Abstract
The tensile failure of rocks is a common failure mode in rock engineering. Many studies have been conducted on the tensile strength and failure mode of rocks after high-temperature treatment under dynamic loading. However, research on the effects of high temperature on the dynamic splitting tensile characteristics of sandstone at actual high temperatures is lacking. To investigate the dynamic tensile characteristics of rocks at actual high temperatures, split Hopkinson pressure bar (SHPB) test apparatus and high-temperature environment box were used to perform dynamic splitting tensile tests under six striker velocities for sandstone specimens at 25°C–800°C. The dynamic splitting tensile strength, radial strain, average strain rate, and failure mode of sandstone under different test conditions were investigated. Test results revealed that the brittleness of sandstone specimens is enhanced at 200°C and 400°C, but slight ductility is observed at 600°C and 800°C. The strain rate effect of dynamic tensile strength is closely related to temperature. When the striker velocity exceeds 2.3 m/s, the dynamic radial strain first decreases and then increases with rising temperature. A quadratic polynomial relationship between the dynamic radial strain and temperature was observed. The temperature effect on the average strain rate is strong at low striker velocity and weak at high striker velocity. In the dynamic splitting tensile tests, high-temperature sandstone specimens are split into two semicylinders along the radial loading direction.
Highlights
In rock engineering, rock mass lies in a certain hydrogeological environment
A quadratic polynomial relation exists between fitting parameters a and b and heating temperature. erefore, the strain rate effect of dynamic tensile strength is closely related to temperature
To investigate the dynamic splitting tensile characteristics of sandstones at actual high temperatures, dynamic splitting tensile tests were conducted on sandstone specimens at different actual high temperatures and loading rates by using split Hopkinson pressure bar (SHPB) device and high-temperature environment box. e effects of loading rate and high temperature on the dynamic stress-strain curves, tensile strength, deformation, and failure mode were discussed. e major conclusions are as follows: (1) Before the peak points, dynamic tensile stress-strain curves gently increase at 25°C, when the heating temperature is higher than 200°C. e brittleness of sandstone specimens is enhanced at 200°C and 400°C, but slight ductility is observed at 600°C and 800°C
Summary
Rock mass lies in a certain hydrogeological environment. Rock engineering under unfavorable hydrogeological condition may lead to some engineering geology disaster, such as rockburst hazard [1,2,3], large deformation, and water inrush hazard [4, 5]. e temperature of rock mass rises with increasing depth, and secondary disasters may be induced in rock mass due to high geothermal situation [6]. By conducting dynamic Brazilian splitting tests for coal specimens, Zhao et al [30] discussed the influence of impact velocity and stratification dip angle on dynamic tensile strength, failure strain, and strain rate. Liu et al [36] conducted dynamic tensile tests for marble Brazilian disc specimens after heat treatment at 25°C to 1000°C. ey analyzed the influence of loading rate and temperature on dynamic tensile strength and failure modes by using an SHPB test system with large diameter. Dynamic splitting tensile tests under six striker velocities were conducted for sandstone specimens under five kinds of real-time temperature conditions (25°C, 200°C, 400°C, 600°C, and 800°C) by using φ50 mm SHPB test apparatus and high-temperature environment box. Dynamic tensile stress-strain curves were obtained based on acquired incident wave, reflected wave, and transmitted wave. en, the influence of high temperature on dynamic splitting tensile characteristics of sandstone was analyze from dynamic tensile strength, dynamic radial strain, average strain rate, and failure modes. e strain rate effect of high-temperature sandstone was studied
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