Abstract
To study the effect of temperature on the dynamic mechanical behaviors and fracture characteristics of thermally treated sandstone, compressive dynamic loading experiments were performed on a series of samples using a split Hopkinson pressure bar (SHPB). In the tests, the dynamic uniaxial compressive strength of the thermally treated sandstone was inversely proportional to the temperature treatment in the range of 200°C–1000°C, while the dynamic elastic modulus first increased and then gradually decreased after different temperature treatments. The results show that two classical mechanical types (i.e., Class I and Class II) are observed from the dynamic stress-strain responses of SHPB tests for thermally treated sandstone. By means of scanning electron microscopy (SEM), the microdifference of postloading microfracture characteristics in Class I and Class II behavior was identified. In Class I behavior, intercrystalline cracks (IE) are the chief form of cracks on the fracture surface of a specimen fractured by SHPB loading even though there some intracrystalline cracks may also be present. In contrast, Class II behavior results from the chief cracking type being intracrystalline cracks.
Highlights
In recent decades, an increasing number of rock engineering projects, such as deep mining of mineral resources [1, 2], borehole drilling in tunnel excavation [3], and geothermal resource exploitation [4], have been encountered in hightemperature environments
Xiong et al [19] studied the mechanical properties of artificial jointed rock mass specimens with a single joint plane after high temperatures; the results show that the uniaxial compressive strength of the specimen is lowest when the dip angle of the artificial joint plane is 60°
Typical thermally treated sandstone samples were used to investigate the effect of temperature on the dynamic mechanical behaviors and fracture characteristics of specimens under split Hopkinson pressure bar (SHPB) tests in the laboratory. e following conclusions can be obtained: (1) In the SHPB tests, when the heating treatment increased from 200°C to 1000°C, the dynamic uniaxial compressive strength gradually decreased
Summary
An increasing number of rock engineering projects, such as deep mining of mineral resources [1, 2], borehole drilling in tunnel excavation [3], and geothermal resource exploitation [4], have been encountered in hightemperature environments. Considering previous work at the rock statics domain level, Shock and Vibration understanding the deformation and failure characteristics of thermally treated rocks that have been subjected to dynamic loading is sometimes challenging. Various experiments have been conducted on the mechanical properties and failure behavior of nonthermally treated rocks that were subjected to dynamic loading. Previous studies [20,21,22,23] show that under dynamic loading, the strain rate, confining pressure, and temperature influence rock mechanical properties. Wong et al [25] carried out dynamic uniaxial compression tests of Carrara marble held at various temperatures using an SHPB and noted that the typical stress-strain curve is a mixture of Class I and Class II fracturing. The postloading microfracture characteristics of the specimens were studied by scanning electron microscopy. e purpose was to identify the rules of rock dynamic mechanical behavior and examine the microfracture characteristics of a sample section
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