Pile negative study and calculation of friction
|School||Ocean University of China|
|Keywords||Negative skin friction Neutral point Settlement Mathematical model Control methods|
Pile as one of the most ancient forms of basic engineering, in the rapid development of modern stage. Pile foundation technology development and innovation of the construction process, the pile foundation has become the most widely used form the basis of project construction, pile foundation design and construction of the negative friction gradually being recognized. Given the important influence of negative skin friction of the pile foundation application process, the negative friction pile foundation has become the basis of a technical engineering field. The measured data at home and abroad show that the pile foundation stage negative friction may produce very large drop-down loading and sedimentation, especially uneven settlement on the basis of hazard. In engineering practice, consider the possible negative friction at the design stage to ensure the stability of the foundation during the construction phase, to take the necessary measures to avoid negative friction, using the stage of negative friction but also timely prevention. This paper described the determination of single pile the advantages and disadvantages of the various methods of negative friction resistance, and simplified model to determine the need for single pile of negative friction resistance affirmed. Negative frictional resistance of the mono pile causes negative friction friction resistance generating mechanism, to reduce the negative friction resistance method, building pile specification method of determining determine negative frictional resistance neutral point position, and on the load transfer basic differential equations derivation are discussed. This paper proposed based on the concept of load transfer, the new method a bilinear model to calculate the negative friction resistance. The the bilinear hardening models to represent the relationship between the relative displacement pile friction pile and soil, different elastic and plastic state, and is based on the pile side soil pile tip disabilities pile axial force and pile-soil relative displacement differential equations , using the continuous and the boundary conditions can be solved relative displacement according to the relative displacement, and then solution pile axial force and a negative frictional resistance. The same time, the relative displacement of zero can be drawn from the location of the neutral point. Multilayer soil, it is assumed that each layer of soil homogeneous, respectively, of each soil layer equations, simultaneous equations can be obtained equations of the whole soil, and then based on the continuous and boundary conditions of the soil layer interface, solvable negative friction and friction resistance. Negative the frictional drag simplified model formula combining two engineering examples of this paper to establish the single pile validate the results agree well with the measured values, has a certain practicality.