Research On The Comprehensive Evaluation Method For The Risk Of Clay Clogging And Prevention Measures

The mud cake is a process which the shield cutting muck reassembles in the cutter head and the soil chamber to form a consolidated or semi-consolidated block.When the shield machine is digging in the clay strata,if the design of cutterhead and the treatment measures of construction are improper,the cutters on the cutterhead will gradually be stuck by the mud cake,and reduce the penetration of the cutter,even the opening of the cutterhead will be clogged,which will seriously reduce the shield tunneling efficiency and even cause construction safety problems.The study was achieved by literature investigation,theoretical analysis,laboratory test,and field parameter analysis.This thesis mainly studied the comprehensive evaluation method of the risk of clay clogging and prevention measures,analyzed the rules of mud cake formation and its influencing factors,systematically summarized the comprehensive evaluation method of the risk of clay clogging and prevention measures,and provide reference and reference for similar projects.The main research content and research results are as follows:(1)Based on the definition of normal adhesion and the theory of interface adhesion mechanism,the interface adhesion pull-out test equipment self-made by the team was improved to explore the influence of different consistency indexes,clay particle content,interface separation speed,interface conditions and other factors on the normal adhesion,systematically summarized a set of highly repeatable normal adhesion test methods.(2)Based on the definition of tangential adhesion and the theory of interface adhesion mechanism,the traditional direct shear test equipment was improved to explore the influence of different consistency indexes,clay particle content,metal material category and other factors on the tangential adhesion,systematically summarized a set of highly repeatable tangential adhesion test methods.(3)The results of the adhesion test and the existing engineering clogging potential diagram were combined to assess judge the clay clogging risk.And on this basis,the clay clogging risk was divided into 5 levels,and a new method for comprehensive evaluation of clay clogging risk was innovatively proposed.(4)Based on the shield tunnel construction between Liuxiandong Station and Baimang Station of Shenzhen Metro Line 13,compared and analyzed shield tunneling parameters to judge the development of mud cake.And introduced the concept of tunneling special energy to study the influence of shield tunneling pertinent configuration,soil conditioning program and other prevention measures on shield tunneling efficiency.