Experimental study on loading and unloading mechanical properties of sandstone under heat and wet cycles
WANG Lehua1，2，JIN Jing1，ZHANG Bingyi1，XIANG Li1，YANG Chao1
(1. Key Laboratory of Geological Hazards on Three Gorges Reservoir Area of Ministry of Education，China Three Gorges University，Yichang，Hubei 443002，China；2. Hubei Key Laboratory of Disaster Prevention and Mitigation，China Three Gorges University，Yichang，Hubei 443002，China)
Abstract：During the high temperature season of summer，frequent rainfall and evaporation result in that rock(rock mass) is under the alternate action of heating and wetting cycles. In this study，the variation of mechanical properties and the effect of heating and wetting cycles were investigated through the triaxial loading and unloading tests to intact sandstone samples under cyclic heating and wetting. The peak strength of triaxial loading and unloading of sandstone was found to decrease with the increasing of heating and wetting cycles and the degradation effect is more obvious in the early cycles. The failure mode of sandstone under triaxial compression after heating and wetting cycles is mainly the shear failures，which are the one with a single shear plane and the conjugated shear failure of “X”and“Y”type. The slipping phenomena appears in the failure surface and the damage occurs along the cone at the end of the sample. The triaxial unloading failures of sandstone under heating and wetting cycles are mainly the shear failure accompanied by the tensile splitting failure. Some specimens have the tensile and shear failures at the same time. The sandstone has more primary and secondary cracks，the modes of failure are more complex，and the extent of damage is more severe than the case of triaxial compression failure. The mechanical properties of sandstone decrease with the increase of heating and wetting cycles，and the trend of variation is consistent. The deterioration coefficient W due to heating and wetting cycles，that is，the absolute value of the coefficient of the term ln(n+1) in the normalized function，was defined to evaluate the deterioration degree of the mechanical parameters in the heating and wetting cycles.
王乐华1，2，金 晶1，张冰祎1，向 力1，杨 超1. 热湿循环作用下砂岩加卸荷力学特性研究[J]. 岩石力学与工程学报, 2018, 37(3): 699-708.
WANG Lehua1，2，JIN Jing1，ZHANG Bingyi1，XIANG Li1，YANG Chao1. Experimental study on loading and unloading mechanical properties of sandstone under heat and wet cycles. , 2018, 37(3): 699-708.
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2018, Vol. 37 
