پديد آورندگان :
Mehdi , Hosseini Department of Mining Engineering - Imam Khomeini International University, Ghazvin , Ahmad , Jabari Department of Mining Engineering - Imam Khomeini International University, Ghazvin
كليدواژه :
heatingcooling cycle , three-point bending , heating , mode I , Fracture toughness
چكيده لاتين :
In cases such as explosion, fire, deep drilling and geothermal
energy extraction, rocks are exposed to high temperatures
influencing the rock toughness. Thus, the aim of this study is to
investigate the effect of temperature on the fracture toughness of the
rocks. In this study, the effect of temperature on the mode I fracture
toughness is investigated. To this end, three-point bending tests were
performed on semicircular specimens of four types of natural rocks
including sandstone, limestone, tuff, andesite, and a series of
concrete specimens to determine the fracture toughness. The
specimens were first heated to 100, 200, 300, 500 and 700 °C. After
reaching the desired temperatures, the specimens were cooled. A
series of tests was performed on the specimens at ambient
temperature (25 °C). The heating rate in the electric furnace was 15
°C/min in accordance with the temperature rise in fires. Petrographic
studies and X-ray diffraction analysis (XRD) were performed to
identify the composition of the rocks. Furthermore, the effective
porosity and the weight loss of heated specimens were determined to
study the behavior of rocks. Comparison of the test results indicated
the higher impact of temperature on the fracture toughness of finegrained
rocks. In addition, the fracture toughness decreased by
increasing the effective porosity and decreasing the weight loss.
According to the results, the mode I fracture toughness of sandstone,
tuff, limestone, andesite and concrete specimens underwent a
heating-cooling cycle up to 700 °C respectively decreased 45, 17, 44
and 9.5 and 37 percent compared with that of unheated specimens
