Experimental study on uniaxial compression of granite under real-time loading at designated low-temperature conditions

Abstract

A low temperature and the degree of saturation have important influence on the mechanical properties of rock surrounding cave-type underground liquefied natural gas storage. Uniaxial compression tests were carried out on dry and saturated granite under different real-time loadings at designated low-temperature conditions (25, 0, −20, −40, −50 and −60°C). The porosity and microstructure were then observed by nuclear magnetic resonance spectroscopy and scanning electron microscopy. The results show that with the decrease in temperature, the uniaxial compressive strength (UCS) and porosity of both dry and saturated granite monotonically increase, while the elastic modulus undergoes an increase–decrease transition and finally stabilises. At the same temperature, the UCS and elastic modulus of dry granite are generally greater than those of saturated granite. The reinforcement in the UCS and elastic modulus is caused by cold shrinkage, while the degradation in the elastic modulus, particularly for saturated granite, is attributed to freezing damage below 0°C. The results of this study can provide technical support for the long-term stability analysis and evaluation of underground cavernous liquefied-natural-gas-storage reservoirs.