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本文介绍了沉垫自升式平台排除沉垫永久性压载水,以减少吃水,才能进入浅水海域作业。通过在ZenStab软件中对沉垫自升式平台建模计算的方式,分析了其在25.8m/s风速下的完整稳性和破舱稳性,验证了排除沉垫压载水后的平台进入浅水海域作业的可行性。 相似文献
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自升式平台在拖航移位时,大部分桩腿位于平台上部,受风面积很大,在平台拖航移位过程中会受到很大的风倾力矩,有可能导致平台倾覆,故需对平台拖航进行稳性分析研究,确保平台拖航安全。本文提出了一种利用Moses软件对FX自升式平台进行完整稳性和破舱稳性分析的方法,该方法简单实用,计算效率高。使用该方法分析平台稳性,得出如下结论:自升式平台的吃水越大,其稳性越差;FX平台完整稳性的危险风向角为15度,破舱稳性的危险风向角为120度,最危险的破舱组合为压载舱2和4。论文成果可为类似平台的稳性分析提供参考,为平台的安全拖航提供技术支持。 相似文献
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以上海中远船务工程有限公司研发的一型正方形自升式生产平台为依托,依照美国船级社MODU规范的要求,分析了平台的完整稳性、破损稳性和剩余稳性,总结了该类平台稳性分析的方法及过程.对方形自升式平台稳性计算具有一定的参考意义. 相似文献
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箱型沉垫地基吸附力作用机理及影响因素 总被引:1,自引:0,他引:1
《舰船科学技术》2014,(5):65-71
坐底式平台与自升式平台在浅海油气开发中得到广泛应用。坐底式平台与沉垫式桩脚自升式平台的沉垫在坐底时与海底地基相互作用,产生地基吸附力,而极限地基吸附力的作用机理及其影响因素一直是计算分析的难点。通过土体应力场与渗流场耦合场的非线性分析,提出大尺度箱形沉垫与海底地基吸附力的作用机理及计算方法,并对土体参数、上拔速度和沉垫底部开孔等研究,明确地基吸附力的影响因素,提出减小地基吸附力的可行方案。 相似文献
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David B. Lorenz 《Marine Structures》1989,2(3-5):385-401
There are several important structural design parameters in the analysis of a mat type structure for a jackup mobile offshore drilling unit. These consist of dimensions for the mat, soil foundation types, and structural loads. Methods for determining the proper dimension of the mat structure, modeling the structure and its loading cases, modeling the soil conditions and a method for identifying critical load cases for each element and load case is presented. By using a database approach for the finite element output for all of the various loading cases, a rational approach is presented which solves the problem of sorting and analyzing all of the elements and load cases, ensuring that all are included and none of the critical cases are missed. 相似文献
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Increasing attention has been focussed in the North Sea and elsewhere on the quantification of the risks of working in a hazardous enviroment: the offshore world. The perception of risk with respect to mobile rigs has often been vague and uninformed. This paper attempts to put the risks with respect to jackup rigs into perspective by quantifying them and comparing them to other risks.
This paper contains a few risk comparisons with fixed platforms, semi-submersibles, and drillships. Historical casualties are used in an example to show how a change intended to make an operation safer, may result in the opposite effect.
Examining risks from losses due to environmental overload, the conclusion is reached that jackups are very safe structures: there appears to be no jackup, in the timeframe examined, that has been lost because of a deficiency in the calculation methods currently in use by knowledgeable experts. 相似文献
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《Marine Structures》2002,15(1):15-34
Many important technical issues in the design of deep water jackup rigs stem from the prediction of extreme values of global design parameters such as platform sway, base shear, and overturning moment. Several analytical methods primarily based on time-domain dynamic simulation have been recommended in SNAME T&R Bulletin 5–5A (hereafter referred to as “the Bulletin”) in the realm of the so-called most probable maximum extreme. This paper compares the four major dynamic, time-domain methods recommended in the Bulletin, investigates the random seed effect on each method, exams the convergence of the statistical properties within the recommended time simulation, and presents the impact on the dynamic response due to various parameters, e.g. leg-to-hull flexibility, P-delta effect and foundation fixity. Comparison among the four methods is presented in terms of the calculated extreme values and the corresponding dynamic amplification factors. The structural models employed in this investigation were constructed to reflect the behavior of two jackup rigs in service. These rigs were purposely selected to represent two of the most widely used jackup designs, which are of different leg types, different chord types, and designed for different water depth. 相似文献
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介绍某型沉垫自升式海上风电安装平台的总体参数及性能、沉垫设计和船体布置,并结合海上风电施工作业的要求,分析在设计该平台时需要考虑的一些特殊因素。该平台针对海上风电施工作业所进行的特殊优化布置,可为类似风电安装平台的设计提供借鉴。 相似文献
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We examined the influence of the Mackenzie River plume on sinking fluxes of particulate organic and inorganic material on the Mackenzie Shelf, Canadian Arctic. Short-term particle interceptor traps were deployed under the halocline at 3 stations across the shelf during fall 2002 and at 3 stations along the shelf edge during summer 2004. During the two sampling periods, the horizontal patterns in sinking fluxes of particulate organic carbon (POC) and chlorophyll a (chl a) paralleled those in chl a biomass within the plume. Highest sinking fluxes of particulate organic material occurred at stations strongly influenced by the river plume (maximum POC sinking fluxes at 25 m of 98 mg C m− 2 d− 1 and 197 mg C m− 2 d− 1 in 2002 and 2004, respectively). The biogeochemical composition of the sinking material varied seasonally with phytoplankton and fecal pellets contributing considerably to the sinking flux in summer, while amorphous detritus dominated in the fall. Also, the sinking phytoplankton assemblage showed a seasonal succession from a dominance of diatoms in summer to flagellates and dinoflagellates in the fall. The presence of the freshwater diatom Eunotia sp. in the sinking assemblage directly underneath the river plume indicates the contribution of a phytoplankton community carried by the plume to the sinking export of organic material. Yet, increasing chl a and BioSi sinking fluxes with depth indicated an export of phytoplankton from the water column below the river plume during summer and fall. Grazing activity, mostly by copepods, and to a lesser extent by appendicularians, appeared to occur in a well-defined stratum underneath the river plume, particularly during summer. These results show that the Mackenzie River influences the magnitude and composition of the sinking material on the shelf in summer and fall, but does not constitute the only source of material sinking to depth at stations influenced by the river plume. 相似文献
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触变泥浆作为冶金、水利等建筑工程行业解决沉井下沉的主要施工技术,设想应用到港口海岸工程,利用相关计算公式对某港护岸工程大圆筒下沉的可行性作了理论分析。 相似文献