Study On Disease Mechanism And Evaluation Method Of Tunnel Engineering Lining

In recent years,the scale and quantity of China's transportation engineering construction has shown an increasing trend in general.According to the survey,most roads and railway tunnels have lining structure diseases.These diseases will cause great harm to traffic quality,which will not only affect the safety of vehicles and pedestrians in tunnels,but also shorten the service life of tunnels.Therefore,it is an urgent problem to be solved by taking a comprehensive health diagnosis of tunnel diseases,estimating the cause of the disease,quantitatively evaluating the health of the tunnel structure,and promptly proposing effective and reasonable maintenance means to delay the further deterioration of tunnel diseases.Through theoretical analysis,numerical calculation and modern mathematical methods,this paper studies the mechanism and evaluation method of tunnel engineering lining disease.The main research contents are:(1)Based on the analysis of the main damage patterns of the tunnel structure,the series of disease indicators affecting the health status of the tunnel are determined,and the tunnel index system is further established by using the analytic hierarchy process;the four-level discriminant method of the special inspection results of highway tunnels in China is introduced as the division of the tunnel health level.Based on the method,a tunnel grade grading scheme is established.On the basis of comprehensively comparing the domestic and international diagnostic index criteria,the leakage water,lining cracks,lining voids,lining material degradation,lining delamination and spalling,lining are comprehensively studied.Judging criteria for the characteristics of six diseases of deformation,movement and settlement.(2)Based on the stratum-structure calculation model including contact algorithm and stress release,the mechanism and influence law of three typical diseases of tunnel lining strength degradation,lining back cavity and lining thickness reduction are studied,and the safety factor of different diseases is adopted.The structure is subjected to comparative analysis of axial force,shear force and bending moment,and the degree of influence and influence range of the disease effect on structural safety is obtained,which lays a solid foundation for the follow-up research work.(3)Considering the diversity,real-time and uncertainty of tunnel diseases,the subjective weighting method based on product scale,and the entropy weight method based on entropy and maximum entropy principle as an objective weighting method,propose an improved method.The subjective and objective comprehensive weight analysis method-the comprehensive weighting method.The method is applied to the fuzzy comprehensive evaluation.Through the tunnel disease case test,the evaluation results are compared with the evaluation results determined by the product scale method and the entropy weight method alone.When the difference between the subjective weight and the objective weight diagnosis result is large,the method can play a numerical optimization role,making the diagnosis result more inclined to the tunnel real situation.(4)Combining the crack image processing technology,the fractal theory is introduced into the evaluation of tunnel lining cracks.Through the fractal analysis of cracks with different characteristic indexes,the variation of crack fractal dimension with crack length,equivalent width and number of cracks is studied.Regularity,the results show that the crack disease has statistical self-similarity.The box dimension method and fuzzy mathematics method are used to calculate the fractal dimension and health value of the crack disease respectively.The corresponding relationship between the two is used to establish a four-level crack disease evaluation method based on fractal dimension,and corresponding levels of different disease levels are given.The range of fractal dimensions.The classification method is applied to the engineering case analysis.The results show that the fracture disease evaluation results based on fractal dimension and health value are basically consistent,indicating that the tunnel fracture disease evaluation method based on fractal dimension has good engineering applicability.Figure 23 Table 48 Reference 108.