软土区不平衡堆载下桩基负摩阻力的数值模拟研究

在沿海软土地区由于吹填造陆等原因,经常存在不平衡堆载现象.由于海滩涂的土体存在含水率和压缩性高等工程特点,使桩基在不平衡堆载下产生明显的负摩阻力.负摩阻力会在桩周产生很大的下拽力,很大程度降低了桩基的竖向承载力,同时,由于堆载的不对称,会在桩周产生不对称的负摩阻力,从而导致附加弯矩的存在.通过大型有限元法软件ABAQUS对软土区不平衡堆载进行建模,在建模过程中,对桩土模型进行一定的简化,模型参数按照经验取值.分别对桩基主动侧和被动侧的位移和负摩阻力进行分析,进而研究了不平衡堆载对单桩负摩阻力的作用性状,为实际工程提供参考.

Numerical Analysis of the Negative Frictional Resistance of the Pile Under the Action of Imbalanced Surcharge Loads

In coastal soft-soil areas, there often exists the phenomenon of imbalanced surcharge loads because of the blowing-filling epeirogenesis. The engineering characteristics of the soft soil being higher in moisture and compressibility make the pile foundation produce obvious negative friction resistance under the action of the imbalanced surcharge load. The negative frictional resistance may result in a large down-pulling force around the pile,which will, to a great extent,reduce the vertical bearing capacity of the pile foundation. At the same time,the imbalanced surcharge load may lead to asymmetric negative frictional resistance around the pile, which will result in the occurring of additional bending moment. The imbalanced surcharge load in the soft soil area is modeled with the help of the finite element software ABAQUS in the paper, in the course of which the model for the pile soil is somewhat simplified and the parameters of the model are chosen according to our experience. The displacement and negative frictional resistance on both the active side and the passive side of the pile foundation are analyzed and studied, upon the basis of which the effects and properties of the imbalanced surcharge load on the negative frictional resistance of a single pile are further studied. The paper may serve as a useful reference for other practical projects.