Experiment On Lateral Load Capacity Of Offshore Platform Pile Foundation Under Scour Conditions

Scour is a form of erosion that occurs around marine structures or structures incoastal environment，it is a very complicated process that involves the interactionbetween the flow, the erodible riverbed, and the bridge pier or abutment. In theprocess of operating，the pile legs of offshore platforms are buried in soil，at the sametime bearing the upper load, wind,wave and current load, pile legs can be destructedfor too large stress. When the scour process occurring, the pile boundary conditionsvaried, thus the stress and displacement redistribute along the pile, affect the safety ofthe offshore platforms. Meanwhile, the reduction of covering thickness of the soil andthe variation of the stress history after scouring process affect the pile foundationbearing capacity directly, the decline of pile bearing capacity can threat the safetyperformance of pile legs and superstructures. Due to the unfamiliar with the loadtransfer mechanism and bearing characteristics, the design calculation process can beunreasonable, lead to unsafety or uneconomic results. It is necessary to get to knowthe load transfer mechanism and variation of load bearing capacity before and afterscouring process, so as to take corresponding measures to enhance the offshoreplatforms safety.In the practical engineering, the static load test is a reliable method to determinethe pile lateral bearing capacity. The author devised laboratory model experimentsunder different scour depths, and introduced the aim of the model test, as well as thescheme design, dial indicator and strain gauges are used to measure the lateraldeflection and the strain along the pile. After that, the finite difference softwareFLAC3Dis used to simulate the test model, and comparing the results between them,and then correct the model parameters according to the model test results. Based onthe revised numerical model, the author discussed the scour angel, the pile head fixedmethod, and different scouring forms, put forward some conclusions that arebeneficial to practical engineering.