高温后两种晶粒花岗岩破坏力学特性试验研究  

Experimental study on failure mechanical properties of granite with two grain sizes after thermal treatment

作　　者：杨圣奇[1,2] 田文岭 董晋鹏 YANG Sheng-qi;TIAN Wen-ling;DONG Jing-peng(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点实验室,江苏徐州221116 [2]中国矿业大学力学与土木工程学院,江苏徐州221116

出　　处：《岩土工程学报》2021年第2期281-289,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金面上项目(42077231);江苏省第五期“333”工程培养资金项目。

摘　　要：晶粒尺寸对花岗岩高温力学行为有着较大影响,进而也影响高放核废料处置库的安全稳定。基于此,选择两种不同晶粒花岗岩进行高温后巴西劈裂及常规三轴压缩试验,分析其物理力学参数随围压及温度的演化规律,结果表明,粗晶花岗岩较细晶花岗岩含有较多缺陷,总体上其强度及弹性模量较细晶花岗岩低,同时粗晶花岗岩对温度更加敏感。但在高围压下粗晶花岗岩峰后呈延性破坏,残余强度随温度升高有所增加;而细晶花岗岩在高围压下,峰后产生脆性破坏。温度升高不仅产生热裂纹,降低了矿物晶粒之间的黏聚力,而且也增加了晶粒之间的摩擦系数,导致花岗岩强度随温度呈现先增加后降低的趋势。围压一方面抑制试样的环向变形,降低泊松比;另一方面施加围压过程中一部分缺陷闭合,导致试样在压缩过程中可调节潜力减小,增加泊松比。所以,不同高温处理后花岗岩泊松比随围压增加表现为不同的趋势。The grain size has a significant effect on the mechanical behaviors of the thermally treated granite and further affects the safe and stable operation of high level nuclear waste(HLW) repository. Therefore, the granite with two kinds of grain sizes under Brazilian splitting and triaxial compression is adopted to investigate the variation of physical and mechanical parameters with confining pressure and temperature. The results indicate that there are more flaws in the coarse-grained granite than in the fine-grained granite, which results in the less strength and elastic modulus in the coarse-grained granite than those in the fine-grained granite, and the strength and elastic modulus in the coarse-grained granite are more sensitive to the temperature. After the peak strength, the coarse-grained specimens show ductile failure under high confining pressure, and the residual strength increases with the temperature. However, the fine-grained specimens show brittle failure under high confining pressure. On the one hand, micro-cracks are induced by high temperature, which results in the reduction of cohesion among grains. On the other hand, high temperature increases the friction among grains. Therefore, the strength first increases and then decreases with the temperature. The confining pressure can restrain the radial strain and decrease the Poisson’s ratio, and partial flaw closure due to the action of confining pressure results in the decrease of the potential of the specimens to adjust when the applied axial compression decreases, which increases the Poisson’s ratio. Therefore, the Poisson’s ratio of thermally treated granite specimens shows different trends with the confining pressure.

关 键 词：岩石力学 花岗岩 晶粒尺寸 高温 三轴强度 变形 

分 类 号：TU45[建筑科学—岩土工程]