断续节理岩体及岩质边坡破坏的细观机制

Meso failure mechanism of rock mass and slope with intermittent joints

以赞比亚穆利亚希北露天铜矿边坡为工程背景,基于颗粒流理论及PFC2D程序,将岩块和节理分别用颗粒体模型与光滑节理模型表征,构建含2条断续节理岩体及顺层断续节理岩质边坡模型,从细观力学角度深入研究其破坏过程中的力学机制。断续节理岩体破坏研究表明:岩桥破坏模式可划分为模式I、模式II、模式III–a和模式III–b破坏4类,且各类模式本质上均是以矿物颗粒间黏结张拉破坏为主的微破裂引起。顺层断续节理岩质边坡破坏研究表明:滑坡产生的微破裂主要从坡底断续节理端部开始产生,逐渐向坡体上部发展;滑体底部形态较为平直,而后部形态较为曲折并呈台阶状破坏;滑坡产生的破碎颗粒体先在边坡面中、下部产生,其体积相对较小,随后在边坡上部产生,其体积相对较大;在滑坡过程中,节理端部岩桥连线方向上的颗粒接触力较大,产生的微震事件强度与次数的关系近似服从正态分布函数。

The slope of Muliashi north open-pit copper mine in Zambia was selected as engineering background. Based upon particle flow theory and PFC2D（Particle Flow Code 2D） program,the rock block and joint were represented by bonded particle model and smooth joint model,respectively. The rock mass model containing two intermittent joints and rock slope model with bedding intermittent joints were constructed,and their failure mechanism were investigated from meso mechanical viewpoint. The failure research of rock mass with intermittent joints shows that the failure mode of rock bridge can be divided into four types such as mode I,mode II,mode III–a and mode III–b,which are essentially lead to by the dominated tensile microcracks between mineral grain bond. The failure research of rock slope with bedding intermittent joints shows that the microcracks caused by landslide primarily generate at the intermittent joint endpoint of bottom slope,and gradually develop towards top slope. The bottom shape of slide mass is relatively straight,while its tail shape is flexural and presents step-path failure. The fragmentized particle assemblies with relatively small volume primarily generate at middle and bottom part of slope,and then they generate at top slope with relatively large volume. During landslide,the particle contact force along rock bridge is relatively high,and the relationship between magnitude and count of microseismic events approximately obeys normal distribution function.