Study On Impact Partition Of Tunnel Construction Adjacent To Bridge Friction Pile Foundation

This study was based on the National Key Research and Development Program of China,whose name is “Key technologies and demonstration for structural risk monitoring and safety control of existing urban road / bridge / tunnel adjacent to typical building works”.The aim of this study was to research the disturbance mechanism and safety risk partition standard of new tunnel adjacent to existing bridge pile foundation and improve the operation and maintenance of security risk prevention ability and technology level of typical traffic infrastructure in Chinese cities.The main content of this study included:(1)Based on catastrophe theory,we used the safety factor based on material strength reserve as the criterion for determining the stability of stratum,then found that the regularity of the stability of rock mass with tunnel depth.Meanwhile,we applied the strength reduction method to the stability of pile foundation,and the results showed effective.(2)Considering the overall stability of the project,we used the safety factor as the evaluation index of the impact degrees,and proposed the partition standards of tunnel adjacent to pile foundation: the strong impact zone was defined that the overall safety factor of stratum is less than 1,the non-impact zone was defined that the safety factor of the adjacent system is equal to the single tunnel,the weak impact zone was defined that the zone where impact degree is between strong impact and no impact.(3)We calculated the overall stability of stratum when tunnel construction adjacent to pile foundation in different location relations,then obtained spatial distribution of overall safety factor of adjacent works.Meanwhile,we analyzed the change law through comparing the different pile foundation sizes and the different stratum parameters,and confirmed the feasibility of the zoning method based on strength reduction method.(4)According to the distribution regularity of the overall safety factor of the tunnel adjacent to pile foundation,we combined the partition standards,and obtained the impact zone of tunnel adjacent to pile foundation consisting of strong impact area,weak impact area 1,weak impact zone 2 and non-impact area.Meanwhile,we used polynomial fitting approximation method to find out the corresponding expression of the boundary lines of each impact zone.