Research On Bearing Characteristic And Consolidation Settlement Of Marine Soft Clay Rigid Pile Composite Ground Based On CPTU

Marine soft soil is an unfavorable foundation soil widely developed in eastern China’s coastal areas,which is a difficult problem in engineering construction.The traditional geotechnical investigation technology has some limitations in the marine soft soil area.The in situ testing technology is convenient and quick and accurate in testing,which is widely used in the exploration and appraisal of soft soil foundation.Piezocone penetration test(CPTU)has the advantages of large test data volume,high stability and wide range of applications,and can obtain the seepage consolidation parameters of soft soil.It is a very ideal method in situ exploration in marine soft soil area.Rigid pile composite foundation has the advantages of post-construction settlement and inhomogeneous settlement,large treatment depth and high bearing capacity of composite foundation.It has been applied in various soft foundation treatment projects.However,there are few practical experiences in deep marine soft soil areas lack of corresponding theoretical research and calculation.Under this background,the multi-functional CPTU test system was used.Based on the project of Construction Industrialization Research and Production Base in Lianjiang of Fujian Province,the marine soft soil project in Lianjiang area of Fujian Province was studied by field test,theoretical analysis and numerical simulation.The bearing capacity and deformation characteristics of the geological foundation and the rigid pile composite foundation were systematically studied.The main contents and achievements are as follows:(1)Through the on-site CPTU test,Geosuite software,which interprets CPTU data,was used to interpret the test data and CPTU method was used to classify soil and stratification of the site.The physical and mechanical parameters of the soil in the project area were calculated,And compared with the indoor test results to prove the applicability of CPTU technology in the deep marine soft soil area.Through a series of experiments and calculations,the paper summarizes a series of experiences of foundation soil and provides some guidance for the local engineering construction.(2)The vertical bearing capacity of pile foundation is theoretically predicted by CPTU method.The finite element model of the rigid pile composite foundation is established and the static load test is simulated.The vertical ultimate bearing capacity results of the composite foundation pile derived from the three methods of theoretical formula calculation,numerical simulation and on-site static load test are comparatively analyzed The destruction form of composite foundation is discussed.On this basis,the eigenvalues of bearing capacity of composite foundation pile are deeply studied and analyzed,and the interaction mechanism between pile and soil and the working characteristics under the design load are studied.(3)Based on the Terzaghi one-dimensional consolidation theory and the consolidation equation of sand well,the one-dimensional two-layer consolidation equation of rigid-pile composite foundation is derived under certain conditions.According to the consolidation equation,The knot factor.Secondly,the application and parameter sensitivity of the modified Cambridge model to the numerical simulation of ground consolidation are discussed.The consolidation deformation of the single pile composite foundation is studied by means of numerical simulation.