武康二线小间距高风险段隧道爆破施工技术

Blasting Techniques for High-risk Section of Liujiagou Tunnel on Second Line of Wu-Kang Railway

武康二线新刘家沟隧道起讫里程为DzK123＋902～DzK124＋772，全长870m，位于半径1600m的曲线上，隧道进口右邻既有线，DzK123＋902～DzK124＋020段距既有花果隧道较近，最小线间距11m，新旧线衬砌背最近距离为4．0m。进口紧接新建千字沟中桥安康端桥台，正下方为316国道，地势陡峭，自然坡度大，处于公路、铁路立体交叉的咽喉部位。由于隧道地理位置特殊，地质复杂，技术含量高，施工难度较大。尤其是爆破施工很可能会影响到既有线结构稳定、运营安全以及316国道行车安全，施工安全形势尤为严峻。

Liujiagou Tunnel on the second line of Wu - Kang Railway is located on a curves with a radius of 1 600 ms. It begins at DzK123 ＋ 902 and ends at DzK124 ＋ 772, with a length of 870 m. The tunnel entrance neighbors the existing railway to the right, and DzK123 ＋ 902 - DzK124 ＋ 020 section is very close to Huaguo tunnel of the existing railway line, with a nearest distance of only 11 m and the minimum distance between new and old lining back is only 4 m. The tunnel entrance is connected with the abutment of Qianzigou Bridge at Ankang end, and directly under it is National Highway No. 316. Located at an interchange of highway and railway and with precipitous topography and steep slope, this section of tunnel is characterized by its special position, complex geology, high technical content and high difficulty of construction. Particularly, the blasting might affect the stability and operation safety of the existing railway and National Highway No. 316, thus the situation of construction safety is very severe.