Abstract
During the construction of geotechnical engineering in cold regions, the stability of rock is inevitably affected by freeze-thaw cycles and hydrochemical corrosion. In order to study the effect of hydrochemical corrosion on dynamic mechanical properties of freeze-thaw rocks, dynamic compression tests were carried out on sandstone samples corroded by four different concentrations of HCl solutions with the same number of freeze-thaw cycles using split-Hopkinson pressure bar (SHPB) test system. The coupling effects of freeze-thaw cycles with different concentrations of HCl solutions and strain rate on mechanical properties of sandstones were explored. The results showed that strain rate could enhance the dynamic compressive strength and peak strain but had no significant effect on the elastic modulus. The coupling effect of freeze-thaw cycles and acid corrosion weakened the dynamic compressive strength, and elastic modulus but enhanced the peak strain. In addition, X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used to analyze the changes of mineral composition and microstructure damage of sandstone samples under the coupling effect of acid corrosion and freeze-thaw cycles. The analysis results were basically consistent with the damage characteristics of macro mechanical properties. The research results can provide reference for open pit coal mining in cold regions.
Highlights
China has abundance of coal resources, but they are not evenly distributed
The results show that the dynamic peak strain of sandstone samples became more sensitive to the pH value at a high strain rate
The dynamic compression tests of sandstone samples corroded by HCl solutions of varying concentrations were performed using the split-Hopkinson pressure bar (SHPB) system under four different impact loads over the same freeze-thaw cycles
Summary
More than 95% of open-pit coal mines are located in cold regions north of 38°N latitude. To increase the efficiency of coal mining via safety and stability, many scholars have conducted extensive study in areas such as roadway excavation [1, 2], stability monitoring [3, 4], and resource utilization [5]. Due to seasonal variations and the diurnal cycle, freeze-thaw damage is unavoidable in coal mining. In open-pit coal mines, bench blasting is the primary method of production. The stress wave produced by blasting may cause strain rates in the range of 101-103 s-1 in the rock mass [7], which corresponds to normal high impact dynamic loading. It is critical to investigate the dynamic impact test of rock under freeze-thaw cycles for coal mining in cold regions
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