Techno-economic Comparative Analysis Of TBM Method And Drilling And Blasting Method

In this paper, the two construction methods of TBM method and drilling and blasting method in the tunnel project has been analyzed for technical and economic comparison,the scope of application for them is determined, and the economic hole long of a circular hydraulic non-pressure tunnel used TBM method and drilling and blasting method has been determined through cost calculations, some construction information for the inside or outside tunnels being built by TBM method and the drilling and blasting method.(1) The scope of application for TBM method and drilling and blasting methodIn the tunnel construction method, TBM method and drilling and blasting method are both the mature construction methods. Contrast drilling and blasting method and TBM method,the working procedure is more,the organization of construction is more complex,the time limit for a project is longer, the ultra-owed dug is larger,the security is poorer, but the ability fitted the geologic condition is better. For TBM method that is easier to control, construction speed is higher, safety is better then drilling and blasting method. From the technical comparison, TBM method is suitable for shorter duration,harder rock mainly circular long tunnel, but drilling and blasting method is suitable for shorter tunne,complex geological conditions and TBM method is not suitable.(2) The economic hole length of TBM method and drilling and blasting methodThe economic hole length of open-type TBM method is more than 5km, double-shield TBM method is more than 9km, when diameter is 4m, depth is 100～500m, gradient is 1/ 800,Ⅱsurrounding rock types and above accounted is 40%,Ⅲclass rock accounted is 30%,Ⅳtype accounted is 20%,Ⅴcategory accounted is 10% of the round rock water Public non-pressure tunnel.(3) The economic hole length of TBM method and drilling and blasting methodSome construction information for the inside or outside tunnels being built by TBM method and the drilling and blasting method show that the current TBM construction method can adapt to the complex geological conditions, cave,gushing water and other special geological conditions had been look-ahead processing, or excavating supported by drill and blast method then using TBM method.In king-size tunnel,using TBM method the economy is good and cost savings is about 5%～20% then drilling and blasting method. In hard rock tunnel, the cost of double-shield TBM is higher than the open-type TBM about 20%, and the economy is more obvious. The development of domestic TBM is stagnant and the management level of domestic companies are relatively backward,which is the main reason that TBM method is difficult to promote in China currently.The cost difference of TBM method and drilling and blasting method will be diminishing with the further development and promotion of TBM method, TBM method will be the mainstream construction method in the long tunnel to replace the drill and blast method.