Investigation of Sinkhole Due to Tunnel Excavation in Oval-shaped Gravel Layers

• Main Authors: Shih-Hsien Yang, 楊士賢
• Other Authors: Ming-Lang Lin
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/11035114619210736632

碩士 === 國立臺灣大學 === 土木工程學研究所 === 102 === Taiwan is a mountainous country. Some gravel layers are located in western Taiwan mountain foot and Huatung Valley. Wuho Tableland is a Quaternary Period fluvial fan and risen by Central Range Fault. In this tableland, it still reserved the indication of fluvial fan that we can found, such as the spread of the gravel layers and gravel arrangement. And in the fluvial fan, the grain size and thickness of gravel layers are not equal, so that the stratum would be anisotropic and inhomogeneous. This stratum would affect the availability of geoengineering. Aug 28, 2012, Typhoon Tembin stroke Taiwan with heavy rain, especially for eastern Taiwan that causes sinkhole. The sinkhole is 10 meters in depth. From bore log and geologic investigation, we found the sinkhole is located in Wuho conglomerate. And we want to draw the connection between the configuration of the strata and the sinkhole. In this research, we analyzed into two aspects: experimental method and numerical simulation. Then, we set up sand-box experiment and verify with discrete element method (DEM). Finally, apply proper thickness, depth of gravel layer and depth of tunnel into this case. The results showed that with deeper tunnel comes shallower and wider sinkhole. And thicker gravel layers comes larger shift of sinkhole. This can be seen from both experiments and DEM simulation.