Abstract
In this paper, the three-dimensional finite element software, 3-D PLAXIS, is used to back study possible failure reason of a deep excavation project in soft clay. The building project is located in Taipei covering an area of 200 m by 200 m. General ground condition consists approximately 29 m of soft with SPT-N of 1 to 5 only. The average elevation of the construction site is plus 4.4 m. It’s planned to excavate down to minus 9.5 m. It is planned to leave a berm into 1(V) by 2.5 (H) slope along with installation of shotcrete and 70 cm of drilled shafts along the east side of the site. Two horizontal layers of H pile will then be installed when reaching the second basement level. Slope failure occurs on the east side during excavation. Comparison between the 3D FEM analytical results and instrumentation measurement data showed asymmetric excavation and misjudgment of the elevation of bedrock are the possible reasons to cause the failure of the excavation.
