单轴加卸载条件下岩盐变形过程能量和声发射特征研究

Study on the Energy and Acoustic Emission Characteristics of Rock Salt Under Uniaxial Loading and Unloading Conditions

利用MTS815 Flex Test GT岩石力学试验系统及声发射(AE)实时监测系统,对取自平顶山和淮安两处矿井的纯盐岩进行单抽加卸载试验,得到岩盐的应力-应变加卸载曲线、声发射振铃计数率和能量率曲线,并从能量与声发射的角度研究纯岩盐变形破坏过程的基本特征。研究表明:岩盐单轴加卸载条件下,弹性变形阶段很短,屈服过程产生很大的塑形变形,且峰后的变形过程没有应力的急剧下降,整个试验过程中加卸、载之间滞回环面积很微小。在整个试验过程中,弹性应变能所占比例非常小;盐岩单轴加卸载变形破坏过程中,其耗散能随应变一直增加,且增长率递增,而当应力接近峰值时,增长率趋于恒定,耗散能曲线开始呈线性增长;弹性应变能在峰前一直增加,且增长率递减,在峰值处达到最大值,峰后开始下降。岩盐在试验初始阶段振铃计数率与能量率大量产生,后在屈服阶段呈现下降进入稳定发展期,直到峰值处,出现一个累计振铃计数和累计能量曲线的拐点,峰后以一个更高的速率稳定且呈现阶梯状发展。本文对于盐岩储气库的水溶开挖和采气过程中逐渐卸载的应力环境施工过程有一定的实际指导意义。

To study the basic characteristics of the energy and the acoustic emission angle in the process of rock salt deformation,the uniaxial loading and unloading tests were carried out with pure salt rocks from Pingdingshan and Huaian by using MTS815 Flex Test GT and acoustic emission monitoring system. The research showed that the elastic deformation stage is very short,the yielding process produces large plastic deformation,the stress did not decrease sharply after peak,and the hysteresis loop area between loading and unloading curve was always very small under uniaxial loading and unloading conditions. In the whole experiment,the proportion of elastic strain energy was very small. In the process of rock salt deformation and failure,the dissipation energy increased with the increase of the strain,the rate of rise was incremental,the rate of rise tended to be constant when the stress was close to the peak value,and the dissipation energy curve began to present linear growth. The elastic strain energy increased before the peak of stress,the rate of rise was diminishing,it reached the peak value at the peak of stress,and decreased after the peak of stress. The AE count rate and energy rate emerged in large quantities in the initial stage of the test,then downwarded into the stable development period in the yield stage. Until the peak of stress,an inflection point,accumulative count and cumulative energy curve appeared,and the ladder shape development appeared at a higher rate after the peak of stress.