Analysis Of Cumulative Displacement Of Monopile For OWT And Highway Subgrade With ABAQUS

A monopile for offshore wind turbine (OWT) will be subjected to cyclic loading its service life, from wind, wave and storm surge and so on. The OWT will not work properly when the angle of rotation of monopile foundation exceeds0.5°. Currently, the studies mainly focus on the lateral displacement of monopile under long-term cyclic loading by means of theoretical analysis and experiment. However, the lateral deformation of monopile in extreme conditions is researched very little. The numerical modeling is an important mean used to analyze the lateral deformation of monopile under short-term cyclic lateral loading. It avoids the disadvantages, namely flexible pile in laboratory model experiments, high price in field test and less factors considered in p-y curve method. The numerical modeling is adopted by more and more researchers. The main problem in the numerical simulation is to employ an appropriate constitutive model. The pre-existing PZ model is showed through explicit expression of the bounding surface model. It has definite formulas of elastic strain, plastic strain, elastic modulus, plastic modulus, loading direction, plastic flow direction, and considers the differences between loading and unloading, stress history, degree of density, accumulation of plastic strain and so on. It is fit for dynamic analysis of sand. In this paper, based on platform of ABAQUS and its secondary development, the PZ model using FORTRAN language is compiled into UMAT subroutine and applied into the analysis of lateral displacement of monopile under short-term cyclic lateral loading. This paper analyzes the influence of number of cycles, embedded depth, pile diameter, loading frequency, loading amplitude and accumulation of pore water pressure on the lateral displacement, and draws some conclusions.In addition, highway, railway, airport runway will be subjected to long-term traffic loads which leads to a cumulative settlement of subsoil. The large settlement will affect the normal operation of the road. In light of calculated cost and engineering practicability, this paper applies the method combining the empirical formulas and layer-wise summation method. But in soil deviator stress calculation, numerical simulation with ABAQUS is used. For the Yangtze River Delta area, the long-term traffic loading induces the degradation of the strength and stiffness and the accumulation of the excess pore water pressure in saturated soft clay, which is responsible for the plastic deformation. Moreover, it is combined with layer-wise summation method to estimate the permanent settlement of road on saturated soft clay subsoil.