Three-dimensional Numerical Study of the Effect of Convex Corners on the Displacements Induced by Excavation for Soil-Nailed Walls

Document Type : Research Article


1 Geotechnical Engineering, Civil Engineering, Yazd University, Yazd, Iran

2 a department of Civil Engineering, Yazd university, Yazd, iran

3 civil engineering department, faculty of engineering, yazd university


In most excavation projects, the excavation plan is irregular in shape, including concave and convex corners. In practice, the 2D (i.e., plane strain) analysis is often employed to evaluate the factor of safety and displacements induced by excavation for concave and convex corners. However, contrary to concave corners, using the plane strain analysis is not on the conservative side for convex corners. The present paper uses a numerical modeling methodology to study the effects of the convex corner on the displacements induced by excavation for soil-nailed walls. In this regard, a series of parametric studies are carried out, involving 2D and 3D deformation analyses of nine soil-nailed excavation models with three wall heights and three types of soil. The results of the paper show that the lengths of the affected zone (i.e., the zone adjacent to the convex corner along which the 3D settlements at the wall crest are higher than the 2D one) increase by decreasing the soil strength. Moreover, the results indicate that the maximum ratios of 3D settlement to 2D one along the affected zone are independent of the wall height and soil type. In addition, the results suggest that giving azimuth to soil nails along the affected zone causes the wall displacements along this zone to increase significantly.


Main Subjects

[1] C. Ou, D.-C. Chiou, T.-S. Wu, Three-Dimensional finite element analysis of deep excavations, Geotechnical Engineering, 122(5) (1996) 337-345.
[2] F.H. Lee, K.Y. Young, K.C.N. Quan, K.T. Chee, Effect of corners in strutted excavations: Field monitoring and case histories, Geotechnical and Geoenvironmental Engineering, 124(5) (1998) 339-349.
[3] R.J. Finno, J.T. Blackburn, J.F. Roboski, Three-Dimensional effects for supported excavations in clay, Geotechnical and Geoenvironmental Engineering, 133(1) (2007) 30-36.
[4] H. Yuan, Q. Zhang, Three dimensional performance observed in an irregular deep excavation in Shanghai soft clay, GEOTECHNICAL SPECIAL PUBLICATION, 206 (2012) 107-113.
[5] W. Zhao, C. Chen, S. Li, Y. Pang, Researches on the influence on neighboring buildings by concave and convex location effect of excavations in soft soil area, Intell Robot Syst,  (2014).
[6] H. Imeni, A. Ghanbari, F. Rashidi, H. Shahir, Numerical study on the effect of convex corner on the behavior of deep excavation, Electronic Journal of Geotechnical Engineering, 22(10) (2017) 3965-3984.
[7] M. Sabermahani, M. Moradi, A. Pooresmaeili, Performance of soil-nailed wall with three-dimensional geometry: centrifuge study, Physical Modelling in Geotechnics, Volume 2, (2018) 1247-1252.
[8] M. Sabermahani, M.N. Shahrbabak, M.M. Bagheri, Three-dimensional effects of nail arrangement on soil-nailed convex corners, Numerical Methods in Geotechnical Engineering IX, Volume 2,  (2018) 1129-1136.
[9] I. Itasca Consulting Group, Fast Lagrangian Analysis of Continua User's Guide, (2019).
[10] C.A. Lazate, H. Robinson, J.E. Gomez, A. Baxter, A. Cadden, R. Berg, GEOTECHNICAL ENGINEERING CIRCULAR NO. 7 SOIL NAIL WALLS - REFERENCE MANUAL, National Highway Institute U.S. Department of Transportation Federal Highway Administration, 2015.
[11] Y. Lim, J.-L. Briaud, Tieback walls in sand: numerical simulation and design implications, Geotechnical and Geoenvironmental Engineering, 125 (1999) 101-110.
[12] M. Zhang, E. Song, Z. Chen, Ground movement analysis of soil nailing construction by three-dimensional (3-D) finite element modeling (FEM), Computers and Geotechnics, 25 (1999) 191-204.