An Investigation into the Performance of Excavation with Inclined Struts Connected to Adjacent Buildings

Document Type : Regular Paper

Authors

1 Department of Civil Engineering; Islamic Azad University, Karaj Branch, Karaj, Iran

2 Department of Civil Engineering, University of Tehran, Tehran, Iran

Abstract

One practical excavation support system is the inclined struts connected to adjacent buildings. This method is very common in small excavations, because of simplicity and minimum cost, when soil is cohesive and depth of excavation is less than stability depth (Hcr) but adjacent structures is at risk of damage due to weakness, old age or lack of proper skeleton frame. Although this method has been used in many small excavations, it is not entirely investigated. This study describes the performance of struts based on field observations and the results of numerical analysis. A small strain constitutive model (Duncan-Chang) was used for analysis. The efficiency of struts was evaluated by comparing the movements of the real case of excavation with struts and the same case but without struts. The results indicate that movements are decreased substantially using struts. A mechanism of struts during excavation is proposed and the effect of installation of the inclined strut on deformation patterns is discussed. The study introduces simple instrumentation designed in the course of the study that can be used in common engineering practice for small to medium-sized excavations.

Keywords


[1] Boscardin, M. D., Cording, E. G. (1989) “Building response to excavation-induced settlement”, Journal of Geotechnical Engineering, vol. 115, no.1 January, pp 1-21.
[2] Burland, J. B. (1995) “Assessment of risk of damage to building due to tunneling and excavation”, Proceedings of 1st International Conference on Earthquake Geotechnical Engineering, IS-Tokyo.
[3] Finno, R.J., Voss Jr F.T.; Rossow, E. and Blackburn, J. T. (2005) “Evaluating damage potential in buildings affected by excavations” Journal of Geotechnical and Geoenvironmental Engineering, Vol. 131, No. 10, pp 1199-1210.
[4] Sadeghian S., Fakher A. (2010) “An investigation into a shoring method to support buildings adja­cent to excavations”, The 17th Southeast Asian Geotechnical Conference Proceeding. Taipei, Taiwan, May 10-13, pp 207-210.
[5] Yong, K.Y., Lee, F.H., Parnploy, U., Lee, S.L. (1989), ”Elasto-plastic consolidation analysis, for strutted excavation in clay”, Computers and Geotechnics 8, pp 311-328.
[6] Ooi, P.S.K., Walker, M.P., Smith, J.D. (2002) “Performance of a single-propped wall during excavation and during freezing of the retained soil”, Computers and Geotechnics, Volume 29, Issue 5, Pages 387-409.
[7] Kim, G.H, Lee, U.K, Park U.Y, Kim, J.Y, Kang, K.I. (2005) “Modified braced wall system with pre-stressed wale for excavation in urban areas”, Building and Environment 40,pp 1689–1696.
[8] Costa P.A., Borges, J.L. (2007),“Analysis of a braced excavation in soft soils considering the consolidation effect”, Geotech Geol Eng 25:617–629.
[9] Tang Y.G., Kung G.T.C., 2010, “Investigating the effect of soil models on deformations caused by braced excavations through an inverse-analysis technique”, Computers and Geotechnics 37 pp 769–780.
[10] Wu C. H., Ou C.Y., Tung N., 2010, “Corner effects in deep excavations establishment of a forecast model for taipei basin T2 zone”, Journal of Marine Science and Technology,18(1), 1-11.
[11] Chowdhury, S.S., Deb, K., Sengupta, A. (2013) “Estimation of design parameters for braced excavation: numerical study”, International Journal of Geomechanics, 13(3)234–247.
[12] Ou C. Y., Hsieh P. G., Lin Y.L. 2011, “Performance of Excavations with Cross Walls”, J. Geotech. Geoenviron. Eng., 137(1), pp 94-104.
[13] Ou C.Y, Hsieh P.G, Lin Y.L. 2013, “A parametric study of wall deflections in deep excavations with the installation of cross walls”, Computers and Geotechnics, 50, pp 55-65.
[14] Puller, M. (2003) “Deep Excavations: A Practical Manual”, Thomas Telford Ltd, Second edition.
[15] Fakher, A. and Sadeghian, S. (2011), “An investigation into Inclined Struts method as a type of shoring”, Geotechnical Aspects of Underground Construction in Soft Ground, Pages 369–375, Rome, Italy, 16-18 May 2011.
[16] Sabzi Z., Fakher A. (2012) “The effect of confining stress on the analysis of excavations adjacent to existing buildings”, International Conference on Geotechnique, Construction Materials and Environment, Kuala Lumpur, malaysia, Nov 14-16 pp162-166.
[17] Sabzi Z., Fakher A. (2015) “The performance of buildings adjacent to excavation supported by inclined struts”, International Journal of Civil Engineering, Vol 13(1).
[18] Sabzi Z., Fakher A. (2017) “3D Response of an Excavation Adjacent to Buildings Supported by Inclined Struts” Acta Geotechnica Slovenica 14 (1), 38-53.
[19] Hibbit, Karlsson, Sorensen, Inc. (2010) ABAQUS/Standard User’s Manual, Version 6.10. Pawtucket, RI, USA.
[20] Brown, P.T., and Booker, J.R. 1985. “Finite element analysis of excavation”.Computers and Geotechnics, 1: 207.220.
[21] Duncan, J.M., and Chang, C.Y. 1970, “Nonlinear analysis of stress and strain in soils” Journal of the Soil Mechanics and Foundations Division, ASCE, 96(5):pp637-659.
[22] Pramthawee P., Jongpradist P. and Kongkitkul W., 2011, “Evaluation of hardening soil model on numerical simulation of behaviors of high rockfill dams”, Songklanakarin J. Sci. Technol. 33 (3), 325-334.
[23] Khoiri, M., Ou C.Y. 2013, “Evaluation of deformation parameter for deep excavation in sand through case histories” Computers and Geotechnics, Volume 47, Pages 57–67.
[24] Dang, H.P., Lin, H.D., and Juang, C.H. 2012, “Evaluation of soil variability influence on deep excavation analysis–simplified approach”, GeoCongress: pp. 2895-2903.
[25] Dang, H.P., Lin, H.D. and Juang, C.H. 2014, “Analyses of braced excavation considering parameter uncertainties using a finite element code”, Journal of the Chinese Institute of Engineers, Volume 37, Issue 2, pages 141-151.
[26] Ou C.Y, Shiau B.Y, 1998“Analysis of the corner effect on excavation behaviors”, Can. Geotech. J. Vol. 35, pp 532-540.
[27] Zhang B., 2012, “Analysis on parameters in Duncan-Chang constitutive model” Advanced Materials Research Vols. 368-373 pp 2900-2903.
[28] Duncan, J.M., Byrne, P., Wong, K.S. and Mabry, P. 1980. “Strength, stress-strain and bulk modulus parameters for finite element analyses of stresses and movements in soil masses”, Report No. UCB/GT/80-01, Office of Research Services University of California, Berkeley California, pp. 20-49.
[29] Ghahreman B. (2004), “Analysis of Ground and Building Response around Deep Excavation in Sand”, PhD thesis, University of Illinois Urbana Champaign.
[30] Hsieh P. G., and Ou, C.Y. (1998) “Shape of ground surface settlement profiles caused by excavation”, Canadian Geotechnical Journal, Vol. 35, 1004-1017.