遮帘式板桩码头结构离心模型试验研究

CENTRIFUGE MODELLING TEST ON COVERED SHEET-PILED STRUCTURE OF WHARF

针对传统板桩结构仅适用于中小码头建设这一长期困扰工程界的难题,结合京唐港待建1.0×105 DWT级深水泊位拟采用的遮帘式板桩结构,运用离心模型试验技术对其结构受力状态和变形特点展开研究。通过对有无遮帘桩、有无码头面荷载、前板桩墙不同嵌入比以及前板桩墙与遮帘桩的距离等进行一系列试验,得出的试验成果表明,这种遮帘式板桩码头新结构解决了深水板桩码头前板桩墙弯矩急剧增大的问题,同时有效地减小码头前沿水平位移和拉杆拉力,实现了传统板桩结构向深水泊位发展的历史性突破。为探求这种新型码头结构中前板桩墙与遮帘桩之间的最佳传力模式,模拟3种不同的连接型式,即前板桩墙与遮帘桩钢筋混凝土胸墙连接、竖向自由的胸墙连接和相对自由的拉杆铰接,结果发现采用拉杆铰接型式时,码头结构内力最为合理。在上述研究的基础上,最后提出拉杆铰接型式的遮帘桩码头结构形式为最优方案,推荐设计采纳。

A covered-type of sheet-piled structure has recently been proposed to overcome the problem that the conventional sheet-piled structure is only applicable in medium and small wharfs, which has long been the difficult problem of port engineering. Incorporating with the construction need of a deep water berth of 100 000 DWT, a study for the proposed covered sbeet-piled structure is conducted by means of centrifuge model test to investigate the distribution of bending moment of the front sheet-piled wall, covered sheet-piled and anchor wall, and the horizontal displacement on the top of the wall and the tension force of connecting rod. To illustrate the contribution of barrier piles to the wharf performance, the conventional structure without barrier piles under no surface work load as well as the proposed new structures are modeled, in which the surface load, ratio of embedment of front wall, and distance between front wall and barrier pile are considered as influential factors. Test results show that the maximum bending moment of the front sheet-piled wall is obviously decreased, with smaller magnitude of seawall horizontal displacement and tensile force of connecting rod. Thus the problem perplexing engineers is promisingly overcome by application of this new structure of sheet-piled wall. Three modes of connection are conducted in the model test to find out the best connection mode between the front sheet-piled wall and the barrier piles, such as rigid connection through breast wall, rigid breast wall connect with vertical freedom, and hinge jointing connection through short connecting rod, respectively. It is found that the third one, i. e. the hinge jointing connection through short connecting rod, is preferable to the others in decreasing bending moment of these structure elements. Based on the analysis of the test results, an optimum scheme is recommended for the project to be built.