第五章 結論與建議
照片 4. 3 同一纜線於不同勁度外填材料下之變形模式
(3) 靈敏度：
圖 4. 12 為各纜線ρpeak-δ關係。其中軟性纜線 RG-8 於 70 mm 及 87 mm 處出現斜率轉折，經比對後發現是因為波形由雙剪發展成單剪之交界。這 意味此試驗配置之外填材料仍屬軟弱土壤，以致於剪動破壞模式非典型之 直剪；另外將 Lin et. al. (2007)以 RG-8 與 P3-500 型纜線外覆石膏之直剪試 驗結果(典型直剪破壞模式)進行比較，發現 RG-8 轉折後之斜率與典型直剪 (Lin et. al., 2007)之斜率約略相同(如圖 4. 12)，因此判定 RG-8 試驗所出現雙 線性曲線是因雙剪模式轉變成直剪模式所造成。因此，RG-8 纜線之迴歸資 料只取到 70 mm 及 87 mm (即出現斜率轉折處)，將迴歸所得靈敏度(ρ /mm)、啟動門檻值整理成表 4. 3，結果顯示 RG-8 纜線在不同勁度之外填材 料下，靈敏度仍會極為相近(S=0.0009791、0.0010713、0.0012770)，而 P3-500 型(S=0.0056710、0.0062864)靈敏度僅約略相近。
圖 4. 12 纜線於不同勁度外填材料下之靈敏度
4.2. 訊號處理用於提早偵測變形之成效訊號處理用於提早偵測變形之成效訊號處理用於提早偵測變形之成效訊號處理用於提早偵測變形之成效
經由 4.1 節室內試驗結果，選出適用於軟弱材料之纜線種類-RG-8 型，
同時也加入 P3-500 型纜線之試驗結果進行訊號處理，探討訊號處理是否適 用於不同種類纜線之可行性。
訊號處理主要步驟為（1）將原始 TDR 反射訊號去雜訊，（2）將去雜 訊後的變形與未變形波形相減，獲得反射係數變化量(Δρ)，期望可藉由這 些步驟更清楚辨識滑動面，並透過門檻值的概念，建立並提供日後現地監 測警戒值，作為滑動發生後監測頻率調整之參考依據。以下就訊號處理各 分析步驟之進行探討：
(1) 去雜訊效果比較：
圖 4. 13 顯示位移 6 mm 之原始訊號與分別使用 db 3 小波方法與 smooth 去雜訊後的波形，結果顯示使用小波方法比 smooth 法較易去除雜訊，因此 後續將以小波方法進行雜訊處理。圖 4. 14 與圖 4. 15 為採用不同門檻參數
與不同母小波的小波方法去雜訊後訊號與原始訊號比較，其中較適合的門 檻參數與母小波為「sqtwolog + soft + sln + Level 3」。
圖 4. 13 原始波形與去雜訊效果比較
圖 4. 14 Threshold 之選擇
圖 4. 15 Mode 與 level 之選擇
決定適當的參數後，針對 RG-8 型與 P3-500 型進行訊號處理，結果如 下：
(2) RG-8 型：圖 4. 16、圖 4. 17 與圖 4. 18 所對應原始波形原本的初始啟 動門檻值分別為 5 mm、9 mm 與 12 mm，經訊號處理後，至少可提 早約 2mm 即察得滑動面，圖 4. 18 甚至顯示可提早約 3 mm。
圖 4. 16 RG-8 纜線，δD=5mm
圖 4. 17 RG-8 纜線，δD=9mm
圖 4. 18 RG-8 纜線，δD=12mm
(3) P3-500 型：圖 4. 19 與圖 4. 20 所對應原始波形原本的初始啟動門檻 值分別為 39 mm 與 43 mm，經訊號處理後，可提早約 5 mm 察得滑 動面。
圖 4. 19 P3-500 Unshielded 纜線，δD=39mm
圖 4. 20 P3-500 Unshielded 纜線，δD=43mm
上述結果顯示經過本節訊號處理後，4.1 節的結果至少可提早約 2 mm
察得滑動。根據已知滑動量，利用門檻值概念，可由上述分析結果訂出門 檻值為 0.001ρ(圖 4.16～圖 4.19 最右側圖片內鉛直紅線)，比對兩種纜線原 始試驗結果（如 4.1 節之結果），顯示門檻值與可目視滑動量相符合，亦即 當反射訊號超過門檻值即為土壤已錯動變形纜線。
4.3. TDR 錯動變形監測安裝標準程序錯動變形監測安裝標準程序錯動變形監測安裝標準程序及量化分析初步錯動變形監測安裝標準程序及量化分析初步及量化分析初步及量化分析初步建議建議建議 建議
應用 TDR 技術於邊坡滑動監測已行之多年，但實務應用時往往只考慮 纜線本身衰減特性，並無考慮纜線種類於不同土壤之反應，使得纜線種類 之選擇並無統一標準與依據。此外，Dowding et al. (2004)以數值模型探討纜 線外填材料影響，提出灌漿強度為周圍土壤之 1~5 倍左右為最佳灌漿配比 [12]，但礙於現地灌漿強度控制不易且水灰比過大亦會造成嚴重縮漿，因此 何謂適當的現地灌漿選擇仍是有待探討的問題。茲將 TDR 錯動變形監測安 裝標準程序與量化分析之初步建議分述如下：
(a) 透過本研究之實驗與分析結果，以及相關研究計畫所累積現場安裝 經驗，針對灌漿與纜線安裝提出一套參考標準程序(如圖 4. 21)。主 要提供：纜線選擇依據、現場安裝不同階段所需合理的考量與準備 (如灌漿配比)，使得 TDR 錯動變形監測應用更具實務性與便利性。
圖 4. 21 TDR 錯動變形監測之標準程序
(b) 由 4.1 節之試驗結果顯示： RG-8 纜線在不同勁度之外填材料下，靈 敏度仍極為相近(S=0.0009791、0.0010713、0.0012770)，同樣，P3-500 型(S=0.0056710、0.0062864)靈敏度僅約略相近。因此，現地若屬堅
硬土層時，建議安裝 P3-500(unshielded)型纜線且以式(4-1)進行量化
第五章
(a) 硬性纜線(solid cable)QR-320 型與 P3-500 型纜線在沒有灌漿材 料之束制下，TDR 反射波形發展不易判釋，亦即沒有灌漿材包 覆之纜線，反射波形成長量與剪力位移量不具唯一性；反之，
有灌漿材所包覆之纜線，反射波形與剪力位移成線性關係成長。
(b) 軟性纜線(braided cable)因外導體較軟而較易反應，藉由灌漿材 料所提高的趨動纜線效果較不顯著。
外力易直接轉稼給纜線，因此在沒有灌漿材料包覆下之
制的 90 度直角，未來可考慮剪力面與纜線之夾角非 90 度的剪 力盒設計，探討不同夾角剪力面對於 TDR 反射訊號之影響。
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