某涵洞悬浮桩复合地基失败原因分析

为研究悬浮桩复合地基,在广州—珠海高速公路灵山软基试验工程中对某涵洞的深厚软基采用悬浮搅拌桩复合地基处理,结果沉降较大,超过要求。试验结果表明,软基高度较大的高速公路采用悬浮桩复合地基也不可行,其主要原因是路基产生的附加应力影响深度大。路基下复合地基沉降计算时必须考虑附近路基荷载、沉降土方荷载及复合地基边界处负摩擦力的影响。     

长江口深水航道浮泥运移规律及精细化维护疏浚

基于2016—2019年长江口深水航道施工区段月度测图和2016—2020年北槽深水航道洪枯季常态天气条件下的浮泥观测资料,研究浮泥输移特征及回淤、高频水深等变化特征,提出航道精细化疏浚维护方案。结果表明,常态天气条件下洪季的高低频水深差幅度大于枯季,北槽航道中段洪季的浮泥厚度要远大于枯季,航道回淤量具有随高低频水深差的增加而增加的特征。建议优先在洪季实施精细化维护疏浚方案,试应用后能有效减小浮泥、高低频水深差等变化过程对航道考核测量和航道维护疏浚的干扰,提高航道维护疏浚的精细化管理水平。     

出口菲律宾铁路起重机的研制与试验

介绍了出口菲律宾铁路起重机的主要结构、用途、主要技术参数、仿真分析和试验情况等。该起重机自动化程度高,操作安全可靠,运用情况良好。     

某起重铺管船航行中的托管架绑扎校核与结构分析

基于MOSES软件,建立某起重铺管船的船体模型及船体-托管架模型,计算船体-托管架在极限工况下的运动响应,得到船体-托管架的响应幅值算子(Response Amplitude Operator, RAO)值,将RAO值导入结构分析计算机系统(Structural Analysis Computer System, SACS)进行船舶航行中的托管架绑扎校核与结构分析。计算结果显示,在极限环境条件下,该船的稳性、总纵强度及艉部托管架结构均满足航行安全要求。计算方法可为同类船舶的航行安全提供参考。     

船用甲板起重机噪声分析及控制措施

文章以船舶噪声要求日趋严格为背景,通过梳理船用甲板起重机噪声规范和标准要求,指出未来船用甲板起重机将受到规范或标准限制。在此基础上,以电动液压船用甲板起重机为目标,分析其机械和液压噪声来源。最后结合相关噪声控制原则和实施途径,提出了船用甲板起重机噪声控制措施。     

Design,modelling, and analysis of a large floating dock for spar floating wind turbine installation

Installation of floating wind turbines at the offshore site is a challenging task. A significant part of the time efficiency and costs are related to the installation methods which are sensitive to weather conditions. This study investigates a large floating dock concept, which can be used to shield a floating wind turbine during installation of tower, nacelle, and rotor onto a spar foundation. In this paper, the concept is described in detail, and a design optimisation is carried out using simple design constraints. Hydrodynamic analysis and dynamic response analysis of the coupled system of the optimum dock and spar are conducted. Two spars of different sizes are considered, and the motion responses of the spars with and without the dock in irregular waves are compared. Through analysis of the motion spectra and response statistics, dynamic characteristics of the coupled system is revealed. The present design of the dock reduces the platform-pitch responses of the spars and potentially facilitates blade mating, but may deteriorate the heave velocity of the spars in swell conditions. Finally, future design aspects of the floating dock are discussed.     

Optimization of submerged floating tunnel cross section based on parametric Bézier curves and hybrid backpropagation - genetic algorithm

The cross-section geometry of a submerged floating tunnel (SFT) has a large effect on hydrodynamic characteristics, structural behavior and service level, making the tunnel cross section the primary factor in optimizing efficiency. Minimizing the mean drag and the dynamic variability in the lift of the SFT cross section under bi-directional (i.e., tidal) flow has a dramatic impact on the reduction of structural displacements and mooring loads. Based on a parametric Bézier curve dynamically comprising the leading-edge radius, tunnel height and width to define the SFT geometry, a sensitivity analysis of the Bézier curve parameters for a fixed aspect ratio with prototype dimensions under uniform flow conditions was conducted by applying Computational Fluid Dynamics (CFD), and the pressure distribution around the SFT cross-section surface was analyzed. A theoretical method comprising the Kármán vortex street parameters was employed to verify the CFD simulation results. In order to determine the SFT cross section with optimal hydrodynamic properties, the mean drag and Root Mean Square (RMS) lift coefficients were selected as optimization objectives, and four Bézier curve parameters were the input variables, in a neural network and genetic algorithm optimization process (a hybrid BP-GA structure), which is less likely to become trapped in local minima. The results show the optimal tunnel cross section has a mean drag and a RMS lift coefficient reduced by 0.9% and 6.3%, respectively, compared to the original CFD dataset.     

The wet-towing resistance of the composite bucket foundation for offshore wind turbines

The composite bucket foundation (CBF) is a new and environmentally-friendly foundation for offshore wind turbines. This foundation can be prefabricated in batches onshore followed by integrated transport and installation at sea. The structure itself has a subdivision air cushion structure that enables the foundation to float stably on the water surface and realize long-distance towing of the foundation. The mechanism of this air-liquid-solid coupling towing process is complicated, and the influence of the bulkheads on the towing resistance is not clear. In this paper, the influence of the subdivision structure on the towing resistance of the CBF is compared with the tow test in hydrostatic water. The structural motion characteristics and the change of the cushion pressure are also analysed. Experiments are used to verify numerical calculation results. The flow field difference between the CBF with bulkheads, the CBF without bulkheads and the real floating structure was analysed. The dynamic pressure coefficient was used to analyze the force at surfaces of different CBF's. For the tow test and numerical calculation of multiple CBFs, the optimal multi-CBF tow distance and towage number are obtained through the calculation of energy consumption rate.     

Hydrodynamic experiment of submerged floating tunnel under regular wave and current actions during construction period

Submerged floating tunnel (SFT) is an innovative cable-supported structural system for crossing deep and long-distance ocean environments. In the complex ocean environment, the construction of SFT needs to consider wave and current forces. Specific construction measures and control also require in-depth study and understanding of the dynamic response of SFT under such environmental loads. In this study, the dynamic response of SFT and cable forces under the action of waves alone and wave-current interactions are investigated by using a large wave-current basin. A total of 138 regular wave and wave-current cases were conducted during the experiments, and the influence of waves and wave-current interactions on the dynamic response of SFT and cable forces are discussed in detail by combining experimental data with corresponding analysis. Results show that the wave height, current velocity, and ratio of wavelength to structure size are important factors affecting the dynamic response of SFT and cable forces. The multi-anchor cable arrangement used in the present experimental tests distribute cable force more effectively and reduce the potential safety hazard caused by cable breakage. This study can provide a useful reference for the construction and control of the single SFT segment under construction in a complex ocean environment, especially under the interaction of waves and currents.