Abstract
To study the effect of high temperature on the dynamic mechanical properties and energy evolution characteristic of limestone specimens, the basic physical parameters of limestone specimens that cool naturally after experiencing high temperatures of room temperature (25°C), 200°C, 400°C, and 600°C were tested. In addition, compression tests with 6 impact loading conditions were conducted using SHPB device. The changes of basic physical properties of limestone before and after temperature were analyzed, and the relationship among dynamic characteristic parameters, energy evolution characteristics, and temperature was discussed. Test results indicated that, with the increase of temperature, the surface color of specimen changed from gray-black to gray-white, and its volume increased, while the mass, density, and P-wave velocity of specimen decreased. The dynamic compressive stress-strain curve of limestone specimens after different high-temperature effects could be divided into three stages: elasticity stage, yield stage, and failure stage. Failure mode of specimen was in the form of spalling axial splitting, and the degree of fragmentation increased with the increase of the temperature and incident energy. With the increase of the temperature, the reflection energy, the absorption energy, the dynamic compressive strength, and dynamic elastic modulus of rock decreased, while its transmission energy, the dynamic peak strain, and strain rate increased. The dynamic compressive strength, dynamic elastic modulus, dynamic strain, and strain rate of limestone specimens all increased with the increase of incident energy, showing a quadratic function relationship.
Highlights
Rock engineering safety problem induced by high temperature had become an important topic in rock mechanics research [1,2,3]
High-temperature rock mechanical behavior was different from normal temperature, and its physical and mechanical properties were closely related to the temperature; studying the mechanical behavior of rock after high temperature had important theoretical and engineering significance [4,5,6]
When the temperature increased to 600°C, a small amount of powder particles appeared on the surface of rock specimen, which illustrated that high temperature action showed damage effect on the structure of limestone and caused degradation of mechanical properties
Summary
Rock engineering safety problem induced by high temperature had become an important topic in rock mechanics research [1,2,3]. Considering the stress state of rock in engineering, Xu et al [9] carried out the triaxial compressive tests on granite and studied the strength and deformation properties of granite under different confining pressures and high-temperature effects. Liu and Xu [13] conducted dynamic impact tests on marble with various high temperatures and air pressures, and the relationship between dynamic stress-strain curve characteristic and failure mode was studied. The dynamic compressive tests on sandstone after high-temperature effects were carried out with 6 impact pressures (0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, and 0.9 MPa), and the dynamic stress-strain curves and failure modes of sandstone specimen with various test conditions were studied. The relationships among dynamic compressive strength, dynamic elastic modulus, dynamic strain, and strain rate, as well as the failure mode of sandstone specimen and temperature, were analyzed from the energy perspective
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