strength models are based on analysis of test results obtained by direct shear or triaxial shear tests at low suction ranges
Summary
Shear strength is the ultimate ability of soil to resist shear force, which is one of the most important indexes of soil mechanical properties. The shear strength of unsaturated soils depends on several factors such as soil type, particle distribution, density, hydraulic path, and stress state [3,4,5]. Over the past few decades, a number of laboratory tests have been conducted to study the hydraulic behavior of unsaturated soils in the low suction range using axial translation techniques [6,7,8,9]. The suction was less than 500 kPa in most direct shear or triaxial tests, and the test soil was mainly sand or silt. The test results of unsaturated soil mechanical behavior under high suction in the literature are still intensely limited. Most existing shear strength models are based on analysis of test results obtained by direct shear or triaxial shear tests at low suction ranges (typically below 500 kPa).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
