The Determination Of Ultimate Capacity Of Plate Anchor In Clay Based On Numerical Method

The ultimate capacity of anchor is an important index to describe its working function. The method to determine the ultimate capacity of anchor is the precondition of obtaining a reliable result and conducting comparison. However, a unified method is yet to be reached. By systematic analysis, this paper recommend the maximum load during the complete pullout process of anchor as the ultimate capacity. Based on the large deformation finite element analysis, the ultimate capacity of anchor is studied.Firstly, two typical load-displacement curves both in test and numerical study are analyzed. In the test, with the growing of displacement, the resisting force grew at the beginning and then decreased. This phenomenon could not be observed in numerical study based on small deformation analysis. Therefore, large deformation finite element method is more proper to model the complete pullout process of anchor. There are mainly three kinds of large deformation finite element method: Rezoned Mesh, ALE and CEL. Compared with the other two methods, the CEL method is more appropriate to simulate the extremely large deformation problems and more convenient in applications.Secondly, ten methods to determine the ultimate capacity of anchor are applied to quantitative analysis on two typical load-displacement curves derived from numerical analysis. The deficiency of these methods are: uncertain, not unique and subjective. Based on the analysis of the curve from test, the maximum load method is recommended to determine the ultimate capacity of anchor.Thirdly, the large deformation finite element analysis method based on CEL is adopted to modeled the pullout process of square anchor in uniform clay, the square anchor in linear clay and the circular anchor in linear clay. Through comparison with model tests, the CEL method is verified. When conducting analysis in linear clay, a user-defined subroutine is used so that the distribution of strength could be updated with the flow of soil. By directly comparing the load-displacement curves in the complete pullout process, the remarkable ability of CEL method to model the behavior of anchor with large displacement is embodied.Finally, together with the large deformation finite element analysis method, the maximum load method is applied to study the ultimate capacity of anchors with various shapes in both uniform and linear soil. It can be seen that with the growing of aspect ratio, the ultimate capacity of rectangular anchors is decreased and the critical embedment depth is increased. The ultimate capacity of anchor in linear clay is higher than in uniform clay. Rectangular anchor with aspect ratio higher than 6 can be regarded as strip anchor. The ultimate capacity of circular anchor is higher than square anchor.