Safety Risk Analysis and Control of Deep Foundation Pit Construction Based on DFT and DT Model

With the development and utilization of urban underground space, deep foundation pit engineering presents the characteristics of large depth, large area, complex technology, and construction environment. Therefore, it is particularly important to strengthen the dynamic monitoring and early warning of safety risks in foundation pit engineering. Considering the dynamic changes and sequential correlations of safety risk factors in foundation pits, this paper proposes a safety risk management method based on dynamic fault trees. Firstly, a statistical analysis of foundation pit accidents from 2020 to 2023 was conducted to identify the main risk sources influencing pit collapse. Secondly, dynamic fault tree technology was used to assess the dynamic correlation among risk factors based on the mechanism of the pit collapse accident and the list of risk sources. Thirdly, the change law of the risk factor important ranking and the risk events of foundation pit collapse are quantitatively assessed using the Markov chain model. Finally, a digital twin framework with risk source monitoring, perception, and identification is designed for security risk dynamic monitoring and intelligent early warning systems.