Corner effects in deep excavations

Abstract

The precise calculation of the anchorage free length used in retaining structures plays a crucial role in the design of such structures. The most important factors to be considered while determining the free length of the anchorages are the slip surfaces and their respective outer boundaries. The reason for that is to reach the calculated anchorage capacities, the roots of the anchorages must be installed in inert soil. There are a lot of factors which influence the outer boundaries of the slip surfaces. The corners in retaining structures are one of the most important of these factors. Models based on plain-strain are not adequate to determine possible active slip surfaces at the corners or at locations close to the corner. Taking this inadequacy into consideration, the effects of corners in retaining structures on active slip surfaces are researched. In this context, how corners between two adjacent retaining walls, the distance from the said corner and the variation of internal friction angle and dilatation angle depending on the relative density affect the outer boundary of the slip surface is researched. For this research, numerical models are created by using a finite element modelling program called Plaxis 3D. But before that, to determine the parameters of the models and verify the accuracy of the models, small-scale retaining wall models carried out within the scope of TUBITAK Project No:114M329 are modelled using Plaxis 3D. The results from the small-scale retaining wall models and the results of their respective numerical models are compared and it is seen that the predetermined parameters match with the results obtained from the numerical model test. Lastly, verified model specifications are used in creating the necessary models and the effects of the variables influencing the outer boundary of the slip surface are shown.