白云岩力学压缩试验及声发射规律研究

Mechanical Compression Test and Acoustic Emission Law of Dolomite

在高地应力近水平岩层中开挖隧道时,由于近水平层理的构造特征,隧道极易出现拱顶离层、掉块、局部超挖、支护结构偏压、初期支护混凝土开裂等现象,甚至发生拱顶失稳坍塌事故。为研究高地应力近水平岩层的破坏特征,本文以大峡谷隧道为工程背景,通过现场钻孔取芯,对岩样进行常规压缩试验,并借助声发射系统分析了岩样压缩破坏过程。研究结果表明:岩石的破坏过程可分为裂纹压密和弹性变形阶段、塑性阶段、峰值阶段、残余阶段;岩样在低围压下主要为张拉劈裂破坏,在中围压下为张拉劈裂破坏和剪切破坏共同存在,在高围压下主要呈剪切破坏且破裂岩体的裂纹扩展更为显著。

Due to the structural characteristics of near-horizontal bedding,tunnel excavation in high ground stress near-horizontal strata is prone to vault separation,falling blocks,local over-excavation,supporting structure bias,initial supporting concrete cracking,and even lead to vault instability and collapse. In order to study the failure characteristics of near-horizontal strata with high geostress,this paper takes the Grand Canyon Tunnel as the engineering background,conducts the conventional compression test by drilling core and systematically analyzes the compression failure process of rock samples with acoustic emission system. The results show that the failure process of rock can be divided into crack compaction and elastic deformation stage,plastic stage,peak stage and residual stage. Under low confining pressure,the failure process of rock samples is mainly tensile splitting failure. Under medium confining pressure,tensile splitting failure and shear failure coexist. Under high confining pressure,the rock samples are mainly shear failure and the crack propagation of fractured rock mass is more obvious.