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某散货码头堆场地基推移破坏离心模型试验及机理分析
徐光明
南京水利科学研究院
摘要:
某散货码头堆场地基中有一层软弱的淤泥质粘土层,堆场荷载区地基先采用真空联合堆载预压处理,再对堆场荷载区两侧地基进行了水泥搅拌桩加固处理,但在矿石试堆载过程中,淤泥质粘土层最厚之处的堆场发生了严重的推移破坏。为了确定该堆场地基修复加固设计大原则,需要认真研究这次滑移破坏真实原因,因此,对该堆场地基重新开展了勘察,获得了地基土层的物理力学特性,在此基础上根据此处堆场地基滑移破坏前的地形设计了一组大型离心模型试验,设置了两种边界约束条件,模拟了矿石堆载体的填筑过程,测量了矿石堆载体和堆场地基表面竖向和水平向位移变形。首先通过这些位移变形发展过程中的转折点,得到堆场地基的极限承载力。其次通过矿石堆载体荷载作用下堆场地基剖面上发生的位移矢量场,分析再现了堆场地基滑移破坏现象和形成机制。发现该堆场此处地基承载力为深厚软弱土层所控制,因承载力严重不足才导致矿石堆载体填筑过程中堆场地基先出现严重下陷和滑动破坏,下沉的浅表两层土体挤占下卧淤泥质粘土层土体空间,迫使其向阻力较小的南柳河一侧推移滑动,造成更大范围的推移破坏,据此建议了该堆场修复加固设计原则。
关键词:  码头堆场,软弱地基,滑动破坏,侧向推移,离心模型试验
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Centrifuge modeling and translation failure mechanism analysis of a bulk cargo terminal yard ground
徐光明
Nanjing Hydraulic Research Institute
Abstract:
A bulk cargo wharf yard foundation contains a weak layer of muddy clay layer, although two side foundations of yard were reinforced by cement mixing pile. However, a sliding failure as well as lateral translation collapse occurred where the thickest muddy clay is during the fill of ore heap on trial. In order to find the real reason for sliding failure and lateral translation collapse and to provide the design basis and reference for repair, a new site investigation was conducted to determine the physical and mechanical properties of the foundation soil. And a large centrifugal model was designed and orepared according to the state of the foundation before sliding failure. The filling process of the ore heap was simulated, and the vertical and horizontal displacement deformation of the surface of the ore heap and the yard foundation was measured. Firstly, the turning points of these displacement and deformation development was identified which is related to the critical point of stability and the ultimate bearing capacity of yard foundation are obtained. Secondly, based on the displacement field on the cross section of yard ground under the load of the ore heap, the failure mode and the development process of the sliding and translation failure of the bulk cargo wharf foundation were analyzed and discussed. The results showed that in the filling of the ore heap, its shallow subsoil subsidence and sliding failure first appeared due to its insufficient bearing capacity. Secondly, the subsidence of shallow subsoil occupied the space of underlying soft muddy clay layer, forcing it to lateral translate towards the side of the Nanliu River, resulting in a wider range of collapse.
Key words:  terminal yard, soft ground, sliding failure, translation collapse, centrifuge model test
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