沙里仙坡地崩滑區之探勘與數值模擬分析

Site Investigation and Numerical Simulation Analyses of a Failed Slope at Salihsien

黃仁德(Ren-De Huang)

指導教授 ： 徐松圻

朝陽科技大學/理工學院/營建工程系/碩士(2014年)

摘要

每年5至10月間會有梅雨季及颱風侵襲臺灣，常夾帶大量的水氣造成山區集中降雨，經常發生嚴重水災、邊坡滑動及土石流，有必要針對其危險程度施以不同程度的邊坡保護以及設置災害預警範圍，並可將數值模擬結果做為防災、治災及疏散之參考。
本研究位於南投縣信義鄉東埔村，陳友蘭溪流域上游及沙里仙溪下游交匯口處，在現地進行取樣、鑽探與基本物理及進行室內夯實試驗，以求現地土壤溼單位重，可能最佳含水量約在5~7%，得知可能岩盤位置約在該處地面下30米處。並試著以大型直剪試驗及直剪試驗，推估飽和及不飽和土壤之剪力強度參數，同時進行基本參數試驗、壓力鍋試驗、現地Guelph滲透計試驗，以獲得後續程式模擬分析，所需要之土壤水分特性曲線及滲透係數。由風災前後之DEM取得沙里仙邊坡剖面圖，並使用Geo-Studio裡的SEEP/W及SLOPE/W，來進行數值模擬，分析因極端降雨時邊坡崩坍之情形，以反推現地可能之剪力強度，在凝聚力為5kPa時，反推出摩擦角下限為35度，連續破壞面皆沿岩盤滑動，而土層厚度較厚時，破壞形式為大規模塊體滑動，反之土層較薄時，屬於漸進式淺層滑動。

關鍵字

不飽和土壤 ； 降雨入滲 ； 邊坡穩定 ； Geo-Studio

並列摘要

Heavy rainfall in mountain areas brought by typhoons and during raining season had caused serious flood, landslide, and debris flow in Taiwan. There is necessary to have some ways to protect the slopes and set up disaster warning system or range at those areas. The results of numerical simulation of this study can be used as disaster prevention, control, and evacuation.
This study is located at Tong-Pu Village, Shin-Ye Township, Nantou County, and is close to the intersection of upstream of Chenyulan River and downstream of Salishan Creek. In-situ sampling, boring, index property tests, and compaction tests have performed to obtain the related index properties and optimum water content, which is around 5~7%. The estimated depth of rock formation is about 30m below the ground surface. Large and regular direct shear tests are used to acquire the saturated and unsaturated shear strength parameters for the colluvium soils. Soil water characteristic curve for the soils are based on the results of pressure plate tests. Guelph permeameter is used to obtain the in situ permeability for the soils. These testing results and related parameters are used for the numerical programs, SEEP/W and SLOPE/W, developed by Geo-Studio. Numerical simulations are performed to obtain the minimum friction angle of the soils, around 35 degrees, while the cohesion is set as 5kPa. The bottom of the sliding surface of the failed slope under extreme rainfall condition is usually located at the interface of soil/rock formation. Larger sliding block is occurred as the thickness of the colluvium is larger.

並列關鍵字

unsaturated soils. ； rainfall infiltration ； slope stability ； Geo-Studio

參考文獻

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