System Dynamics Simulation Study On Safety Risk Of Deep Foundation Pit Construction In Rich Water Geology

With the further acceleration of China’s modernization process,the contradiction between the further expansion of land demand and the shortage of space above the ground is increasingly obvious.It has become an inevitable trend for the further development and utilization of underground space,and the foundation pit works are also developing in a larger and deeper direction.As a result,a series of safety problems have gradually attracted people’s attention,especially in the water-rich geology with high groundwater level and poor soil stability,deep foundation pit construction,slightly inadvertent will lead to safety production accidents.In view of this,this paper is based on the construction of deep foundation pit in water-rich geology,takes safety risk as the starting point,comprehensively identifies safety risk factors by combining text excavation and literature analysis,constructs safety risk system dynamic model of deep foundation pit construction in water-rich geology with system dynamic method,and carries out safety risk simulation analysis with the project of Baili Qiantang in Haining City as an example,and puts forward corresponding risk control measures as follows:Firstly,the investigation report of safety production accident in foundation pit construction is excavated and the excavation results are subject-marked by literature analysis.It is concluded that the subjects applicable to safety risk in foundation pit construction are divided into five categories: personnel safety risk,material state safety risk,management safety risk,environmental safety risk and construction technology safety risk.Then,specific safety risk factors are identified,and a questionnaire is established based on this.The reliability and validity of the collected questionnaire are tested by SPSS 26.0 software to verify the rationality of the risk factors after sorting out.A safety risk index system for construction of deep foundation pit in water-rich geology is established,which includes 5 categories and 35 risk factors.Secondly,based on system dynamics theory,the causal relationships of safety risk factors of each subsystem are sorted out,and the causal relationships and system dynamics flow diagrams are defined and drawn.The three-point valuation method and the improved CRITIC method are used to determine the model parameters and the mathematical relationship between the variables in the flow chart,and then the equation in the system is determined,so as to establish the dynamic model of safety risk system for deep foundation pit in water-rich geology.Finally,based on the case study of Haining Baili Qiantang Project,the construction safety risk value of deep foundation pit is simulated,and the change trend of construction safety risk value of five subsystems and the difference of construction safety risk value of different subsystems in reducing construction safety risk value of foundation pit are obtained through sensitivity analysis and comparison of each subsystem.The research shows that the construction safety risk of deep foundation pit in water-rich geology always shows an upward trend before the foundation pit is excavated to the end.Then,according to the analysis results,put forward relevant suggestions on safety risk prevention and control,in order to provide reference for construction safety risk management of similar projects.