板墙及预应力钢支撑在深基坑跨阶段回筑中的分析与实践

依托上海宝山新城SB-A-4上港十四区07地块二期项目，其地下三层基坑整体一次性开挖至基底，因工程需要，需大幅提前特定超高层建筑区域的回筑进度。设计采用弹性地基板结合空间框架梁的计算方法，建立非完整状态下的基坑与主体结构的一体化耦合分析模型，计算特定状态下基坑及主体结构的相互作用机理及荷载分布。最终在基坑不分区开挖前提下，达成特定区域的先行拆撑及主体结构的回筑。实测数据证明，板墙结合预应力钢斜撑作为一种承载力大，结构刚度高的换撑结构，通过施加相匹配的预应力，可确保板墙具有较好的抗侧刚度及抗倾覆作用，具备作为深大基坑的跨阶段换撑体系的条件。项目的成功实施，为局部需提前回筑的深基坑提供了一定的参考价值。

Analysis and Practicality of a Plate Wall and Prestressed Steel Struts in the Interstage Backfill Construction of Deep Foundation Pits

Based on the phase II project of Block 07, District 14 of Shanggang, Baoshan New City SB-A-4, Shanghai, the underground three-layer foundation pits were excavated to the basement at one time. Due to project needs, the backfill construction progress of specific super high-rise building areas needed to be excavated sig-nificantly in advance. The calculation method of an elastic ground slab combined with a space frame beam was used to establish an integrated coupling analysis model for the foundation pit and the main structure in the incomplete state and to calculate the interaction mechanism and load distribution between the foun-dation pit and the main structure under a specific state. Under the premise of non-zoned excavation of the foundation pit, the preliminary removal of the supports in the specific area and the backfill construction of the main structure were achieved. The actual measurement data verify that, as a type of strut structure with a large bearing capacity and high structural stiffness, a plate wall combined with prestressed steel diagonal braces can ensure that the plate wall has better lateral stiffness and overturning resistance through the application of matching prestresses. This meets the conditions of an interstage support replacement system for deep foundation pits. The successful implementation of the project provides certain reference value for deep foundation pits that need backfill construction in advance.