A Case Study of The Performance of A Pile-Supported Bracing Method for Basement Building

Abstract

Deep excavations in urban areas are highly hazardous due to extensive settling of the surrounding soil, which can lead to the failure of retaining wall systems and the consequent collapse of adjoining properties. The retaining wall and bracing system are important for completing deep excavations for a basement building project. This paper evaluates the performance of an alternative, innovative, low-cost pile-supported bracing system (PSBS) method during excavation for two-level basement construction. Assessed PSBS performance in terms of ground settlement, lateral movement of supporting systems, schedule, and cost comparison. The PSBS excavation method was designed and then implemented to construct a two-level basement using the bottom-up method. The total station was utilized to monitor three-dimensionally, like the adjacent school building, ground surface settlement, and lateral movement of supporting systems. A schedule and cost comparison were performed using internal bracing and the PSBS technique. The recorded filed data was analysed, and it found that the lateral movement of the support system, adjacent building, and ground settlement is within the allowable limit. According to the estimated results, the PSBS method reduces construction time by 272 days compared to the internal bracing system. The PSBS approach is also less expensive than internal bracing for a two-level basement.

Keywords

• Bracing system
• excavation method
• two-level basement
• ground settlement
• lateral movement

References

1. Zhang, J.F., Chen, J.J. Wang, and Zhu, Y.F., Prediction of tunnel displacement induced by adjacent excavation in soft soil, Tunnelling and Underground Space Technology, 36, 24-33, 2013.
2. Li, S. and Lu, W., Characteristics of ground surface settlement associated with deep excavation in Beijing city, 2020 International Conference on Urban Engineering and Management Science (ICUEMS), 159-163, 2020.
3. Konai, S., Sengupta, A., and Deb, K., Effect of excavation depths on ground surface settlement for embedded cantilever retaining structure due to seismic loading, Procedia engineering, 199, 2342-2347, 2017.
4. Hsiung, B.C.B. and Dao, S.D., Prediction of ground surface settlements caused by deep excavations in sands, Geotechnical Engineering, 46(3), 111-118, 2015.
5. Godavarthi, V.R., Mallavalli, D., Peddi, R., Katragadda, N., and Mulpuru, P., Contiguous pile wall as a deep excavation supporting system, Leonardo Electronic Journal of Practices and Technologies, 19, 144-160, 2011.
6. Blackburn, J.T. and Finno, R.J., Three-dimensional responses observed in an internally braced excavation in soft clay, Journal of Geotechnical and Geoenvironmental Engineering, 133(11), 1364-1373, 2007.
7. Finno, R.J., Bryson, S., and Calvello, M., Performance of a stiff support system in soft clay, Journal of Geotechnical and Geoenvironmental Engineering, 128(8), 660-671, 2002.
8. Hashash, Y.M., and Whittle, A.J., Mechanisms of load transfer and arching for braced excavations in clay, Journal of geotechnical and geoenvironmental engineering, 128(3), 187-197, 2002.

9. Hsieh, P.G., and Ou, C.Y., Shape of ground surface settlement profiles caused by excavation, Canadian geotechnical journal, 35(6), 1004-1017, 1998.
10. Hudson, M.B., Cefali, D.A., Lew, M., and Crow, M.R., Design of a Deep Tied-Back Excavation Adjacent to the Los Angeles Metro Red Line Subway, Geotechnical and Structural Engineering Congress 2016, 537-550, 2016.
11. Liao H., and Hsieh, P., Tied-back excavations in alluvial soil of Taipei, Journal of geotechnical and geoenvironmental engineering, 128(5), 435-441, 2002.
12. Xiao, H., Zhou, S., and Sun, Y., Wall deflection and ground surface settlement due to excavation width and foundation pit classification, KSCE Journal of Civil Engineering, 23, 1537-1547, 2019.
13. Kung, G.T.C., Comparison of excavation-induced wall deflection using top-down and bottom-up construction methods in Taipei silty clay, Computers and Geotechnics, 36(3), 373-385, 2009.
14. Li, H., Liu, S., and Tong, L., Evaluation of lateral response of single piles to adjacent excavation using data from cone penetration tests, Canadian Geotechnical Journal, 56(2), 236-248, 2019.
15. Zhang, C., Huang, M., and Liang, F., Lateral responses of piles due to excavation-induced soil movements, Geotechnical Aspects of Underground Construction in Soft Ground: CRC Press, 865-872, 2008.
16. Wang, J., Xu, Z., and Wang, W.,Wall and ground movements due to deep excavations in Shanghai soft soils, Journal of Geotechnical and Geoenvironmental Engineering, 136(7), 985-994, 2010.
17. El Sawwaf, M., and Nazir, A.K., The effect of deep excavation-induced lateral soil movements on the behavior of strip footing supported on reinforced sand, Journal of Advanced Research, 3(4), 337-344, 2012.
18. Hsieh, H.S., Wang, C.C., and Ou, C.Y., Use of jet grouting to limit diaphragm wall displacement of a deep excavation, Journal of geotechnical and geoenvironmental engineering, 129(2), 146-157, 2003. [19] Clough, G.W., Construction induced movements of in situ walls, Design and performance of earth retaining structures, 439-470, 1990.