RE-PENETRATION OF A SPUDCAN ON SAND NEAR AN EXISTING FOOTPRINT
RE-PENETRATION OF A SPUDCAN ON SAND NEAR AN EXISTING FOOTPRINT
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发表时间：
2019
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通讯作者：
Yu Fang;Cheng Liu;Ying-Chu Shih
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作者：
Yu Fang;Cheng Liu;Ying-Chu Shih
本文介绍了与泥浆罐在现有足迹附近的沙子上重新穿透有关的分析和实验数据。利用仪表化的1-g物理模型试验装置，研究了垂直反力、水平反力和反力矩随侵彻深度的变化规律。锥形推土罐直径D为200 mm，海底材料为饱和松散渥太华砂。根据实验数据，得出了以下结论。对于第一次侵彻，所测得的垂直反作用力与海军建筑师和轮机工程师学会(SNAME 2008)的设计指南计算的理论解符合得很好。在0~0.1D的侵彻深度范围内，偏置距离为零的二次侵彻，由于压痕凹陷的存在，桩罐处于“压空”状态，所有测得的桩罐反应均为零。但在侵彻深度为0.15D时，由于足迹土在第一次侵彻过程中受到严重的压缩和剪切，测得的竖向反力随侵彻深度的增加而迅速增大。对于侵彻深度为0，偏移距离为0.5D的再侵彻，桩基-足迹的相互作用类似于在斜坡上或其附近加载基础。然而，在相同的贯入深度为0.2d时，诱发土体的行为类似于浅基础下的一般剪切破坏。在不同的贯入阶段，地基土体的破坏机制不同，导致水平反力和反力矩随深度增大的异常反转。当偏移距离大于spudcan直径的两倍时，现有示意图的效果将消失。对于SPUCAN在砂土上的再渗透，临界偏移距离在0.25~0.5D之间变化。临界偏移距既受贯入深度的影响，又受海床土类型的影响。
This paper presents analytical and experimental data associated with the re-penetration of a spudcan on sand near an existing footprint. The instrumented 1-g physical model spudcan testing facility was used to investigate the variation of vertical reaction force, horizontal reaction force, and reaction moment on the spudcan with increasing penetration depth. The diameter D of the conical spudcan was 200 mm, and saturated loose Ottawa sand was used as the seabed material. Based on the experimental data, the following conclusions were drawn. For the first penetration of the spudcan, the measured vertical reaction force on the spudcan was in fairly good agreement with the theoretical solution calculated with the design guideline by the Society of Naval Architects and Marine Engineers (SNAME 2008). For the re-penetration with an offset distance equal to zero at the penetration depth from 0 to 0.1D, due to the existence of the footprint depression, the spudcan was in a “stamp-on-void” condition, and all measured reactions on the spudcan were zero. However, after the bearing spudcan surface was embedded in soil at the penetration depth of 0.15D, since the footprint soil had been heavily compressed and sheared during the first penetration, the measured vertical reaction increased rapidly with increasing depth of penetration. For the re-penetration with an offset distance of 0.5D at the penetration depth of zero, the spudcan-footprint interaction was similar to the loading of a footing on or near a slope. However, with the same offset distance at the penetration depth of 0.2D, the induced soil behavior was similar to the general shear failure below a shallow foundation. The unusual reversal of horizontal reaction and reaction moment measured with increasing depth was induced by different failure mechanisms in foundation soil at different penetration stages. When the offset distance was greater than twice the spudcan diameter, the effects of the existing footprint disappeared. For the re-penetration of spudcan on sand, the critical offset distance varied between 0.25D and 0.5D. The critical offset distance was influenced by both the penetration depth and the type of seabed soil.