冻融循环条件下英安岩损伤劣化力学机理研究  

Mechanical Mechanism of Dacite Damage Deterioration under Freeze-thaw Cycles

作　　者：汪鑫 郑达 吴鑫泷 姚青 WANG Xin;ZHENG Da;WU Xin-long;YAO Qing(School of Environment and Civil Engineering, Chengdu University of Technology, Chengdu 610059, China;China Huaxi Engineering Design & Construction Co., Ltd., Chengdu 610031, China;Henan Provincial Communications Planning & Design Institute Co., Ltd., Zhengzhou 450018, China)

机构地区：[1]成都理工大学环境与土木工程学院,成都610059 [2]中国华西工程设计建设有限公司,成都610031 [3]河南省交通规划设计研究院股份有限公司,郑州450018

出　　处：《科学技术与工程》2021年第24期10421-10429,共9页Science Technology and Engineering

基　　金：国家重点研发计划(2018YFC1504905);国家自然科学基金(41772317);国家重点实验室自主课题(SKLPG2020Z008)。

摘　　要：岩石的变形及破坏是高寒地区较为常见的工程地质问题,为了揭示岩石在冻融环境下的损伤及变形破坏演化深层规律,选取西藏如美水电站中坝址右岸出露的英安岩为研究对象进行深入分析。首先利用扫描电镜-X射线能谱仪(scanning electron microscope-energy dispersive X-ray spectrometer,SEM-EDS)对英安岩进行矿物成分分析,随后开展单轴压缩试验并结合相关、偏相关分析确定对试样力学特性影响最大的矿物成分。通过模拟研究区真实的冻融环境开展冻融循环试验,结合不同冻融次数下试样物理性质及细观结构的变化情况进行深入分析并采用数值仿真模拟重现冻融循环过程中试样内部温度及应力应变的演化特征,揭示英安岩冻融损伤劣化的力学机理。研究结果表明:英安岩呈现脆性破坏主要是由斜长石和石英的损伤劣化所引起的,其中斜长石和石英矿物晶体间产生的脆性裂纹以及两者游离态晶体颗粒的析出是英安岩劣化微裂隙扩展的关键因素,沿石英和斜长石晶体晶界结构所产生的脆性断裂是英安岩细观损伤延伸扩展的主要形式。数值模拟结果表明:冻融循环过程中英安岩内部的温度变化响应及分布形态主要受细观结构控制,裂隙端部所产生的拉应力及剪应力集中区是裂隙延伸扩展的力学基础。Rock deformation and failure are common engineering geological problems in Alpine regions.In order to reveal the deep law of rock deformation and damage under freeze-thaw conditions,the dacite exposed on the right bank of the middle dam site of Rumei Hydropower Station of Tibet was taken as the research object.Firstly,the mineral composition of dacite was analyzed by scanning electron microscope-energy dispersive X-ray spectrometer(SEM-EDS),and then the uniaxial compression test was carried out to determine the mineral composition which has the greatest impact on the mechanical properties of the sample.The freeze-thaw cycle test was carried out by simulating the real freeze-thaw environment in the study area.The changes of physical properties and microstructure of samples under different freeze-thaw times were analyzed in depth.The evolution characteristics of internal temperature,stress and strain of samples during freeze-thaw cycle were reproduced by numerical simulation,and the mechanical mechanism of freeze-thaw damage deterioration of dacite was revealed.The results show that plagioclase and quartz are the basis of brittle failure in dacite.The brittle cracks appear between plagioclase and quartz crystals and the precipitation of free plagioclase crystals and quartz crystals is the basis of dacite’s deteriorated micro-crack expansion.The brittle fracture along the crystal boundary of quartz and plagioclase is the main form of microscopic damage extension.Numerical simulation results show that the distribution characteristics of the meso-structure are the main factors affecting the temperature distribution in the rock.The tensile stress and shear stress concentration area generate at the end of the crack are the mechanical basis of the crack extension.

关 键 词：冻融作用 英安岩 矿物分析 细观结构 损伤劣化 

分 类 号：TU452[建筑科学—岩土工程]