Province highway No.24 Wu-Tai-Ku-Tran Bridge (No. 1 Bridge) location on San-Di-Men Township and Wu-Tai Township intersection. This bridge has been destroying on Mo-La-Kei Typhoon in 2009. Third Maintenance Office Directorate General of Highways conducts reconstruction now for restoration local traffic. Well Foundation, Cassion, pier and upper structure has done, Ancillary works items continue construction. This study first not only introduces design background and factor of this bridge but also research Well Foundation encounter difficult condition on construction procedure. Secondly introduces the different type upper special structure and how to surmount many difficult technical.
After typhoon Morakot in 2009, the Soil and Water Conservation Bureau, Council of Agriculture, takes positive steps based on the concept of national land conservation to implement the post-disaster reconstruction over hard-hit watersheds in central and southern Taiwan. To begin with assigning hazard potential ratings in different watersheds by considering several factors including sedimentation balance, hydrologic process, ecological conservation, environment development and slopeland management. Afterwards, soil and water conservation strategies and master plans are established in accordance with ratings in each watershed. Detailed conservation management plans also have to be created and carried out step by step. At the same time, the feedback of the field work efficiency evaluation has to be transferred to the conservation management plans for dynamic adjustment and correction in order to achieve the goals of soil and water conservation in different watersheds and to protect the lives of properties of the residents who live in the areas prone to slopeland disasters.
The Morakot Typhoon attacked Taiwan on August 8, 2009. The accumulated rainfall for three consecutive days is more than 2500mm which is equivalent to the average rainfall of the whole previous year. The abundant rainfall causes severe damages, such as landslides, debris flow, and flooding. In particular, the torrential rain hit the access roads and caused a very serious disaster at the Alishan area. Also, people suffered casualties and displaced in these area. The rail and road traffic has also undergone a very serious disaster in southern of Taiwan. This article cited two engineering cases which are line No. 18 59.1k, post-disaster road reconstruction project of Chiayi County at Alishan area. It is expected that the two engineering design and construction cases could be served as the reference bases of the related engineering practices.
High Resolution DEM Generation and Geohazards Susceptibility Analysis for the Disaster Areas Caused by Typhoon Morakot
2009年莫拉克風災衍生小林村重大的崩塌事件，造成嚴重的生命財產損失，經濟部中央地質調查所自2010年起以3年時間利用空載光達完成受災區域的地形掃瞄，產製1m X 1m高解析度數值地形及同步的航照正射影像，藉以建立災後高精度的數值地形資料庫，並應用於調查分析地質敏感區、地質特性與地形、地質災害潛勢評估與水系特性分析等；其中對於潛在大規模崩塌的判釋與調查視為重點工作，經過初步之判釋與現地調查結果，臺灣中部與南部地區可找出超過數百處可能屬於大規模崩塌的潛勢區域，並對於有聚落保全對象的崩塌潛勢區域設置單頻的GPS接收儀、雨量計與經偉儀測距儀器等簡易監測儀器，藉以觀察各崩塌地的地表滑動趨勢與活動性，未來再針對再針對具有較明顯地表變形位移的區域逐步進行地質鑽探、測傾管、孔內伸縮計、地表伸張計、地層變位計等細部觀測。
The heavy rainfall of Typhoon Morakot caused severe damage to infrastructures, property and human lives in southern Taiwan in 2009. The most atrocious incident was the Hsiaolin landslide which buried more than 400 victims. Consequently the airborne LiDAR survey was carried out from 2010 to 2012 by Central Geological Survey, MOEA in Taiwan to produce 1m x 1m high resolution DEM and aerial ortho-photo images in order to build up post-disaster high resolution DEM database and apply to such as investigate and analysis for geologically sensitive areas, Geological and Topography characteristics, Potential geological disaster, River system analysis. the key projects is to investigate and analysis large-scale landslides, the results shows that there are hundreds of large-scale landslides area in central and southern Taiwan. For those potential landslides site near villages, monitoring instruments such as single-frequency GPS, rainfall recorder and electro-optical theodolite have been set up to detect the surface displacement. More monitoring instruments such as tiltmeter, inclinometer, rain gauge, extensometer and Time Domain Reflecometry (TDR) will be deployed in high susceptibility landslide area in the near future.
Typhoon Morakot struck central and southern Taiwan on August 8, 2009 with high rainfall intensity and accumulated rainfall, and induced several landslides, debris flows and floods. In this work, the Hong-shui-xian debris-flow caused by Typhoon Morakot in Xinfa Village of Liouguei District in southern Taiwan was selected for case study. A two-dimensional model (FLO-2D software) was used to simulate the debris flow. Firstly, hydrological and geomorphological data in the debris flow event were collected, and the rheological property of slurry taken from field was analyzed. Secondly, the relationship between debris flow discharge and water flow discharge that used to determine the inflow hydrograph was discussed; influence for the resistant parameters, such as sediment concentration and Manning coefficient, on debris flow simulation were analyzed. The simulation results were then compared with the aerial photos, and the deposited area and depth in field investigation. Finally, the bulked coefficient of discharge and the resistant parameters for using this model in the case study were presented. In this study, parameters and processes needed for the simulation of landslide induced debris flow are proposed to provide a reference for hazard zone mapping or debris-flow hazard mitigation.
Extreme weather has recently caused many disasters worldwide. In August 8, 2009, Southern Taiwan suffered from serious floods during Typhoon Morakot. In this extreme rainfall event, the Chiuliao 1st levee in the Laonong River basin experienced catastrophic failure. Therefore, this study focuses on the levee failure mechanisms based on variations in levee water levels. Specifically, this study investigates four mechanisms based on limit state equilibrium. The first mechanism involves the slope stability under hydrostatic conditions at various water levels. The results of this analysis show that the levee cannot fail under this mechanism. The second mechanism involves the levee slope stability with steady state seepage. Because the water levels are different on the protected and flood sides, the water recedes much faster on the flood side than the protected side. Based on this analysis, the levee slope might fail when the water level at the protected side is close to the top of levee and the water level at the flood side starts to recede. The third and fourth mechanisms involve the levee foundation failure in terms of sliding and overturning failure. The results of this study indicate that the levee foundation is more prone to sliding failure than overturning failure. Based on these results, this study shows that the levee failed when the water level at the protected side neared the top of levee while the water level at flood side started to recede. At this moment, the levee may fail because of the slope failure with seepage and sliding failure of the levee foundation.
During Typhoon Morakot, the flood level induced by high intensity rainfall was beyond the design limit of many river embankments in southern Taiwan. It is therefore desirable to estimate the peak flow-discharge in a future extreme event. In this study, a simplified rational formula is used to estimate the peak flow-discharge in extreme events in the Gao-Ping River of southern Taiwan. A hydraulic model was also developed using the simplified rational formula and Manning formula. This model is calibrated by real data and is applied to determine the flow depths and velocities at some cross sections in the Gao-Ping River.
Hazard Analysis of Seismic Slope Displacement for Liouguei District in Laonong River Basin
本研究旨在利用與地震危害度諧和(hazard consistent)之成對震力參數(最大地表加速度PGA及地震規模M)，考慮地文因子之變異性，應用蒙地卡羅模擬(Monte Carlo simulation, MCS)，以98年8月莫拉克颱風後高雄荖濃溪流域旁之六龜區坡地為例，來分析及探討邊坡受自然環境之衝擊後，將來受震所可能引致之Newmark永久位移量，並繪製對應475年及2475年回歸期之永久位移危害度空間分布圖。本研究成果可作為擬定邊坡受震防災策略之參考。
In this research, a method to construct the GIS-based hazard map with return period of 475 and 2475 year for Newmark displacement by hazard-consistent seismic parameters using Monte Carlo simulation (MCS) is proposed. The pair of earthquake magnitude (M) and the associated peak ground acceleration (PGA) can be considered simultaneously. The uncertainties and variability of associated analysis parameters are all included in the MCS analysis. A case study of Liouguei district in Laonong river basin is performed using the digital elevation model (DEM) and satellite images taken after Typhoon Morakot in 2009. It is showed that the magnitude of displacement is largely influenced by the ground water level and the characteristics of earthquake.