Experimental study on tensile strength of warm frozen soil based on hydraulic fracturing method

Tensile strength is one of the important parameters of frozen soil mechanics, which is widely used in engineering design of frozen soil and theoretical research of frost heave. At present, the research on tensile strength of frozen soil mainly focuses on low-temperature frozen soil, while that of warm frozen soil is less studied, thus limiting scientific evaluation of the tensile strength characteristics of warm frozen soil. In order to enrich the knowledge of tensile strength of warm frozen soil, the tensile strength experiments of silt clay from the Tibetan Plateau are carried out under various temperatures higher than-2 degrees C using the hydraulic fracturing method (HFM). Our results show that HFM can enable a reliable evaluation of the tensile strength of warm frozen soil, and the relationship between the tensile strength of warm frozen soil and negative temperature can be described by a power function. Compared with the results of uniaxial tension method (UTM) and radial splitting method (RSM), the feasibility of HFM can be regarded as an indirect tensile method in determining the tensile strength of frozen soil, and the suggestion for correcting the test results of indirect tensile method is given. In addition, the mechanism behind the influence of initial water content and temperature on tensile strength of warm frozen soil is analysed. Our results provide a new approach for researchers to analyse the tensile strength of warm frozen soil, thus can benefit the development of frost heave theory, and can reveal the influence of initial water content and temperature on the tensile strength of warm frozen soil.