Performance of DSM walls on shoring excavation subjected to influence of nearby high building loads and rapid drawdown in the lower mainland, Vancouver, BC

ABSTRACT: The use of deep soil mixing (DSM) as a method of shoring for excavations is a common practice in engineering. This study presents a finite element 2D model in Plaxis to analyze the support of a 4.3 m excavation for a new high-rise development using a DSM wall reinforced up to a depth of 10m, while the rest remains without reinforcement up to another 22 m below ground level. The design of the DSM wall aims to protect the excavation against ground collapse from the self-weight and the presence of a 16-storey existing high-rise building. To consolidate the ground, stone columns were constructed up to the less permeable soil layers for soil densification, and a preload height of 3.5m was applied. The DSM wall was numerically designed with respect to the superstructure, consolidation settlement for the soft clay layer, and the rapid drawdown during the excavation process. Additionally, the horizontal deflection and vertical settlement of both the excavation wall and the high-rise building were analyzed based on different water content for DSM cement mixing with two target layers viz., the loose sand and clayey silt. The study provides valuable insights into the design of DSM walls for excavations, taking into consideration various factors that can affect the stability of the structure.