Research On Differential Settlement Control Technology Of Pile Foundation Used In Widenned Beam Bridge For Expressway Widenning

The technology to control the differential settlement between the new and old pile foundation is oneof the key technical problems in expressway widening and reconstruct engineering. However, whether inthe domestic or foreign, there has less research about the control technology. The design and constructiontechnology specification about bridge widening is brewing in China, which rarely involved in thefoundation part and mainly follows the theories and methods of geotechnical engineering. Combined withZheng Luo expressway widening engineering, based on theoretical analysis, numerical simulation, field testand theoretical prediction, the stress and deformation mechanism of the new and old pile foundation wereresearched and the technology to control the differential settlement was put forward. The main results wereshown as followings:1. Based on numerical simulation, the control standard of the differential settlement between the newand old pile foundation should be5mm was put forward, and the pore-forming process of new pilefoundation had a certain impact on the stress and deformation of old pile foundation was pointed out, thecorresponding engineering recommendations were put forward.2. According to the field test, the settlement deformation law changed with time of the new pile underconstruction load and structural weight was researched. And the differential settlement was about3mm,which verified the applicability of the differential settlement control standard.3. Used gray system theory to predict the settlement variable tendency of the pile foundation, andwhen compared with the measured results, the predictions were in good agreement with the measuredresults, which provided a scientific basis for the settlement control of similar widening bridge pilefoundation.4. Combined with the engineering characteristics and used elasticity theory, the stress characteristicsand the law of settlement under the interaction of the new and old pile foundation were researched, and atheoretical calculation formula to calculate differential settlement of pile foundation was put forward.5. The quite perfect design technology to control the widening pile foundation settlement was putforward, which filled the shortcomings of the existing beam bridge design technology specification inwidening engineering.The research results with strong pertinence and applicability solved the technical difficulties in control thedifferential settlement of pile foundation was used in widened beam bridge, which have an important theoryand project practical value and have broad application prospect.