中文摘要：

为获取岩石力学试验碎片表面的分形特征,特别是码尺在亚毫米级以下的二维分形特征,利用投影覆盖法对大理岩岩爆试验碎片表面特征进行研究。首先,利用岩爆试验模拟隧洞开挖时洞腰的卸载破坏现象并分析大理岩试件破坏特征。然后,利用激光共聚焦扫描显微镜对碎片进行表面测量,获取其三维表面数据,并使用三角剖分法求取不同码尺所对应的表面积,分析表面积随码尺变化的规律即碎片的二维分形特征。最后,论证使用投影覆盖法计算大理岩碎片表面积的码尺下限。试验结果表明：（1）碎片表面积在0.625-639.375μm范围内具有多重分形特征;（2）表面积增长率的分布在0.625-319.688μm范围内类似于正态分布,在0.625μm范围以下,碎片表面积的增长极为有限,故分形规律计算碎片表面积的码尺下限可以取0.625μm;（3）基于扫描电镜的断口分析进一步证实碎片表面积计算中的码尺下限及其二维多重分形特征。

英文摘要：

In order to obtain surface fractal characteristics of fragments from rock mechanics test,especially the two-dimensional fractal characteristics at yardstick below sub-millimeter,Projective Covering Method was utilized. Firstly,unloading damage phenomenon at cave waist was simulated by rock burst test,and then marble samples damage characteristic was studied. Secondly,3D surface data of fragments from rock burst test was acquired by Confocal laser scanning microscope. Surface area at different yardstick was acquired by Triangulation method and two-dimensional characteristic of fragments was analyzed. Thirdly,lower limit of yardstick was confirmed in surface area calculation by Projective Covering Method. Three conclusions were drawn. Firstly,surface area of fragment had multi-fractal characteristic at yardstick from 0.625 μm to 639.375 μm. Secondly,the distribution of surface areas growth rate was similar with normal distribution. At yardstick below 0.625 μm,increase of surface area was little,so 0.625 μm could be regarded as lower limit of yardstick in surface area calculating by Projective Covering Method. Thirdly,fracture analysis from scanning electron microscopy confirmed the lower limit of yardstick in surface area calculating and the multi-fractal characteristic of fragments.