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| EVOLUTIONS OF DEBRIS FLOW AND SLOPE HAZARD MITIGATION MEASURES IN TAIWAN-RESEARCH DEVELOPMENT AND STRATEGIES |
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| 林美聆、陳天健 |
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| 土砂災害、防災、科技、政策 |
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| 台灣山坡地地勢陡峭、岩質破碎，再加上常遭遇颱風、暴雨及地震等侵襲，易造成坡地災害，其中土石流因具有流速快、衝擊力大等特性，災害發生時往往造成人民生命財產的重大損失。台灣近數十年之土砂災害防治政策，以往主要較偏重於治山防洪及土地開發利用等工程措施，但受到各國逐漸採行土砂災害預警、土地管理、教育宣導、防災演練、土砂災害保險、社區自主防災等非工程措施，並納入環境保護與生態保育觀念，倡導全流域治理理念，我國土石災害防治政策亦開始參酌平時減災、災前整備、災時應變及災後復原等四階段災害管理精神。土砂災害防災科技之研究結構也隨之轉變，開始進入跨領域整合性的研究理念，大量引進現代資訊科技後，形成即時化、預先化及主動化的土砂災害防救概念。 |
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| Due to the fragile geological conditions and steep terrain of the mountain area, Taiwan is prone to the debris flow and slope hazards caused by typhoons, severe rain falls, and earthquakes, which often caused human lives and induced severe damages to properties. In the earlier stage of mitigation strategies of such hazard, emphases were laid on the engineering facilities and land use development. Starting the past decade, the concepts such as: early warning, land use management, education, insurance, and community involvement gradually evolved, and have been materialized in the mitigation measures. In recent years, the concepts of ecological system and environment protection, and management of watershed were introduced into the forming of strategies of hazard mitigation. The evolvements of the research development and strategies for debris flow and slope hazard mitigation measures in Taiwan are introduced in this paper. |
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| INVESTIGATION ON THE HAZARDS OVER THE HILLY REGIONS IN TAIWAN – EXPERIENCE AND INTROSPECTION |
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| 鄭富書、林銘郎、李順敏、周坤賢 |
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| 勘災、土石流、山崩、省思 |
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| 自1996年賀伯颱風開始，臺灣坡地災害之勘災史邁進一個里程碑，民眾開始重視廣域自然災害；而學術界與工程界也具體以團隊合作協力勘災，從廣域及不同專業面進行整合，分析災害之原因與提供相關建議。根據勘災的經驗，台灣存在一些特有的問題，在勘災的忙碌之後，值得進一步省思。本文探討的議題包括：台灣土石流具量大及間斷發生的特性、生態工法使用的場合與合理方式、復建工程與山區道路是否皆應復建、是否應原地原狀復建或採用較低等級復建策略，尤其是在地質不穩定區域。另外，在更廣域的方面，有關社會資源合理分配、調查方式與技術、防災資源整合等，有需要進行系統性思考，及研擬更成熟的配套措施。透過前揭議題之探討，冀望未來台灣在防、減、救災方面，能凝聚共識，能考量社會資源分配的合理性；最重要的是人民的安全可以獲得確保。 |
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| Investigation on hazards induced by typhoon or earthquake in Taiwan has approached a new era within 1990s, since then the collaboration of the academic institutes and the industry becomes an emerging operation pattern. The teamwork includes cooperation in hazard investigation and relief planning provided by different professions and expertise. Based on the experience of conducting hazard investigation, issues raised from introspection are discussed in this paper. The issues include: the debris flows in Taiwan is characterized with huge in amount while compared to other countries and discussion on the validity of adopting eco-engineering methods in Taiwan. Meanwhile, discussions on the fairness of public resource allocation, the concepts and techniques for proper investigation and the integration of hazard prevention resources are also provided to look into possible solutions which may improved the future situations especially when taking actions on rehabilitation. It is the authors’ wishes that these discussions may call for further attentions and actions which will enable a more reasonable resource distribution and safer environment for the people on this island. |
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| REVIEW AND PROSPECT ON LANDSLIDE SUSCEPTIBILITY ANALYSIS |
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| 李錫堤、黃健政 |
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| 山崩、山崩潛感分析、邊坡穩定、判別分析 |
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區域性山坡穩定分析有別於一般特定邊坡常用之極限平衡分析，它在缺乏可用之強度資料及地下水文資料下，須進行廣大區域之山坡穩定評估及繪製全區之山坡穩定分級圖，以供區域規劃，工程選址及防災決策制定之需。它一般被稱為山崩潛感分析，早年多由專家根據經驗或簡單統計方法選擇及決定各種山崩潛感因子的內部評分與因子間的權重，並以線性疊加法計算山崩潛感值及繪製山崩潛感分級圖。近年來，統計多變量分析方法成為山崩潛感分析的主流；類神經網路方法也被運用來預測山崩的發生；採用極限平衡計算的無限邊坡分析方法也被廣泛的用來模擬地震或颱風誘發的山崩分布。本研究以台灣中部國姓地區最近的山崩潛感分析研究為例，說明國內此方面之最新進展。
未來於區域性山坡穩定分析之研究可能有下列幾個重點發展方向：(1)機率式山崩潛感分析，(2)與地震暨雨量機率分析之結合，(3)以山崩機率做為山崩潛感分級及製圖之依據，(4)更具物理意義的綜合性因子的追求，(5)各種山崩類型的山崩潛感分析，(6)廣域山崩潛感分析暨製圖之問題探討。
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Landslide susceptibility analysis (LSA) is different to a specific slope stability analysis; it needs to analyze slope stability in a region in a circumstance that strength data and groundwater data are lacking. The LSA is complicated, but it is required by regional planning, site selection, and policy making in hazard mitigation.
At the early stage, the LSA required expert decision of scoring of landslide susceptibility factors and weighting among them. A weighted summation of factors are use to calculate the landslide susceptibility index. Bivariate analysis was used to treat a factor and to assist the decision of weighting, sometimes in this stage.
In the recent years, multivariate analysis becomes master stream in the LSA. It is objective and efficient. The neural network method was also used to predict landslides. The infinite slope limit equilibrium method was also applied to the earthquake-induced landslide study and the storm-induced landslide study. A study in Central Taiwan, at Kuohsing, is selected to demonstrate recent development in the LSA of Taiwan.
Further study may include: (1) to develop probabilistic landslide susceptibility analysis, (2) to join the probabilistic analysis with a seismic hazard analysis or a frequency analysis of rainfall, (3) to use landslide probability in susceptibility mapping, (4) to search a more meaningful factor for LSA, (5) LSA for different landslide types, (6) LSA and mapping in a wide region.
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| THE EXPERIENCE OF GEOTECHNICAL ENGINEERING APPLICATION FOR THE DEVELOPMENT OF WIDELY HILLY LAND |
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| 周建國 |
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| 截水盲溝、崩積層、地層傾度儀、漸進後退式破壞、後續補強灌漿、微型樁、加勁土擋土牆 |
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| 坡地開發可供參考之案例甚多，地質特性及其工程規畫設計亦不盡相同，若只詳細討論單一個案難以完整說明地工技術之重要。本文擬分類及列舉並探討各種代表性之案例，包括崩積土地層邊坡之處理經驗、豐富地下水匯積區域之處理方法、陡峻邊坡上施作橋墩基礎之案例、面對困難之地形地質條件下之建築開發案例以及大填土邊坡失敗案例之檢討等，希望讀者可藉本文獲致不同邊坡狀況之地工技術處理經驗，並凸顯地工技術對山坡地開發及水土保持之重要性。 |
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| There are many referable cases of hilly land developments but they have various geology condition and different planning, we could not understand thoroughly the importance of geotechnical engineering by discussing only one detail case. Therefore, this paper tries to classify and illustrate various typical cases including colluvium slope, plenty groundwater area, bridge on steep slope, building on difficult geology region and failed widely fill slope in order that the readers could get the geotechnical ideas for developing various slope. Besides, we could highlight the importance of geotechnical engineering to slope stability and soil & water conservation. |
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| INVESTIGATIONS ON THE SLOPE FAILURE AND ITS REMEDIATION METHODS OF THE MOUNTAIN HIGHWAY—ALISHAN HIGHWAY |
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| 李德河、林宏明、張舜孔 |
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| 公路邊坡，地震，颱風 |
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近年來，在人口急速增加，平原可利用的土地趨近飽和，導致山區土地開發與使用之需求大增，也促成山區公路大量的興建。由於山區公路的開闢，造成沿線邊坡受到擾動，再加上我國位處板塊交界處，造山運動發達，地震頻繁、地質破碎，且氣候上屬於亞熱帶季風型氣候，每年夏秋兩季極易遭受颱風及其所夾帶豪大雨的侵襲，因此在山區頻頻引發邊坡崩壞甚至是土石流等災害，對於在山區的居民以及山區公路的使用者形成嚴重威脅。
為減輕此等威脅，首先應了解山區道路邊坡崩壞的特性，進而研發其整治方法，本文以國內知名景點「阿里山」的主要聯外道路阿里山公路（台18線）為對象，探討在不同海拔下，山區公路邊坡在颱風豪雨作用下之崩壞特性，並且對於沿線不同區域以及不同型態的邊坡提出適當的整治方案，以供各界參考。
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Slope failures induced by earthquakes and rainfalls are the natural phenomena of the earth, especially in the mountainous areas. In Taiwan, one-third of the area contains mountains. Therefore, there has been a great demand for the development of the slopeland and the mountain highway as the population increases. Except for the fact that slope failures are caused directly by earthquakes, most of the slope failure such as the debris flow are induced by heavy rainfall associated with typhoons. Typhoons occur in Taiwan during the summer-autumn season every year.
Because it is a serious problem for the tourists and the people who live in the mountain area, it is necessary to obtain the information on the cause of slope failures of the highway in the mountain area. Therefore, this paper provides more useful information about slope failures of highways in the mountain area, and concentrates on discussing characteristies of slope failures of mountain highway induced by earthquakes and typhoons in Alishan. Several remediation methods were also proposed for the slope failures in different areas in Alishan.
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| STUDY ON THE GROUNDWATER INVESTIGATING METHOD OF LANDSLIDE |
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| 廖瑞堂、吳佳陵、陳志南 |
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| 地下水文、地下水、調查方法、整治、地下排水 |
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| 地下水常是崩塌地主要致災因子，崩塌地整治時，地下水有效導排扮演重要的角色。但由於山坡地之地下水分佈較平地複雜，地下水的調查不易，導致大型崩塌地整治相對困難，本文主要介紹常用地下水調查方法的原理及適用性，這些方法包括水位觀測井或水壓計觀測之地下水位法、微流速儀法、地下水檢層法、地電阻法、抽水試驗及水質分析等方法，綜合各種調查結果綜合研判，以瞭解地下水之水位、水壓、含水層位置及流向等水文地質之特性，做為整治對策之參考，從本研究可知，由於崩塌地之地下水文雜複多變，採用更周延、更有效的調查方法有其必要性。 |
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| Groundwater has significant influence of landslide. Effective drainage plays an important role of slope remediation strategy. Groundwater pattern in the hill is more complicated than in the plain. Investigating the distribution of groundwater around hill is still not easy but very important for landslide remediation. The principle and suitability of a certain groundwater investigating methods of large landslide are introduced first. These methods include the monitoring of groundwater table and hydro-pressure, survey of micro-flow velocity, logging of groundwater resistance, survey of electric resistance, performance of pumping test and water ion test. The purpose of groundwater and hydrological investigation is to capture the information related to pressure, distribution, aquifer and underflow of groundwater. The groundwater distribution in landslide region is complicated. Selecting adequate and efficient investigating tools to assess groundwater distribution is necessary. |
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| ROOT MECHANICS OF VEGETATION ENGINEERING - PART I |
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| 林德貴、黃伯舜、林信輝 |
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| 土~根系統、根系調查、根系力學試驗 |
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| 為確實掌握植物根系之物理及力學特性在土~根系統行為中之實際效應，並提供含根邊坡穩定性之量化數值分析所需之根系力學材料參數，本文除廣泛彙整根系各類型調查方法、分類原則、力學試驗及其相關試驗設備與程序外，亦比較各種植物根系之力學試驗成果。其中，力學試驗部分包含：單根抗拉強度試驗、現地拉拔強度試驗、及室內與現地含根土壤之直接剪力試驗。由試驗成果：首先可知，根系之單根抗拉強度可表為平均根徑之關係式；其次，根系之現地極限拉拔力可表為植物試樣地際直徑、樹高、試樣根部乾重量 、及試樣地上部與地下部重量之關係式；最後，依室內與現地含根土壤之直剪強度，可將根系加勁效應轉換成當量之剪力強度增量，此增量又與根系之單根抗拉強度、平均根徑及生長密度有直接關聯。 |
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| In order to capture the realistic effects of physical characteristics and mechanical properties of root system on the soil~root interaction behavior and provide the required material parameters of root system for numerical analyses of vegetated slope, this paper extensively integrates various methods of site investigation, type classification and mechanical experiment of root system through well-organized tabulation and discussion. According to the experimental results, it appears rational to correlate the tensile strength of single root with average root diameter. On the other hand, the ultimate pull-out strength frequently was associated with near-ground diameter of root, plant height, dry weight of root, and width of plant crown, weights of plant above and under ground surface. Eventually, based on the direct shear strength of soil~root sample, the effect of reinforcement of root system on soil layer can be converted into an equivalent shear strength increment of soil mass and which alternately can be expressed in term of tensile strength of a single root, average root diameter and growth density of root. |
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| A DISCUSSION ON SOME TECHNICAL TERMS OF SPECIAL ACT FOR SLOPELAND CONSTRUCTION |
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| 田永銘、郭明傳、朱正安、連進春 |
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| 建築技術規則、山坡地建築專章 |
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| 「建築技術規則」建築設計施工編第十三章「山坡地建築」為國內山坡地開發最重要的技術規範，於民國87年1月1日開始實施，迄今已歷經六次修訂，然而本章第261、262條中之部分技術用語仍與土木、大地工程或工程地質領域之學理定義不盡相符，有待進一步釐清、修正。本文針對第261條之部分技術用語，如：「順向坡」、「自由端」、「岩石品質指標」、「活動斷層」、「工程壓密」、「有效應力深度」等，從土木、大地工程及工程地質學的角度，探討這些技術用語適當性，並就可能產生疑義的技術用語提出條文修正建議。 |
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| The special act for slopeland construction had been legislated as chapter 13 of construction and design section of the building technical regulation on Jan.1st, 1998. Although the special act had been revised for six times, the definitions and concepts of some technical terms for slopeland construction, special act chapter 13 are still improperly stated. The properly and strictly definition in regulations affects the general public consideration for geotechnical technician executions and the results of trial fairs. In this article, the terms of definition of “dip slope”, “free end”, “rock quality designation”, “active fault”, “engineering consolidation” and “depth of effective stress” that exist in the No.261 of special act chapter 13 had been investigated and revised from the viewpoint of geotechnics. |
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