The Research On Reconnaissance Of Shield Metro Tunnel In Karst Area Of Guangzhou

In recent years,with the continuous development of GuangZhou’s rail transit,more and more problems was encountered during the construction in Karst region,in addition,a large distribution of karst areas is the most of the history of the construction of urban rail.Karst caves,Karst water,caves filler and Karst collapse are the three main types of hazard.If survey measures are not appropriate,it will lead to an imperfect pretreatment,thereby will cause many security problems in the process of shield construction and leave security hidden trouble in the subway operating period.According to the special geological conditions of the Karst area and the problems of the survey of shield tunnel,this paper takes the Huang-Guang section project of Guangzhou metro line 9 as the background,on the basis of theoretical research and engineering data,through site investigation and numerical simulation,put forward a set of integrity guiding scheme of survey and pretreatment,The main research works and results are as follows:(1)Through the investigation of Guangzhou karst region geological environmental conditions,collect the existing geological datas and summarize the geological and geomorphologic characteristics in this area and the development mechanism of all kinds of disasters in Karst.Futhermore,study on the influence on shield subway tunnel by this geological conditions,providing the basis for make survey and pretreatment scheme reasonably and accurately.(2)Combined with the geological characteristics of karst region and disasters,researching on the integrated survey technology in Guangzhou Karst area,summarizes different survey means including the investigation of different geophysical prospectings,and research on the grouting pretreatment of shield subway tunnel,forming a guiding survey and pretreatment scheme of shield subway tunnel that apply to Guangzhou Karst area.(3)Relying on the Huang-Guang section project of Guangzhou metro line 9 project,describe the survey and pretreatment scheme,and through Three-dimensional finite element software Midas GTS/NX to analysis the shield tunnel construction process under existing caves with different cases,with the ground settlement caused by shield construction and the distribution of stress as safety judging index,the survey and pretreatment scheme that being adopted is corroborated that it is feasible.