花岗岩高温疲劳效应研究

我国花岗岩分布十分广泛,花岗岩岩体稳定性直接关系到其上部或内部构筑物的安全。目前,关于花岗岩在高温循环作用后物理力学性质变化规律研究较少,为研究高温循环作用对花岗岩岩体物理力学性质的影响,在对花岗岩进行高温—淬火循环(100~700 ℃,循环1~7次)处理后,对花岗岩岩样进行单轴压缩试验,分析其抗压强度与弹性模量变化规律;对花岗岩岩样进行巴西劈裂试验,分析其抗拉强度变化规律。结果表明:(1)在100~700 ℃范围内,随温度升高抗拉强度、抗压强度、弹性模量变化均呈现下降趋势,其中抗拉强度降幅不断加大、弹性模量和抗压强度降幅呈现由大到小再增大的趋势;(2)在循环1~7次范围内,随循环次数增加,抗拉强度、抗压强度、弹性模量均呈现下降趋势,变化幅度在10％以内;(3)抗压强度与弹性模量变幅波动均为V字形,且V字开口方向相同,其中,随温度升高V字开口向下、随循环次数增加V字开口向上。

Study on Fatigue Effect of Granite at High Temperature

Chinese granite distribution is very extensive,and the stability of granite rock mass is directly related to the safety of its upper or internal structures.At present,there are few studies on the change of physical and mechanical properties of granite after high temperature cycling.In order to study the effect of high temperature cycle on the physical and mechanical properties of granite rock mass,after the high temperature-quenching cycle of granite(100~700 ℃,cycle 1~7 times),the uniaxial compression test of granite rock samples was carried out to analyze the change law of compressive strength and elastic modulus;the granite split test was carried out on granite rock samples,and the variation law of tensile strength was analyzed.The results show that:(1) In the range of 100~700 ℃,the tensile strength,compressive strength and elastic modulus decrease with temperature.The decreasing amplitude of tensile strength increases continuously,and the decreasing amplitudes of elastic modulus and compressive strength present a trend from the decrease to increase;(2) Within the range of 1 cycle-7 cycles,with the increase of the number of cycles,the tensile strength,compressive strength and elastic modulus all show a downward trend with a variability of 10％(3) The compressive strength and the elastic modulus fluctuate all are in a V-shape,and the V-shaped opening direction is the same.Wherein the V-shaped opening is downward with increasing temperature,and the V-shaped opening is increased with the number of cycles.