Postgrouted helical piles behavior through physical modeling by FCV

Piling procedure may disturb the surrounding soil, due to the installation particularly for cast-in-place piles. It causes a reduction in the soil strength parameters and, consequently, pile capacity. To overcome shortcomings and also for improving piles’ capacity, postgrouting as a compensation method is recognized and more developed in recent years. Helical piles, those are used widely in marine and land projects, although, are driven by torque implementation, but soil disturbance is noticed, where number of the helices become up to 3 and more. In this paper, an experimental study program is performed by frustum-confined vessel (FCV) to investigate bearing capacity of model helical piles and also postgrouted cases’ performance. FCV has been used because of its linear distribution of vertical and horizontal stresses from zero at top to maximum at bottom which simulates real field stress conditions. Through experimental study, small-scale helical model piles were made of 4-mm-thick steel plate and have been used with a length of 750?mm. The shaft and helix diameters of model piles have been 32 and 89?mm, respectively. So, the helix-to-shaft ratio (wing ratio) was about 2.8. The helical model piles installed in fine-grained sand as a surrounding soil and then axial loading tests before and after grouting were performed to achieve ultimate pile capacity. Results indicated postgrouting can improve both ratios of toe and frictional soil–pile interactions including upgrading β and N_t factors. In addition, the post grouting phenomena can change the pile geometry due to treated soil bond, resulting better functioning. Therefore, it is a proper method to improve helical piles performance and compensate installation effects in capacity mobilization.     

渔船主机排废气特性的研究

通过对东京水产大学研究练习船－神鹰丸主机转速、功率，以及排废气的测定，优化渔船主机操纵主机可以使船舶在各种航行工况下主机NOx的排放率达到最低值。结果表明，当船舶航速为4节时，主机转速应设定在750转／分，此时NOx的排放率最低为10．3g/kWh，比常规操纵减少9％；当船舶航速为8节时，主机转速应设定在750转／分，此时NOx的排放率最低为10．5g/kWh，比常规操纵减少4．6％；当船舶航速为10节时，主机转速应设定在875转／分，此时NOx的排放率最低为11．6g/kWh，比常规操纵减少1．7％；当船舶航速为12节时，主机转速应设定在750转／分，此时NOx的排放率最低为12．5g/kWh，比常规操纵减少6％；当船舶航速为13节时，主机转速应设定在750转／分，此时NOx的排放率最低为12g/kWh，比常规操纵减少3．2％。在拖网作业过程中，船舶航速为4节，主机转速应设定在875转分，此时NOx的拓放率最低为12．3g/kWh，比常规操纵减少2．8％。在延绳钓作业过程中，船舶航速为10节，主机转速应设定在875转／分，此时NOx的排放率最低为11．5g/kWh,比常规操纵减少1．7％。     

现代测量船的装船建造技术

论证了测量船建造工程各个技术环节对测量系统工作效益的重要作用,分析了测量船总体设计和测量系统装船工程的实施效果对测量系统技术性能的巨大影响。通过对比近期测量船建造工程中正反两方面的经验,提出了能够适应当代海洋测量飞速发展要求的测量船建造保障技术措施。     

基于AIS信息校准的双频地波雷达的船只融合跟踪

高频地波雷达（HFSWR）和自动船只确认系统（AIS）是船只跟踪的重要传感器。高频地波雷达可以用来跟踪探测区域的所有船只,而AIS只能用来确认合作船只的信息。由于海杂波的干扰,使用单频率地波雷达的船只跟踪会淹没在布拉格峰值的盲区里,改变探测频率是克服这一缺点的有效手段。在这种背景下,我们提出一种基于AIS校准的双频雷达融合探测算法。因为不同频率的地波雷达测量与AIS的测量值存在系统误差,所以AIS信息可以用来估计和校准地波雷达的每个频率的系统误差。首先,将合作目标的点迹测量与地波雷达的点迹测量通过JVC分配算法进行点迹关联。从合作船只的点迹关联结果中,双频雷达的系统误差可以估计和校准。其次,基于校准的双频雷达数据,使用融合JPDA-UKF算法进行船只跟踪。通过真实探测的数据的实验结果显示所提算法可以实时跟踪船只,相比单频率跟踪可以进一步提高跟踪能力和跟踪精度。     

A Unified Computational Method for Simulating Dynamic Behavior of Planing Vessels

High speed planing hulls have complex hydrodynamic behaviors. The trim angle and drafts are very sensitive to speed and location of the center of gravity. Therefore, motion simulation for such vessels needs a strong coupling between rigid body motions and hydrodynamic analysis. In addition, free surface should be predicted with good accuracy for each time step. In this paper, velocity and pressure fields are coupled by use of the fractional step method. On the basis of integration of the two-phase viscous f...     

国际海上救援效率比较研究 ——以东海特定水域为例

为研究东海海域海上救援效率和国际协作的协调性,以国际救援为视角,基于ArcGIS构建了海事救援效率评价模型。根据巡逻船舶密度数据确定了救援船舶的概率分布,得出了救援船舶与遇险船舶的可能距离,同时考虑了风浪影响下遇险船舶的漂移以及巡逻船舶失速的情况,分别计算了常风向和次常风向下中国、日本和韩国在东海特定水域的海上救援效率。结果表明:以各国现有的巡逻船舶配备对研究区内漂移的遇险船舶展开救援时,常风向下先后抵达的顺序为韩国、日本和中国,驰援时间分别为5.14、8.18和9.67 h;次常风向下抵达的顺序为韩国、日本和中国,驰援时间分别为5.45、8.25和10.08 h;为提高我国的救援效率,需要在东海海域部署9～10艘巡逻船舶开展常态化巡逻。本文研究可为我国有关部门科学制定和完善海上救援方案,调整海上救援力量配备,进一步加强国际间的协调与合作提供参考。     

一种深海热液原位探测设备供能装置的设计

为了解决深海热液原位探测设备的能量供给问题,设计了一种实用的供能装置.该供能装置采用了一种定制的高能量密度电池,电池组的容量达31.5 Ah,最大输出电压为12 V.供能装置的耐压壳体采用了压力容器的设计原则进行设计,其最大承受压力达70MPa.放电实验表明该供能装置具有较稳定的放电电压;海试实验表明该供能装置能用于深...     

深水管道S型铺设监测研究

目前,深水管道S型铺设取得了优异的铺设成果,逐渐成为深水海底管道铺设的重要方法,但其铺设环境复杂,上弯段管道与托管架动态接触,现有分析手段无法有效模拟。同时,S型铺设关键设备的设计技术还不成熟,没有相应的设计规范。首先对深水管道S型铺设开展监测研究,提出了深水管道S型铺监测方案,最后利用实验室模型实验验证了该方案的可行性,可以为深水S型铺设关键设备的设计提供必要的设计数据。