Study On Assessment Of Operation Adaptability Jack Up Platform In The Ice Zone

As a typical flexible anti-ice structure,jack-up rigs are widely used in offshore oil exploration and mining.In recent years,the development of marine resources in the international polar regions has gradually warmed up,and the development of offshore oil in the ice zone has become a new hot spot.How to make safe operation of the jack-up drilling platform in the ice zone has become an important issue of the offshore oil industry.At present,the research on the safety assessment of jack-up rigs with ice load is insufficient,especially the lack of systematic research on the ice characteristics of truss rigs,which greatly limits its use in ice areas.In order to realize the efficient and safe operation of the truss type jack-up platform in the ice area and ensure the safety and reliability of the platform during service,it is necessary to evaluate the operational adaptability of the ice truss type jack-up platform.Based on the self-elevating drilling platform brand engineering(type II)of the research project of China Ministry of Industry and Information Technology: the platform structure optimization design and operational adaptability analysis research,the system carries out the adaptive evaluation of the truss type jack-up drilling platform ice area operation.Technical research.The following important research progress has been made:(1)Study on ice load characteristics of self-elevating platform truss pile legsThe physical model test of the interaction between the truss leg and the ice platoon is carried out,the collision mechanism between the pile leg and the ice platoon is revealed,the failure mode of the ice platoon is analyzed,and the variation law of the static ice force value with different ice attack angles and different water levels is discussed.The section coefficient and the angle coefficient are used to correct the sea ice specification ice load formula.The calculated ice force value is similar to the experimental value.It is considered that the extreme static ice force of the self-lifting platform truss leg can be evaluated.The viscoplastic constitutive model was used to simulate the characteristics of sea ice,and the process of interaction between flat ice and overlapping ice and truss legs was simulated.The flat ice with high probability of large ice force in the drift ice was selected as the design load for the jackup platform.Security analysis.(2)Research on adaptive evaluation method of self-elevating platform ice area operationThe adaptability evaluation method of the truss type jack-up platform ice area operation is formulated.The adaptability evaluation is mainly carried out from three aspects: pile foundation stability,pile leg safety and personnel comfort.The pile foundation stability is evaluated by the dynamic strain effect of the soil.Based on the analysis of elastoplastic mechanics,the safety evaluation of the self-lifting platform truss pile legs is carried out,and the adaptability range of the pile legs is divided into three states: normal operation,dangerous operation and inoperable operation,and the failure mode of the truss type pile legs is revealed.Explore the intrinsic relationship between ultimate bearing capacity and failure mode.Through the environmental parameter ice thickness,the safety of the self-lifting platform legs is quantitatively evaluated;the self-lifting platform leg safety window is drawn;the annoyance rate model is quoted,and the self-elevating platform staff comfort is evaluated by the acceleration rms value.