摘要
岩溶塌陷是土体损伤孔洞发育并最终导致盖层失稳的动力地质过程,故查明土体损伤特征及演化过程是提出有效监测预警方法的重要前提。文章利用声发射与光纤光栅传感技术对岩溶塌陷形成过程展开模型试验,甄别与筛选声发射关键信号特征,并建立其与岩溶塌陷的响应机制。试验结果表明:(1)大雨条件下岩溶塌陷的形成演化过程里,覆盖层深部声发射信号振铃计数较浅部增大6.78~6.89倍,幅度增大1.02~1.12倍,能量扩大了4.45~16.60倍。在暴雨条件下,覆盖层深部声发射信号振铃计数较浅部增大14.85倍,幅度增大1.51倍,能量扩大了213.39倍;(2)大雨试验工况下是以土洞扩展并失稳破坏的蠕变破坏型岩溶塌陷,暴雨试验工况下是土层整体错断坍塌的压剪断裂型岩溶塌陷,不同塌陷类型的声发射信号特征有明显差异;(3)岩溶塌陷过程中会出现土体滑移、层面错动、孔洞发育和塌陷四类信号波形,信号波形释能幅值、上升与下降时间、波形持续时间等与岩溶塌陷演化过程土体变形密切相关;(4)岩溶塌陷过程中声发射频谱信号波形为高频窄脉冲,其中土体滑移、层面错动、孔洞发育和塌陷等四类信号频域能量分别集中在50 kHz和20 kHz左右的高频区段;(5)声发射累计振铃计数与覆盖层孔隙水压力、土压力和土体位移的变化过程存在紧密的关联性,在土体变形与塌陷时会导致声发射振铃计数增加或突发性跃迁现象,因此证明声发射技术用于岩溶塌陷监测预警是可行的。
The karst collapse is a dynamic geological process in which the damage of soil mass and development of cavity ultimately result in the instability of the overburden layer.Therefore,identifying the characteristics and evolution of the damage of soil mass are the important prerequisite to develop effective monitoring and early warning methods for karst collapses.However,the commonly used early warning methods that utilize hydrodynamic conditions and optical fiber monitoring technique often overlook both the process of microscopic damage of the soil mass and the effect of damage on karst collapses.Previous studies on karst collapses induced by groundwater or rainfall typically employ qualitative or semi-quantitative methods.These approaches appear to be one of the reasons why karst collapses−major and prevalent geological disasters in karst regions−have seen limited advancement in monitoring and early warning system.In this study,acoustic emission(AE)and fiber grating technology have been firstly applied to conduct model tests on monitoring and early warning methods of karst collapses.The research on dynamic characteristics of AE has been conducted under different rainfall conditions.In addition,the characteristics of key time domains and frequency domains of AE have been identified and selected to establish a spatial-temporal responding mechanism between AE and karst collapses through model experiment.The results show that as follows,(1)The total ringing count,amplitude,and energy of AE in the shallow overburden layer ranged from 1 times to 348 times,30.5 dB to 175.9 dB,and 0 PJ to 57×10^(-3),respectively,under heavy rainfall conditions.In contrast,the same parameters in deep overburden layer ranged from 1 times to 2,361 times,30.5 dB to 179 dB,and 0 PJ to 946.4×10^(-3)PJ,respectively.In addition,under rainstorm conditions,these parameters in shallow overburden layer ranged from 1 times to 89 times,30.5 dB to 140.9 dB,and 0 PJ to 22×10^(-3)PJ,respectively,while in deep overburden layer,they ranged between 1
作者
潘宗源
戴建玲
文日海
蒙彦
蒋小珍
马骁
白冰
吴远斌
张心
PAN Zongyuan;DAI Jianling;WEN Rihai;MENG Yan;JIANG Xiaozhen;MA Xiao;BAI Bing;WU Yuanbin;ZHANG Xin(Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamics,MNR&GZAR/International Research Center on Karst under the Auspices of UNESCO,Guilin,Guangxi 541004,China;Key Laboratory of Karst Collapse Prevention,CGS,Guilin,Guangxi 541004,China;Pingguo Guangxi,Karst Ecosystem,National Observation and Research Station,Pingguo,Guangxi 531406,China;College of Civil Engineering and Architecture,Guilin University of Technology,Guilin,Guangxi 541004,China;Guilin Hydrological Engineering Geological Survey Institute Co.,Ltd.of Guangxi Zhuang Autonomous Region,Guilin,Guangxi 541002,China)
出处
《中国岩溶》
CAS
CSCD
北大核心
2024年第5期1166-1178,共13页
Carsologica Sinica
基金
中国地质科学院岩溶地质研究所基本科研业务费项目(2021003)
中国地质科学院岩溶地质研究所基本科研业务费项目(2023016、2023017)
中国地质科学院基本科研业务费项目(JKYQN202369)
中国地质科学院岩溶地质研究所基本科研业务费项目(2023013)
广西自然科学基金资助项目(2023GXNSFAA026432)
广西重点研发计划项目(桂科AB23026028)
中国地质调查局地质调查项目(DD20230441)。
关键词
岩溶塌陷
降雨条件
声发射
信号特征
监测预警
karst collapse
rainfall
acoustic emission
time-frequency characteristic
monitoring and early warning
