ACOUSTIC EMISSION AND CRACK DEVELOPMENT IN ROCKS

来源 :岩石力学与工程学报 | 被引量 : 0次 | 上传用户:liyan19821021
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
of PkD tbesis The research concentales mainly on the development of faiIure process in rock materials and the charateristics of associated acoustic emission through both laboratory and numerical investigations. Various asPectS are discussed in detail, and these include Kaiser effecL acoustic emission (AE) behaviour under uniaxial compression and tension, visualization of failure process and parametric stUdies using numerical approach. Laboratory testS have been carried out tO Study the Kaiser effect on severa tyPes of rock in Hong KOng. Recognizing that the AE counts are transient elastic waves due to local damages of rock, the quantitative relation betWeen AE countS and deformation of rock sPecimens has been established. Subsequently, an expression for Kaiser effect under uniaxial stress state is derived based on damage theory. The prediction of acoustic emission behaviour is found to be in good agreement with exPerimental results. TeChniques on servo controlled teSts on rock and acquisition of AE signals are also exPlored and discussed. Source location algorithms and techniques are aPplied to determine the AE sourees in tWo and threedimensional rock sPecimens. AcouStic emission behaviour of rock sPecimen under load has been scrUtinital by anaIysing AE parameters and AE sources in both comPression and tension. be charateristic stages of failure can be identified according to the featUI’e POints on the AE curves. For each Stag, micro-cracks which are reSPOnSible for the main sources of AE can be beed so that the process of crack formation, coalescence and development can be virtUally “visualized” step by step. Simultueously, numerical simulations are carried out in order to study the changes in stress and deformation distribution during the failure process. It provides new insigh on the fOrmation mechanism of failure zones and the development of cracks. Parametric stUdies are also conducted tO assess the effect of various factors on the failure process and failure mode. of PkD tbesis The research concentales mainly on the development of faiIure process in rock materials and the charateristics of associated acoustic emissions through both laboratory and numerical investigations. Various as Pects are discussed in detail, and these include Kaiser effecL acoustic emission (AE) behavior under uniaxial compression and tension, visualization of failure process and parametric stUdies using numerical approach. Laboratory testS have been carried out tO Study the Kaiser effect on severa tyPes of rock in Hong KOng. Recognizing that the AE counts are transient elastic waves due to local damages of rock , the quantitative relation betWeen AE countS and deformation of rock sPecimens has been established. An, an expression for Kaiser effect under uniaxial stress state is derived based on damage theory. The prediction of acoustic emission behavior is found to be in good agreement with exPerimental results TeChniques on servo controlled teSts on rock and acqu ision of AE signals are also exPlored and discussed. Source location algorithms and techniques are aPplied to determine the AE sourees in tWo and threedimensional rock sPecimens. AcouStic emission behavior of rock sPecimen under load has been scrUtinital by an alpha Iysing AE parameters and AE sources in both comPression and tension. be charateristic stages of failure can be identified according to the featUI’e POints on the AE curves. For each Stag, micro-cracks which are reSpenetrable for the main sources of AE can be be so so that the process of crack formation, coalescence and development can be virtUally “visualized ” step by step. Simultueously, numerical simulations are carried out in order to study the changes in stress and deformation distribution during the failure process. It provides new insigh on the fOrmation mechanism of failure zones and the development of cracks. Parametric stUdies are also conducting tO assess the effect of various factors on the failure process and failuremode.
其他文献
企业改革极大地推动着经济发展,近年来武汉市一直保持着二位数的高经济增长速度,去年首次工业总产值过千亿元。人均国内生产总值(GDP)首次过万元,经济增长速度高于全国及全
【摘要】区角活动作为幼儿园教育中的重要组成部分,以自主、舒适、愉悦等独特的优势深受幼儿的喜爱,为幼儿提供了充分的自由交往与沟通的机会,让幼儿在区角活动中自觉的调整身心状况,保持愉快的心情,同时也促进了幼儿社交技能和情感表达能力的提高。但是,幼儿在区角活动中,幼儿常常会为了抢夺活动区间和活动材料而发生冲突,并为此争吵不休,那么如何才能让幼儿学会分享,学会与同伴合作探究呢?  【关键词】区角活动 幼儿
随着《幼儿园工作规程》《幼儿园教育指导纲要》《幼儿园教师专业标准(试行)》《3-6岁儿童学习与发展指南》等学前教育相关政策的颁布,民办幼儿园如雨后春笋般层出不穷,民办
江泽民主席3月3日在参加八届全国人大五次会议上海代表团全体会议时指出,部分国有企业在改革和发展中出现的困难是前进中的问题。我们要积极工作,锐意进取,既要充分看到解决
本文通过解析方法分析了Pr与Sc不为1的情况下挥发燃料平面上平行氧化剂来流形成的边界层中的火焰面。对给定的物性,火焰位置和温度以及气化率可以被显式表达。同时也得到了和
国内外研究发现β射线皮肤损伤存在两大难题,一是创面难愈,反复溃疡坏死;二是远期易恶变致癌或疤痕增生.笔者自1988年至1993年,应用游离皮瓣与皮片移植修复深度β射线皮肤损伤4例,随访13~18年,现报道如下。
研究粘性、不可压缩、导电流体,在磁化可渗透竖直平板上作自然对流时,数值地分析辐射和磁流体组合的影响.采用两种方法数值地求解非相似的控制方程:1)对所有吸入参数值ξ,采
只生产一种饮料的可口可乐能称雄全球,我国的茅台酒早已饮誉海内外,但它的售价只有 XO 的几分之一。原因何在?社会学家告诉我们:当人们从温饱型迈入小康型甚至富裕型的生活
A numerical method for bearing capacity analysis by the upper bound theorem is presented. Based on the well- known Mohr-Coulomb failure criterion and the associ
随着中国经济的发展,随着振兴民族品牌意识的加强,国人对于民族品牌的关注日益增强。国家经济的发展离不开民族名牌队伍的日益壮大,而民族名牌的发展又离不开国家对于这些品