| The jacked pile technology is widely used because of its small pollution,light vibration,high automation level,strong controllability and other advantages,which is specially and widely used in areas where population density is relatively intensive or there are vibration control requirements of surrounding buildings.In this paper,the characteristic of interfacial stress is studied by the pile-soil interface shear test and the influence mechanism of factors from interface roughness to soil water content is analyzed.Combined the measured data in construction and results of finite element numerical simulation,the sinking resistance and relative law of the carrying capacity are summarized,which provide some references to the engineering design,construction,testing of the actual pile foundation.The main contents of this paper are as follows:(1)The interfacial shear test was conducted in silty clay from field sites and prefabricated concrete slabs by using the pile-soil interface shearing instrument made by Qingdao Technological University.The effects of different factors such as the roughness of concrete slab,soil moisture content and shear rate under different normal stress conditions were comprehensively analyzed.Drawing the interface resistance-shear displacement curve and linearly fitting the interfacial resistance under different normal stress,in order to find the variation law of the relevant linear parameters.(2)Innovatively combined the ordinary interface shear test and the silicon piezoresistive sensor,real time monitoring the earth pressure and pore water pressure in the pile-soil interface,exploring the variation law of pore water pressure and normal stress and it’s influence on the force of the pile-soil interface.The methods of expansion head installation in pore-water pressure sensor and non-destructive storage of data wire are proposed creatively,which provide technical support for the installation of silicon piezoresistive sensor in subsequent field test.(3)Considering the excess pore water pressure effect caused by pile driving in cohesive soil,a new concept of "interfacial resistance" is put forward.The interfacial resistance is composed of adhesion and friction between the cohesive soil and the concrete slab.The adhesion is the cohesion between the cohesive soil and the concrete slab,the frictional force is the product of the interface normal earth pressure reducig the pore water pressure and the interfacial friction coefficient.(4)Based on the research achievements both at home and abroad,the pile driving mechanism of static pressure pile is described and the characteristics of pile driving under different geological conditions are analyzed.The piles resistance in Liao Cheng where the field test was conducted was measured and the relationship curve between pile resistance and penetrating depth was drawn.The change rule of piling resistance in Liao Cheng was summarized,which can provide technical guidance for practical engineering.(5)The ABAQUS software is used in the simulation study of jacked pile continuous penetration process form a engineering in Liao Cheng.During the process,controlling the displacement boundary condition makes it possible to displacement penetration method.The Mohr-Coulomb model is adopted and operate it with the asymmetric solver,thus leading to a better convergence result.The radial and normal stresses of different depths are analyzed and the axial forces of the model are compared with the measured data by the method of section definition. |
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