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第57期 |
從地工技術看賀伯颱風 |
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潘國樑 |
1996/10/01 |
90 |
無庫存
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| GEOLOGICAL FACTORS TO INFLUENCE THE LANDSLIDES IN THE HOSHE AREA, NANTOU HSIEN |
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| 林慶偉 |
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| 賀伯颱風，崩塌，地質構造，岩性 |
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| 本次賀伯颱風於南投縣多處地方引發嚴重之崩塌，造成重大的生命財產損失。本文從地質的觀點討論南投縣新中橫公路信義-和社-自忠一線及其附近地區的地質構造與出露岩層之岩性，對崩塌地發育之潛在影響。本區岩體受到陳有蘭溪斷層作用及和社背斜與同富山向斜作用的影響，岩體為斷層與褶皺作用伴生之破裂面所切割而異常破碎，而其經過風化、搬運與堆積等作用後，造成大量未固結與膠結之第四紀沈積物堆積於河床與河流之兩側。因此當賀伯颱風在兩天內帶來近乎兩千公釐之降雨時，本區多處地區即發生大規模之崩塌與土石流。 |
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| Several landslides which had resulted in serious property's damage in the Hoshe area, Nantou Hsien were triggered by heavy rainfalls of the typhoon Herb. In this paper, geological factors, mainly geological structures and lithology, that influenced the landslides along the New Central-Cross-Island Highway and its nearby area are discussed. Rock masses of the study area were highly fractured due to faulting and folding. Quaternary deposits are widely distributed along main rivers in the study area. Therefore, serious landslides and debris flows occurred when the typhoon Herb brought about two thousand mm rainfall within two days. |
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| A GEOMORPHOLOGICAL VIEW ON THE DISASTER IN THE CHENYULAN CREEK DURING THE TYPHOON HERB |
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| 李錫堤 |
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| 山崩，土石流，沖積扇，防災 |
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陳有蘭溪發源自台灣第一高峰─玉山的北坡，從標高3000公尺以上的高山，直洩向標高300公尺左右的濁水溪本流河床，平均坡降高達百分之七。地形起伏極大，加以地質條件不佳，在賀伯風災所帶來的遠超過200年重現週期的雨量及超大的降雨強度侵襲下，促發了多處山崩及土石流，造成了當地27人死亡及頗大的財產損失。
台灣地區地質變動頻繁，侵蝕速率特高。陳有蘭溪更是台灣地區河谷沖積扇最為發達的河川之一，顯示了其沖刷力特強及淤積物來源特多的本質。故本次災變若能從這個瞭解來看，則就不會覺得意外了。只是，過去的我們未重視從地形上的訊息去解讀自然史與災變，而未能防患於未然。陳有蘭溪賀伯風災的案例，頗值得我們在做區域規劃及工程設計時參考。 |
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The Chenyulan Creek headed from northern slope of the Yushan mountain - the highest peak in Taiwan, runs from area of elevation more than 3000 meters down to junction at main course of the Choshui River, where elevation of riverbed is only about 300 meters. The average slope gradient reaches 7%. During Typhoon Herb event, a large and intense rainfall (larger than 200 year return period ) occurred, many landslides and debris flows were triggered in the area of high relief and poor geological conditions. It causes twenty seven persons died and a large of property loss.
The geological environmental processes are very active in Taiwan and they have caused extremely high erosion rate. The Chenyulan Creek is one of the very active rivers in Taiwan. As characterized by the development of alluvium fans, it may indicate that the creek is very wild. High denudation and high carry of sediments is the nature of the river. If we understand these causes, we will never feel the disaster is unexpected. Because we seldom pay attention to understand the history and natural hazard of a terrain from a geomorphological point of view, so that we can not prevent the attack of a natural event. The disaster in the Chenyulan Creek is a good example for us to learn about it, and this knowledge may be useful when we are doing land-use planning or engineering design. |
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| TYPHOON HERB,THE NEW-CENTRAL-CROSS-ISLAND-HIGHWAY AND SLOPELAND FAILURES IN CENTRAL TAIWAN |
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| 洪如江 |
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| 賀伯颱風、新中橫公路、坍方、土石流 |
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賀伯颱風侵台，最大24小時雨量高達1748.5公厘，最大二日雨量高達1986.5公厘，在新中橫公路水里玉山線之沿線坡地造成嚴重之坍方及土石流災害，此與該地區之地形、地質及水系不無關係；但與當年新中橫公路之開挖方法及棄方堆積也有部分關連；而道路通車後之濫伐、濫墾及濫建更有重大影響。本文除了討論坡地災害之自然及人為因素以外，也以多年來及此次災害後之照片補充說明。
台大實驗林溪頭營林區之森林，成功地阻擋了土石流之延伸而避免了一場巨災之事實，說明了森林對防治坍方及土石流之功能。
此次災害，也再一次說明：任何濫伐、濫墾及濫建，必將禍延子孫。 |
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From 31st July to 1st August 1996 when Typhoon Herb attacked Taiwan, the record breaking rainfall(max. 24-hours intensity was 1748.5mm) in the central Taiwan resulted in many disastrous landslides and debris flows along the New-Central-Cross-Island-Highway(NCCI-Highway). Heavy loss of human lives and properties has shocked the whole Country.
The topographic conditions, geological settings and drainage patterns of the mountain terrain where the NCCI-Highway passing through are always thought to be unfavorable for the construction of highway. Route selection and construction operation of the Highway were also poor in quality. Deforestration and over-cultivation after the completion of the Highway has long been recognized as the number one killer of the mountain slopes there. The disasters happened this August yield once again evidences of the grave influence of deforestation and over-cultivation on the slopelands in mountainous areas in Taiwan.
The effectiveness of forest in stopping a high speed debris flow has been observed in the National Taiwan University Experimental Forest. |
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| DISASTERS ALONG
NEW CENTRAL CROSS-ISLAND HIGHWAY |
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| 林銘郎、鄭富書、吳俊傑 |
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| 賀伯颱風、土石流、地質、地形、天然災害 |
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| 新中橫公路為此次賀伯颱風所造成受災最嚴重的地段之一，災害顯著地點至少有20處，並造成至少27人死亡。本文乃一系列報導此次風災在新中橫沿線之主要天然災害，並探討其在氣候、地質及地形方面之肇因。在氣候方面，賀伯颱風含豐沛水氣、移動緩慢且引進之西南氣流受地形強迫舉升作用，在中南部造成強烈對流性豪雨。在地質與地形方面，研究區各種適合土石流發生之條件，如畚箕形地形、平日沖刷之大量土石累積在河床等因素、河床坡度高等，造成達13處之土石流。此外，河流之攻擊岸及台地側之陡坡等脆弱之地形及地質條件，亦分別造成5處橋樑中斷與道路坡腳坍方及3處邊坡滑動災害。這些土石流、邊坡崩塌並造成後續之道路中斷、路基流失、橋樑中斷、田地淤埋等災害 |
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| The super typhoon, Herb, seriously damaged the middle region of Taiwan, especially, the areas along the New Central Cross-Island Highway. This paper systematically presents the major disasters occurred along this highway. There are a total of 20 disaster sites having been occurred, which includes the natural disasters, I.e., debris flow and slope sliding and the associated disasters including damage of roadway, breakdown of bridges and loss of human lives as well. The causes of these disasters, including the characteristics of the Herb typhoon, geomorphological features and geological settings are then discussed in this paper. |
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| APPLICATION OF REMOTE SENSING IMAGES IN THE ANALYSIS OF GEOLOGIC HAZARDS IN THE AREAS ALONG NEW CENTRAL CROSS－ISLAND HIGHWAY CAUSED BY TYPHOON HERB |
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| 潘國樑 |
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| 地質災害、遙測、賀伯颱風、土石流 |
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賀伯颱風於民國85年7月31日夜晚登陸台灣，在阿里山地區創下超過兩百年一遇的暴風雨，結果在新中橫公路兩側造成非常嚴重的災害。由於該區地形陡峻，且地質複雜，非常適於利用遙測技術來勘查災害情形及進行災害原因之分析。
經過衛星影像的判釋及現場勘驗的結果，公路兩側的地質災害主要有淺層崩塌、土石流、洪水泛濫及河岸沖刷等四大類型；它們大都會復發，在影像上顯現許多過去發生同型災害的遺跡。災害的主要肇因包括山高谷深，溝谷的源頭多呈適合土石流發育的湯匙地形，加上岩體破碎及風化劇烈，同時公路開闢、坡地超限開墾及產業與林業道路多；當然，最重要的是降雨猛烈及集中。為減輕未來的災害，宜建立基本資料庫及公路防災系統，並以建立災害預測與災害預報能力為目標。 |
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Widespread damage in slopeland areas along the New Central Cross-Island Highway resulting from Typhoon Herb in 1996 focused attention on risks to life and property from geologic hazards, including surficial slope failures, debris flows, floods and stream erosion. Both natural and artificial slopes underwent damaging surficial failures. However, foothill areas where alluvial fans had developed were covered by new debris flow deposits again.
Because of the rugged topography and limited time, SPOT images were employed for interpretation and analysis of the geologic hazards and their causes. It was found that steep slope, highly developed gullies, highly decomposed rocks, replacement of deep-rooted vegetation by shallow rooted one, and construction of highway and service roads had caused the slopes particularly susceptible to failure. And of course, the heavy precipitation with an intensity of greater than 100 mm/hr lasting for 8 hours had triggered the severe slope failures. |
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| THE GIS/GPS TECHNOLOGY APPLIED ON INVESTIGATING THE DISASTERS CAUSED BY TYPHOON HERB ALONG NEW CENTRAL CROSS ISLAND HIGHWAY |
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| 蔡光榮、宋益明、王弘祐、林金炳 |
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| 賀伯風災，公路邊坡，地理資訊 |
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新中橫公路全線長約為185公里，歷經熱、溫、寒三大氣候帶。因其特有之地質構造和本省之不均勻降雨分佈，該公路常易於颱風豪雨季節時，發生邊坡崩塌滑落，對其運輸功能，影響至鉅。
影響該公路邊坡崩塌之主誘因涵括地質因素、底土滲流、逕流沖刷、岩層風化和人為開路挖斷其順向坡坡趾等五大因素。本研究以ARC/INFO地理資訊系統整合GPS實地調查定位資料後，發現全線崩塌總數達177處，其中台18線（阿里山公路）崩塌達117處，佔全線之65.4%，而台21線（水玉線）則亦有60處，佔總崩塌數之34.6%，且其分佈在台18線亦均以中高海拔（1000～2000公尺），坡度在30°～70°之南向坡面（東南、西南與正南）為主，而台21線則集中在中低海拔（500～1000公尺），坡度為30°～70°之北向坡面。區域內土層之淋溶作用盛行，覆土層與底土層之透水性差異極大，且其在飽和不排水試驗之土壤抗剪強度均較飽和排水試驗者降低達1/4～1/2。 |
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New Central Cross Island Highway is a major traffic line connecting the southern and central parts of Taiwan through mountainous areas. Due to the complex geological structure and uneven rain fall, rock falls and landslides are abundant along the highway.
The investigation results indicated that the slope failures along the highway were mainly caused by five factors: geology, groundwater seepage, runoff erosion, weathering of rock strata, and removing support at the toe of dip slopes during the highway construction. The investigation conducted by using GPS and GIS (ARC/INFO) concludes that there are 177 slope failures along the New Central Cross-Island Highway. Along Highway 18, slope failures mostly occurred at south-facing slopes with steepness of 30-70° and 1000-2000m in altitude, while slope failures occurred along Highway 21 are usually found on north-facing slopes with steepness of 30-70° and 500-1000m in elevation. |
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| ENGINEERING DEFICIENCIES EXPOSED BY TYPHOON HERB |
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| 鄭富書、林銘郎 |
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| 颱風災害、土木設計、道路、橋樑 |
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| 賀伯颱風帶來空前之災害，包括先期之自然災害，如土石流及邊坡崩塌，及後期之災害，如道路中斷、路基流失、橋樑中斷、房屋損壞、田地流失、作物損失乃至人命之喪生。此次災害，固然有其天然因素，如大量降雨、地質條件不佳、地形條件不良等；但後期之災害卻不一定必然會發生。本文首先對台大營林區災害歷史報導，以提供此區域之災害情況之全盤觀。接著，檢討造成後期災害之工程因素，以檢討賀伯颱風所暴露之工程方面的缺失。結果發現賀伯颱風所暴露之工程方面之缺失包括：公路選線不良、道路型式不宜、涵洞過小、橋樑型式及選址不宜及設計時未以土石流量來考慮等；本文並建議因應之土木設計理念。 |
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| Typhoon Herb caused serious disasters in the areas along the New Central Cross-Island Highway. The disasters include block of highway, bridges, farming losses and a toll of human lives. The natural disasters including debris flow and land sliding may not be avoidable due to the heavy rainfall. However, some other disasters including damages of roads, bridges may not be necessary. The article aims at reviewing the engineering deficiencies exposed by the Herb Typhoon. The deficiencies include inadequate layout of highway, excavated roadway, bridge design and drainage pipes of the road way. Better designs which are able to accommodate the poor geological settings and weather conditions in the study area are then accordingly proposed. |
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| THE RELATIONSHIP BETWEEN RAINFALL AND LANDSLIDE |
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| 陳時祖 |
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| 雨量，邊坡崩塌 |
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| 賀伯颱風帶來之豪雨為台灣中南部山區道路帶來嚴重坍方及土石流之災害。本文乃敘述雨量與邊坡崩塌之關係，除了綜合前人之研究結果外，也加入個人的研究心得。著者認為用簡易方法將邊坡分類後再預測其崩塌雨量以及用或然率觀念表達某一雨量狀況下邊坡崩塌的可能性是將來可推動研究的方向。 |
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| A recent typhoon brought heavy damage to the highways in the mountainous area of Taiwan. This paper summarizes the previous research about the correlation between rainfall and landslide. Some simple classification method for the slopes would improve the prediction work for landslide occurrence by rainfall data. Probability concept will be also a choice for future prediction work. |
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| INVESTIGATION ON SLOPE FAILURE INDUCED BY TYPHOON HERB AT LOW ELEVATION AREA AT ALI-SHAN HIGHWAY |
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| 李德河、田坤國、黃嵩傑、林國忠 |
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| 邊坡崩塌、預測、阿里山公路 |
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賀伯颱風在阿里山公路沿線造成相當多之崩塌、滑動災害，本文則以低海拔路段之邊坡破壞為調查對象，嘗試瞭解其破壞的特性與誘發之因素。同時本文亦以阿里山公路26K+800m之邊坡上所設置之地表伸縮計、地下水位計以及氣象局設於瀨頭的雨量計等所量測得到之資料探討低海拔邊坡破壞時之實際變動情形，以及使用伸縮計及雨量計之觀測資料作為邊坡崩壞預測之適用性。
由調查結果顯示，阿里山公路低海拔路段之邊坡破壞多屬小規模之坡面淺層崩壞形式，其中自然邊坡產生崩壞者其坡度多在40度以上，而以40°～44°者居多，然而人工開發邊坡，其坡度在30°～34°左右便會產生破壞。
由26K+800m處所設置之伸縮計僅在淺層滑移發生前數分鐘才有較大之變化，顯示對於邊坡發生淺層崩壞的時間預測，只利用伸縮儀是不夠的，必須再掌握降雨量及地下水位變動的資料，方能有良好的預測成果。 |
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Typhoon Herb attacked Taiwan and brought several disasters all around the island. The disasters occurred in hilly areas, especially the Ali-Shan highway, including slope failure, landslide and debris flow, etc. In order to understand the mechanism and find out the influential factors of the slope failure, the low elevation area on Ali-Shan highway was selected to promote this investigation work. This investigation was strengthened by the in-situ measurenont data acquired from extensometer and piezometer, which had installed in the slope at 26K+800m of Ali-Shan highway. These data are not only adopted to investigate the actual movement of slope, but also used to assess their suitability for predicting the time of slope failure.
The results of investigation showed that most slope failures occurred in low elevation areas of Ali-Shan highway being small scale and induced by the failure or erosion of heavily weathered layer. The slope angle of failed natural slope is greater than 40 degrees；however, quite a lot of man-developed slope were failed with a slope angle from 30°to 34°. A slope failure happened at 26K+800m, just few minutes after a significant movement of slope surface occurred. Although the movement was catched by an extensometer which had been installed there, it seems that only the extensometer without other instruments can not predict failure of a slope and alarm the danger perfectly. Therefore, the data regarding precipitation and variation of water table have to be included if the accuracy of slope failure prediction needs to be elevated. |
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