Study on the effect of axial force coherence of servo steel strut in deep foundation pit

Purpose This study aims to investigate the axial force coherence phenomenon in servo steel struts used in deep foundation pits, where changes in the axial force of one strut affect adjacent struts. The research seeks to quantify the axial force loss in neighboring struts due to such coherence and propose predictive models to support better engineering control strategies. Design/methodology/approach Model tests were conducted to analyze the axial force changes in servo steel struts under various loading conditions. Numerical simulations were then performed to validate the experimental results. The influence of strut spacing and initial axial force on coherence effects was examined, and an empirical formula for axial force loss rate was derived. Findings The axial force in struts increases with excavation depth, with the growth rate accelerating deeper down. Loading a single strut causes axial force loss in adjacent struts, negatively correlated with distance and positively correlated with initial axial force. The loss rate decays exponentially with horizontal distance. Synchronous loading of nearby high-force struts is recommended to mitigate coherence-induced losses. Originality/value This study provides the first comprehensive model test and numerical analysis of axial force coherence in servo steel struts, considering both vertical and horizontal interactions. It introduces an original empirical formula that quantifies axial force loss as an exponential function of horizontal distance and initial strut force. The findings offer practical value by proposing a synchronous loading strategy to compensate for coherence-induced force loss, enhancing the safety and precision of support systems in deep excavation projects.