防灾减灾工程学报2024，Vol.44Issue(2)：434-441,458,9.DOI:10.13409/j.cnki.jdpme.20221204002
砂土含水率对DAS振幅响应影响的试验研究
Experimental Study on Impact of Moisture Content in Sandy Soil on DAS Amplitude Response
摘要
Abstract
Using distributed acoustic sensing(DAS)technology in conjunction with underground tele-communication fiber networks for dynamic urban security monitoring,including perimeter security(in-trusion)monitoring,pipeline leakage detection,and traffic condition assessment,represents a new ap-proach.This research aimed to investigate the influence of moisture content variations in geotechnical mediums around unlit fibers on DAS amplitude response characteristics.To achieve this,the paper de-signed DAS amplitude response tests using sandy soils with varying moisture contents(0%,5%,10%,15%,and 20%)and two excitation modes:a small ball impacting a disc and directly on sandy surface.The test results revealed that:(1)Vibration signals generated by a free-falling ball impacting the sandy surface,coupled with the setup of a ring sensing optic fiber,could enhance the DAS signal-to-noise ratio,thereby increasing the reliability of the testing apparatus and the reproducibility of the results.(2)This study also identified a critical moisture content level that affected the DAS signal am-plitude,which was caused by the combined effects of the sand's pseudo-cohesion and the attenuation of the acoustic wave propagation.Below this critical level,the DAS signal amplitude decreased with increasing moisture content,whereas above it,the amplitude increased with higher moisture levels.(3)The contact method between the balls and the sand had a significant impact on DAS amplitude re-sponse due to the differences in sand's pseudo-cohesion and the energy conversion upon impact.The findings provide a theoretical basis for the application of DAS technology in precise monitoring of ur-ban underground engineering safety.关键词
DAS/砂土/含水率/振幅响应特性/似黏聚力/声波衰减Key words
DAS/sandy soil/moisture content/amplitude response characteristic/pseudo-cohesion/acoustic wave attenuation分类
建筑与水利引用本文复制引用
李俊鹏,张诚成,施斌,陈卓,谢涛,郭君仪..砂土含水率对DAS振幅响应影响的试验研究[J].防灾减灾工程学报,2024,44(2):434-441,458,9.基金项目
国家自然科学基金重点项目(42030701)、国家自然科学基金青年科学基金项目(42107153)资助 （42030701）
