| Karst problem is worldwide problem,it has encountered a variety of karst hazard in the construction of the tunnel in various countries.The karst is developmental in the tunnel of karst areas,and often causes sudden mud,sudden water,collapse and so on,which lead to casualties and equipment damage,seriously affecting the construction period,increasing substantial cost.So how to avoid and deal with various problems of karst will be the key of the construction of the tunnel.The region of karst is very extensive in china,according to statistics the distribution areas of carbonate rocks is more than 340 million square kilometers.The developmental features of karst include complication,many types,uncertainy sizes,different patterns and so on.The main forms of karst consist of cave,depression,filler, sinkhole,collapse,underground river and so on.This paper not only studies the influence which karst exerts on the tunnel surrounding rock,but also studies the treatment technology of karst in the construction of the tunnel,which are applied to the construction of most tunnels in the ZHANG HUA Highway.The main reseach content of this paper as follows:1.It discusses the influence of karst on the tunnel project,summing up the general rules and the controlling factors of karst development.The technologies of advanced geological forecasting of the tunnel,which mainly include TSP method,advanced drilling method and GPR method,are used to explore the location, developmental status of karst,which can provides the datas for the treatment of karst.2.Based on the background of Kedong tunnel in Zhang Hua highway, a numerical analysis concerning the influence of karst caves in the top,at the bottom,in laterral positive of tunnel on deormation features and stress distribution of the surrounding rock is carried out by using FLAC3D software:The discussion of karst caves of different position, different sizes and diffent distance of tunnel on stability of the surrounding rock, and initial appearance unstable region in surrounding rock.3.The treatment of karst is analyzed specifically with the specific project examples.The karst cave is dealed with legitimately accoding to the size,location,availability of filling,the type of filling of karst and so on.In addition,the karst water is dealed with by the thinking " block is main,combining block with drainage".4.This paper makes some suggestions on the basis of existing theories and experiences in order to ensure the security and stability of the structure during tunnel construction in karst areas. |
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