花岗岩岩爆试验碎屑分形特征分析  

ANALYSIS OF FRACTAL CHARACTERISTICS OF FRAGMENT FROM ROCKBURST TEST OF GRANITE

作　　者：李德建[1,2] 贾雪娜[1,2] 苗金丽[1,2] 何满潮[1,2] 李丹丹[2] 

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,北京100083 [2]中国矿业大学力学与建筑工程学院,北京100083

出　　处：《岩石力学与工程学报》2010年第A01期3280-3289,共10页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家重点基础研究发展计划(973)项目(2006CB202200;2010CB226800);国家自然科学基金重大项目(50490270);教育部创新团队发展计划项目(IRT0656)

摘　　要：采用真三轴应力状态下单面突然卸载试验方法,进行莱州花岗岩岩爆试验,获得花岗岩岩爆碎屑。对碎屑特征进行测量,包括碎屑质量、长度、宽度、厚度,并对粗粒、中粒、细粒以及微粒等不同粒径范围内的碎屑数量、质量及粒度分布进行分析。对花岗岩岩爆碎屑分别按照长度、宽度、厚度与累计数量的关系,小于某一等效边长的累计质量与总质量之比与等效边长之间的关系,以及等效边长与累计数量的关系进行分形计算,结果表明花岗岩岩爆碎屑破碎程度较高,片状特征明显。对岩爆后的微粒碎屑(颗粒直径<0.075mm)利用激光粒度分析仪进行粒度分析。破坏后微粒碎屑所占百分比以岩爆试验最多,其次为真三轴试验,单轴压缩试验最少。微粒碎屑的粒度分布曲线形状不同,岩爆的平缓,小尺度的多,三轴和单轴压缩的大致相同,粒径大。分布曲线上百分比最大值对应的粒径岩爆的最小,为40和60μm,三轴的为80μm,单轴的为100μm。对微粒碎屑按照粒度-体积分布进行了分形维数计算,结果表明岩爆微粒碎屑符合分形物理意义,三轴和单轴微粒碎屑不具有分形特征。岩爆微粒碎屑较多,反映其破坏时消耗的能量要多于三轴和单轴破坏。Rockburst test of Laizhou granite is carried out under true triaxial experimental machine system with one surface of the sample unloading suddenly, and the roekburst fragments are collected. The roekburst fragments are measured including the mass, length, width and the thickness. The fragment quantities of coarse, medium, fine and micro grains in different size ranges, quality and particles distribution are analyzed also. Rockburst fragment fractal of the granite is obtained according to the relations of the fragment length, width, and thickness to cumulative number. Respectively, the relation of ratio of cumulative mass of equal length which is smaller than it divided by the total mass to equal length, as well as the relation of equal length to cumulative number of fragments The results show that the degree of crushing of granite rockburst fragments is higher and with obvious slab characteristics. The micro-particles（approximately〈0.075 mm） of rock sample after rockburst are analyzed by laser-particle machine. The most, moderate and smallest micro-particles mass of rock sample after failure is generated under rockburst test, true triaxial uniaxial compression test condition, respectively. The characteristics of particles distribution curves appear that it is gradual of rockburst test, steep of both true triaxial compression test and uniaxial compression test. Most micro-particles diameters of rockburst failure are smaller than of others. The particle diameter corresponding to the largest volume percentage value in the micro-particles distribution curves of rockburst are 40 and 60μm. The particle diameters of true triaxial compression and uniaxial compression test are 80 and 100μm respectively. The fractal dimension of micro-particles is calculated with the diameter-volume distribution. It implied that the micro-particles of rockburst failure fits the physics concept of statistics self-similar fractal rules, the others are not. More energy is dissipated during rockburst than that of true triaxial and unia

关 键 词：岩石力学 花岗岩岩爆 岩爆碎屑 分形维数 碎屑特征 等效边长 

分 类 号：TU45[建筑科学—岩土工程]