温度与冲击荷载耦合下花岗岩动力性质

Dynamic properties of granite subjected to coupling action of impact loading with actual temperature

摘要:

为考察岩石的热动力学特性，利用改进的分离式霍普金森压杆，对不同实时温度下的花岗岩试样进行了50~250 s^-1应变率的冲击压缩试验.基于测试数据，研究发现不同温度下应变率敏感性有所差别，700 ℃时花岗岩抗压强度的应变率效应最弱，而峰值应变的率效应非常明显,弹性模量的应变率效应无明显规律，如20 ℃和700 ℃时，弹性模量表现出随应变率升高而增大的趋势，但300 ℃和500 ℃时，其随应变率的增大而降低；较常温状态，300 ℃时花岗岩的抗压强度变化不大，当温度升高到500 ℃时，花岗岩热损伤效应明显，其动态抗压强度与弹性模量均大幅降低，而峰值应变呈增大趋势.700 ℃时热损伤现象突出，抗压强度与弹性模量迅速降低;此外，还发现当温度升高时，不但岩石的破碎程度加重，而且岩样的颜色也发生改变.

Abstract:

To investigate the thermodynamic property of rock, the impact compression tests of granite within different temperatures were performed under different strain rates (50-250 s^-1). Results show that the strain-rate sensitivities subjected to different temperatures are quite different. When the temperature rises to 700 ℃, the effect of strain rate on compressive strength is the weakest, while that on peak strain is obvious. The effect of strain rate on elastic modulus tends to have no regularity. The elastic modulus increases with the increase of strain rate at 20 ℃ and 700 ℃, but it takes on a downward trend at 300 ℃ and 500 ℃. There is little change in the dynamic compressive strength at 300 ℃ compared to the room temperature. When the temperature reaches 500 ℃, the thermal damage becomes obvious, the dynamic compressive strength and elastic modulus significantly reduce, but the peak strain increases. At 700 ℃, the thermal damage phenomenon is serious, and the compression strength and elastic modulus sharply decrease. In addition, with increasing the actual temperature, the color of the tested rock changes and its breakage degree also deepens.