Three-Dimensional Analysis of Buttress and Cross Walls on Controlling Wall Deformation Induced by Deep Excavation

The buttress and cross walls are commonly used to control wall deformation induced by deep excavations. In this paper, the optimum performance of the buttress wall along two cross-wall intervals in deep excavations is evaluated through the three-dimensional finite-element analysis. A well-documented case history of a deep excavation was initially utilized to validate numerical analysis. Furthermore, extensive numerical parametric studies were performed to investigate the most effective design of deep excavation with buttress and cross walls. The results concluded that the implementation of buttress walls could enhance the overall flexural rigidity of the retaining system and provide additional frictional resistance, in which its mobilized friction area was highly dependent on the location of the buttress wall along the interval of two cross walls. Furthermore, a new design chart is proposed to evaluate the most optimum buttress wall location along two cross-wall intervals in reducing wall deformation, which was verified by a real excavation case and can be reasonably used as design recommendations for deep excavation with buttresses and cross walls.