The Pile Negative Skin Friction Of Calculation & Research

With the development of the economy & technology, the buildings are getting taller and taller. So there are some long piles, super long piles. The influence of negative friction were little, but nou, they are getting more and more important. Now, in this situation, the problem is a hot spot in Geotechnique Engineering field.Because of the complex of pile-soil intercation, the study on this subject is far from clear so far. With the plentiful use of pile foundation, many problems were presented and theory lagged behind the practice, espescially in the aspect of pile negative skin friction.The inadequacy in understanding of pile skin friction bring some engineering problems after some pile pile foundation projects putting into use.This article introduced the various methods of calculating the pile negative skin friction in detail, and spdcifically analyzed the load transferring function.And then based on the analysis and summary for the load transferring function of the side and the top of the pile, the author puts up with a new method which uses double broken line model to calculate negative friction. Utilizing double broken line model to show relation between friction and displacement according to elastic or plastic condition that soil around or in the tip of the pile lies in. And the, the paper worked out the formla on the displacement of pile and soil, which lead to the negative friction, the position of neutral point and axel force of single pile.In the end, combined with the actual project, the author tests the precision of the method, which show that it's result of calculation is close to the measured and finite element simulation value. Therefore, the new model can be applied in the actual project.