高温后花岗岩-混凝土组合体静态力学特性研究OA

Static uniaxial compression tests were conducted on five groups of granite-concrete composite(GCC)specimens with different rock proportions(0.4,0.5 and 0.6)after exposure to temperatures of 25,200,300,400 and 500℃,as well as on granite and concrete specimens separately.To investigate the static compressive mechanical properties and failure evolution mechanisms of GCC after high-temperature treatment,scanning electron microscope(SEM)was employed to characterize the fracture morphology of the interfaces between granite and concrete.The results show that the peak strength,elastic modulus,and mass of GCC specimens fall between those of concrete and granite and increase with increasing rock proportion.During strength deterioration,the concrete component plays a dominate role.With increasing temperature,the overall stress-strain curves become smoother,while the abruptness and brittleness of failure decrease and the gradual deformation and plasticity increase.Temperature variation leads to different failure modes in GCC specimens,with concrete shear failure in a"Y"-shaped pattern and granite splitting failure being the predominant modes.Moreover,the number of microcracks increases significantly during failure.These findings provide theoretical support for the safety assessment of underground engineering structures after fire exposure and offer a foundation for engineering design and monitoring under complex environmental conditions.