Study On Soil Resistance Of Offshore Platform Pile Foundation During Pile Driving

As a result of large diameter super long steel piles and poor construction environment and complex geological conditions,pile installation is very difficult in the offshore platforms.Prediction of pile drivability is an essential link before pile construction,knowing the change of soil resistance of driving?SRD?well is firstly considered.Very few people pay attention to the change of soil resistance of driving caused by different piling process.In this paper,the problem is studied by the wave equation analysis method combined with the calculation of bearing capacity based on CPT method.First,the basic principle and method for solving the wave equation are described and the wave equation analysis software GRLWEAP is introduced briefly,the selection of parameters in the simulation of pile driving process is summarized.The soil resistance calculation based on CPT method commonly used at present are introduced,four kinds of methods establish the relationship between the CPT index and the side friction resistance and end resistance from the pile side resistance degradation and condition of pile,respectively.Secondly,the two records from different pile piling process were analyzed,combined with the wave equation analysis method,calculation of soil resistance based on CPT method and the American Petroleum Institute?API?standard,the influence of different pile driving process on soil resistance is analyzed from the plug formation conditions and Load cycle.The pile in the sand,even for the larger diameter?the test pile diameter is 2.438m?may also form the plug,which has a significant impact on the soil resistance to driving;the soil resistance of two piles and the blow counts showed a good correlation that means side resistance degradation is associated with the load cycle.Finally,the comparative analysis of the pile driving records and CPT results in a certain area,the empirical formula between h and E/q_c is derived in fine sand and silty sand and cohesive soil,according to the results from field CPT data estimate the piling energy,providing a basis for the selection of pile hammer.