The Negative Skin Friction Characterristics And Research On Design Method Of Rock-Socketed Piles In Deep Recent Filling Soil Areas

With the large-scale development of Western China and infrastructure, there are many thick filling engineering projects. The most obvious feature of the thick filling engineering projects is high-specific-weight fillings that bring great compression settlement and foundation settlement. Pile in deep recent filling soil areas (DRFSA) will get a considerable negative skin friction, and the study with it has important practical significance.On the basis of the actual monitoring of the fields in Juteng international project in Neijiang, analysis negative skin friction (NSF) on the behavior of pile in DRFSA with combined theoretical analysis and numerical simulation.(1) Combined field tests with monitoring data, summarized the regular pattern with the time of the NSF characteristics with the pile received loads on top in the soil consolidation and deformation on the construction process and after completion of construction of the main structure. Then analyze the effects and regularities of the NSF under different factors.(2) Through the summary and analysis of single pile load transfer mechanism, NSF characteristics and basic theory of rock-socket piles, discussed the using scope and main problems of various norms on the NSF calculation and the rock-socket pile designing. Analysis and comparison of the calculated results as well as the field-test results verity the applicability of method for determining NSF under thick filling conditions in norms. Based on the conclusion of designing methods of norms, integrated the designing ideas of some foreign scholars on rock-socket piles and then put forward the improved design methods, design ideas, procedures and significance of parameters which considering the filling NSF, bearing capacity, settlement and other factors.(3) Analyze the influences of the neutral point, down-drag due to NSF, sedimentation on the position of the pile load, pile-soil modulus ratio, pile-soil friction coefficient and other factors with the use of ABAQUS finite element software, and also get the NSF characteristics of rock-socket pile in DRFSA.