An experimental study on characteristics of impact compression of freeze–thawed granite samples under four different states considering moisture content and temperature difference

Bo Ke,Hang Lin,Yun Zheng,Yixian Wang,Ning Li,Linmin Ding,Chunyang Zhang,Chuanju Liu

doi:10.1007/s12665-021-09952-5

Abstract

The mechanics of rock masses in cold regions have attracted the attention of researchers from all over the world, and the concern here is that the mechanical properties of rock masses are inevitably weakened under freeze–thaw cycles. In this paper, first, granite samples were subjected to different freeze–thaw cycles, and then treated in four different states, such as saturated and frozen states, saturated and normal temperature states, dry and frozen states, as well as dry and normal temperature states. The impact compression test was carried out using the Split Hopkinson Pressure Bar (SHPB) device. Results show that the impact strength of granite samples deteriorates with the increase of freeze–thaw cycles in the same state; for samples in different states, although the number of freeze–thaw cycles is equal, the degree of deterioration of the impact strength is different. For freeze–thawed granite samples in the same state, the dynamic elastic modulus decreases with the increase of freeze–thaw cycles, and its degree of decrease is different for different states. Under the same freeze–thaw cycles, the deterioration of mechanical properties of granite samples is different in four different weather states; for example, the dynamic elastic modulus from large to small is generally as follows: saturated and frozen states, saturated and normal temperature states, dry and frozen states, as well as dry and normal temperature states. Finally, the freeze–thaw influence factor is proposed to describe the damage of granite samples. All in all, it can be concluded that water and low temperature strengthen the influence of freeze–thaw cycles on the dynamic mechanical properties of granite.

Highlights

Rockmass stability, on the one hand, depends on the geological conditions and mechanical properties (Cao et al 2020c; Zhao et al 2020b; Zheng et al 2020b; Lin et al 2020a), on the other hand, is affected by variable external conditions, such as water (Zhang et al 2020a), temperature (Deprez et al 2020a), external load (Lin et al 2020c), etc
The results show that the freeze-thaw influence factor has the maximum value in saturated and frozen states, and the minimum value in dry and normal temperature states
It can be concluded that water and low temperature improve the effect of freeze-thaw cycles on the dynamic mechanical properties of granite samples in this study

Summary

Introduction

On the one hand, depends on the geological conditions and mechanical properties (Cao et al 2020c; Zhao et al 2020b; Zheng et al 2020b; Lin et al 2020a), on the other hand, is affected by variable external conditions, such as water (Zhang et al 2020a), temperature (Deprez et al 2020a), external load (Lin et al 2020c), etc. We first carried out the damage experiments of granite samples under freeze-thaw cycles, after that, considering the actual situation of rock masses in high altitude area, especially the different states caused by seasonal changes, the impact compression characteristics of freeze-thawed granite samples are studied under four different states, such as moisture content and temperature difference. When reaching the set-point temperature, samples are taken out from the freeze-thaw tester, and placed in the heat preservation container, and the impact compression test of freeze-thawed samples is carried out by using SHPB device

Comparison of impact strength

The stress-strain characteristics

Influence analysis of freeze thaw cycles

Conclusions