三点弯梁开裂过程及尺寸效应的连续-非连续方法模拟  

Modeling of Cracking Processes and Size Effects of Three-point Bending Beams Using a Continuum-discontinuum Method

作　　者：王学滨 郭翔[2] 芦伟男[2] 祝铭泽 Wang Xuebin;Guo Xiang;Lu Weinan;Zhu Mingze(Institute of Computational Mechanics,Liaoning Technical University,Fuxin,Liaoning 123000,P.R. China;College of Mechanics and Engineering,Liaoning Technical University,Fuxin,Liaoning 123000,P.R. China)

机构地区：[1]辽宁工程技术大学计算力学研究所,辽宁阜新123000 [2]辽宁工程技术大学力学与工程学院,辽宁阜新123000

出　　处：《地下空间与工程学报》2018年第6期1587-1593,共7页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(51574144);辽宁省百千万人才工程项目(2017)

摘　　要：本文利用自主开发的一种适于模拟准脆性材料(岩石、混凝土等)变形、开裂、接触、摩擦及转动的连续-非连续方法(该方法借鉴了拉格朗日元法、变形体离散元法及虚拟裂缝模型的有关原理),通过在梁跨中预设允许分离节点,开展了位移控制加载条件下三点弯梁开裂过程及尺寸效应的数值模拟研究。研究发现,随着加载点位移的增加,梁跨中的节点不断分离,裂缝不断发展,最大主应力始终集中于裂缝尖端附近;随着裂缝的张开,裂缝两侧发生卸载。梁的跨高比越大,梁的载荷峰值越小,梁的载荷-位移曲线的峰前和峰后部分越平缓。梁的高度越大,储存的应变能越高,梁的开裂越迅速,这可解释煤矿中采掘活动引起的巨厚砾岩层的开裂和运动诱发的冲击地压现象。The self-developed continuum-discontinuum method,which is applicable for modeling a series of complex mechanical behaviors,such as deformation,cracking,contact,friction and rotation of quasi-brittle materials ( such as rocks and concretes) ,introduces the Lagrange element method,the discrete element method and the fictitious crack model. Cracking processes and size effects of three - point bending beams are modeled under displacement-controlled loading,in which a few nodes permitted to separate are prescribed at the middle spans of beams. It is found that as deformation proceeds,nodes at the middle span of the beam continuously separate,cracks continuously extend,and the maximum principal stresses always concentrate at the tip of the crack. With an opening of the crack,unloading occurs at two sides of the crack. For the beam with larger span-depth ratio,the load-carrying capacity is lower,and less steep pre-peak and post-peak load-displacement curves can be expected. For the thick beam,the stored elastic strain energy is high; cracking is fast at a short time. This finding can explain the phenomenon that rockbursts can be induced by the cracking and movement of super - thick conglomerate strata overlying working faces in coal mines.

关 键 词：三点弯梁 开裂 尺寸效应 连续-非连续方法 冲击地压 

分 类 号：TU451[建筑科学—岩土工程]