吹填珊瑚砂场地高层建筑复合地基工程实践与沉降估算

针对马尔代夫胡鲁马累岛礁灰岩吹填珊瑚砂场地7000套16栋25层高层社会保障性住房项目，基于珊瑚砂(钙质砂)及礁灰岩的工程特性，首次提出采用素混凝土桩复合地基处理方案，探究并改进长螺旋钻孔压灌混凝土成桩工艺，其工程实践成效为单桩静荷载试验与单桩复合地基静荷载试验以及建筑物沉降监测结果所验证。根据建筑物沉降监测结果，对比分析《建筑地基处理技术规范》(JGJ 79—2012)和《高层建筑岩土工程勘察标准》(JGJ/T 72—2017)中复合地基沉降计算方法，并进行有限元分析验证。分析结果表明：后者计算结果较符合该工程实际，且规避前者在吹填珊瑚砂地基压缩模量较难准确取值的问题；此外，在类似重大工程项目中，可采用基于载荷试验反演计算参数的有限元法对规范法沉降计算结果进行校验，以优化工程设计。

Application practice and settlement estimation of composite ground for high-rise buildings on coral sand site of hydraulic fill

For the social housing project in Hulhumale Island of Maldives in which 16 25-storey residential buildings composed of 7000 houses are built on the coral sand site of reef limestone of hydraulic fill, the composite ground scheme of plain concrete pile is proposed for the first time to treat coral (calcareous) sand ground according to its engineering characteristics. The piling technology of long helical pile of pressure grouted shaft is discussed and improved. The reinforcement effectiveness of the proposed treatment scheme is verified by the static load tests of single pile and composite ground of single pile as well as the monitored results of building settlement. The settlement calculation methods of composite ground by referring to “Technical Code for Ground Treatment of Buildings” (JGJ 79—2012) and “Standards for Geotechnical Investigation of Tall Buildings” (JGJ/T 72—2017) are compared and then verified by the finite element analysis results. The analysis results disclose that the finite element results agree well with the monitoring results, and moreover the finite element approach may obviate the difficulty in accurately determining the compression modulus of coral sand ground of hydraulic fill which is generally required by the Code method. Hence, in similar major projects, the finite element method, in which the calculation parameters can be attained from back analysis in terms of the static load tests, is capable of verifying the calculation results of the Code method and optimizing the engineering design.