高温后石灰岩的物理力学特性研究

Physical and mechanical characteristics of limestone after high temperature

对焦作石灰岩在常温及经历100℃～800℃不同温度作用后的物理力学特性进行了试验研究,详细分析了加温后石灰岩的表观形态、体积、质量、密度和纵横波波速以及单轴下石灰岩的峰值应力、峰值应变和弹性模量等的变化情况,并对石灰岩高温劣化的影响因素进行了分析。研究结果表明,高温使石灰岩的表观形态发生改变:在400℃以内,温度对石灰岩的物理力学性质的影响不大;200℃以下石灰岩的体积略微减少,超过200℃后石灰岩的体积明显增大,石灰岩的密度随温度的升高而逐步减少;随温度的升高,石灰岩的纵、横波波速大都呈现下降;高温后石灰岩的波速比变化呈无规律性;高温后石灰岩的动弹性模量随温度上升而下降。经历的温度超过400℃后石灰岩的峰值应力和弹性模量均有不同幅度的降低,而800℃内石灰岩的峰值应变随温度的升高变化不明显。温度引起的热应力作用、矿物组分和微结构变化导致石灰岩物理力学性质发生改变与高温劣化。

The laboratory tests are performed to study the physical and mechanical properties of Jiaozuo limestone after undergoing different high temperatures.The temperature varies in the range of 100℃,200℃,400℃,600℃ and 800℃.The scopes of this study include the description of apparent shape,the measurement of volume,mass and density and the detection of longitudinal wave and shear wave of limestone.The peak stress,peak strain and Young＇s modulus of limestone are also investigated under the uniaxial compression.The factors of degradation of limestone under high temperatures are discussed.The test results show that the high temperatures lead to variation of the apparent shape for limestone.The temperatures do not obviously affect the physical and mechanical properties of limestone below 400℃.The volume of limestone reduces slightly below 200℃,but increases obviously over 200℃.Meanwhile,the density of limestone decreases gradually with the increase of the temperatures.As the temperatures increase,the S-wave velocity and the P-wave velocity for limestone generally decrease.The variation of ratio of wave velocity for limestone is irregular after high temperature.The dynamic elastic modulus of limestone after high temperature decreases with the increase of the temperatures.When the temperature is above 400℃,the mechanical properties of limestone exhibit deterioration with the increase of the temperature,and the peak stress and Young＇s modulus of limestone decrease to different extents.The variation of the peak strain of limestone is unconspicuous before 800℃.The thermal stress,variations of mineral formation and microstructure due to the temperatures result in the variation of physical and mechanical properties and degradation of limestone.