考虑鼓胀和自重的散体材料桩复合地基承载力分析  

Bearing capacity of composite foundation with granular material pile considering bulging effect and self-weight of soils

作　　者：臧一平 刘聪 ZANG Yi-ping;LIU Cong(The Third Geological Team of Jiangsu Geology and Mineral Bureau,Zhenjiang 212001,Jiangsu,China;Faculty of Civil Engineering and Mechanics,Jiangsu University,Zhenjiang 212001,Jiangsu,China)

机构地区：[1]江苏省地矿局第三地质大队,江苏镇江212001 [2]江苏大学土木工程与力学学院,江苏镇江212013

出　　处：《地基处理》2021年第6期451-457,共7页Journal of Ground Improvement

摘　　要：散体材料桩以鼓胀破坏为主,但目前鲜见能同时考虑鼓胀破坏特性、桩与桩周土间相互作用及自重的承载力计算方法。鉴于此,从半空间轴对称弹性理论出发,深入分析散体材料桩复合地基的力学特性,考虑散体材料桩的侧向鼓胀破坏,根据桩土径向变形协调及桩土界面径向应力相等,给出考虑径向变形的桩和桩周土体竖向应力表达式,获得桩土应力比计算公式。在此基础上,应用土体莫尔-库仑破坏准则并考虑桩周土体自重的影响,获得散体材料桩极限承载力计算公式,并进而得到复合地基承载力。最后,利用得到的承载力计算公式开展室内模型试验和实际工程案例计算。考虑鼓胀和自重的理论计算结果仅与室内模型试验复合地基承载力偏差20.2%,而经典的BRAUNS方法计算偏差高达229.4%。上海洋山深水港人工岛散体材料桩复合地基理论计算结果与实测偏差15.4%,而经典的HUGHES&WITHERS方法偏差高达59.4%。表明考虑鼓胀和自重的计算方法较经典方法更接近于工程实测值,说明其应用于实际工程具有一定的可行性。The granular material piles are damaged by lateral bulging,while the calculation method for bearing capacity of composite foundation with granular material piles by considering both the bulging effect and self-weight of soils as well as pile-soil interaction,is rarely reported in the literature.In view of this,based on the elasticity theory of axisymmetric half-space,the mechanical properties of composite foundation with granular material piles are analyzed.Considering the factors,such as lateral bulging of piles,the coordination of pile-soil deformation in radial direction and the equality of radial stress on the pile-soil interface,the vertical stress expression of both pile and soil with consideration of radial deformation is given,and the corresponding calculation formula of pile-soil stress ratio is provided.Furthermore,the Mohr-Coulomb failure criterion of soils is applied to develop the calculation formula of ultimate bearing capacity of piles by considering the influence of the self-weight stress of soils around the pile,then the bearing capacity of composite foundation with granular material piles is obtained.Finally,the calculation formula of bearing capacity for composite foundation is applied to calculate the indoor model tests and the actual engineering case.The deviation of bearing capacity of composite foundation between the theoretical calculation results in this study and the indoor model test is only 20.2%,while that obtained by classical BRAUNS’method instead of the proposed theoretical calculation is as high as 229.4%.The theoretical calculation results of the artificial island in Shanghai Yangshan port have a deviation of 15.4%from the measured value,while the deviation by the classical HUGHES and WITHERS’method is up to 59.4%.These results show that the calculation results by the proposed method is closer to the measured values than those by classical methods,which indicates that the proposed calculation method is feasible to be applied in the actual project.

关 键 词：散体材料桩 复合地基 桩土应力比 极限承载力 侧向鼓胀变形 

分 类 号：TU473.1[建筑科学—结构工程]