Geological Line Selection in Karst and Dangerous Rock Falling Area of Daba Mountain District Railway – A Case Study on the Scheme of Both Sides of Qianhe River in Xi’an-Chongqing High-Speed Railway

As an important part of the national high-speed rail network “eight vertical and eight horizontal” package Baotou (Yingchuan)-Hainan channel and Beijing-Kunming channel, Xi’an-Chongqing high-speed railway passes through the Daba Mountain District fromnorth to south. The topography and geomorphology of Daba Mountain area are precipitous and complex, especially in the South of Daba Mountain area, high-pressure water-rich karst is strongly developed, the structure is developed, the slope is steep, the dangerous rock is developed, and there are many problems such as high construction difficulty, high project risk and poor operation safety. The Qianhe River is located in the South of Daba Mountain area. The mountains of both sides of the Qianhe River are high and the valleys are deep. The dangerous rocks and falling rocks are very developed. In this paper, the opinions of engineering geological comparison are proposed for two route schemes from the entrance of Qigan Mountain Tunnel to Xiangyang No. 1 Tunnel through Mingtong Town east side (Qianhe East bank) and through Mingtong Town west side (Qianhe West bank). Through the combination of traditional and modern investigation methods, we use remote sensing interpretation, ground mapping, unmanned aerial vehicle photography and other comprehensive investigation methods, the karst development characteristics of this section are mastered, and the distribution range of dangerous rock falls at the bridge site of the comparison scheme is identified. Through the engineering geological analysis and evaluation of the comparison scheme, a railway line with controllable safety risk is selected.