| Most mainline of theChangchun two horizontal and two vertical expressway is viaduct,bridge superstructure is mainly of cast-in-place continuous box beam, substructure is composed of pile columnar pier and cast-in-site bored pile foundation.In the construction of Changchun Expressway Viaduct Project, the engineering problems that occur in the construction of the bored piles, the construction progress is slow,and the design of the pile diameter is too large. In order to solve this problem, according to the Changchun city expressway engineering geotechnical engineering detailed survey report,borehole histogram and Main Road Viaduct Pile Foundation Design of statistical data, to bored pile design and actual construction technical data based, through a comprehensive analysis of the identified projects with representative SK19-21 section pile and SK16-18 segment piled as the research object, using ANSYS software respectively, Changchun Expressway elevated section of SK19~21 two different pile foundation scheme and SK16-18 section of two different pile foundation scheme of finite element numerical simulation.A three dimensional finite element model of SK19-21 segment was established with 5 pilesand 8 piles. In the same time,Aanother three dimensional finite element model of SK16-18 segment was established with 6 piles and 8 piles. Considering the elastoplastic property of soil and the contact characteristics between soil and soil, the finite element analysis of the two groups was carried out.The influence of the parameters on the working behavior of the pile foundation is analyzed, the parameters of S, L, etc.Secondly, the optimal design method of pile diameter is pushed down to the objective function.By using this method, the two groups of different pile foundation schemes are compared and analyzed.Under the premise of satisfying the bearing capacity, 8 piles plan is better than 5piles plan in SK19~21 segment and 8 piles plan is better than 6 piles plan in SK16-18 segment.Finally, the efficiency coefficient method of single pile vertical bearing capacity is put forward, and it is applied to this project, the conclusion is correct and simple.Suggestion of reasonable pile diameter for viaduct in Changchun can save the construction time of about 10%, reduce the pile foundation project cost of about 20%, with obvious social and economic benefits. The efficiency coefficient of vertical bearing capacityof single pile is more reasonable for the scheme comparison of pile foundations.The research of this project provides a good reference for the schemecomparison ofbored piles and determination of reasonable pile diameter of bridge pile foundation in Changchun City. |
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