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排序方式: 共有174条查询结果,搜索用时 31 毫秒
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由于在抗拔承载力和深水安装中的优势,拖曳锚在深水系泊系统中具有良好的发展前景。在拖曳锚安装过程中,安装缆绳和锚之间存在复杂的相互作用,安装缆绳在海床土中的反悬链形态将直接影响锚的嵌入和运动,对反悬链形态的研究有助于提高锚的嵌入性能、准确预测锚的运动轨迹以及解决锚在安装中的精确定位问题。基于嵌入缆单元在海床土中的力学模型,推导出适用于黏性土和无黏性土的反悬链方程,利用该方程可求出安装缆绳在海床土中的反悬链形态;通过在缆绳上布置倾角传感器并运用圆弧递推方法,设计出可实时测量嵌入缆形态的试验技术,为验证试验技术的合理性,在空气中分别选取3种典型缆绳形态进行模拟,结果表明:模拟形态与真实形态吻合良好,并具有较高精度;利用实时测量技术开展模型试验,对反悬链方程进行了考察,验证了其模拟嵌入缆反悬链形态的精度,并获取了对拖曳锚安装过程中反悬链形态变化规律的直观认识。 相似文献
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In the present study, we simulated the reel-lay installation process of deepwater steel catenary risers(SCRs) using the finite element method and proposed multiaxial fatigue analysis for reeled SCRs. The reel-lay method is one of the most efficient and economical pipeline installation methods. However, material properties of reeled risers may change, especially in the weld zone, which can affect the fatigue performance. Applying finite element analysis(FEA), we simulated an installation load history through the reel, aligner, and straightener and analyzed the property variations. The impact of weld defects during the installation process, lack of penetration and lack of fusion, was also discussed. Based on the FEA results, we used the Brown-Miller criterion combined with the critical plane approach to predict the fatigue life of reeled and non-reeled models. The results indicated that a weld defect has a significant influence on the material properties of a riser, and the reel-lay method can significantly reduce the fatigue life of SCRs. The analysis conclusion can help designers understand the mechanical performance of welds during reel-lay installation. 相似文献
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Mao Fangguan Lu Shunchang Luo Ruiren
Senior Engineer Naval Medical Research Institute P. L. A. of China Shanghai Senior Engineer Navigation Guarantee 《中国海洋工程》1995,(4)
The Diver Gas Recovery Installation (DGRI) was evaluated at 80 msw saturation - 100 msw excursion diving on HeO2 in the Naval Medical Research Institute (NMRI) of China in April, 1995. The diving depth, lockout time, breathing gas flow rate and consumption, inspired oxygen partial pressure (PO2) and carbon dioxide partial pressure (PCO2) were monitored. The results indicated that PO2 was controlled to fluctuate from 64.3 to 84.0 kPa and PCO2 went up from 0.01 kPa up to O.I kPa during 4 hours excursion diving; recovery of breathing gas reached 95%; three divers felt well and breathed comfortably during simulating heavy work. The test showed that it met desired performance goals. The DGRI is a kind of important equipment for long duration deep dive. It enables the gases exhaled by the divers to be re-cycled, and therefore it has great social, military and economic significance for diving operation and submarine rescue. 相似文献
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桶形基础平台海上沉放安装 总被引:3,自引:1,他引:3
桶形基础平台是世界上一种最新型的海洋平台,可广泛应用于海上油气田开发。为满足我国际油气田开发中卫星平台的结构和功能要求,桶形基础平台采用新的压载沉放方法安装,具有更高的效率和经济性。沉放过程中桶形基础平台受到水流和波浪的作用,结合模型试验对平台运动进行数值模拟分析,以了解在整个沉放过程中相应参数的变化趋势。根据桶形基础平台的特征,制定联台沉放方案,并通过压载实现平台的沉放控制。 相似文献
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Giovanni Spagnoli Cristina de Hollanda Cavalcanti Tsuha 《Marine Georesources & Geotechnology》2020,38(9):1013-1036
AbstractHelical piles are used mainly to resist tension forces generated by uplift and overturning moments of various structures, therefore they have been suggested as a potential alternative to driven piles as offshore pile because they provide a large uplift capacity due to the anchor effect of the helix. To date no standards are available for the assessment of the use of helical piles in the offshore environment. State-of-the art installation and uplift capacity assessment is based on field onshore tests on small helical piles. The purpose of this review is to critically evaluate the current knowledge on helical piles considering uplift capacity, cyclic load, installation torque models and the parameters affecting the installation torque, to understand whether they can be considered for potential offshore applications. The paper could be of valuable interest for engineers and contractors involved in the offshore installation of piles. 相似文献
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This paper presents a numerical analysis of the influence of initial stress state on the response of deep excavation supported by retaining wall. Indeed, the influence of diaphragm wall installation prior to excavation works may affect the soil response and lateral wall deflection induced by excavation process. The first part of this paper gives a short review of the numerical methods aimed to reproduce the retaining wall installation. Numerical analysis of a deep excavation in two‐dimensional and three‐dimensional conditions is then performed according to the methods previously presented. In three‐dimensional conditions, diaphragm wall installation is performed considering a sequence of panels, described by their number and length. Results of three‐dimensional calculations confirm that stress state is disturbed by wall installation, which has a sensitive effect on the ground response induced by soil excavation. It is also noted that these results are not easily reproduced in two‐dimensional conditions. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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