含偏置缺口玄武岩原位三点弯曲细观断裂研究  

INVESTIGATION ON MESO-FRACTURE MECHANISM OF BASALT WITH OFFSET NOTCH BASED ON IN-SITU THREE-POINT BENDING TESTS

作　　者：左建平[1,2] 黄亚明[1] 刘连峰[1] 

机构地区：[1]中国矿业大学力学与建筑工程学院,北京100083 [2]中国矿业大学煤炭资源与安全开采国家重点实验室,北京100083

出　　处：《岩石力学与工程学报》2013年第4期740-746,共7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(2010CB732002);国家自然科学基金资助项目(11102225);教育部新世纪优秀人才支持计划项目(NCET-09-0726)

摘　　要：通过含偏置缺口的玄武岩试件在扫描电镜(SEM)下的三点弯典实时加载试验,得到不同偏置缺口的荷载–位移曲线以及高倍率裂纹扩展照片。一方面,根据矿物颗粒在岩石中总是以一定三维尺度存在,认为裂纹不仅在表面非线性扩展,而且沿厚度方向也是非线性扩展,结合断裂力学中表面能S的计算公式,给出一个考虑岩石非均值和裂纹纵向非线性扩展的表面能密度表达式,并用这个表达式成功解释裂纹扩展中的一些随机现象;另一方面,通过对不同偏置量的荷载–位移曲线对比分析,给出含偏置缺口玄武岩三点弯典荷载–位移曲线的3个典型阶段,并解释各个阶段的微观机制,提出用偏置量影响系数计算偏置缺口三点弯典试样的断裂性能并给出其计算公式,通过对不同偏置缺口试件峰值荷载以及断裂耗能的分析计算,得到峰值荷载与断裂耗能的偏置量影响系数表达式。Load-displacement curves of different offset notch positions and high-precision photos of crack extension are obtained through a three-point bending test by using scanning electron microscope（SEM） with loading system.As the mineral particles in the rock always exist in a certain three-dimensional scale,we analyze that the crack is not only nonlinear extension in the surface but also along the thickness direction.Surface energy expression is rewritten with the consideration of inhomogeneity of rock and crack nonlinear extension along the thickness direction.The new surface energy expression can well explain random phenomena of crack propagation.Through the analysis of load-displacement curves,we obtain that there are three typical stages and the mesomechanism of each stage has been explained by the new expression of surface energy in detail.A new parameter of offset notch crack influence coefficient is proposed to calculate the fracture properties of three-point bending specimens and its formula is given.According to experimental results,the changes of peak load and fracture energy with their offset amount are compared;and then their offset notch crack influence coefficients are obtainted.

关 键 词：岩石力学 偏置裂纹 三点弯典试验 断裂机制 扫描电镜 

分 类 号：TU45[建筑科学—岩土工程]