Mechanical properties and dynamic breaking mechanism of plateau frozen soil

Abstract

AbstractThis work studies and evaluates the mechanical properties of frozen soil, FS, from Yulong mine in Tibet, under different freezing temperatures ranging from −12 °C to −1 °C, using experimental tests. In addition, the effects of temperature and time on the freezing depth of FS were investigated. Based on the cantilever beam theory, the mechanical model of FS breaking under blasting stress wave was established, and the theoretical formula for the fracture length (FL) of FS was deduced. Moreover, the major influences on FL were analyzed. The results showed that the frozen depth curves at different temperatures were approximately linear in single or double segments, and the lower the temperature, the greater the early freezing rate. Additionally, the uniaxial compression strength, elastic modulus, and tensile strength of FS were found to decrease with the increase in temperature. The findings highlight that the shear strength, cohesion, and internal friction angle decreased first and then increased with the increase in temperature. It was shown that the thickness, friction coefficient, weight density, and tensile strength of FS are positively correlated with the FL, while there is an inverse proportionality with respect to the pressure of the detonation wave.

Keywords

• Plateau permafrost
• freezing temperature
• mechanical properties
• breaking mechanism
• mechanical model