Reliability Analysis Of Tunnel Initial Support Based On Convergence Constraint Method

The development of underground space has become an inevitable trend of the development of the ground space under the increasingly tense environment.Tunnel as one of the most important way for underground space development and use,combined with the production and living of people increasingly close.The scientific evaluation of tunnel construction and the overall structure of the safety and reliability put forward higher requirements.The traditional probabilistic reliability is highly dependent on the probabilistic data of the parameters,the amount of calculation is huge,and the method of dealing with uncertainty is single.It is more and more difficult to judge the reliability of tunnel support structure.In recent years,the method of non-probabilistic reliability has been proposed,which can be used to determine the reliability of the structure by the calculation of the magnitude of uncertainty.It can effectively make up for the deficiency of the traditional method.In this paper,the non-probabilistic reliability method is used to analyze the reliability of the primary support of the single track tunnel at the speed of 350 km passenger dedicated line:(1)According to the "formation-structure" theory,the mixed orthogonal experimental model was established,and the finite element software is used to simulation of tunnel excavation and supporting.Based on the analysis of the formation characteristic curve and its influencing factors of the railway tunnel structure,the variation range of the formation characteristic curve is obtained.(2)Based on the principle of supporting effect,this paper analyzes the supporting limit curve and its influencing factors of the railway tunnel support structure,and obtains the change range of the support limit curve.(3)Based on the non-probabilistic reliability theory and the range of the curve of the formation and the limit curve,the maximum radial pressure of supporting structure is defined by structural resistance,and the final formation pressure is defined by action effect,Then,the function is established.Based on the convergence constraint method,the variation range of structural resistance and action effect is summed up and the non-probabilistic reliability index of tunnel initial support structure is obtained.The reliability analysis of the initial support structure is realized.