Study On Bearing Behavior Of Rock-socketed Piles In Coastal Areas Of Thick Fluid-plastic Soft Soil

Rock-socketed pile is a good foundation reinforcement form,It has the advantages of high bearing capacity,small settlement,good seismic performance and small impact of pile group effect on pile group bearing capacity.It is widely used in the Greater Bay Area.However,because the soft soil layer in this area is thick and high water content.In the construction process of rock-socketed pile,it is easy to produce various defects,among which Reduced-diameter is one of the main defects.The reduceddiameter pile directly affects the bearing capacity of rock-socketed pile and threatens the safety of the project.Therefore,it is necessary to carry out detailed research on the formation and bearing characteristics of reduced diameter pile.In this paper,the Fluid-plastic soft soil,which is one of the important factors to produce the reduced-diameter pile,is tested systematically at the macro and micro level.Firstly,the physical and mechanical properties of soft soil are mastered through basic geotechnical tests.Then,the material composition of soft soil is analyzed by X-ray diffraction technology,and the causes of macroscopic engineering properties are explored from the microscopic point of view.Finally,the horizontal and vertical microstructures of soft soil under different consolidation pressures were compared and analyzed by scanning electron microscope,and Six microscopic parameters were selected for quantitative characterization,so as to reveal the microscopic mechanism of fluid-plastic soft soil macro deformation.Secondly,according to the measured data of three rock-socketed piles,On the one hand,it is used to invert the reliability of pile-soil interface parameters,and on the other hand,it verifies the rationality of using PLAXIS 3D finite element software to carry out solid modeling of rock-socketed pile in this paper.on this basis,The bearing characteristics of rock-socketed piles in this area were systematically studied from the aspects of load settlement of each stratified interface,pile axial force,pile lateral friction resistance,pile tip resistance and bearing behavior.At the same time,combined with the site geological conditions,emphatically studied the influence of different soft soil thickness on bearing characteristics of rock-socketed pile.Finally,based on the understanding of the engineering properties of convectionplastic soft soil above,Set out from the Angle of construction technology to summarize Cause of reduced-diameter pile.Create a entity model of reduced-diameter pile,select respectively three influencing factors of shrinkage position,shrinkage degree and shrinkage length,and the quantitative analysis is made from three perspectives of bearing characteristics,stress field and displacement field and safety of the pile.In terms of security,Security determination assumptions based on this paper,presented the function relation between pile tip reduction coefficient and influencing factors.It provides the basis of analysis and judgment for engineering reuse of reduced diameter pile.The paper has 88 Figures,18 Tables and 108 references.