The structural support system is the key element in any design of deep excavations, particularly in difficult ground conditions, and an adequate safety margin is required to cover uncertainties inherent in geotechnical engineering. When deep excavations are supported e.g., by a diaphragm wall and, depending on the depth of excavation, multiple layers of struts, usually the struts are the critical elements and overall failure will generally occur if a complete strutting level fails. However, if failure of an individual element occurs, the system should be robust enough not to fail due to 3D effects allowing for stress redistribution within the support system. An additional factor is the embedment depth of the wall. A parametric finite element study in 3D has been carried out to demonstrate the consequences of individual struts failing by analysing a 30-m deep excavation in marine clay supported by a diaphragm wall and multiple layers of struts. The following imperfections have been investigated, namely insufficient embedment depth of the wall into the stiff soil layer and failure of individual struts. It could be shown that, provided a robust design is put in place, significant stress redistribution capacity is available to avoid catastrophic failure of the excavation when individual support elements fail.
|Journal||International Journal of Geomechanics|
|Publication status||Published - 7 Apr 2020|