成贵铁路观音山隧道水文地质勘察与选线

The Hydrogeology Survey and Line Selection for the Guanyinshan Tunnel of Chengdu-Guiyang Railway

研究目的:新建成都至贵阳铁路观音山隧道位于贵州省毕节市大方县境内,由于云贵高原抬升快,河流切割深度达600 m以上,加之地质构造发育及雨水较多等原因,使得二叠系、三叠系灰岩岩溶发育程度极高,溶蚀基准面低,造成地表水系不发育,地表水环境极为恶劣、敏感,石漠化极为严重。地质工作需查明影响线路方案的地质因素,综合分析其危害,预测其对工程可能产生的不利影响,为线路选择及工程设置提供依据。研究结论:(1)隧址区位于黔西"山"字形构造体系脊柱与小路坡东西向构造带复合部位之冒沙井南北向构造带内,断层、褶皱及垂直于断层、褶皱轴线的横张节理发育;(2)启化田坝背斜为倾覆背斜,两翼及倾覆端环闭状泥页岩阻隔了岩溶水发育通道,形成局部垂直于背斜轴部的小型分水岭,极大地减弱了观音山分水岭南侧的岩溶发育程度,同时也为高原山塘型芦塘水库的形成创造了条件;(3)线路选择在观音山小型分水岭南侧岩溶不发育区,并远离芦塘水库,不仅绕避了岩溶及水库水环境的风险,同时缩短了线路长度,节约了工程投资,线路方案是切实可行的;(4)本研究结论可为复杂岩溶山区铁路、公路地质选线提供指导。

Research purposes： The Guanyinshan tunnel of new Chengdu - Guiyang railway is located in Dafang county, Bijie city of Guizhou province. On the account of the fast uplift of Yunnan - Guizhou plateau, the deep river cutting over 600 m and the development of geological structure and heavy rainfall, the karsts in the limestone area of Permian and Triassic were extremely developed and the corrosion datum became very low. As a result, the surface water system was not developed and the surface water environment became extremely harsh and sensitive. What~ more, the karst rocky desertification was quite serious. Therefore, we need to identify the geological factors which can affect the route plans and study their hazards, to predict the adverse effects on the engineering and provide the basis for the railway location and project settings. Research conclusions： （ 1 ） This tunnel was located in the south - north tectonic belts of sandblasting well, which combined the backbone of epsilon - type structures with the east - west tectonic belts of road slope in western Guizhou. The faults, folds and transverse tension joints which were perpendicular to their axis were developed. （2） The Qihua - tianba anticline was capsized anticlines and the ring closure shaped mud shale in two wings and capsized sides cut off the channel of the karstie water. Thus, the local small watershed perpendicular to the anticline axis not only greatly weakened the karst development level in the south of Guanyinshan watershed, but also created the conditions for the formation of Lutang reservoir with the plateau - mountain pool type. （ 3 ） The line was chosen in the un - development karst area far away from the Lutang reservoir. Based on these conditions, it can not only avoid the risk of karst and reservoir water, but also shorten the railway length and save the engineering investment. （4） The research results may provide guidance for geology route selection of railway and highway in complicated karst mountainous area.