Study On The Collaborative Penetration Method Of Jack-up Drilling Platform Under Non-uniform Loading Conditions

With the development of marine oil and gas,the application of jack-up drilling platform is more and more extensive.In order to prevent punch-though accident effectively and maximize the protection of platform security,it has to be ensured that the jack-up drilling platform "stands firmly".Therefore,this paper adopts the method of model test and numerical simulation to study pile penetration.Finally,the CEL simulation results are combined with the actual engineering,which proves the applicability of the research method to the engineering practice.The following aspects of the work were carried out and the relevant conclusion were obtained.Firstly,under the condition of non-uniform load,the interaction between the different types of platform piles and the soil must be different,and this difference is bound to cause some influence on the pile penetration.Though the indoor full model test of pile penetration and theoretical analysis,the penetration curves of cylinder pile and truss pile are obtained respectively.The results show that the penetration resistance at the same depth increases as the penetration speed increases.In the depth of 10cm~18cm,the penetration curve difference between cylinder pile and truss pile is obvious.The cylinder pile curve is more smooth,while the truss pile curve is more steeper.Two key factors influencing the pile penetration process of the jack-up drilling platform are the type of pile and the soil properties.Aiming at the non-uniform load problem that caused by the complex nature of the soil,the numerical simulation method is used to study the effect of non-uniform load on the pile penetration process.The results show that for single layer soil,the penetration speed and the shear strength of soil are two important factors influencing the pile penetration process.The penetration speed has a great influence on the quality and efficiency of the calculation results.Through different penetration speed simulations,it is finally determined that 3mm/s is the most suitable penetration speed for the model.The soil strength mainly determines the degree of soil backflow during the penetration process.When Su<0.2kPa,the degree of soil backflow is the largest;when Su=5kPa,the soil backflow is partially;when Su>20kPa,there is almost no soil backflow.For complex soil,the effect of soil strength ratio and upper soil thickness is mainly considered.In the soil where the soft soil layer exists,the lower soil strength ratio is,the higher peak gets.The higher the thickness of the upper soil is,the higher peak gets.Secondly,the CEL method is used to simulate the whole pile penetration process for the jack-up drilling platform on the complex foundation.Through the comparison of the single penetration method and collaborative penetration method,it is found that single penetration method causes the surrounding soil disturbed heavily,and may lead to penetrate difficult.While the collaborative penetration method disturbs the surrounding soil slightly,and the penetration resistance of pile is stable.Finally,compared with the simulation results of the JU2000 E jack-up drilling platform and the theoretical results,and combined with the actual data,the results show that under the same amount of preload,the penetration depth is 9.5~10.3m in the collaborative method,the theoretical calculation depth is 9.8 m,and the actual depth for JU2000 E jack-up drilling platform is 10.5m,which is more closer to the result of the collaborative method.So it can prove that collaborative method is applicable for the engineering practice.