Abstract
In order to study the effect of high temperature cycling on the physical and mechanical properties of rock materials, a box-type resistance furnace was used to conduct high temperature cycling at 400°C 10 times on sandstone specimens in coal mine, and the impact compression tests under 8 loading rates were carried out using a split Hopkinson bar (SHPB) device. Results showed that, with the increase of cycle times, the gray white sandstone specimen gradually showed reddish brown spots, and the volume of specimen increased, while the mass, density, and longitudinal wave velocity decreased; in addition, the volume increase rate, the mass decrease rate, the density decrease rate, and the longitudinal wave velocity decreased rate with cycle times showed quadratic function relationship. The dynamic compressive stress-strain curve of sandstone specimens subjected to high temperature cyclic action under impact load was obviously different from that under normal temperature. The dynamic elastic modulus was obviously larger than that under static load. The failure mode of dynamic and static specimens showed brittleness and ductility characteristics, respectively. In the SHPB test, the impact pressure, reflected energy, transmitted energy, and absorbed energy of the rock specimen all increased linearly with the increase of incident energy. The dynamic compressive strength, elastic modulus, and strain rate of sandstone specimens were positively correlated with the incident energy, while the dynamic strain showed negative correlation.
Highlights
As a kind of brittle material, rock is a complex solid material widely existing in nature and formed by the aggregation of heterogeneous mineral components
Yin et al [14] conducted static and dynamic tests on sandstone at 25°C to 800°C; the results show that, with the increase of temperature, the static and dynamic mechanical properties of sandstone change significantly. e failure modes of rock are splitting failure and tensile failure. e peak strength decreases with the increase of temperature, and the peak strain increases with the increase of temperature
Wu et al [17] studied the dynamic uniaxial compression test of sandstone under different loading rates at 25°C to 1000°C, and the results show that the peak strength and loading rate increase by quadratic polynomial, the peak strain and loading rate increase linearly, and the dynamic elastic modulus varies greatly under different temperature scopes
Summary
Received 22 May 2020; Revised 17 June 2020; Accepted 24 June 2020; Published 10 July 2020. In order to study the effect of high temperature cycling on the physical and mechanical properties of rock materials, a box-type resistance furnace was used to conduct high temperature cycling at 400°C 10 times on sandstone specimens in coal mine, and the impact compression tests under 8 loading rates were carried out using a split Hopkinson bar (SHPB) device. E dynamic compressive stress-strain curve of sandstone specimens subjected to high temperature cyclic action under impact load was obviously different from that under normal temperature. E dynamic elastic modulus was obviously larger than that under static load. E dynamic compressive strength, elastic modulus, and strain rate of sandstone specimens were positively correlated with the incident energy, while the dynamic strain showed negative correlation In the SHPB test, the impact pressure, reflected energy, transmitted energy, and absorbed energy of the rock specimen all increased linearly with the increase of incident energy. e dynamic compressive strength, elastic modulus, and strain rate of sandstone specimens were positively correlated with the incident energy, while the dynamic strain showed negative correlation
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