The impact of muddy bottoms in ports

Ports are drivers of regional and of countries’ economic development. Most ports are built close to coastlines, where waters are shallower and tend to suffer from deposit sedimentation processes, which reduce depths in operational areas. In presence of shallow waters and sedimentation, ports must decide whether to dredge or not, where both decisions have significant impacts on ports’ annual incomes. Nevertheless, there are seabeds, namely muddy bottoms, in which vessels can navigate with a safety degree. This paper aims at investigating the extent to which the theoretical knowledge of vessel’s control in muddy waters is valid at a certain nautical bottom, as defined by the Permanent International Association of Navigation Congresses (since 2009 the World Association for Waterborne Transport Infrastructure but the acronym stays PIANC) and its impact on port economics. To achieve the proposed objective, an email survey was sent to worldwide pilots that manoeuvre ships in muddy waters. The survey validated the theoretical knowledge, showed that navigation in muddy waters is possible, that it can contribute to reduce ports’ operational costs, and that the subject can be rather controversial.     

船舶下沉量的实测研究

大型船舶进出港的关键之一是富余水深的控制 ,确定富余水深的最重要的问题是确定船舶航行时的下沉量 ( Squat)。提出了一种测量船舶下沉量的实测方法 ,可以精确测量船舶实际下沉量 ,找出船舶下沉量和船速之间的关系 ,为精确确定大型船舶富余水深的标准 ,最大限度地提高港口水深的利用率提供保证。对测量原理、传感器的选择、系统的集成及数据处理方法作出了详细的阐述。该测试方法已在多次实船测试中应用 ,测量结果表明 ,该方法正确、可靠、精确 ,测量结果对指导港口船舶控制具有实际意义     

GPRSTK在航潮位测量及在天津新港航道的实现

在分析传统潮位测量方法和潮位模型缺陷的基础上,给出了GPS在航潮位测量方法。基于GPSRTK动态定位技术,系统地研究了GPS RTK在航潮位测量、数据处理的基本理论和流程,并对潮位测量和数据处理中的GPS RTK高程质量控制、姿态改正、动态吃水改正、潮位提取、垂直基准转换5个关键问题进行了深入研究,最终确定了测量船测量期间的在航潮位。将这些研究成果应用到天津新港航道的在航潮位试验中,2 d的试验结果表明,GPS在航潮位测量方法相对传统的潮位测量方法在实施的简便性、精度等方面具有较大的优越性。鉴于该方法的特点以及航道的特点,建议该方法广泛推广应用于航道在航潮位测量中。     

黄骅港进港航道航行船舶下沉运动量试验

船舶下沉运动量是影响船舶在黄骅港进港航道富裕水深的重要安全问题之一。通过船模试验研究分析了浅水域影响船舶下沉量的主要因素,非接触式采集技术在试验中得到了应用。在分析结果的基础上,得到了影响下沉运动量的主要条件并给出了考虑航速、波流共同作用、水深等因素的船舶下沉运动量。     

超大型船浅水域压载航行最小艏吃水的确定方法

根据船舶在波浪中运动理论、浅水流体动力学、船模试验数据和船舶操纵理论，确定超大型船在浅水域中压载航行最小艏吃水的计算方法。     

The vertical and the longitudinal dynamic responses of the vehicle–track system to squat-type short wavelength irregularity

The squat, a kind of rolling contact fatigue occurring on the rail top, can excite the high-frequency vehicle–track interaction effectively due to its geometric deviations with a typical wavelength of 20–40 mm, leading to the accelerated deterioration of a track. In this work, a validated 3D transient finite element model is employed to calculate in the time domain the vertical and the longitudinal dynamic contact forces between the wheel and the rail caused by squats. The vehicle–track structure and the wheel–rail continua are both considered in order to include all the important eigencharacteristics of the system related to squats. By introducing the rotational and translational movements of the wheel, the transient wheel–rail rolling contact is solved in detail by a 3D frictional contact model integrated. The contact filter effect is considered automatically in the simulations by the finite size of the contact patch. The present work focuses on the influences of the length, width and depth of a light squat on the resulted dynamic contact forces, for which idealised defect models are used. The growth of a squat is also modelled to a certain extent by a series of defects with different dimensions. The results show that the system is mainly excited at two frequencies separately in the vertical and the longitudinal dynamics. Their superposition explains the typical appearance of mature squats. As a squat grows up, the magnitude of the excited vibration at the lower frequency increases faster than the one at the higher frequency.     

向家坝升船机承船厢设计水深标准*

通过1:16的物理模型研究了船舶进出升船机承船厢时的最大下沉量与船厢水深、船舶航速及船厢断面系数间的变化规律。提出船舶出厢过程是船厢设计水深的控制条件,建立了船舶下沉量的无量纲计算公式。通过综合比较不同船厢水深船舶下沉量及船底安全富余水深,提出了向家坝升船机合理的船厢设计水深标准。     

浅水影响造成的船舶下沉量分析

针对10.8万t深吃水成品油轮在浅水水域航行时所出现的船体下沉现象,分析可能的影响因素,并研究给出了不同航行状态下沉量、安全航速的计算方法。     

苏北沿海大丰港大型船舶富余水深的研究

针对苏北沿海大丰港的实际情况,通过比较4种富余水深的计算方法,找出适于大丰港大型船舶航行富余水深的计算方法;并以此对大丰港大型船舶航行富余水深提供安全建议。