高温后花岗岩断裂特性及热裂纹演化规律研究  

Fracture behavior and thermal cracking evolution law of granite specimens after high-temperature treatmentFracture behavior and thermal cracking evolution law of granite specimens after high-temperature treatment

作　　者：黄彦华 陶然[1] 陈笑 罗一鸣 韩媛媛 HUANG Yanhua;TAO Ran;CHEN Xiao;LUO Yiming;HAN Yuanyuan(School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China;School of Electrical Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学力学与土木工程学院,江苏徐州221116 [2]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 [3]中国矿业大学电气工程学院,江苏徐州221116

出　　处：《岩土工程学报》2023年第4期739-747,共9页Chinese Journal of Geotechnical Engineering

基　　金：江苏省自然科学基金项目(BK20221547);中国博士后科学基金项目(2021M693424);国家级大学生创新创业训练计划项目(202110290017Z)。

摘　　要：在深部地热能开发中高温岩体会经历不同速率降温过程,研究高温作用后岩石力学行为对深部地下工程具有重要意义。然而,不同冷却方式下高温花岗岩断裂特性演化规律及作用机制尚不明晰。基于此,进行了不同冷却方式下花岗岩半圆盘试样三点弯曲试验,分析了高温后花岗岩荷载-位移曲线、断裂韧度以及破裂特征,探讨了微裂纹分布及矿物含量演化规律。试验结果表明:①随着温度的升高,花岗岩断裂韧度呈减小趋势,遇水冷却方式下断裂韧度低于自然降温条件;②三点弯曲作用下花岗岩半圆盘试样裂纹首先萌生于切槽尖端,逐渐向加载点方向扩展并将岩样劈裂。随着温度的升高,花岗岩试样的断裂痕迹曲折程度、与中心线之间的距离有所增大;③随着温度的升高,花岗岩矿物成分未明显变化,基于图像处理技术获得的微裂纹密度逐渐上升,遇水冷却方式下微裂纹密度大于自然降温方式,表明高温引起的微观结构劣化降低了花岗岩断裂韧度。During the exploitation of deep geothermal energy,the thermal rocks will cool with different cooling rates.A comprehensive understanding of mechanical behavior of the thermal-treated rock is very important for deep underground engineering.However,the fracture behavior and influence mechanism of thermal granite specimens under different cooling ways are unclear at present.Therefore,in this study,the three-point bedding tests are carried out on the semicircular bend granite specimens after high-temperature treatment.The load-displacement curves,fracture toughnesses and failure patterns of the post-heated granite specimens are analyzed,and the evolution laws of micro-cracks and mineral components are discussed.The experimental results show that:(1)As the temperature increases,the fracture toughness of the granite specimens decreases.The fracture toughness of the specimens after quenching in water is lower than that after cooling down naturally in the furnace.(2)The crack initiated from the tip of notch propagates toward the loading point and splits the specimen into two parts.As the temperature increases,the tortuosity degree and deviation of fracture trace of the semicircular bend granite specimens increase.(3)The mineral components of granite are not significantly changed after high-temperature treatment.The micro-crack rate identified by the image processing increases with the increase of high temperature,and that of the specimen after quenching in water is higher than that after cooling down naturally in the furnace,which indicates that the deterioration of micro-structure of rock induced by high-temperature treatment reduces the fracture toughness of granite.

关 键 词：岩石力学 花岗岩 高温 断裂韧度 图像处理 

分 类 号：TU452[建筑科学—岩土工程]