Experimental study on negative skin friction resistance on piles in collapsible loess area

As it has long been recognized that negative skin friction resistance most possibly exists on piles when the soil around pile move downward relative to the pile,especially in collapsible loess in Northwest China.Once it is disposed improperly,the pile foundation will lose its efficacy.So to determine the distribution law of the negative skin friction is of important practical significance in engineering.Concerning the many factors,which always influence the disiribution and numerical value of negative skin friction, the field immersion test under static load is still the most effective method in measuring the negative friction.Combined with the experiment of foundation disposal of a power plant in Shanxi Province,the distribution law of negative friction and the influence of collapsible deformation on the bearing capacity of piles are analyzed;and some beneficial results are obtained through these analysis, that will provide instruction for the engineering application.