台灣都會區建築物非常密集，加上地下開挖深度加深，為保障鄰產之安全，開挖安全監測於工程中扮演重要角色。過去，監測單位常使用傾度管、地表沉陷釘以量測因開挖引起之壁體側向變形與地表沉陷，然而，為此不但付出相當多的時間與人力成本，對於開挖引致變形較小之案例，其監測精度更是非常低。由於光達技術之區域性、便利性與高精度，近年來，許多研究人員已將光達技術用於隧道、邊坡與開挖等大地工程中；惟因施工與點雲處理問題，變形分析結果往往只能得到一個較為發散的變形區間，而不能獲得一個具體的變位值，對此，工程人員對於光達技術於大地工程中之可行性不免有些疑慮。考慮前述原因，本研究擬對光達技術於開挖工程之應用進行更深一層之驗證。

首先，在對點雲進行預處理後，考慮前人於該領域之經驗，本研究以M3C2算法進行點雲變形分析，並以迭代最近點法進行修正。同時，對三軸試驗之應力應變曲線作圖，並使用平鈑載重試驗之數值模型進行反算分析以獲得一組適用於PLAXIS之土壤參數；之後，利用此組土壤參數建立一完整之三維有限元素法模型，再將計算出之數值分析結果、傳統監測儀器收測資料與點雲分析結果進行交互比對，最後，假設傾度管數據為真值，算出點雲結果與數值結果之RMSE，並依照現場掃描經驗給出光達於開挖工程應用時之具體建議。

In Taiwan's metropolitan areas, buildings are densely concentrated. Coupled with the increased depth of excavation for foundations, ensuring the safety of neighboring properties becomes crucial. Excavation safety monitoring plays a vital role in construction projects for this purpose.

In the past, monitoring agencies commonly used inclinometers and settlement pins to track the lateral deformation of retaining walls and surface settlement caused by excavation. However, this approach entailed considerable time and manpower costs. Furthermore, when dealing with small displacements caused by excavations, the monitoring accuracy was notably low.

Due to its regional coverage, convenience, and high precision, LiDAR technology has been increasingly employed by researchers in various geotechnical engineering applications, such as tunnels, slopes, and excavations. However, due to construction problems and point cloud processing challenges, deformation analysis results often yield a broad deformation range instead of a specific displacement value. This limitation has raised concerns among engineers regarding the feasibility of LiDAR technology in geotechnical engineering. Considering these reasons, this study aims to further validate the application of LiDAR technology in excavation projects.
Firstly, after preprocessing the point cloud data, consider previous experience in the field, this study uses the M3C2 algorithm for point cloud deformation analysis and uses the Iterative Closest Point (ICP) method for subsequent correction. Additionally, stress-strain curves from triaxial tests were plotted to determine the secant modulus, and numerical modeling of plate load tests are employed for back- analysis to obtain soil parameters for PLAXIS.

Subsequently, a comprehensive three-dimensional finite element model is developed using these soil parameters. The calculated results from the numerical analysis, data collected from traditional monitoring instruments, and point cloud analysis results are then mutually compared and cross-checked. Lastly, based on the comparison results and on-site scanning experience, recommendations are provided for the application of LiDAR technology in excavation projects.

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