Study on Mechanical Behavior of Tunnel Construction Considering Age Characteristics of Sprayed Concrete
As an important part of the primary support structure system,sprayed concrete has a significant influence on the deformation and stress redistribution of surrounding rock due to the time effect of its initial me-chanical parameters.At present,most of the relevant literatures only consider the final value parameters of sprayed concrete and ignore the influence of the physical property index changing with time during the initial strength growth process.The numerical simulation results fail to fully reflect the mechanical behavior and sup-port effect of the primary support structure during tunnel construction.The mechanical parameters of C25 sprayed concrete under different typical age conditions were measured by laboratory tests,and the formula of the evolution of each parameter with time was fitted.Python script was used to realize the cyclic assignment of sprayed concrete support parameters in finite difference software.The influence of sprayed concrete age charac-teristics on surrounding rock displacement field,support structure displacement and stress state under different tunnel buried depths of Ⅳ and Ⅴ surrounding rocks was mainly studied.The numerical results show that in deep buried weak surrounding rock,the design of tunnel support structure should pay enough attention to the influence of age characteristics of sprayed concrete mechanical parameters.At the same time,it is suggested that early strength sprayed concrete should be used under complex engineering geological conditions to reduce the ad-verse effects of its time-varying.
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