| In this paper,MIDAS/GTS software and geological data of Na Wen hydraulic tunnel are used to establish the traditional steel arch support structure analysis model and the new extended steel arch support structure analysis model respectively,so as to explore the influence of concrete thickness and steel arch spacing on the vault subsidence value and arch foot displacement value in the two support structures.According to the simulation data of two kinds of support structures,the supporting effect of two kinds of support structures is analyzed synthetically.By comparing the simulation data and monitoring data of the new extended steel arch support structure with the case of tongli trunk canal no.1 tunnel project,the following conclusions are drawn:(1)On the basis of the traditional steel arch support structure,the arch foot is lengthened by 10 cm to form a new lengthened steel arch support structure.The new extended steel arch support structure USES the extended part of the arch foot and the unexcavated surrounding rock of the lower step to provide horizontal binding force for the arch.The lengthened end of the steel arch is placed on the concrete blocks in the pits on both sides of the upper steps.The interaction between the lengthened end of the steel arch and the concrete block increases the contact area between the end of the steel arch and the surrounding rock,provides more vertical reaction force for the steel arch support structure,and reduces the subsidence value of the arch.By using MIDAS/GTS software and geological data of Na Wen hydraulic tunnel to build an analysis model,it is concluded that the new extended steel arch support structure can effectively solve the defects of traditional steel arch support structure in the aspects of arch foot movement and vault subsidence.(2)The use of MIDAS/GTS software and the hydraulic tunnel geological data analysis model is set up,maintain two kinds of supporting structure in the adjacent steel arch span and the thickness of concrete are phase at the same time,the fourth nature,vault subsidence value of the steel arch and arch foot of value,found that the fourth cross steel arch vault subsidence rate and arch foot of convergence rate with the increase of excavation step are gradually slow,eventually vault subsidence value and arch foot of stable;Two kinds of supporting structure in the thickness of concrete and steel arch spanare equal,using new extended type steel arch support within the arch foot horizontal shift from traditional steel arch support within the arch foot horizontal move by around 69%,with new extended type steel arch support vault vertical subsidence compared with traditional steel arch support vault vertical settlement by around 58%.(3)The control variable method is used to borrow group of MIDAS/GTS software and the hydraulic tunnel geological data to establish change adjacent steel arch span or change the thickness of concrete analysis model,it is concluded that change the adjacent steel arch span and the thickness of concrete arch structure of two kinds of supporting all affect the sinking and arch foot inside,as the adjacent steel arch span increase or decrease the thickness of concrete,two types of supporting structure vault subsidence value and arch foot of both increased.However,the increment of the traditional steel arch support structure in the vault subsidence value and the arch foot displacement value is greater than that of the new extended steel arch support structure.(4)To adopt the new extension type steel arch supporting structure Tong Li main canal 1 # tunnel simulation analysis and field monitoring,and take the fourth common steel arch simulation data and the monitoring data of comparative analysis,field monitoring and simulation data deformation trend,to verify the new extension type steel arch supporting structure in Tong Li main canal in 1 # tunnel engineering supporting effect,promote the development of new type of supporting structure and perfect.Figure [35] table [10] reference [56]... |
PDF Full Text Request