Study On Safety Impact Of Tunnel Construction On Overlying High Voltage Transmission Tower And Evaluation Method

High voltage transmission tower plays an irreplaceable role in power supply system.Due to the rapid development of underground space in our country,the demand of tunnel increases sharply,so the transmission tower often exists above or near the tunnel.Tunnel excavation will disturb the existing stress state of undisturbed soil,resulting in plastic deformation.Uneven settlement of the ground surface will lead to the inclination of the transmission tower,which may cause collapse in serious cases,resulting in the loss of power system in the whole area It is very important to analyze the overlying transmission tower in tunnel construction.In this paper,A transmission tower is taken as an example(1)Firstly,based on the engineering example of a power tower,according to the geological survey report and design drawings,the relevant parameters are calculated,and the overall model of soil tunnel transmission tower is established in Midas GTS /NX software,and then the influence of tunnel construction on power tower is analyzed.(2)Based on the single factor numerical simulation analysis of the transmission tower above the tunnel,the necessary simplification of the model in the previous chapter,orthogonal design of a variety of calculation conditions,statistical analysis of the modeling results,the influence of seven factors such as tunnel buried depth,tower distance,Poisson’s ratio,normal consolidation line slope on the transmission tower above the tunnel construction is obtained.(3)Finally,in order to understand the influence of the influence factors on the transmission tower above the tunnel at the same time,this paper uses EFAST to determine the distribution type and range of seven influence factors,and establishes three output indexes from the perspective of transmission tower and tower foundation.By analyzing the sample data on the SIMLAB platform,we can get the First order sensitivity index of each influence variable and the Total sensitivity index that interacts with other parameters.In the global sensitivity analysis of EFAST,the condition of EFAST analysis is to need a large number of samples.If the finite element model is used for calculation,it needs a lot of time and high-performance computer.Therefore,LSSVM is constructed.Through continuous training of sample data,the predicted value can be basically consistent with the actual value,so as to obtain a large number of sample data.(4)In view of the situation that the transmission tower can not be avoided by the selection of the tunnel line,the transmission tower can be removed by reinforcement.This paper designs two reinforcement schemes from the perspective of tunnel construction and transmission tower,and analyzes the reinforcement effect by numerical modeling.