Study On The Negative Skin Friction Of Piles In Geogrid-Reinforced And Pile-Supported Embankment Of Soft Ground In Chaoshan Railway Station

Geogrid-reinforced and pile-supported embankment has been widely used in treatment of soft ground in the world for its perfect treatment, easy construction and highly cost-effective. In this dissertation, based on the prototype of treatment engineering for wide deep soft soil of ChaoShan station of Xiamen-Shenzhen railway, using the soft of FLAC3D, the characteristics of geogrid-reinforced and pile-supported embankment with various parameters, such as pile spacing, pile cap dimensions, elastic modulus of cushion and angle of internal friction of embankment fill, have been simulated. The contents are showed as follows:(1) According to the simulation results, correlation curves were drawn and conclusions were shown as follows:①Pile-soil relative displacement is the most direct factor influencing magnitude of negative skin friction and position of neutral point.②As increment of embankment height, the position of neutral point decreases, and the negative skin friction increases.③As increment of pile spacing, the position of neutral point decreases, and the negative skin friction increases.④As increment of width of pile cap, the position of neutral point rises, and the negative skin friction decreases.⑤As increment of elastic smodulus of cushion, the position of neutral point rises, and the negative skin friction decreases.⑥As increment of internal friction angle of embankment fill, the position of neutral point rises, and the negative skin friction decreases.⑦As increment of length of pile, the position of neutral point decreases while the negative skin friction rises, and length of pile has a significant influence on neutral point and negative skin friction.(2)The negative skin friction has adverse effect on geogrid-reinforced and pile-supported embankment because it leads the settlement of pile to rise, leads bearing capacity of pile to reduce, and leads performance of geogrid-reinforced pile-supported embankment to reduce. The adverse effects of negative skin friction should be adequately considered in order to reduce hazards in the process of design. The influence on geogrid-reinforced and pile-supported embankment of main factors, such as pile spacing, width of pile cap, height of embankment, length of pile and property of underlying should be comprehensively considered.