高速铁路隧道岩溶陷落柱成因及工程地质特征分析

Analysis of Geological Characteristics and Cause of the Karst Collapse Column in High-speed Railway Tunnel

成都至贵阳高速铁路铁盔山隧道施工过程中,部分地段遇到松散堆积不良地质体,且伴有大量涌水,给施工造成较大困难,必须通过系统勘察查明该不良地质体的成因、工程力学性质、水文地质特征,为设计施工提供准确、全面的地质依据。通过区域水文地质调查、地质钻探、物探、原位测试、室内试验及数值模拟等方法进行综合勘察和分析研究,判定该不良地质体为岩溶陷落柱,由岩溶洞穴上覆的非可溶性岩层持续塌陷而成,柱体直径约60 m,发育高度200~300 m。研究结果表明,该岩溶陷落柱及其柱边围岩属于地质体薄弱带,工程力学性质较差;该岩溶陷落柱为发育于地下水强径流带上的导水陷落柱,涌水量大,宜先利用迂回导坑进行泄水降压,再施工正洞。

During the construction of the Tiekuishan Tunnel of Chengdu-Guiyang High-speed Railway,there were loose and accumulated poor geological bodies,accompanied by a large amount of water inrush,which caused great difficulties to the construction.The mechanical properties and hydrogeological characteristics of the bad geological bodies had to be identified through systematic investigation,so as to provide an accurate and comprehensive geological basis for the design and construction.Through regional hydrogeological survey,geological drilling,geophysical exploration,in situ testing,indoor testing and numerical simulation and other methods of comprehensive investigation and analysis,it was determined that the undesirable geological body was a karst collapse column,which was formed by the continuous collapse of the non-soluble rock layer over the karst cave,with a cylinder diameter of about 60 m and a development height of 200~300 m.The result shows that,the karst collapse column and its column-edged surrounding rock belong to the weak zone of geological body and have poor engineering mechanical properties;The karst collapse column is a typical development in the groundwater strong flow belt of the water sinking column.The amount of water inrush is large,it is advisable to use the roundabout guide pit for water discharge and pressure reduction before the construction of the main hole.