Two dimensional upper and lower-bound numerical analysis of the basal stability of deep excavations in clay

The basal stability of deep excavations in clay is often analysed using the classical approaches of Terzaghi (1943) and Bjerrum & Eide (1956). Terzaghi’s approach seems to be appropriate to excavation with small depth to width ratios, h/B, whereas Bjerrum & Eide give better results for greater h/B ratios. Not many attempts have been made to unify the two situations. In the present paper, the problem is analysed using upper and lower-bound considering two two-dimensional cases: a basic case, where the rigid stratum was considered deep, not affecting the stability of the excavation, and a case considering a rigid stratum at a certain depth. The embedded length of the wall was assumed null. A proposal for the stability numbers at failure is presented, for a wide range of h/B ratios.publishersversionpublishe