| 摘要: | 總計畫：近年來因為極端氣候發生之頻率愈來愈高，岩石邊坡若受到豪雨、地震、河流沖刷等自然因素或其他人為因素，可能會使得岩坡發生規模大小不一之滑動或破壞，造成鄰近聚落居民的生命財產損失。因此，國內外產官學界已對於岩石邊坡之防災相關工作，投入了大量的人力物力。由前人研究已可以得知，岩坡滑動之規模或影響範圍與其岩坡種類以及尺寸等因素有關，對於要避免或是減輕岩坡滑動所造成之災害，實有必要由不同調查或是分析尺度著手，以達成 (1)災前破壞潛勢區有效判釋，(2)災中預警以及應變避難方式之擬定以及(3)災後進行快速且廣域之破壞型態以及影響範圍調查等目的。總計畫以整合岩石邊坡在不同調查尺度下之破壞、變形特徵以及堆積影響範圍為研究主軸，規畫進行一系列涵蓋不同調查尺度之方法(如現地災害調查或地球物理探測之分析等)，並搭配不同比例尺圖資之應用以及現化代調查工具，輔以物理試驗以及數值分析方法，探討不同促崩因子(如降雨、地震、不同尺度或邊界條件等)對岩坡失穩後變形、破壞特徵之影響，預期可為台灣常見之岩坡滑動災害，建議災前災後快速廣域評估調查之方法，並為災中預警及應變計畫之擬定提出創新之分析方式。子計畫四：近年來岩石邊坡之破壞案例，大多受到極端降雨、地震等外在因素，或是坡體內部力學性質(如孔隙水壓力、剪力強度變化)等內在因素之影響，如莫拉克颱風造成小林村上游獻肚山順向坡滑動，集集地震時草嶺產生大規模順向坡滑動，國道三號七堵段之順向坡滑動，嘉義潮洲湖之岩坡楔型破壞等，上述案例之致災原因雖然不盡相同，但由破壞案例亦可以得知，岩石邊坡產生滑動之機制以及其規模，可能也與岩坡之種類以及其尺寸或內在、外在邊界條件有關。為了了解不同岩坡種類在不同幾何尺寸下的變形特徵以及堆積特性，子計畫四規畫以物理試驗(正常重力場以及離心重力場下)以及數值模擬(分離元素法)進行簡化岩坡模型之穩定性以及變形分析，物理試驗的部分，以採用人造離心重力場之方式提升簡化岩坡之內部應力，並採用研磨石做為簡化物理模型之基本單元，將研磨石依所需之岩層特性膠結堆放，再照預計採用之重力場或其他邊界條件等情形施加於岩坡模型中，研究中並利用分離元素模型建立與物理試驗相同之數值模型，以進行模型驗證以及參數分析，以歸納岩石邊坡在不同尺寸以及內在或外在條件影響下之變形特徵以及堆積特性，做為往後判釋大規模山崩之變形特徵或堆積特性之參考依據。 ;Main project:Due to the frequent extreme weather conditions in recent years, when the rock slopes are subject to natural triggering factors such as heavy rainfalls or earthquakes or artificial triggering factors, slope failure may occur and cause damages to the surrounding areas. To prevent or reduce the damages during and after rock slope failure, one has to capture the failure mechanisms, accumulation characteristics and the deformation features of rock slope failure. From earlier researches about rock slope stability, it is well-known that the rock slope failure is related to the rock slope types, and the geology conditions. However, to better plan for the evacuation routes or early warning system, it is also necessary to understand the deformation features and accumulation characteristics under different conditions. Hence, it is the purpose of this main project to integrate the information from different investigation scales, in order to facilitate the field investigation during and after the rock slope sliding disaster. Further, in addition to the fact that the rock slope failure is related to the rock slope types and the geology condition, it is also crucial to explore the effect from different triggering factors, such as heavy rainfall, earthquakes or the size of the slopes. With the deformation and accumulation features under different triggering factors, the rock slope failure mechanisms can be better characterized. It is therefore expected that proper site investigation method may be proposed to better and more efficiently understand the rock slope sliding condition, and innovative methods to analyze certain rock slope conditions are also suggested, in order to better predict the deformation and accumulation features of certain rock slopes with high failure susceptibility under given scenarios.Sub-project No. 4:The failure of rock slopes is of crucial importance in that it can cause severe damages to the surrounding areas and the residents. From previous researches related to the rock slope sliding failure mechanisms, it is known that the failure mechanisms are related to the rock slope types and its boundary or inner conditions. In this sub-project no. 4, the main target is to explore the failure mechanisms, deformation characteristics and the accumulation features of rock slope avalanches with different sizes of slopes. The study will be carried on employing both the physical testing (featuring geotechnical centrifuge tests) and numerical simulation (featuring discrete element method). The centrifuge gravitational field can be applied to the in-house physical models to achieve similar stress levels as these in the field conditions, therefore the scale effect of the rock slopes can be discussed with the test results. The discrete element models are also established for parametric study, after they are verified with the results from centrifuge testing. It is expected that the results of sub-project no. 4 can yield possible deformation and accumulation features of simplified rock slopes, hoping to shed light on characterizing the rock slope failure features in actual conditions. |
