夹心立管极限强度分析

针对夹心立管极限承载能力问题,通过ABAQUS软件建立了立管的非线性有限元模型,对纯外压、纯弯矩、以及外压和弯矩联合作用下的立管极限强度进行研究。研究夹心材料、初始椭圆度以及偏心焊接等因素对立管的极限承载能力影响。经有限元计算可知,胶合材料夹心立管与聚丙烯材料夹心立管在极限强度上有明显的差异;对于胶合材料夹心立管,随着初始椭圆度增加,立管的极限外压和极限弯矩均减小;对于偏心焊接的单壁立管而言,随着偏心焊接量的增大,立管的极限弯矩减小。     

大型钢管桩的动力测试和分析研究

本文介绍了用高应变法对某专用码头大直径钢管桩进行动力量测及ＣＡＰＷＡＰＣ法计算分析结果，提出了单桩极限承载力及该地区停锤标准，供设计部门参考。     

Spar平台硬舱结构弯曲极限强度有限元分析

Spar是一种新型的深海油气资源开发平台,由于结构比较复杂,平台硬舱结构的弯曲极限强度很难用常规的理论方法进行计算。采用非线性有限元分析方法,分析结构构件、边界及载荷条件对硬舱结构弯曲极限承载能力的影响。结果表明:单舱段和两舱段的极限弯矩计算结果基本一致;当弯矩载荷方向平行中心井对角线方向时,结构的抗弯强度较弱;重力载荷对舱段的极限弯矩影响较小;结构内部的环向框架能显著提高舱段的抗弯强度。     

大型全钛海洋资料浮标结构强度有限元分析

为了分析校核全钛海洋资料浮标的整体结构及拖曳强度,本文依据相关标准规范计算了全钛海洋资料浮标作业工况和极限工况下所受的风、浪、砰击载荷,利用有限元方法对全钛海洋资料浮标进行了整体及拖曳强度计算分析。依次分别计算浮标结构为8 mm板厚和6 mm板厚两种方案的应力,并对照《海上浮式装置入级规范（2014）》进行了应力衡准。研究结果表明：无论采用8 mm的板厚还是6 mm的板厚,浮标结构强度及稳定性满足规范要求。在满足强度要求的前提下,使用6 mm板厚方案更具有经济性,也有利于提高浮标的设备承载能力。     

套管加强T型管节点在平面外弯矩作用下极限强度分析

对用套管加强的T型管节点在平面外弯矩作用下的极限强度作了参数化分析。同时将相应的套管以及管节点的几何参数对极限强度的影响进行评估,并且和未加强的T型管节点作了比较。在计算结果中可以得出在管节点的弦管和撑管的连接处用合适的套管加强,可以将管节点在平面外弯矩作用下的极限强度提高到3倍多。     

受轴向压力开孔板极限强度有限元分析研究

使用有限元方法对不同边界条件下受轴向压力的多种类型开孔板的极限强度进行了研究。考虑到板的极限强度所涉及的非线性问题,运用ABAQUS/Standard弹塑性大挠度分析来求解极限强度。在计算了系列不同开孔位置及开孔大小的板的屈曲强度后,分析了各种边界条件及开孔形式对开孔板的极限强度的影响程度。最后在得到规律的基础上提出了适用于一定边界条件下的经验公式,可以在初步设计中用于估算开孔板的极限强度值。     

Ultimate Bearing Capacity of Subsoils to Marine Pipelines

- Based on the theory of limit analysis, the Finite Difference Method (FDM) is established for evaluating the ultimate bearing capacity of subsoils to bear the unburied pipelines. The analytical results of bearing capacity of the ideal clay is given. The approach to bearing capacity evaluation of cohesionless subsoils without surcharge is suggested. The results from this method are consistent with those obtained from model tests.     

Static Analysis of Collision Strength of Offshore Platform

In this paper a numerical analysis method combining FEM incemental technique with limit analysis concept is proposed for the study of the static strength of offshore platform in collision. Large deformation and plasticity are accounted for and the limit yield surface expressed by generalized stress for a tubular section is derived. The modified stiffness matrix of space beam element is formulated by Plastic Node Method. The buckling behavior of beam columns can also be taken into account. It can trace the generation of plastic hinges during loading and finally the ultimate strength of offshore platform against collision is obtained.     

海上风机斜壁桶形基础承载特性研究

基于验证的三维有限元方法,考察了斜壁桶形基础的承载特性,得到了变形网格、位移增量分布、位移等值面分布等结果,探讨了斜壁倾角与各极限承载力之间的定量关系。计算表明,桶形基础发生竖向位移时,主要是桶体内部和桶基正下方的土体发生沉降,而桶侧的土体基本不发生沉降。桶形基础受到水平荷载发生转动时,转动中心轴大致位于桶基底面内,桶基水平承载力主要由桶内土体和桶基外侧中上部受压侧土体产生的抵抗反力构成。桶基因受到较大竖直向上荷载而失效时,桶内土体和桶基外侧靠近海床面附近土体产生了较大的向上位移。桶壁倾角β每增加1°,竖向抗压极限承载力、竖向抗拔极限承载力、水平极限承载力分别提高12%、17.4%及3.8%。     

Ultimate Strength Analysis of Offshore Jacket Platform

- The ultimate strength analysis of offshore jacket platforms is a research project which has been developed in recent years. With the rapid development of marine oil industry, the departments of design and IMR (Inspection, Maintenance and Repair) in the offshore engineering have attached great importance to this project. The research procedure applies to both the stress check of new design platforms and the whole safety assessment of existing platforms. In this paper, we combine the pseudo non-linear technique with the linear analysis program and successfully analyze the ultimate strength of the space frame structure subject to the concentrated load and a real jacket platform subject to the dead load and environmental load.     

海底管线稳定性影响因素分析

实现管线的稳定性是埋设海底管线并使其正常运营的前提。分析了波浪、海流、管线周围土体性质及液化发生等方面对海底管线稳定性的影响，并提出了相应的对策建议．     

导管架式海洋平台结构极限承载力分析的整体推进法及其软件

根据非线性有限元逐步分析的思想,以已有的结构弹性分析软件为计算核心,提出了一种近似分析结构极限承载力的方法——整体推进法;采用整体推进法,以导管架式海洋平台结构线弹性分析软件ＥＮＳＡ为计算核心,考虑结构构件的损伤影响和维修加固效果,编制了导管架式海洋平台结构极限承载力近似分析软件ＵＡＰ,为导管架式海洋平台结构的安全度评定提供了方法和手段;最后对渤海八号生产／储油平台在１９９３年的状态和ＪＺ２０２ＭＵＱ平台的完好状态进行了极限承载力分析     

日照海洋保护区现状及发展对策研究

人类对海洋的青睐和倚重日益凸显为实现海洋未来可持续发展建立海洋保护区是一种有效的预防性海洋综合管理方式。文章根据日照海洋保护区当前发展状况,分析保护区发展中存在的问题,并相应的提出相关建议及对策。希望这些对策能够进一步提高保护区的保护价值。     

An Analysis of the Coastal Fish Assemblage of the Ustica Island Marine Reserve (Mediterranean Sea)

A study of the coastal fish assemblages in the marine park of Ustica Island (Southern Tyrrhenian Sea, Mediterranean) was conducted from June 1994 to September 1995 and from June 1996 to September 1997. The principal aims of the research were to: (1) define the faunistic features of local fish communities; (2) assess the effectiveness of the protection regime of the marine park on the fish assemblages ('reserve effect'); (3) provide information on the distribution of some Epinephelus and Diplodus species in the shallowest depth zone of the island. During seasonal surveys, underwater visual censuses were carried out at several sites located in three zones of the island, each with a different level of protection. Observations were made along 250 m² transects at 3–5, 10–15 and 25–30 m depth ranges. Additional surveys were made by SCUBA diving and snorkelling. A statistically significant effect of depth on the fish community parameters was observed, whereas differences linked to protection level, zones, sites and seasons were not significant. The abundance and frequency of occurrence of some species, particularly dusky grouper Epinephelus marginatus , were positively correlated with the degree of protection of the different zones of the marine park. Certain sites of the island are important as nursery areas for three species of the genus Diplodus ( i.e., D. puntazzo, D. sargus and D. vulgaris ).     

Strength Sensitivity of Marine Ariake Clays

Natural Ariake clays are characterized by high sensitivity. In this study, the mechanism and the factors controlling undrained shear strengths of both undisturbed and remolded Ariake clays are discussed. A series of unconfined compressive tests were performed on undisturbed samples of natural Ariake clays. The remolded undrained shear strength is predicted using a quantitative expression derived from extensive data of remolded undrained shear strength for a number of soils compiled from resources in the literature. The sensitivity of natural Ariake clays derived from the ratio of half of unconfined compressive strength for undisturbed samples to remolded undrained shear strength is found to be affected by both natural water content and normalized water content that is defined as the ratio of natural water content to liquid limit. The smaller the natural water content, the higher the sensitivity is at the same normalized water content. At the same natural water content, the larger the normalized water content, the higher the sensitivity is.