Research On The Self-elevating Platform During Piles Drugging And Pulling

The soil structure of seabed is complex, the jack-up platform often encounters penetration and difficulty to pull up the leg during drugging and pulling operations. Therefore the paper built the CEL numerical model of the jack-up platform’s pile, and made static analysis by using the finite element software ABAQUS/Explicit. On the basis of this, a jack-up platform’s plugging and pulling analysis system was developed based on the theoretical calculation method. Finally, a jack-up wind power installation platform’s numerical modeling was made, and by making the simulation analysis based on the system, the analysis method’s guiding significance in engineering practice was proved. The main studies and research results are as follows:(1) On the basis of elastic-plastic theory, the paper studied the Mohr-coulomb model of soil constitutive model, Drucker-Prager model and von-Mises model. And the von-Mises model was chose to simulate the soil’s construction. Then the Eulerian- Lagrange coupling method and the soil’s failure mode are introduced. This makes preparation for the paper’s study.(2) Based on the CEL method, the grid file of the spudcan and soil was made by using the HYPERMESH software. Then after importing the file into ABAQUS software, we starts the simulation calculation of the model. The soil’s contact method chose the general contact calculation method, and the boundary condition was simulated by the strengthen dropping method. Then the soil’s initial ground stress was balanced by the keyword method. On the basis of this, the various influences on the resistance of plugging and pulling were analyzed. In addition, by analyzing the soil’s deformation diagram during plugging, we got that the soil experienced surface uplift, cavity formation, wall collapse and soil backflow four failure modes. And by analyzing the soil’s deformation during pile’s pulling, the soil’s flow mechanism in shallow and deep foundation was found.(3) The paper studied the calculation formula of classic plugging and pulling system. Based on the modeling method and the parameters’ influences, a jack-up platform plugging and pulling analysis system was developed. By inputting the soil’s parameters, plugging and pulling speed and other parameters, the system can quickly get the theoretical calculation results and the source files used for finite element analysis and calculation.(4) The physical jack-up platform’s plugging test was carried out based on a company’s wind power jack-up platform. And the test result showed that the final plugging depth was 7.3m. Then the numerical modeling was built by the jack-up platform plugging and pulling analysis system. And after inputting it to the finite element software ABAQUS, we got the simulation result. The result shows the plugging depth is 6.7m, and it is just a little smaller than 7.3m. In addition, the FEA result shows that the plugging resistance increases quickly in 1# layer and then slows down. When coming to the 2# layer, the resistance has a sudden change and begin to increase again in the 3# layer. The soil experienced surface uplift, cavity formation, wall collapse and soil backflow four failure modes.