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沿海吹填围垦地区土质较差,淤泥软弱土层较厚,在后期填土作用下土体会产生很大的固结沉降。后期不同堆载填土方式对桥梁基础影响较大,可降低基桩承载力,同时平衡堆载主要增加基桩的沉降,而不平衡堆载则对基桩水平位移影响较大。结合台州湾大桥工程建设,选取3根基桩进行了平衡堆载(围载)试验,另外,选取了3根基桩进行了不平衡堆载试验,研究不同堆载条件下对桩基承载特性的影响。现场试验结果表明,平衡堆载条件下主要引起桩侧产生负摩阻力,堆载高度达到4 m,堆载面积为24 m×16 m时,负摩阻力总和达到2 687 k N左右,中性点深度约为29.5 m,约为0.36倍桩长,且负摩阻力的发展是随时间而变化的;不平衡堆载条件下主要产生土拱效应,使桩基产生较大的水平位移,试验中不平衡堆载对吹填区的影响主要在距离地面20 m范围之内,土中最大水平位移出现在距离地面4~5 m左右位置,而桩身最大水平位移出现在桩顶。
Coastal reclamation reclamation area of poor soil, silt soft soil thicker, soil filling in the later period will have a great consolidation settlement. In the later stage, different loading and filling methods have a greater impact on the bridge foundation, which can reduce the bearing capacity of the pile, meanwhile, the balance pile increases the settlement of the pile mainly, while the unbalanced pile load has a greater impact on the pile horizontal displacement. In combination with the construction of Taizhou Bay Bridge, three foundation piles were selected to carry out the equilibrium loading (containment) test. In addition, three foundation piles were selected to carry out the unbalanced loading test to study the influence of pile loading characteristics under different loading conditions . The field test results show that under the condition of balanced loading, the negative friction force is mainly caused by pile side, the pile height reaches 4 m and the stacking area is 24 m × 16 m, the sum of negative frictional resistance reaches about 2 687 kN. The depth of the point is about 29.5 m, about 0.36 times the length of the pile, and the development of negative friction resistance changes with time. The soil arching effect is mainly caused by unbalanced loading, which results in a large horizontal displacement of pile foundation. The unbalanced load affects the landfill mainly within 20 m from the ground. The maximum horizontal displacement in soil occurs about 4 ~ 5 m away from the ground, while the maximum horizontal displacement of pile body occurs at the top of the pile.