Performance of Cross and Buttress Walls to Control Wall Deflection Induced by Deep Excavation in Dense Urban Area

Abstract

The paper presents the performance of two deep excavation Case-histories and their three-dimensional finite element analyses. Case 1 describes the application of cross walls and buttress walls in controlling the diaphragm wall deflection and avoiding the low-story adjacent buildings from damages, in which those low-story buildings were founded on shallow foundations and located 1 to 2 m from the excavated area. Moreover, Case 2 demonstrates the application of cross walls and buttress walls to limit the movement of adjacent existing twin metro tunnels induced by deep excavation. In addition, the diaphragm wall of Case 2 defected due to heavy rain while concreting process and causing the excavation more challenging to be executed safely. Three-dimensional finite element analyses were conducted to simulate and examine the performance of cross and buttress walls to control movements induced by deep excavation. The result shows that the cross walls have a significant effect in controlling deformations induced by deep excavation. The dense interval between cross walls could yield a very rigid retaining wall system and cause very small wall deflections. The measure can be used for an excavation project nearby metro systems to reduce the potential settlement of the metro tunnels.