高温后含孔花岗岩拉伸力学特性试验研究

The tensile mechanical behavior of granite containing pre-existing holes after high temperature treatment

为考察高温作用对岩石物理及力学特性的影响,对经历常温~900℃高温处理后花岗岩圆盘试样进行巴西试验,分析了高温后岩样的物理性质(如颜色、体积、质量和密度)变化,研究了力学性质(如荷载-位移曲线、拉伸强度和刚度)与温度关系,探讨了高温后花岗岩裂纹演化特征.试验结果表明,高温作用后花岗岩体积增大,而质量和密度减小.随着温度的升高,花岗岩试样峰后脆性减弱,延性增强,拉伸强度呈先增大后减小趋势.含孔试样拉伸强度低于完整岩样,而且降幅与孔洞分布倾角密切相关.水平和倾斜分布孔洞试样是由于中心孔边缘萌生的裂纹造成劈裂破坏,而竖直分布孔洞试样是由于3个孔洞边缘萌生的裂纹贯通导致最终破裂.

To investigate the influence of high temperature on the physical and mechanical prop-erties of rock, a series of Brazilian tests was carried out on granite specimens which were treated from 25℃ to 900℃. The physical characteristics （colour, volume, mass and density, the mechanical properties, e. g. ）, load-displacement curve, tensile strength and stiffness, and the crack evolution process of granite specimens were analyzed. Compared to the specimens at room temperature, after high temperature, the volume of them increases, while the mass and density decreases. As the temperature increases, the brittleness of granite weakens, and the ductility enhances. The tensile strength first increases and then decreases with the increasing temperature. Moreover, the strengths of pre-holed specimens are lower than that of intact specimen, and the reducing extent is dependent on the bridge angle. The granite specimens containing three horizontal and diagonal holes show splitting failure, which is induced by the propagation of crack from the central hole. However, the granite specimen containing three vertical holes fails due to the coalescence of cracks from the three pre-existing holes.