Study On Mechanical Characteristics For Pile Foundation During The Construction Of Viaduct And The Road Under Bridgein Soft Soil Area

With the sustained development of economy,the scale of expressway construction in China is expanding,especially in the southeastern coastal areas where the economy is more developed,there is a large range of soft soil in this area,and the engineering properties are poor.During the construction of the pile foundation and the road under the bridge,the backfill soil and the large construction load on the pile group foundation will cause the consolidation settlement of the soil around the pile foundation,and then produce negative skin friction,which will have a negative impact on the mechanical characteristics of the pile foundation.Based on the Wenzhou section of Ningbo-Taizhou-Wenzhou Expressway,this paper firstly designed the test scheme according to the actual situation of the project,and selected different types of test piles for field test.Secondly,during the construction of bored piles,axial force sensors are embedded in steel cages to test the mechanical characteristics of pile group foundation.And the mechanical characteristics and their changing rules of pile group foundation in different construction stages of viaducts and under-bridge roads were analyzed.Finally,a three-dimensional finite element model considering Biot consolidation theory and R_inter's parameters of pile-soil interface is established by using PLAXIS 3D finite element analysis program.The mechanical characteristics and settlement deformation law of pile groups under embankment load were studied.The research results in this paper can provide some reference for the design and construction of super long pile groups in soft soil area.