Study On The Reserved Collapse Space In A Loess Tunnel

In loess tunnel construction,it is difficult to determine the amount of reservation deformation of lining.Given the particularity of the deformation of the loess tunnel,super dig fashion can be filled with concrete,Once the underbreak occurred exceeding clearance limit,cause the thickness of the secondary lining is insufficient,which have a certain effect on the project of the progress,quality,safety and cost,therefore,it is an important subject to predict the deformation of the tunnel lining in loess area.Based on the background of the loess tunnel project,through numerical simulation and field test of the deformaionn of surrounding rock of loess tunnel for statistical analysis,and The theoretical basis of a loess tunnel lining reserved deformation determined the reasonable and feasible suggestion value in this paper,which has certain reference value for loess highway tunnel,loess tunnel,loess tunnel construction,for the actual construction services.(1)In this paper,the theoretical basis for the prcdicction of the deformation of the lining of the loess tunnel is discussed.Before and after excavation,the displacement field of surrounding rock has a certain amount of change,and it should be chosen to study the stress section of the tunneel with the most unfavorable geological conditions.And the outer lining of loess tunnel reserved deformation of loess tunnel surrounding rock deformation should not be less,than the maximum amount of guarantee.In adverse conditions of loess tunnel still has enough lining reserved deformation.(2)In this paper,the influence of loess tunnel lining reserved deformation of main factors were classified,and combined with practical engineering background to set the scope of the main impact factors of changes and deformations in each main influencing factors are the single variable contrast effect of rules.The paper simulated using ABAQUS simulation software to calculate the two-dimensional model and the influence of different factors of surrounding rock deformation monitoring values.The variation law of the respective deformation is analyzed,and the size of the reserved deformation in the outer lining of the loess tunnel is predicted.(3)In view of the initial support,complex geological conditions and local water immersion,the deformation of surrounding rock of loess tunnel is greatly affected.According to the survey report and the design code of highway tunnels and railway tunnels,the use of spray anchor,and the steel frame and reinforced the supporting role in the conversion to jet concrete.This paper calls Cambridge-Clay elastoplastic model.On the loess tunnel the monitoring section pile,three-dimensional model of the surrounding rock deformation by simulation calculation and classification statistic and comparative analysis of surrounding rock deformation volume changes,the loess tunnel lining reserved deformation values of in-depth analysis.(4)In this paper,the surrounding rock deformation of a loess tunnel to carry out on-site monitoring.The calculation results and the field test results are analyzed,and the reason of the difference is analyzed.The rationality and reliability of the calculation results are evaluated by the monitoring results.Based on the effective results,the proposed value of the reserved deformation of the lining of a loess tunnel was predicted.