Current Issue

THE MAJOR CAUSE FOR SLIDING FAILURE OF SIDE WALLS DURING BASEMENT EXCAVATION IN HIGH-RISE BUILDINGS

Tse-Shan Hsu

Honorary President, Institute of Mitigation for Earthquake Shear Banding Disasters

Professor, Feng-Chia University, Taichung, Taiwan, R.O.C., This email address is being protected from spambots. You need JavaScript enabled to view it.

Lin-Yao Wang

Ph.D. and Director, Bureau of Transportation and Public Works, Yunlin, Taiwan, R.O.C.

Abstract

Despite the high shear strength of the strata in Zhubei, Taiwan, repeated side wall sliding failures have been observed during basement excavations for some high-rise buildings. This study uses the Fengcai-520 high-rise basement excavation as a case study to explore the underlying causes of sliding failures by comparing the results obtained from traditional design methods with those from performance-based design approaches. The results of this study reveal the following three conclusions: (1) Both design approaches encounter side wall sliding failures during excavation; (2) Increased shear banding during seismic events leads to greater brittleness of rock within shear bands, and resulting in highly concentrated excess pore water pressures in shear bands. This can cause rock debris to float, creating interconnected drainage pathways that direct water inflow into the basement; (3) Performance-based design is more effective than traditional methods. It swiftly addresses side wall sliding failures by dissipating concentrated excess pore water pressures, thus preventing further impacts on reinforced concrete side walls and ensuring the structural safety of the building. It is recommended that future basement excavations adopt performance-based design to reduce construction costs and enable rapid emergency responses, thereby ensuring the structural safety of the completed building.

Keywords: shear bands, basement excavation, sliding failure, performance-based design, traditional design.