Research on evolution law of safety risks during high formwork construction based on SNA-SD model

In order to scientifically control the safety risks during high formwork construction and reduce the likelihood of accidents, firstly, based on the investigation report of high formwork accidents, social network analysis (SNA) was used to screen risk factors, and a safety risk index system for high formwork construction was constructed from five dimensions: personnel, construction technology, management, mechanical equipment and materials, and environment.Secondly, through establishing a system dynamics (SD) model, the weight of each risk index was calculated by using the order relation analysis method (G1).Finally, taking the high formwork construction of the main and auxiliary powerhouse in Hunyuan Pumped Storage Power Station (in Shanxi Province) as an engineering example, the safety risks evolution law was studied.The results showed that the absolute centrality and relative centrality of construction workers′ illegal operations were the highest, and they were more likely to combine with other risk factors to cause accidents.With the implementation of safety investment and risk control measures, the safety risk of high formwork construction began to show a trend of rapid rise first, rapid decline after reaching the peak, rise again to the second highest and then decline, and finally tended to be gentle, which was basically consistent with the actual situation on site, and verified the model effectiveness.In addition, it is necessary to strengthen the prevention and control of management and environment during the construction, both of which are highly sensitive to the initial value of each safety risk.