To date, deep excavations in soft clays were constructed routinely by either the bottom-up (BU) or the top-down (TD) method. Because of its mega size, special underground space arrangements and tight construction schedule, the oversized basement of Shanghai International Finance Centre (SIFC) was divided into five zones for construction, following an innovative synchronous-cross zoned excavation procedure in combination of BU and TD methods and retained by both regular and T-shaped cross-section diaphragm walls (DWs); in addition to cross-lot struts and slabs, DWs were propped by large-diameter circular beam-truss element strutting systems (CB-TESSs). To mitigate adverse influences of dewatering on urban environments, trench cutting and remixing deep soil mix walls (TRD-walls) in place of the conventional overlapped grouting columns were constructed as waterproof curtains. The comprehensive field instrumentation data revealed that on average SIFC exhibited better performance than those local excavations and TRD-walls had excellent watertightness. Since the unsymmetrical plane geometries of CB-TESSs and inconsistent lateral deflections, , of the perimeter and inner partition DWs impaired the roundness of circular beams, DWs braced by CB-TESSs developed much greater than DWs braced by cross-lot struts. Due to its excessively long excavation duration, the TD zone propped by cast slabs experienced much larger than the BU zones propped by struts. DWs played a governing role in restraining time-dependent at shallow excavation levels; whereas, strutting systems gradually played a more important role as excavation went deeper. Distinct from governed by several major factors, vertical movement of earth retaining structures was dominated by excavation depth. The presence of another excavation nearby reduced lateral earth pressures against the adjacent DW of SIFC and thus it underwent smaller . Contrary to the assumption made in the theoretical models for calculating the factor of safety () against basal heave instability, the strata behind DWs and below excavation levels underwent upward rather than downward movement during excavation, which interprets why data were irrelevant of numbers in the excavation databases worldwide. Finally, technical implications of the observed excavation behaviors to the future design and constructions are discussed.

中文翻译：

---

自下而上与自上而下相结合的上海国际金融中心超大地下室同步跨分区开挖：结构与岩土性能


迄今为止，软粘土的深基坑通常采用自下而上（BU）或自上而下（TD）的方法进行施工。上海国际金融中心超大型地下室因体量庞大、地下空间布置特殊、施工工期紧张，分五个分区施工，创新采用BU与TD相结合的同步交叉分区开挖工艺并由规则和 T 形横截面地下连续墙 (DW) 保留；除了跨地块支柱和板之外，DW 还由大直径圆形梁桁架元件支撑系统（CB-TESS）支撑。为了减轻脱水对城市环境的不利影响，用切沟和重新混合深层土壤混合墙（TRD墙）代替传统的重叠灌浆柱建造防水幕。综合现场仪器数据显示，SIFC 的平均性能优于局部开挖，TRD 墙具有出色的水密性。由于 CB-TESS 的不对称平面几何形状以及周边和内部隔断 DW 的横向偏转不一致，损害了圆形梁的圆度，因此由 CB-TESS 支撑的 DW 比由跨地段支柱支撑的 DW 发展得更大。由于开挖时间过长，由现浇板支撑的 TD 区域比由支柱支撑的 BU 区域大得多。 DW 在抑制浅基坑的时间依赖性方面发挥了主导作用；而随着挖掘的深入，支撑系统逐渐发挥出更重要的作用。与受几个主要因素控制不同，挡土结构的竖向运动主要受开挖深度的影响。 附近另一个基坑的存在减少了 SIFC 相邻 DW 的侧向土压力，因此其规模较小。与计算抗基础隆起失稳的安全系数 () 的理论模型中所做的假设相反，DW 后面和开挖水平面以下的地层在开挖过程中经历了向上而不是向下的运动，这解释了为什么数据与开挖中的数字无关。全球数据库。最后，讨论了观察到的开挖行为对未来设计和施工的技术影响。