摘要
灰岩溶隙随其发育阶段呈现不同形状,溶隙形状将影响受力作用下的灰岩裂纹演化机制。利用单轴压缩试验下声学特征(RA-AF)对“裂隙”、“椭圆孔”、“类蘑菇孔”和“类哑铃孔”等4类溶隙形状的灰岩微裂纹演化机制进行了研究。根据单轴压缩试验的声学特征、力学特征,将声发射演化过程分为初始非线性段(Ⅰ)、类线性段(Ⅱ)、非线性阶梯状幂律段(Ⅲ)和峰值活跃段(Ⅳ)等4个阶段,通过分析RA-AF演化特征,以及基于二维高斯混合模型(GMM)的RA-AF值聚类分析,获得不同阶段的演化规律。研究结果表明:完整灰岩和溶隙灰岩随着加载的进行,RA和AF值均表现出明显的原点集中性;完整灰岩和“椭圆孔”灰岩的破坏模式以拉裂为主,“裂隙”灰岩是以剪切为主的拉剪混合破坏,“类蘑菇孔”灰岩是以拉裂为主的拉剪混合破坏,“类哑铃孔”灰岩则是先剪后拉的拉剪混合破坏;溶隙形状对微裂纹的形成产生较大影响,“裂隙”灰岩表现出极强的剪切性质;“椭圆孔”的剪切性质减弱,拉裂性质增强;“类蘑菇孔”的破坏受溶隙上下部的“菌伞”和“菌柄”控制,控制次序是先下后上;“类哑铃孔”则先由“菌伞”控制,再由整个溶隙孔控制,并且第Ⅲ阶段“菌基”出现抑制效应,这种抑制效应能够明显延长岩样的寿命。
Karst-fissure limestone has different shapes in different stages,which affects the crack evolution mechanism of limestone under load.Based on the acoustic emission characteristics(RA-AF),this study investigates the microcrack evolution mechanism of limestone with four types of Karst fissure,namely,“fissure-like,” “elliptical,” “mushroom-like,” and “dumbbell-like” under uniaxial compression.The acoustic characteristic process can be divided into four stages:the initial nonlinear stage(Ⅰ),linear-like stage(Ⅱ),nonlinear stepped power law stage(Ⅲ),and peak active stage(Ⅳ),according to the acoustic and mechanical characteristics under uniaxial compression.Simultaneously,based on the two-dimensional Gaussian mixture model(GMM) RA-AF value cluster analysis,this study obtains the evolution law of the five different stages.The research results show that as the loading progresses,the RA and AF values of both intact and karst-fissure limestone show an obvious origin concentration.The failure mode of intact limestone and “elliptical” limestone is mainly tensile failure;that of “fissure-like” limestone is tensile-shear mixed failure,and the shear mode dominates;that of “mushroom-like” limestone is tensile-shear mixed failure mode,where tensile failure is the main factor;that of “dumbbell-like” limestone is tensile-shear mixed failure mode,where shear failure occurs first,followed by tensile failure.The shape of the karst fissure affects the formation of microcracks during the failure process:the “fissure-like” limestone shows extremely strong shearing properties;the shearing properties of “elliptical” are weakened,but the tensile properties are enhanced;the “mushroom-like” limestone’s failure is controlled by the “stalk” and “umbrella” sequentially;the “dumbbell-like” limestone is controlled by the “umbrella” first,followed by the entire hole,and the inhibitory effect of the “bacterial base” appears in the third stage,and this inhibitory effect can significantly extend the “life” of the rock sample.
作者
王桂林
王润秋
孙帆
曹天赐
WANG Gui-lin;WANG Run-qiu;SUN Fan;CAO Tian-ci(School of Civil Engineering,Chongqing University,Chongqing 400045,China;National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas,Chongqing 400045,China;Key Laboratory of New Technology for Construction of Cities in Mountain Area,Ministry of Education,Chongqing University,Chongqing 400045,China)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2022年第8期118-128,共11页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51978106)。
作者简介
王桂林(1970-),男,江西寻乌人,教授,博士研究生导师,工学博士,E-mail:glw@cqu.edu.cn。
