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Geomechanics and Engineering Volume 9, Number 4, October 2015 , pages 513-530 DOI: https://doi.org/10.12989/gae.2015.9.4.513 |
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A numerical study on the seepage failure by heave in sheeted excavation pits |
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Serdar Koltuk, Tomas M. Fernandez-Steeger and Rafig Azzam
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| Abstract | ||
| Commonly, the base stability of sheeted excavation pits against seepage failure by heave is evaluated by using two-dimensional groundwater flow models and Terzaghi's failure criterion. The objective of the present study is to investigate the effect of three-dimensional groundwater flow on the heave for sheeted excavation pits with various dimensions. For this purpose, the steady-state groundwater flow analyses are performed by using the finite element program ABAQUS 6.12. It has been shown that, in homogeneous soils depending on the ratio of half of excavation width to embedment depth b/D, the ratio of safety factor obtained from 3D analyses to that obtained from 2D analyses FS(3D)/FS(2D) can reach up to 1.56 and 1.34 for square and circular shaped excavations, respectively. As failure body, both an infinitesimal soil column adjacent to the wall (Baumgart & Davidenkoff's criterion) and a three-dimensional failure body with the width suggested by Terzaghi for two-dimensional cases are used. It has been shown that the ratio of FS(Terzaghi)/FS(Davidenkoff) varies between 0.75 and 0.94 depending on the ratio of b/D. Additionally, the effects of model size, the shape of excavation pit and anisotropic permeability on the heave are studied. Finally, the problem is investigated for excavation pits in stratified soils, and important points are emphasized. | ||
| Key Words | ||
| seepage failure; heave; sheeted excavation pit; three-dimensionality; finite element method | ||
| Address | ||
| Department of Engineering Geology and Hydrogeology, RWTH Aachen University, Lochnerstr. 4-20, D-52064 Aachen / Germany. | ||