Degradation of Mechanical Behavior of Sandstone under Freeze-Thaw Conditions with Different Low Temperatures

Jingwei Gao,Chao Xu,Lifeng Fan,Yan Xi

doi:10.3390/app112210653

Abstract

This study investigated the effects of freezing temperature under freeze-thaw cycling conditions on the mechanical behavior of sandstone. First, the sandstone specimens were subjected to 10-time freeze-thaw cycling treatments at different freezing temperatures (−20, −40, −50, and −60 °C). Subsequently, a series of density, ultrasonic wave, and static and dynamic mechanical behavior tests were carried out. Finally, the effects of freezing temperature on the density, P-wave velocity, stress–strain curves, static and dynamic uniaxial compressive strength, static elastic modulus, and dynamic energy absorption of sandstone were discussed. The results show that the density slightly decreases as temperature decreases, approximately by 1.0% at −60 °C compared with that at 20 °C. The P-wave velocity, static and dynamic uniaxial compressive strength, static elastic modulus, and dynamic energy absorption obviously decrease. As freezing temperature decreases from 20 to −60 °C, the static uniaxial compressive strength, static elastic modulus, dynamic strength, and dynamic energy absorption of sandstone decrease by 16.8%, 21.2%, 30.8%, and 30.7%, respectively. The dynamic mechanical behavior is more sensitive to the freezing temperature during freeze-thawing cycling compared with the static mechanical behavior. In addition, a higher strain rate can induce a higher dynamic strength and energy absorption.

Highlights

In cold regions, the rock generally suffers from freeze-thaw cycling action induced by the environment temperature change
A series of physical and mechanical behavior tests have been conducted on the rock specimens under the freezing conditions, including the ultrasonic wave test [6], the uniaxial compression test [7], the indirect tensile test [8], the triaxial compression test [9], the fracture toughness test [10], the dynamic tensile test [11], and the dynamic compression test [12]
The mechanical strength, static elastic modulus, and P-wave velocity of rock specimens generally increase as freezing temperature decreases

Summary

Introduction

The rock generally suffers from freeze-thaw cycling action induced by the environment temperature change. The mechanical strength, static elastic modulus, and P-wave velocity of rock specimens generally increase as freezing temperature decreases. The increase in the content of the ice filling in the pores can induce an increase in the strength of rock to a certain extent [19] In this case, the ice has strengthening effects. When the frost heaving force induced by the volume expansion of the ice in pores exceeds the strength of the material, the micro-defects are generated and accumulated in rock [2]. In this case, the ice has weakening effects. The rock is subjected to the freezing action and the freeze-thaw cycling action

Objectives

Results

Conclusion