Experimental Investigation on the Energy Properties and Failure Process of Thermal Shock Treated Sandstone Subjected to Coupled Dynamic and Static Loads

Abstract

Thermal shock (TS) is known as the process where fractures are generated when rocks go through sudden temperature changes. In the field of deep rock engineering, the rock mass can be subjected to the TS process in various circumstances. To study the influence of TS on the mechanical behaviors of rock, sandstone specimens are heated at different high temperatures and three cooling methods (stove cooling, air cooling, and freezer cooling) are adopted to provide different cooling rates. The coupled dynamic and static loading tests are performed on the heated sandstone through a modified split Hopkinson pressure bar (SHPB) system. The influence of heating level and cooling rate on the dynamic compressive strength, energy dissipations, and fracturing characteristics is investigated based on the experimental data. The development of the microcracks of the sandstone specimens after the experiment is analyzed utilizing a scanning electron microscope (SEM). The extent of the development of the microcracks serves to explain the variation pattern of the mechanical responses and energy dissipations of the specimens obtained from the loading test. The findings of this study are valuable for practices in rock engineering involving high temperature and fast cooling.

A New Index of Energy Dissipation Considering Time Factor under the Impact Loads

“…In the research of Li [17] et al, the energy calculation was used to explain the law of energy dissipation density under different strain rates for cemented backfill. Li et al [18] found a correlation between the various patterns of energy dissipations and the development of microcracks. In the study of Zhang et al [19], the energy dissipation density as an important parameter of the damage variable can better express the dynamic stress-strain relationship of sandstones under real-time high temperatures.…”