應用電氣探測法探討新佳陽地滑地之地層分布

有鑒於新佳陽部落一再發生地層滑動災害，而該地區之文獻資料短缺，航照判釋及鑽孔資料難以代表該區域之地滑特性、滑動深度及範圍，故本研究乃採用電氣探測法、地表伸縮計、孔內傾斜儀與地表露頭配合鑽探柱狀圖等，進行點、線、面之分析，據此推判新佳陽地滑地之地層分布、滑動體之幾何型態、滑動深度及範圍。經調查分析可歸納出下列結論： 1. 將新佳陽部落依地質區分，新佳陽西側為眉溪砂岩，東側坡面(含大部份保全對象)為盧山層。眉溪砂岩滑動弱面之ρ 值範圍為0~1000Ω-m，因含石英礫，砂岩多具有泥質，故部份滑動弱面之ρ 值高達17000Ω-m；廬山層滑動弱面之ρ 值範圍為0~2400Ω-m，小於600Ω-m之地層可視為含水反應，部份ρ 值高達9600Ω-m處，應為地層破碎所致，相較之下，新佳陽部落之東側地層較西側破碎、風化程度較高。 2. 根據露頭調查得知，崩積層露頭之ρ 值為450~1290Ω-m，而破碎板岩之露頭ρ 值則為150~430Ω-m。 3. 由伸縮計資料及上述電氣探測分析得知，新佳陽部落之滑動現象由數個滑動體組成，滑動深度深及岩盤，岩層以風化嚴重之板岩為主，劈理面相當發達，由於受到地形、向源侵蝕、氣候等自然環境因素影響，加上農業行為開發利用頻繁，導致岩盤風化相當深，推估風化深度可達80m。 4. 除地表0~1m含水外，新佳陽地區岩層100m以內之滑動弱面大致上可分為兩至三層，包含表土風化層(部份回填土層)、崩積層與岩盤，地層愈深，含水量愈多，故滑動弱面ρ 值較淺層滑動低。

關鍵字

地滑；電氣探測；地層；風化岩

並列摘要

Sinjiayang area has the slide fanlt conduction slofrequently, about this research very few. It’s difficult to indicate the geological stratum at landslide region by aerial photograph and boring exploration. This research is using earth electrical logging, surface extensometer, inclinometer, surficial geology investigation to detect the landslide, match up the local situation and geological drilling to analyze the geological stratum and indicating the sliding surface. After analyzing, there are four conclusions: 1. Classifies the Sinjiayang landslide area with the geology, it west side is meichi sandstone, east side is lushan stratum. Meichi sandstone sliding surface ρ-value is situated between 0~1000Ω-m, the rock layer includes the particle of quartz, and the sandstone includes the clay mineral, the ρ-value arrives at 17000Ω-m in this erea; lushan sliding surface ρ-value is situated between 0~2400Ω-m, contains water the response to be smaller than 600Ω-m, and the ρ-value arrives at 9600Ω-m in some part area. After mutual comparison, may discover east side stratum compared to west stratum broken, rock layer efflorescent degree highly. 2. Obtains the result based on the surficial geology investigation, ρ-value of colluvium is 450~1290Ω-m and ρ-value of broken slate is 150~430Ω-m. 3. Overall, sinjiayang landslide area glide pattern is by many glide formations, glide depth arrives at the laccolith, mainly makes decent the slate primarily, receives the terrain, the regressive erosion, the climate and so on, natural environment factor influence, cause weathering depth arrives at 80 meters. 4. Includes the moisture content except the place surface 0~1 meters, sinjiayang landslide area underground 100 meters contains two or three stratum level, contains the surface weathering soil, residual soil and rock. The stratum is deeper, the water content are more, and ρ-value is lower.

並列關鍵字

Landslide ； Earth Electrical Logging ； Geological Structure ； Mantle Rock

參考文獻

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38. 謝豪榮，1997，坡地之泥砂災害與其防治法，水土保持學報，第9卷，第2期，第125-135頁。

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