西非深水钻井实践与认识   总被引：1，自引：0，他引：1  

褚道余  张忠强  张灵军 《海洋地质译丛》2010,(4):111-116

JDZ B-1井是中石化作为作业者完成的第一口海洋深水探井,该井位于西非几内亚湾尼日利亚—圣多美和普林西比联合开发区内,作业水深1 655 m。井区地质情况较为复杂,地层破裂压力低,钻井作业压力窗口窄,井眼稳定性差。特别是该井目的层距海底泥线浅（只有778 m）以及目的层段长等,给钻井工程设计带来了诸多挑战。针对钻井施工中面临的挑战与深水钻井的特点,从井身结构设计到施工中均采取了合适的钻井技术和措施,有效地解决了问题,取全取准了各项资料,高效、优质地完成了该井的施工任务。该井的成功完钻,为中石化海洋深水钻井积累了经验,可供该区域及国内海洋深水钻井借鉴。  相似文献   

无人船系统应用于水库水样离岸采集——以棘洪滩水库为例     

金久才  崔文连  张杰  孙立娥 《海洋科学》2018,42(1):11-14

水库水质监测是水库水质评价的重要依据,通常需要现场采水样后带回实验室进行检测与分析。然而一些特殊情况下,例如库区无船、情况复杂等,只能获得沿岸水样,导致水质监测结果无法代表水库整体水质质量。本文针对水库的水样离岸采集,基于自研发的无人船系统,设计集成了采水泵,并利用无人船位点跟踪技术,实现了远距离定点遥控采水样功能。在青岛棘洪滩水库,利用该系统,设置了两个采样点(离岸50 m和离岸1300 m),并成功获取了水样。在实验室内,利用分光光度计、离子色谱仪、电感耦合等离子体质谱仪等设备,完成了所采集水样的水质分析。实验结果表明,无人船应用于水库水样离岸采集具有可行性、实用性。  相似文献   

近海风电场水下打桩辐射噪声特性测量分析   总被引：1，自引：0，他引：1  

吉新磊  杨红  丁骏  王春峰 《海洋科学》2018,42(3):11-16

对滨海海上风电场一次完整的打桩过程不同水深处环境噪声进行监测和分析。结果表明:打桩过程水下辐射噪声脉冲信号,在所研究海域附近环境噪声级由原来打桩前的130 d B左右瞬间增加约20~50 d B,20~20 000 Hz频段,打桩噪声谱级高于工程前该海域背景环境噪声谱级约30~65 d B,100~1 000 Hz频率打桩辐射噪声谱级出现多个峰值,不同水深谱级最高峰值频率为200 Hz。根据打桩水下辐射噪声监测结果和浅海Marsh和Schulkin半经验公式,计算打桩辐射噪声声源级(距声源中心1 m处)为210.2 d B(参考声压1μPa)。为水下打桩辐射噪声的深入研究提供了基础数据,分析结果可供海洋环境和海洋生物保护研究参考。  相似文献   

海上风电大直径加翼桩水平承载性能研究     

陈灿明  苏晓栋  何建新  王曦鹏  黄卫兰 《海洋工程》2018,36(4):97-104

为改善海上风电大直径钢管桩的水平承载性能,基于ABAQUS有限元软件对单桩改进形式的加翼桩结构进行了系统研究,计算分析了软黏土地基中加翼桩在水平荷载作用下桩身弯矩、应力、位移、桩身泥面处倾斜率和极限承载力,研究了加翼桩面积、形状、埋深和刚度等翼板参数对加翼桩水平承载性能的影响规律,根据加翼桩的桩-土作用机理,参考现行规范模式提出适用于软黏土地基大直径钢管桩的P-Y曲线。研究结果表明,加翼桩通过在泥面处设置翼板可降低桩基泥面处倾斜率50%、提高桩基极限承载力60%以上,加翼桩水平承载性能明显优于单桩。  相似文献   

Elastoplastic consolidation above and beneath strip anchors under uplift forces     

Vikram Singh 《Marine Georesources & Geotechnology》2018,36(5):505-514

Although the uplift behavior of offshore plate anchors under undrained conditions has been investigated well in the past, studies on the behavior of anchors under long-term sustained loading are in relatively few numbers. The time required for consolidation under sustained load is important because the shear strength of soil changes after dissipation of excess pore pressure. In this paper, small strain finite-element analyses have been performed to investigate the consolidation time history above and beneath strip anchors. The modified cam clay plasticity constitutive model is used for modeling coupled pore fluid stress analysis. The effects of magnitude of preloading with embedment level have been studied. As expected, the FE results have shown that excess pore pressure dissipation time for soil above the anchor increased with the increase in embedment depth and the magnitude of preload. Rapid dissipation of negative excess pore pressure beneath the anchor was observed with increasing embedment depth, if the preload magnitude is equal to or more than 60% of the undrained capacity. Observed consolidation responses are presented as nondimensional design charts and simplified equations for ease of practice.  相似文献   

Bearing capacity of shallow foundations in clay with linear increase in strength and adhesion factor     

Boonchai Ukritchon  Sothoan Yoang  Suraparb Keawsawasvong 《Marine Georesources & Geotechnology》2018,36(4):438-451

In this paper, the computational lower bound (LB) limit analysis using finite element with second-order cone programming was used to investigate the LB solutions of the undrained bearing capacity of continuous footing with a linear increase in the strength profile and an adhesion factor at the soil–footing interface. A full range of parametric studies of the dimensionless strength gradients and adhesion factors at the soil–footing interface were performed in the LB calculations. The results were verified by comparison with the available solution from the method of characteristics (slip-line analysis) for perfectly smooth and rough footings. The LB analyses were able to complete a prior solution of undrained bearing capacity with a linear increase in the strength profile by incorporating the influence of adhesion factor at the soil–footing interface. Based on the nonlinear regression to the computed LB solutions, an approximate expression of the LB solution regression was proposed, which is applicable to an accurate prediction of a safe load for offshore shallow foundations in clay with an arbitrary linear increase in strength and adhesion factor at soil–foundation interface in practice.  相似文献   

基于卫星高度计资料提取浙江近海的潮汐信息   总被引：1，自引：0，他引：1       下载免费PDF全文

赵杰  汪一航  王永刚  王建 《应用海洋学学报》2018,37(3):356-365

利用Topex/Poseidon(T/P)、Jason-1和Jason-2卫星24a的原始轨道及6a的变轨轨道高度计资料,对浙江近海区域内进行潮汐调和分析,得到8个主要分潮(Q_1、O_1、P_1、K_1、N_2、M_2、S_2和K_2)的调和常数.比较卫星轨道交叉点处潮汐调和常数结果显示,8个分潮总体综合误差在原始轨道,变轨轨道及原始轨道与变轨轨道交叉点处的和方根RSS值分别为3.16、7.02、5.54cm;用卫星高度计资料及31个近岸验潮站得到的潮汐分布与21个验潮站资料结果进行比较,M_2、S_2、N_2、K_1和O_1主要分潮的多点向量均方根偏差分别为4.32、3.64、1.97、2.61、1.83 cm;本研究结果与前人数值模拟结果比较显示M2、S2分潮在对比点处的多点向量均方根偏差在11、8 cm左右,最后给出了浙江近岸及近海区域更为精确的5个主要分潮(M_2、S_2、N_2、K_1和O_1)的同潮图.  相似文献   

Tidally driven pore water exchange within offshore intertidal sandbanks: Part II numerical simulations   总被引：1，自引：0，他引：1  

B. Gibbes  C. Robinson  L. Li  D. Lockington  H. Li 《Estuarine, Coastal and Shelf Science》2008,80(4):472-482

Field measurements presented by [Gibbes, B., Robinson, C., Li, L., Lockington, D.A., Carey, H., 2008. Tidally driven pore water exchange within offshore intertidal sandbanks: Part I Field measurements. Estuarine, Coastal and Shelf Science 79, pp. 121–132.] revealed a tidally driven pore water flow system within an offshore intertidal sandbank in Moreton Bay, Australia. The field data suggested that this flow system might be capable of delivering nutrients, and in particular bio-available iron, across the sediment–water interface. Bio-available iron has been implicated as a key nutrient in the growth of the toxic marine cyanobacteria Lyngbya majuscula and therefore this pore water exchange process is of interest at sites where L. majuscula blooms have been observed. In this study two-dimensional numerical simulations were used in conjunction with hydraulic data from field measurements to further investigate the tidally induced pore water flow patterns. Simulation results generally showed good agreement with the field data and revealed a more complex residual pore water flow system in the sandbank than shown by the field data. The flow system, strongly influenced by the geometry of the sandbank, was characterized by two circulation cells which resulted in pore water discharge at the bank edge and also to a permanently ponded area within the sandbank interior. Simulated discharge volumes in these two zones were in the order of 0.813 m³ and 0.143 m³ per meter width (along shore) of sandbank per tidal cycle at the bank edge and sandbank interior respectively. Transit times of pore water circulating through these cells were found to range from ≈ 17 days to > 60 years with an average time of 780 days. The results suggest that the tidally driven flow systems might provide a mechanism for transport of bio-available iron across the sediment–water interface. This flow could constitute a previously unrecognized source of bio-available iron for L. majuscula blooms in the Bay.  相似文献   

Research on Motion Performance of the Mobile Double-Causeway Pier System     

余建星  田佳  徐金利  张翼飞  杨晓蓉  谭振东  董文斌  杜尊峰 《中国海洋工程》2008,22(2):267-276

Mobile offshore double-causeway pier system, a type of seashore unloading equipment, consists of two groups of multiple connected semi-submersible modules. This structure has wide application because most of the middle or mini type of vessels and ships can be moored to it. Based on the analysis of computational methods of multi-body motion response, a hydrodynamic model is set up and the three-dimensional potential theory in finite depth is adopted to calculate the three-dimensional motion response of this system. The double P-M spectrum is used to analyze the motion response in irregular waves. Different wave directions are specially taken into consideration, due to their various effects to the motion response. Furthermore, the calculated result is compared with that of the experiment, and it is proved that sway, heave, pitch and yaw motion are greatly constrained by mooring system. The comparison also indicates that the model can forecast the motion performance of the target, and that the calculated result can also be used as reference in connector and mooring system design.  相似文献   

基于小波变换的固定式海洋平台结构损伤识别方法研究     

张强  嵇春艳  范佰明 《海洋技术学报》2008,27(2):52-56

小波变换在分析非平稳信号方面较傅立叶变换更有效,为了检测出海洋平台结构中裂缝或因刚度降低引起的损伤,对海洋平台的响应信号进行离散小波变换,通过分析变换后的信号是否有突变现象判断结构是否出现损伤,并结合模态应变能法实现了对结构损伤的定位,探讨了传感器位置对识别效果的影响。  相似文献