大規模崩塌區地下排水系統集水井／橫向集水管之工程設計與參數研究

Engineering Design and Parametric Studies on Drainage Well and Horizontal Drains in Subsurface Drainage System for Large Landslide Stabilization

林德貴(Der-Guey Lin) ； 張國欽(Kuo-Ching Chang) ； 王勝賢(Sheng-Hsien Wang) ； 劉文宗(Wen-Tsung Liu)

《中華水土保持學報》 52卷2期 (2021/06) Pp. 49-72

https://doi.org/10.29417/JCSWC.202106_52(2).0001

摘要

在大規模崩塌區之邊坡三維數值模型中，配置集水井與橫向集水管（以下簡稱集水管）並進行穩態及暫態排水分析，以檢核其在不同配置高程、長度、間距、及位置情況下，對邊坡地下水排水效率及穩定性提升效果之影響。由參數研究可知，集水管打設高程越低或集水井施作位置越處下邊坡，排水效率及穩定性提升效果也越顯著。集水管長度L_d必須足以穿過潛在滑動面外一段有限距離，方能獲得經濟有效之排水及邊坡穩定效果。在條件相同情況下，集水管長度L_d對水位最大洩降量h_(wmax)之影響度遠大於集水管間距S者。因此，若欲提高排水效果，則增加集水管長度L_d會比減小集水管間距S（或增加集水管數量）來的經濟有效。基本上，扇狀與平行兩種排列方式之集水管在排水後之水位最大洩降量h_(wmax)及排水率Q很相近。

關鍵字

集水井 ； 橫向集水管 ； 地下排水 ； 地下水水位洩降 ； 安全係數

並列摘要

Through the numerical modeling of large-scale landslides, a drainage well with horizontal drains was configured with a different elevation, length, spacing and location, and steady/transient seepage analyses were performed to determine the effects on drainage efficiency and slope stability. The parametric studies indicated that the lower is the installation elevation of horizontal drains or drainage well, the more efficient is the drainage and the more stable is the slope. The drain length, L_d, must be sufficient to pass through the potential sliding surface, PSS, to obtain economical and effective subsurface drainage and slope stabilization. Under identical conditions, the effect of the drain length, L_d, on the maximum groundwater drawdown, h_(wmax), is much greater than that of the drain spacing, S. Consequently, to improve the groundwater drawdown and drainage efficiency, it is more economical and effective to increase the drain length than to decrease the drain spacing (or increase the number of horizontal drains). Generally, the h_(wmax) and discharge rate, Q, of subsurface drainage is similar in parallel and fan-array drains.

並列關鍵字

drainage well ； horizontal drain ； subsurface drainage ； groundwater drawdown ； factor of safety