九份二山崩塌地穩定性觀測及地下水流動特性之研究

Study on the Observation of slope stability and Characteristics of Groundwater flow at Joe-Fen-Er-Shan Landslide Area

曾俊偉(Chun-Wei Tseng)

指導教授 ： 陳明杰

國立臺灣大學/生物資源暨農學院/森林學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00189

摘要

九二一集集大地震重創南投縣國姓鄉九份二山地區至今已歷時四年之餘，然而該地區的地層構造及地下水流動特性，仍有可能為坡面再度發生崩塌的潛因，本研究在該地區潛在崩塌區域配置1 0個地質鑽孔，針對此兩項特性進行調查試驗，研究方法包括地質鑽探判釋地層構造、地中傾斜管觀測、地下水觀測、降雨量觀測以及食鹽水檢層試驗等 ， 並以地層穩定性及地下水流動特性為研究主軸做綜合討論，研究結果期能對日後之整治工程有所助益。
配置的10個鑽孔之中，BH1∼BH4因鑽探深度不足，不以採用做地下水流動調查及試驗。 BH5∼BH10六個鑽孔由試驗的資料分析結果發現：（1）由地質鑽探岩心研判，崩塌前坡面之地質弱面早已存在，深度大約分佈在 3 0 m∼5 0 m，因受地震力影響而產生順向坡滑動。（2）由孔內傾斜管觀測結果，目前尚未發現明顯的位移變化，即使在某特定深度有位移量變化，其變動值均在容頂~差的範圍內。（3）根據食鹽水檢層結果及岩心柱狀圖研判，此處之地下水多屬深層地下水，鑽孔深度內並無發現被壓含水層及複層的地下水構造，初步排除超額孔隙水壓對地層穩定性之影響，而地層之剪裂帶為地下水流出的層次。（4）鑽孔中具有地下水流動區間的比電阻值，往往大於不流動或無明顯流動區間的比電阻值，且差異非常明顯。由於六個鑽孔位置之地下水比電阻基準值均不一致，顯示地下水流脈不一致。（5）六個鑽孔經食鹽水檢層研判之其流動面，大多為準確定流動面及潛在流動面，其深度約在深度3 0 m以下，與崩塌坡面的深度大略符合，故地下水流動層位置與潛在滑動面位置可能有關。

關鍵字

九份二山 ； 崩塌地 ； 地下水 ； 傾斜管 ； 食鹽水檢層

並列摘要

921 chi-chi earthquake caused the enormous landslide at Joe-Fen-Er-Shan area. Until today, four years after the earthquake, two potential factors of the instability of geological structure and the movement of groundwater probably cause sliding again. Therefore, the main objective of this study was to investigate the stratum structure and the characteristics of groundwater movement that to make further discussion on sliding mechanism. Research methods include geological drilling, inclinometer observation, groundwater observation, precipitation observation, and salt logging test. Also, this research may benefit the landslide renovation project in the future.
Ten drilling holes BH1~BH10 were placed in the study area, but drilling holes BH1~BH4 were not used for groundwater movement investigation owing to not having enough depth. Six drilling holes BH5~BH10 were mainly investigated and analyzed. The research results include: (1) Analyses of the core samples by geological drilling showed that the shear zone was already distributed at the depth of 30m~50m, and then the earthquake caused the dip slope failure. (2) The continuous observation of inclinometer has not found obvious displacement. Even if there was displacement occurred in some depth of the drilling hole, the variation was within the permitted error range. (3) According to the result of salt logging test and core sample analysis, the groundwater was mostly in-depth type. In six drilling holes, the confined aquifer and complex groundwater layer were not found, that were initially excluded to be possible impact on stratum stability. Also, the shear zones in strata were the same position where groundwater flows out. (4) The specific resistance values of groundwater flowing region in drilling holes were greater than those of unflowing or uncertain flowing region. The specific resistance values of groundwater among six drilling holes suggested the inconsistent groundwater flow arteries. (5) According to the results of salt logging test, definite and probable flowing regions located at the approximately depth of 30m, which is consistent with the sliding depth of slope. Therefore, the position of the groundwater flowing region is probably related to the potential sliding depth.

並列關鍵字

Joe-Fen-Er-Shan ； Landslide ； Groundwater ； Inclinome

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