Landslide-related maintenance issues around mountain road in Dasha River section of Central Cross Island Highway, Taiwan
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ORIGINAL PAPER
Landslide-related maintenance issues around mountain road in Dasha River section of Central Cross Island Highway, Taiwan Meng-Chen Tsao 1 & Wei Lo 1 & Wen-Ling Chen 2 & Tai-Tien Wang 2 Received: 17 December 2019 / Accepted: 2 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The winding Dasha River section of the Central Cross Island Highway in Taiwan is 9.44 km long. More than 20% of its length has been rerouted in the past six decades due to landslide-induced maintenance problems. To investigate the influence of geological conditions on the maintenance of this mountainous road section, this study establishes inventories of highway alignments and nearby landslides based on interpretations of multi-temporal aerial photos and highway maintenance records. Types of landslide and topographic features are verified through field investigation, and the engineering characteristics of rock masses are evaluated using the Q-method semi-quantitatively. The results reveal that three sections with rerouting of road or structural modification are located near the undercut slopes of the Dasha River and the boundaries of strata where water erosion and scouring are active and considerable gullies develop. Various metamorphic strata with intricate folds are formed by orogenic deformation and metamorphism under the influence of weathering, such as water erosion and scouring; these evolve into meanders and steep slopes. Gullies develop along the boundaries of strata with distinct lithology, where the engineering characteristics of rock masses vary markedly, disturbing the stability of nearby slopes and hindering the maintenance of the mountain road for long periods. Rerouting the highway and the use of a tunnel instead of the slope-cut-in halfway road effectively mitigate the influence of landslides near meanders where water erosion and scouring are significant. A gallery tunnel effectively mitigates rock fall. However, a gallery tunnel must be constructed without causing overcut-induced slope instability. Keywords Mountain road . Maintenance . Reroute . Landslide . River erosion . Gully
Introduction Steep terrain and rapid rivers in mountainous areas lead to unfavorable engineering geological and hydrological conditions for the construction of infrastructures. The cutting of
* Tai-Tien Wang [email protected]; [email protected] Meng-Chen Tsao [email protected] Wei Lo [email protected] Wen-Ling Chen [email protected] 1
Institute of Mineral Resources Engineering, National Taipei University of Technology, Taipei, Taiwan
2
Department of Civil Engineering, National Taiwan University, Taipei, Taiwan
slopes or the filling of roadbeds during the construction of mountainous roads may affect the stability of neighboring slopes (Conforti and Ietto 2019). Even when open to traffic following construction, the roadbeds of a mountainous road often subside unevenly as a result of the scouring of nearby rivers or deep-seated gravitational slope deformations, affecting the track
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