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71.
72.
The dynamics of jacket supported offshore wind turbine (OWT) in earthquake environment is one of the progressing focuses in the renewable energy field. Soil-structure interaction (SSI) is a fundamental principle to analyze stability and safety of the structure. This study focuses on the performance of the multiple tuned mass damper (MTMD) in minimizing the dynamic responses of the structures objected to seismic loads combined with static wind and wave loads. Response surface methodology (RSM) has been applied to design the MTMD parameters. The analyses have been performed under two different boundary conditions: fixed base (without SSI) and flexible base (with SSI). Two vibration modes of the structure have been suppressed by multi-mode vibration control principle in both cases. The effectiveness of the MTMD in reducing the dynamic response of the structure is presented. The dynamic SSI plays an important role in the seismic behavior of the jacket supported OWT, especially resting on the soft soil deposit. Finally, it shows that excluding the SSI effect could be the reason of overestimating the MTMD performance. 相似文献
73.
The mechanical properties of shallow soils in deep water play an important role in drilling design and construction as well as later oil and gas development. Since it is difficult to collect soil samples from layers deeper than 10 m below the sea floor, the acquisition of shallow soil mechanics, based on the variation of drilling parameters in the deep-water drilling process, is not only economical but also reliable. In this article, we analyze the variation of subsea soil properties based on the variation of deep-water jet-drilling construction parameters, calculate the lateral friction resistance of conductor by use of weight-on-bit (WOB) and displacement parameters in the jetting process, and determine the drilled formation’s shear strength and internal friction angle in consideration of restored friction resistance. To verify the accuracy of the prediction-while-drilling model on seabed shallow soil mechanics, indoor unit and field simulation experiments were separately conducted. Moreover, the calculations from field application examples indicate that the prediction-while-drilling of deep-water seabed shallow soil mechanics achieves high conformity with the local practice results, which also indicates that this method could effectively guide field construction operations. 相似文献
74.
中国盆地动力学研究现状及展望 总被引:3,自引:1,他引:2
沉积盆地既是人类最重要的资源宝库,又包含了丰富的全球气候变化、流体流动和地球动力学等相关信息。人类社会对矿产资源和水资源的大量需求推动盆地分析领域的快速发展,地球科学家对沉积盆地开展了多年的系统性探索,在盆地形成和演化机制、沉积充填、盆地流体及相关资源的聚集过程等诸多方面的研究取得了一系列重要的进展和突破,形成了一门新兴的学科—盆地动力学。近年来,我国学者在大型叠合盆地和大陆边缘盆地的动力学过程、陆相盆地层序地层、深水沉积、源—汇系统等方向取得了显著成绩和突出进展。相关成果不仅有效地服务于能源、矿产、水资源等各类资源勘探,而且为地球动力学、重大构造事件、全球环境变迁及气候演变研究提供了丰富资料和详实证据。 相似文献
75.
侵入砂体对深水油气勘探的研究意义 总被引:2,自引:0,他引:2
侵入砂体是指深水沉积砂体在超压流体作用下侵入至上覆泥质沉积物中形成的砂体,它是深水盆地松散沉积物变形构造中常见的地质现象。侵入砂体由于其特殊的形成特点,可以明显改变原生沉积地层的几何形态和深水沉积物的物性参数,进而使储层复杂化,影响深水油气的勘探与开发,主要表现在:①侵入砂体改变了深水储层的性质及分布;②侵入砂体可能形成油气运移或散失的通道,并且改变了深水油气储层的垂向连通性;③大规模的侵入砂体本身也可以作为良好的油气储层;④侵入砂体的研究可以揭示未固结砂的流动机理,对于研究深水环境中广泛出现的浅水流的成因具有重要的借鉴意义。 相似文献
76.
In this paper a new nondestructive damage identification method is introduced. The method based on flexibility matrix can be used to detect and locate structm'al damage and evaluate the severity of damage in legs of jacket platforms by modal parameters of a structure. With the modal data for only the few lower modes in both the intact and damaged states, the one-dimensional and two-dimensional distributed curvatures can be used to analyze damage location and the severity. Instead of directly comparing the curvatures before and 'after damage, the method here uses modal parameters only in the damaged structure to detect the damage and it consists of three parts. First, ilexibility matrix is obtained by use of the absolute maximum in each column. Second, because the legs of jacket platforms are the pipe-like structure, the circumferential flexibility curvature matrix is obtained by use of the circular curvature. At last, equivalent curvature ratio is defined and the curve meaning equivalent curvature ratio and the severity of damage relationship for one element is given through the data of damage severity from ten percent to ninety percent by numerical simulation. Many existing damage detection methods need two steps, locate the damage firstly and evaluate the severity of the damage. However, the method present- ed! in this paper can locate and then evaluate the severity of damage at the same time. The numerical analysis results in- dicate that the present method is effective, useful and only need the first and the second mode data of the structure. 相似文献
77.
Owing to the ageing of the existing structures worldwide and the lack of codes for the continued safely management of structures during their lifetime, it is very necessary to develop a tool to evaluate their system reliability over a time interval. In this paper, a method is proposed to analyze system reliability of existing jacket platforms. The influences of dint, crack and corrosion are considered. The mechanics characteristics of the existing jacket platforms to extreme loads are analyzed by use of the nonlinear mechanical analysis. The nonlinear interaction of pile-soil-structure is taken into consideration in the analysis. By use of FEM method and Monte Carlo simulation, the system reliability of the existing jacket platforul can be obtained. The method has been illustrated through application to BZ28-1 three jacket platforms which have operated for sixteen years. Advantages of the proposed method for analyzing the system reliability of the existing jacket platform is also highlighted. 相似文献
78.
导管架海洋平台自振特性的简化计算方法 总被引:2,自引:0,他引:2
本文提出了一个方程中只考虑剪切、弯曲、转动惯量效应,而塔架形状变化、平台面转动惯量及台面集中质量变化等其他影响因素均以修正系数方法确定,得出平台基本频率的简化算法。 相似文献
79.
Crack detection procedures by different modal parameters are analyzed for identitying a crack and its location and magnitude in a jacket plafform. The first ten natural frequencies and modal shapes of the jacket models are obtained by numerical experiments based on NASTRAN Code. A crack at different locations and of different magnitudes is imposed in the model at the underwater beams. Then, the modal evaluation parameters are calculated numerically, to illustrate the evaluation of modal parameter criteria used in jacket crack detection. The sensitivities of different modal parameters to different cracks are analyzed. A new technique is presented for predicting the approximate location of a breakage in the absence of the data of an intact model. This method can be used to detect a crack in underwater menbers by use of incomplete mode shapes of the top members of the jacket. 相似文献
80.
定量风险评估是风险评估发展的主要趋势。论文基于TOPS IS和神经网络响应面法,提出一种定量风险分析方法,并运用此方法对导管架海上安装过程进行深入分析,以及时查找并消除各方面的事故隐患。首先找出潜在的风险事件及相关风险因素,然后对风险事件的模糊概率和损失程度后果进行量化,最后依据风险评价结果对需要控制的风险事件给出控制措施。实例表明,该方法是一种实用而有效的定量风险评估方法。 相似文献