Bearing Capacity Study Of Offshore Platform With Positive Pressure Spouted And Strengthened Pile Foundation By Numerical Computation Method

Offshore platform with positive pressure spouted and strengthened pilefoundation is one of the most significant items for the national 863 oceanology project,which is in the field of resource and environment technique. The advantages of thisplatform are that it has short pile foundation and needs less amount of steel, less timeof installation at sea, and that it can locate on the site where geological stratum ofseabed is in bad condition. Its emergence makes up the defects of the traditional jacketplatform and bucket pile platform. Thus the research and use of the platform is ofpractical and economic value. For studying the offshore platform with positivepressure spouted and strengthened pile foundation, the first important step is tocalculate the bearing capacity of foundation. This kind of platform is such a new typeone that there is no existing criterion to follow. Furthermore, the situation of thegroundwork is complicated due to the application of strengthening technique, so theconventional computation method of bearing capacity does not take its properties intoaccount. It is one of the key problems of investigation to choose the right andeffective calculation way of the platform bearing capacity. The paper aims at this purpose. Account for the characteristics of ground base,the concept of 'radial-layered' is put forward. And after comparing of all variouskinds of numerical methods, the 3D nonlinear finite element one and ANSYS programis chosen to compute the bearing capacity. Then based on the process of finite elementmethod and particularities of the problem, two most difficult questions are analyzed.One is the simulation of the ground base, and the other is how to deal with theinteraction of the soil and pile. Through the analysis of the interaction and theelasto-plastic constitutive model theory, the D-P model is selected and thesurface-to-surface contact element is established between the pile and soil. During theanalysis course, a series of problems about the process is solved, such as how to treatwith strengthened segment, the simulation of short pile, the failure criterion of theground base and how to ensure the value of bearing capacity. After solution, thefailure mechanism of the soil can be obtained via plotted result, and the security of theplatform is analyzed. The successful application of the analysis of the platformbearing capacity by ANSYS program proves that the finite element method for thisproblem is correct, practical, and effective. It is suitable for the analysis of this newtype of platform.