单矿物石英岩高温损伤破裂机理细观研究  

MESOSCOPIC STUDY ON DAMAGE AND FRACTURE MECHANISM OF MONOMINERAL QUARTZITE AT HIGH TEMPERATURE

作　　者：彭潇 周剑 张路青[2,3] 杨志法[2,3] 董庭发 张德宇 PENG Xiao;ZHOU Jian;ZHANG Luqing;YANG Zhifa;DONG Tingfa;ZHANG Deyu(Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education,Beijing University of Technology,Beijing 100124,China;Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institutions of Earth Science,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]北京工业大学,城市与工程安全减灾教育部重点实验室,北京100124 [2]中国科学院地质与地球物理研究所,中国科学院页岩气与地质工程重点实验室,北京100029 [3]中国科学院地球科学研究所,北京100029

出　　处：《工程地质学报》2024年第6期2175-2187,共13页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:41972287)。

摘　　要：基于颗粒离散元计算架构建立单矿物石英岩的颗粒簇模型(grain based model,GBM),以石英岩微裂纹发展规律为约束优化矿物模型的弹性模量及其边界强度参数,开展热-固耦合下石英岩的高温损伤及强度劣化细观机理研究,获得以下结论:(1)优化矿物弹性模量及其边界强度参数后可很好地再现石英岩高温作用下微裂纹演化规律:首先从石英晶粒边界萌生,逐渐扩展至晶粒内部,最终形成裂纹网络。(2)单轴压缩模拟中石英岩弹性模量随温度的升高总体上呈现出先增大后减小的趋势,泊松比表现为先减小后增大,且泊松比较弹性模量对热损伤表现出更高的敏感性。(3)随着温度的升高,石英岩单轴压缩过程中微裂纹的离散性增加,破坏模式从多斜面剪切破坏逐渐转变为无明显宏观裂纹的分散式拉伸(劈裂)破坏。(4)岩石的力学强度劣化规律与其本身的致密性及矿物成分、含量密切相关,与花岗岩相比石英岩热损伤温度阈值高,约为200℃。(5)3种不同石英含量的岩石的热损伤结果表明:矿物边界和力学强度较低的矿物内部首先发生热破裂,矿物之间的镶嵌结构对石英矿物的热损伤有抑制作用。A grain-based model(GBM)of monomineral quartzite is constructed using the framework of particle discrete element calculation.The elastic modulus and boundary strength parameters of the mineral model are optimized using the development law of microcracks in quartzite as constraints.This model is used to study the meso-mechanism of high-temperature damage and strength deterioration of quartzite under thermal-solid coupling.The following conclusions are drawn:(1)The microcrack evolution law of quartzite under high temperature can be well reproduced by optimizing mineral elastic modulus and boundary strength parameters.Microcracks first germinate from the boundary of quartz grains and gradually extend to their interior,eventually forming a crack network.(2)In uniaxial compression simulations,the elastic modulus of quartzite initially increases and then decreases with rising temperature.Poisson's ratio follows an inverse pattern,decreasing at first and then increasing.Poisson's ratio is more sensitive to thermal damage than the elastic modulus.(3)As temperature increases,the discreteness of microcracks in quartzite increases.The failure mode gradually shifts from multi-slope shear failure to dispersed tensile(splitting)failure without obvious macroscopic cracks.(4)The mechanical strength deterioration of rock is closely related to its compactness,mineral composition,and content.The thermal damage temperature threshold of quartz rock is higher than that of granite,at approximately 200℃.(5)Thermal damage results from three types of rocks with different quartz content show that thermal fracture first occurs in minerals with low mechanical strength.The mosaic structure between minerals can inhibit the thermal damage of quartz minerals.

关 键 词：石英岩 热破裂 强度劣化 颗粒簇模型 颗粒流方法 

分 类 号：P642.3[天文地球—工程地质学]