Study On The Optimum Design Of Lining Of Tunnel Support Through Bad Geological Section

Due to the complexity of engineering geology,the line selection of tunnel design often cannot avoid some special geological sections,and even the whole tunnel is in this kind of geology.Although the current highway tunnel design specification puts forward relevant engineering measures,there is no specific design parameters.Its design mainly adopts engineering analogy method to design and design changes,which makes the lining structural parameters of tunnel design different,resulting in unnecessary increase of engineering investment,and even a considerable potential safety hazard.Firstly,this paper collects and analyzes the design information of all kinds of bad geology.Secondly,based on the design parameters of the original support structure,according to the design specifications,combined with the actual geological conditions of the project,and analogy of the construction experience and technology of tunnel engineering in China,to optimize the tunnel in plaster and karst section.Its main achievements are:1.According to the safety and economy principles,the pre-design deficiencies were optimized according to the field feedback and the actual conditions of the surrounding rock samples,and put forward the design parameters suitable for the project.2.The ANSYS software and load structure method are used to analyze the lining structure force of each unit in pre-design and the optimized design,and use the safety factor method of concrete to calculate the safety of tension elements.According to the calculation results,the optimization design not only meets the specification requirements on the safety factor,but also reduces the construction cost of the tunnel.3.The MIDAS / GTS software was adopted to reduce the C and ? values(strength reduction method)to repeatedly calculate the lining structure force in pre-design and the optimized design,until the ultimate failure state was reached,so as to obtain the surrounding rock safety factor.4.In this paper,the data obtained from the field monitoring and measurement are used to verify the feasibility of the optimized design.To consider the post operation safety,the operation monitoring points are set up in the location of the optimal design area,and the stress early-warning value is put forward according to the ultimate bearing capacity of the lining.This paper takes different methods with traditional optimization design.First,the optimization design parameters are put forward according to the actual situation in the field,then analyze the feasibility and safety of the optimized design,finally,Verify through the actual situation on site.The optimization design not only made up for the risks existing in the original design,but also optimized the pre-designed partial over safety parts,which greatly reduced the cost of tunnel completion.The optimization method has a great reference significance to the design of bad geology of tunnel.