| 摘要: | 地層下陷代表受自然過程和人類活動相互作用的一個複雜的全球現象，對環境和基礎設施都構成重大風險。儘管人們越來越認識到其重要性，但有效監測地層下陷仍然面臨各種挑戰。為增進對地層下陷機制的理解，本研究試圖引入布里渊光時域反射技術（Brillouin Optical Time Domain Reflectometry, BOTDR）來進行監測。本研究通過在等距離沉降環之間的光纖，測量其相對拉伸壓縮變化，以探索地層的變形特徵。相關設計可提供米級空間分辨率，允許對沉降機制進行全面檢查。此外，實驗室相關率定測試可有效檢視地層下陷監測系統的效率，其監測位移的標準偏差 ≤ 0.23 mm。此外，現場BOTDR結果進一步與磁環和地下水位進行比較，研究結果揭示整個鑽孔中地層下陷的分佈，揭示造成地層下陷的主要因素和變形過程的演變。BOTDA系統記錄到2023年4月11日最大的下陷量為13.68 mm， BOTDR則記錄到2024年4月17日的下陷量為13.65 mm。綜合上述成果，BOTDR方法具有持續且長期的監測性能，凸顯提供地層下陷洞察力的潛力。因此，本研究建議BOTDR技術可以用於沿海和沖積扇地區，有助於理解地層下陷過程，為現有監測方法提供創新和有益的作為。;Land subsidence represents a complex global occurrence influenced by a blend of natural processes and human activities, posing significant risks to both the environment and infrastructure. Despite the growing recognition of its importance, various challenges persist in effectively monitoring land subsidence. To enhance our comprehension of the mechanisms driving land subsidence, this research endeavors to introduce an innovative experimental model involving Distributed Fiber Optic Sensors (DFOS) employing Brillouin Optical Time Domain Reflectometry (BOTDR). This model aims to gauge the relative change in each sinking ring of the fiber, connected in a sequence of polyvinyl chloride (PVC) catheters at uniform intervals, in order to delve into the deformation characteristics of the stratum. The experiment offers a meter-scale spatial resolution within boreholes situated in Taiwan, allowing for a comprehensive examination of subsidence mechanisms. In addition to that, Laboratory as well as field experiments have carried out to investigate the efficiency of the proposed monitoring system for land subsidence evaluation. During laboratory experiments standard deviation of ≤ 0.23 mm was observed in the monitored displacement. Moreover, the Brillouin optical time domain analyzer (BOTDA) system recorded maximum subsidence of 13.68 mm on April 11, 2023, While the Brillouin optical time-domain reflectometry (BOTDR) has been recorded a subsidence of 13.65 mm on April, 17, 2024. Furthermore, results have compared with the magnetic ring as well as the ground water level thoroughly. The findings reveal the distribution of deformation across the entire borehole, shedding light on the primary contributors to subsidence and the evolution of deformation processes. Moreover, the consistent and long-term monitoring performance displayed by the DFOS approach underscores its potential to provide valuable insights into subsurface deformation. Consequently, this study suggests that DFOS technology can serve as a valuable tool in comprehending land subsidence processes, particularly in coastal and deltaic regions, offering an innovative and beneficial addition to established monitoring approaches. |
