砂岩单轴压缩试验P波速度层析成像及声发射特性研究  

P-wave velocity tomography and acoustic emission characteristics of sandstone under uniaxial compression

作　　者：张光 吴顺川 张诗淮[4] 郭沛 ZHANG Guang;WU Shun-chuan;ZHANG Shi-huai;GUO Pei(Faculty of Land Resources Engineering,Kunming University of Science and Technology,Kunming,Yunnan 650093,China;Key Laboratory of Ministry of Education for Efficient Mining and Safety of Metal Mine,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of Geohazard Forecast and Geoecological Restoration in Plateau Mountainous Area,Ministry of Natural Resources of the People’s Republic of China,Kunming University of Science and Technology,Kunming,Yunnan 650093,China;Department of Earth Sciences,ETH Zürich,Zürich,Switzerland 8092)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [2]北京科技大学金属矿山高效开采与安全教育部重点实验室,北京100083 [3]昆明理工大学自然资源部高原山地地质灾害预报预警与生态保护修复重点实验室,云南昆明650093 [4]苏黎世联邦理工学院地球科学系,苏黎世瑞士8092

出　　处：《岩土力学》2023年第2期483-496,共14页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51934003);云南省重大科技专项计划项目(No.202102AG050024);云南省高层次人才引进计划“高层次创新创业团队”。

摘　　要：深部矿井开采极易诱发矿柱型岩爆,矿柱型岩爆严重威胁着矿山的安全高效开采,为探究矿柱型岩爆破坏机制和前兆信息,选用自贡红砂岩进行单轴压缩试验,并采用主动超声和被动声发射对破裂过程进行监测,联合主动超声与被动声发射监测数据对波速进行层析成像反演,分析试样破裂过程中波速演化规律。研究结果表明:砂岩试样在加载过程中速度模型呈现高度非均质性,在加载过程中会出现低速区,且声发射事件集中出现在低速区内部;P波速度离散度可反映全局波速变化特征,在峰值附近变化剧烈,随荷载增加P波速度离散度持续增大;声发射事件在峰前、峰后定位结果相差较大,峰前阶段声发射事件随机分布,峰后阶段声发射事件定位结果集中。此外,研究发现选用均质速度模型进行声发射事件定位会增大定位误差,试样最终失稳前b值的降低表明试样大尺度裂纹活动加剧,导致岩石非均质性增大,也间接证明了采用非均质速度模型进行声发射震源定位的必要性。该研究结果可用于现场矿柱稳定性监测,定期反演获得矿柱波速变化为矿柱型岩爆提供先兆预警信息。Pillar burst is one of the most frequent dynamic disasters in deep mining,which poses a serious threat to safe and efficient mining.In this study,the failure mechanisms and precursors of pillar burst are investigated by active ultrasonic survey and passive acoustic emission(AE)monitoring in uniaxial compression tests on Zigong red sandstone.Combining active and passive AE monitoring data,a P-wave velocity tomography inversion is performed to analyse the temporal and spatial variations of P-wave velocity structure during the sample failure.Results show that the velocity structure of the sandstone sample is highly heterogeneous during loading,and a low-velocity zone emerges,within which most of the acoustic emission events are present.The dispersion of P-wave velocity reflects the global variations of P-wave velocity.It changes drastically during the peak stage,and increases with the ongoing loading.The AE events differ significantly between the pre-peak and post-peak stages.In the pre-peak stage,AE events are randomly distributed in the sample,while in the post-peak stage,clustered AE events are identified.In addition,it is found that using the homogeneous velocity structure for AE events location results in a higher positioning error.The decreasing b value before the eventual failure of the sample indicates that large-scale crack activities are intensified,leading to the increase of sample heterogeneity,which also proves the necessity of applying the heterogeneous velocity structure for AE events location.The research results can be further used for on-site pillar stability monitoring,and the periodic P-wave velocity tomography provides precursors for pillar bursts.

关 键 词：声发射 超声波 层析成像 矿柱型岩爆 单轴压缩 

分 类 号：TU45[建筑科学—岩土工程]