红层岩溶场地高层建筑复合地基设计

Design of Composite Foundation for High-Rise Buildings in Complex Red Bed Karst Site

浅覆盖岩溶区深基础施工经常发生地面塌陷,对人身安全和工程质量构成重大隐患。本文结合红层岩溶场地某高层建筑(35层)地基基础优化设计,通过地质雷达扫描揭示"蜂窝"状非均质各向异性岩体结构特征;采用岩溶注浆对巨型溶洞管道进行填充加固,构筑"人工坝"阻断地下水运移通道。基于溶洞顶板抗冲切稳定性分析结果,提出采用低承载力与高置换率相结合的素混凝土刚性桩复合地基;对极薄溶洞顶板区,利用钢管桩进行托换加固,有效规避了有效桩长短、桩端应力大导致地基局部失稳及施工塌陷的风险。建筑竣工后运行良好,监测显示高层建筑沉降变形最大仅9.63mm。

The ground collapse occurs frequently in the construction of deep foundation in the shallow overlying rock-karst area,which constitutes a major hidden danger to personal safety and engineering quality.In this paper,combined with the foundation optimization design of a high-rise building(35 floors)in the red layer karst site,the structural characteristics of"honeycomb"heterogeneous anisotropic rock mass are revealed through the geological radar scanning.Meanwhile,the giant karst cave pipeline is filled and reinforced by karst grouting,and the"artificial dam"is constructed to block the groundwater transport channel.Based on the analysis results of the stability against punching and cutting of the karst cave roof,the composite foundation of plain concrete rigid pile with low bearing capacity and high replacement rate is proposed.As for the extremely thin karst cave roof area,the steel pipe pile is used for underpinning and reinforcement,which effectively avoids the risk of local instability and construction collapse caused by the effective length of pile and large stress at the pile end.After the completion of the building,it runs well.Meanwhile,the monitoring shows that the maximum settlement deformation of the high-rise building is only 9.63 mm.