Identifying failure connection area on wall for deep excavation based on system stiffness influence factor

In this study, a methodology to identify weak or failure connection area on the wall of deep excavation was proposed based on the system stiffness influence factor (I_F), which can be beneficially utilized for wall-collapse prevention and forecasting system. Irregular excavation configuration common in urban areas and various weak-connection locations were considered. Three-dimensional finite element analyses with full consideration of actual staged excavation and strut-waler connection condition were performed. It was found that wall deflection and ground movement increased as the location of weak connection became deeper. It was also found that the influence of weak connection on the wall behavior became more pronounced as it located towards the center of the wall. The effects of weak connection on wall deflection were evaluated and quantified using I_F. A modification procedure for I_F was introduced to consider the effects of depth and horizontal weak-connection locations. The modified I_F was adopted to establish a method for quantifying and identifying weak or failure connection area on the wall based on measured wall deflection from field monitoring. Case examples were selected to check the validity of the proposed method. The compared results showed that monitored and predicted locations of weak connection were in close agreement.