红砂岩蠕变过程中应变与声发射特性关系研究

发布时间：2018-03-08 19:26

本文选题：红砂岩　切入点：蠕变破坏　出处：《江西理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：岩石蠕变现象广泛存在于各类地下工程中,对岩石蠕变声发射特性进行研究,将有利于工程稳定性的监测。本文在红砂岩蠕变声发射试验的基础上,首先研究岩石在蠕变状态下应变率与声发射的关系,并通过声发射表征岩石蠕变损伤过程;然后通过应变百分比与声发射参数的关系,探讨了损伤与应变的关系;最后,通过单轴压缩状态下应变与声发射的关系,探讨了两种状态下岩石的损伤过程,建立岩石蠕变破坏的声发射判据。主要得出以下结论:(1)岩石在蠕变破坏过程中,声发射参数变化率随着应变率增大而增大;并且声发射累计振铃计数—时间曲线与蠕变应变—时间曲线具有相似性,在一定程度上可表征岩石的损伤过程。(2)在蠕变破坏过程中,随着应变率的增大,主频值升高,频带范围变宽。在等速阶段主频主要维持在100~350kHz之间,进入加速阶段,主频最大值为500kHz,频带基本维持在75~450kHz之间。由此说明在蠕变加速阶段,岩石内部微裂纹不断萌生、演化贯通形成宏观裂纹,并且新裂纹的萌生和宏观裂纹的形成具有同步性。(3)不同应变率的红砂岩蠕变破坏具有相似的应变与声发射参数特征。(4)红砂岩在单轴压缩状态下应变率与声发射幅度、事件率等无明显线性关系,事件率随应变的增加变化较平稳,当应变达到一定范围时,事件率开始显著增加直至破坏;然而,在蠕变状态下应变率与声发射幅度、事件率呈线性关系,事件率随应变的增加变化较为起伏,在破坏前事件率存在多次“突增”的现象。(5)通过应变与声发射事件率关系以及应变率与声发射幅度、事件率的关系,可判定岩石的蠕变状态。
[Abstract]:Rock creep phenomenon exists widely in various underground projects. The study of rock creep acoustic emission characteristics will be beneficial to the monitoring of engineering stability. This paper is based on the creep acoustic emission test of red sandstone. First, the relationship between strain rate and acoustic emission in creep state of rock is studied, and the creep damage process of rock is characterized by acoustic emission, then the relationship between damage and strain is discussed by the relationship between strain percentage and acoustic emission parameter. Based on the relationship between strain and acoustic emission in uniaxial compression state, the damage process of rock under two states is discussed, and the acoustic emission criterion of rock creep failure is established. The rate of change of acoustic emission parameters increases with the increase of strain rate, and the accumulative ringing counting-time curve of acoustic emission is similar to that of creep strain-time curve, which can be used to characterize the damage process of rock in the process of creep failure to a certain extent. With the increase of strain rate, the value of main frequency increases and the range of frequency band becomes wider. In the constant speed stage, the main frequency is kept between 100 kHz and 350 kHz, and the maximum value of main frequency is 500 kHz, and the frequency band is basically maintained at 75450kHz, which shows that in the creep acceleration stage, the maximum frequency is 500 kHz and the frequency band is between 75kHz and 450 kHz. The microcracks in rock continuously germinate and evolve through to form macroscopic cracks. Moreover, the initiation of new cracks and the formation of macroscopic cracks have synchronism. 3) the creep failure of red sandstone with different strain rates has similar strain and acoustic emission parameters. 4) under uniaxial compression, the strain rate and acoustic emission amplitude of red sandstone are similar. There is no obvious linear relationship between event rate and so on. The change of event rate with the increase of strain is more stable. When strain reaches a certain range, the event rate begins to increase significantly until it is destroyed, however, under creep condition, strain rate and acoustic emission amplitude, The event rate shows a linear relationship, and the event rate fluctuates with the increase of strain. The phenomenon of "sudden increase" exists in the event rate before destruction. The relationship between strain and AE event rate, the relationship between strain rate and AE amplitude and event rate is obtained. The creep state of rock can be determined.
【学位授予单位】：江西理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU45

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