Failure Mechanism for a Large Landslide at Qidu

• Main Authors: CIAO-WEI YANG, 楊喬維
• Other Authors: T.S HSU
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/63571949079671483926

碩士 === 逢甲大學 === 土木工程所 === 98 === National Highway No. 3 (Formosa Freeway) is the second North-South freeway which is passed through nationwide in Taiwan; however, on April 25th, 2010, under a condition of “no wind, rain and earthquake”, around the segment at 3.1 km toward south and 2.8 km toward north, a historic landslide accident occurred near Qidu. Some scholars and experts via media who expressed that the causes of such disaster would be dip slope, ground anchor quality, maintenance and long-term water leakage, etc.; in order to further understand those professional disaster causes of such landslide, this author is adopted the slope stability analysis of dual sliding surfaces that complied with the current condition of such disaster to respectively carry out the analysis of slope stability for the regular time, earthquake and torrential rain to sort out the professional disaster causes with conforming to essential elements, including Uniqueness, Entirety and Comprehensiveness, etc. Research results of this study showed: (1) under the condition of 100% contact ratio (CR) for the sliding block and its underneath stable block, such slope will still maintain stably even in torrential rain or earthquake; (2) slope’s safety coefficient will be reduced along with the decrease in CR; in addition, when CR<60%, such slope tends to become unstable; (3) discovered from the in situ examination that before occurring the landslide, the brittle fractured shear zone rocks have already existed on the sliding surface, and their brittle fractured level will be increased if the felt earthquake occurred continuously; (4) since the brittle fractured level of shear zone rocks is continuously increased while CR is reduced; therefore, only the slope with small dip angle (16°~19°) may have the possibility of the sliding damage under the condition without wind, rain and earthquake.