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采用电液伺服试验系统对高温后的花岗岩试样进行巴西圆盘劈裂试验,比较分析不同温度(25℃~1 000℃)作用后花岗岩的劈裂破坏形态、荷载–位移曲线、抗拉强度等,提出径向模量的概念,并据此定义热损伤变量,从损伤力学角度研究花岗岩在拉伸破坏条件下的热损伤特性。研究结果表明:随着温度的升高,花岗岩试样发生脆–塑性转化,其荷载–位移曲线由“下凹”向“上凸”转变,试样的抗拉强度与径向模量均呈下降趋势,并表现出较明显的阶段特征,其中径向模量在100℃时不减反增;热损伤变量总体上随温度升高而递增,但在100℃时出现“负损伤”;最后,推导适用于本文条件的热损伤演化方程与热–力耦合本构模型,模型曲线与试验曲线基本吻合。
The Brazilian sapphire splitting test was carried out on the granite samples after high temperature using the electro-hydraulic servo test system. The splitting failure morphology, load-displacement curve and tensile strength of granite after different temperatures (25 ℃ ~ 1 000 ℃) Then, the concept of radial modulus was put forward and the thermal damage variables were defined accordingly. From the point of view of damage mechanics, the thermal damage characteristics of granite under tensile failure conditions were studied. The results show that as the temperature increases, the brittle-plastic transition occurs in the granite samples, and the load-displacement curves change from “concave” to “convex”. The tensile strength and radial Modulus showed a downward trend, and showed more obvious characteristics of the stage, in which the radial modulus at 100 ℃ without decreasing anti-increase; thermal damage variables generally increase with temperature, but at 100 ℃ when the “ Negative damage ”. Finally, the thermal damage evolution equation and the thermo-mechanical coupling constitutive model which are suitable for the present condition are deduced. The model curve and test curve are basically consistent.