Study On Tunnel Collapse Law And Distribution Characteristics Of Surrounding Rock Pressure Based On Statistical Analysis

With the development of our city,the construction of underground space,city traffic tunnel(railway tunnel,highway tunnel)construction has achieved rapid development,which in the construction of highway tunnel,railway tunnel and subway tunnel,the geological environment becomes more and more comlex.In order to ensure the safety of tunnel design,it is necessary to make a correct judgment on the size and nature of the surrounding rock pressure.This paper starts from the tunnel collapse,through the summary and statistical analysis of a large number of actual landslide cases,we obtain the main influencing factors of tunnel collapse and distribution regularity of tunnel collapse height,on this basis,the calculation formulas of surrounding rock pressure(Broken-rock pressure)of highway tunnel is obtained by fitting,and then by using Monte Carlo simulation method,the distribution characteristics of the surrounding rock pressure was studied.The main research conclusions are as follows:(1)Based on the statistical analysis of a large number of tunnel collapse,three types of tunnel collapse were obtained,its including roof fallen,arch collapse and special-shaped collapse.The main influencing factors of tunnel collapse in three categories:engineering geological conditions(rock grade,groundwater,bias),basic facts of tunnel(buried depth of tunnel,the span of tunnel and the ratio of height and span of tunel)and human factors(blasting vibration,design factors,construction factors).The influence of various factors on tunnel collapse were analysis by using the concept of relative collapse degree.(2)The Fuzzy Comprehensive Evaluation and Analytic Hierarchy Process is used to calculate the influence weight of each factor on the tunnel collapse.On the basis of this model,the risk analysis model of tunnel collapse is established,which is used to evaluate the grade of tunnel collapse risk.(3)The calculation method of surrounding rock pressure and problems were summarized.Based on the analysis of highway tunnel collapse height statistics,the calculation formula of surrounding rock pressure were obtained,which applied to the rock grad of ? and ?,and deep buried highway tunnel.Compared with thepoTogbaKOHOB's pressure arch show that the formula have some applicability.(4)Through the investigation and study,the structure of the joint angle,joint spacing,cohesion and friction angle of structural plane and gravity of rockmass were obtained,on the basis of this,the distribution characteristics of the surrounding rock pressure was studied by using Monte Carlo simulation method.The results show that the pressure of the surrounding rock obeys normal distribution.which is consistent with the actual monitoring results.