滇西高黎贡山南段腾越隧道沿线岩石-构造特征及其工程影响

Rock-structural Characteristics Along Tengyue Tunnel in the Southern Segment of Gaoligong Mountain, the Western Yunnan, China and Their Engineering Influence

横断山地区的复杂地质构造条件是制约滇西大环线、沿边高速和滇中城市群高速路网等重点工程规划与建设的最突出问题。以拟穿越横断山南段高黎贡山的超长深埋公路隧道(腾越隧道)为例,基于隧道工程区详细的岩石地层、构造地质与工程地质勘查资料,对该区的隧道围岩、地质构造以及相关的水热活动特征等进行了详细剖析,总结了面临的主要工程问题。结果表明:高黎贡山南段是较为典型的以韧性剪切带及所夹持的花岗岩体和变质岩块为主构成的动力变质变形带;隧道工程区主要包含9类岩石工程单元,主体以形成于上地壳下部至中地壳的中深层次变质岩类和花岗岩类为主;对工程建设可能产生显著影响的主要断裂带有10条,分属怒江断裂系、高黎贡山断裂系(或泸水—瑞丽断裂系)和龙川江断裂系三大构造体系,并控制了区域上主要水热活动带,其中第四纪仍可能存在活动性的断裂带有5条,高黎贡山西侧边界断裂带是影响隧道工程的主要活动断裂。综合分析结果表明,研究区隧道围岩的工程地质属性多属于较破碎的坚硬—较坚硬岩,高地应力和高地温将是影响隧道工程稳定性的主要因素,其次是变质岩和花岗岩的岩体特性与构造节理发育程度,以及相关的断裂涌水和花岗岩区段的密集节理带透水问题。

In recent years, the construction of transportation infrastructure in Yunnan province has entered a stage of rapid development. However, the complex geological structure of Hengduan mountain range seriously restricts the planning and construction of several major projects, such as the western Yunnan ring road, the border expressway, and the central Yunnan urban agglomeration expressway network. Taking the super-long deep-burial Tengyue tunnel, which would pass through Gaoligong mountain of the southern Hengduan mountain range as an example, based on the lithostratigraphy, structure and engineering geology, the surrounding rock, geological structure, and related hydrothermal characteristics of the tunnel engineering area were analyzed in detail, and the major engineering problems that the project will face in the construction stage were summarized. The results show that the southern segment of Gaoligong mountain is a typical dynamic metamorphic deformation zone, which is mainly composed of ductile shear zone and the clamped granite and metamorphic rocks. The tunnel engineering area mainly contains 9 rock engineering units, and the main body is the metamorphic rocks and granitoids in the middle and deep levels formed from the lower part of the upper crust to the middle crust. 10 project-affecting active faults of Longchuanjiang, Nujiang, and Gaoligong mountain fault systems, controlling the hydrothermal activity in study area, are also studied;5 of them have been active since Quaternary, and the one in the western piedmont of Gaoligong mountain is the top priority on affecting the stability of the engineering area. In summary, the engineering geological properties of the tunnel surrounding rock in the study area mostly belong to the relatively broken-relatively hard rock, and the stability of tunnel engineering is significantly affected by the high ground stress and high ground temperature. The rock mass characteristics and tectonic joints of metamorphic rocks and granites, and the related water inrush from faults and permeability of dense joint zone in granite section secondarily contribute to the instability. The new result is helpful for the stability assessment of tunnel engineering in the meso-kata metamorphism area of Hengduan mountain range.