岩桥剪切破坏的声发射特征研究

Laboratory Investigation on Acoustic Emission Characteristic During Shear Failure of Rock Bridge

浙江省山地众多,山体地质灾害发生频繁。为实现声发射技术在浙江地区地质灾害监测预警中的应用,选取浙江4种典型岩石(砂岩、灰岩、凝灰岩及玄武岩),通过一系列不同岩石的斜剪试验,对岩桥剪切破坏全过程的力学特征和声发射特征进行研究。结果表明,4种典型岩石发生岩桥剪切破坏时,累计振铃计数及累计能量与剪应力的变化特征相似,二者的相关性较明显;当岩桥剪切位移达到2.0~3.9 mm时,随着剪应力出现快速增长,开始产生大量声发射事件;声发射特征参数中累计振铃计数比累计能量更能及时反映出剪应力的增长变化趋势;玄武岩在岩桥剪切破坏过程中的声发射呈现一定的台阶式递进上升变化特征。研究结果将为浙江地区岩质滑坡声发射监测预警提供参考。

There are many mountainous areas in Zhejiang Province,and geological disasters occur frequently.In order to realize the application of acoustic emission(AE)technology in geological disaster monitoring and early warning in Zhejiang Province.Four typical types of rocks such as sandstone,limestone,tuff and basalt in Zhejiang province were chosen,and a series of skew shear tests for these different kinds of rocks were carried out to investigate the mechanical and acoustic emission characteristics during shear failure of rock bridges.The results show that(1)the variation characteristics of cumulative ring count and cumulative energy are similar to those of shear stress,and the correlation between the two types of characteristics is obvious;(2)when the shear displacement of rock bridges reach 2.0-3.9 mm,a large number of AE events begin to occur as the shear stress increases rapidly;(3)compared with the cumulative energy,the cumulative ring count can be more timely to reflect the increasing trend of shear stress;(4)the AE of basalt in the process of shear failure of rock bridge presents a step-by-step progressive change feature.The research results will provide reference for monitoring and warning of rock landslides in Zhejiang Province.