Numerical studies of upwelling in coastalareas of the East China Sea——Ⅰ The tide-induced upwelling

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河嘉203H含硫水平气井测试工艺实践

河嘉203H井是川东北河坝构造嘉二高压含硫气藏部署的第一口水平井,具有埋藏深、储层压力高、腐蚀分压高、地层易漏失、水平井压井堵漏难度大的特点,通过开展工具优选、管柱结构优化设计、流程优选,并对替浆、放喷油嘴控制及压井等主要工序的施工工艺参数进行研究,形成了河坝嘉二含硫气藏水平井测试工艺技术体系,并在河嘉203H井获得成功应用。     

Buckling of multi-segment underwater pressure hull

Results of a numerical and experimental study into buckling performance of multi-segment pressure hull subjected to uniform hydrostatic pressure are discussed. Constituents of multi-segment configurations are bowed-out cylindrical shells with, and without flanges. Details about five collapse tests of laboratory scale mild steel, CNC machined models are given. Segments were about 200 mm diameter, 100 mm long and had uniform wall thickness of 3 mm. Experimental collapse pressures were in the range from 12 to 20 MPa. Numerical collapse pressures agreed well with those obtained during experiments.     

南黄海悬浮体浓度的平面分布特征及其输运规律

重点分析和探讨了南黄海悬浮体浓度的平面分布及其水平输运,结果显示悬浮体浓度具有显著的空间区域化分布特征,其与该海域环流场的布局和季节转换存在良好的对应关系,南黄海环流是该海域悬浮体运移的主要动力和控制因素;江苏近岸海域在一年四季均为悬浮体浓度的最高值区,其悬浮体主要来源于潮流和海浪所引起的沉积物再悬浮以及苏北沿岸水的携带和输送,而且夏季悬浮体在该海域的累积还可为冬半年在黄海西部沿岸流作用下将其输运至东南海域提供很好的物源保证;长江口东北部海域在春、夏、秋三季出现东北向扩展的高值区,体现了长江冲淡水的影响;石岛外海在冬、春、秋三季也存在悬浮体浓度高值区,并具有向南黄海中部泥质区扩展的态势,这是鲁北沿岸流将现代黄河物质输运至此的结果。发现调查海域中部表底层在春秋季均存在云团状高值区,而且该海域悬浮体浓度自春季至秋季出现"双峰现象",这与春秋季水华期间浮游植物繁殖所产生的有机碎屑有关,并使作为悬浮体组成的海洋浮游生物有机质向沉积物转移,据此进一步指出这一物源可能对南黄海冷涡泥质区的形成、发育也具有一定的作用,该观点深化了对南黄海中部冷涡泥质区受上层生物活动影响以及泥质区物源的认识。     

Effects of long-term cyclic horizontal loading on bucket foundations in saturated loose sand

A 1-g model experimental study was conducted to investigate the accumulated rotations and unloading stiffness of bucket foundations in saturated loose sand. One-way horizontal cyclic loading was applied to model bucket foundations with embedment ratios 0.5 and 1.0. Up to 10⁴ cycles of loading were applied at a frequency of 0.2 Hz varying load amplitudes. The accumulated rotation of the bucket foundations increased with the number of cycles and the load amplitudes. Empirical equations were proposed to describe the accumulated rotation of the foundations. The unloading stiffness of foundations increased with the number of cycles but decreased with an increase in load amplitude. The initial unloading stiffness of L/D = 1.0 (L is skirt length; D is foundation diameter) was approximately twice that of L/D = 0.5. Excess pore water pressure difference of 50% was observed between L/D = 0.5 and 1.0. The suction and static capacity of the bucket increased with increase of bucket embedment ratio with a difference of 69.5% and 73.6% respectively between L/D = 0.5 and 1.0.     

Semi-analytical solution for the water wave diffraction by arrays of truncated circular cylinders in front of a vertical wall

The present study investigates the combined wave field that is induced by the continuous interaction of plane waves with an array of truncated circular cylinders in front of a rigid wall. The long-term goal of the study is the investigation of possible increase in the efficiency of cylindrical Wave Energy Converters (WECs) by putting in the vicinity of the array a barrier to propagation, a wall, that could assist the reflection of the incoming waves. The main task is to develop a generic solution method that is free of conceptual simplifications employed, e.g. by the method of images and the assumption of “pure” wave reflection. To cope with the set task, the proposed method relies on the semi-analytical formulation of the velocity potentials, while the solution is sought by combined expressions that involve polar and elliptical harmonics. The wall is represented as an elliptical cylinder with zero semi-minor axis. This assumption has eventually a beneficial effect to the underlying formulation given that it simplifies significantly the expansions of the involved diffraction potentials.     

影响南海混合层盐度季节变化的因素分析

通过对1950-2012年的南海混合层盐度数据进行分析,发现影响南海北部和南部盐度季节变化的最主要因素存在很大的差异.在南海北部,影响混合层盐度季节变化的最主要因素是蒸发降水,其次是水平平流.随着逐步南移,蒸发降水对盐度季节变化的影响递减,水平平流的影响逐渐增大;而在南海南部,水平平流的作用超过蒸发降水成为影响盐度的季节变化的最主要因素.在整个南海区域,冬季海水垂直混合变强,混合层变厚,下层高盐海水进入混合层,使混合层海水盐度变高,从而对冬季海水盐度的上升趋势产生促进作用;夏季南海北部混合层底存在上升流,南海东南部由于Ekman输运导致混合层变厚,都会将混合层以下高盐海水带入混合层,使混合层海水盐度变高,从而对夏季海水盐度下降趋势产生阻碍作用,但垂直混合对盐度季节变化的影响不大,远小于蒸发降水和水平平流.     

明基床上开孔沉箱垂直力峰值对应的水平力分析

利用水槽二维物理模型对规则波及不规则波作用下明基床上开孔沉箱所受到的波浪力进行了较为系统的试验研究。分析了开孔沉箱总垂直力峰值时刻对应的总水平力与相对基床高度、消浪室相对宽度、波陡、相对水深以及开孔率等影响因素之间的关系,给出了明基床上开孔沉箱总水平力比值(总垂直力峰值时刻对应的总水平力/总水平力峰值)与各影响因素之间的计算关系式。研究成果可供实际工程参考应用。     

Higher harmonics induced by a submerged horizontal plate and a submerged rectangular step in a wave flume

The decomposition of a monochromatic wave over a submerged plate is investigated experimentally in a wave flume. Bound and free higher harmonic modes propagating upstream and downstream the structure are discriminated by means of moving resistive probes. The first-order analysis shows a resonant behaviour linked to the ratio of the plate's width and the fundamental mode wavelength over the plate. The second-order analysis shows an energy transfer from the fundamental mode towards free harmonics propagating downstream the structure. This transfer is linked to the ratio of the width of the plate and the bound harmonic wavelength over the plate. We also performed experiments with a submerged step to compare the efficiency of both structures. The submerged plate is shown to be a more efficient breakwater than the step, at the first as well as the second-order.