摘要
花岗岩以其优越的力学性质在工程中被广泛利用,提出一种多级平行黏结晶体模型(MultiPb-GBM)用以模拟类晶体花岗岩的微观结构。以平行接触模型代替传统的光滑节理模型来刻画晶体边界,将平行接触模型分为3种类型:晶体内部接触、同种矿物内部的晶体边界接触以及不同种矿物的边界接触。应用单轴压缩试验和巴西劈裂试验对模型的微观参数进行校正,开展多组数值试验研究晶体尺寸分布系数影响下脆性花岗岩试样的动态损伤破裂演化过程,并基于Fish函数建立一套完整的裂隙监测系统以记录微裂缝的行为特点。研究结果表明:(1)晶体尺寸分布系数对破裂模式会产生影响,单轴压缩试验与劈裂试验中张拉裂纹均占据主导,随着花岗岩晶体尺寸的增大,单轴抗压强度(UCS)和抗拉强度(UTS)均呈现出增大趋势。(2)不同矿物晶界处的裂纹数量多于同种矿物晶界处的裂纹数量,随着平均晶体尺寸分布系数的增大,晶界处的裂纹数量逐渐减少,内部破裂数量相对增多。(3)微裂纹首先出现在第三级接触处,随后二级接触处发生断裂,最后一级接触裂纹数目迅速增大。(4)单轴压缩试验是由钾长石–石英边界为主的晶间破裂向钾长石–斜长石为主的晶内损伤转化的过程,直至宏观破坏的发生。
Granite is widely used in engineering for its superior mechanical properties. A multilevel parallel bonded-grain based model(Multi Pb-GBM) was proposed to revel the micro structure of crystalline granite,in which parallel bonded-grain model(Pb) was introduced to replace smooth joint model(SJ) to represent the grain boundaries. The bonded mode of the samples were clarified into three types including intra-grain contact,inter-grain contact inside one mineral and inter-grain contact between two different minerals. Parameters of the model were calibrated through uniaxial compression tests and Brazil splitting tests,and simulations were conducted to study failure modes and dynamic damage evolution of brittle granite rock under the influence of the grain size distribution coefficient. An intact fracture-monitored system was established based on Fish function,and the behaviors of the micro-fracture were discussed. The results indicate that the grain size distribution coefficient has an effect on the failure modes,tensile cracks are dominant in uniaxial and Brazil splitting tests,and that both UCS and UTS show an increasing tendency with increasing granite crystal size. The number of cracks at grain boundaries of different minerals is larger than that at grain boundaries inside the same mineral. With increasing the grain size coefficient,the number of cracks at grain boundaries gradually decreases while the internal fractures increase. The microcracks first appear at the third level contacts,followed by the fractures at the second level contacts,and then the number of first level cracks increases rapidly. During uniaxial compression tests,a transformation process from inter-grain fracturing with kalium feldspar-quartz boundary to intra-grain damaging within kalium feldspar-plagioclase occurs until macroscopic failure.
作者
刘帅奇
马凤山
郭捷
曹家源
王志文
LIU Shuaiqi;MA Fengshan;GUO Jie;CAO Jiayuan;WANG Zhiwen(Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2020年第11期2283-2295,共13页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(41831293)
国家重点研发计划项目(2018YFC1505301)
第二次青藏高原综合科学考察研究资助(2019QZKK0904)。
