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Project portfolio networks (PPNs) are becoming increasingly interdependent at multiple levels to better realize enterprises' strategic objectives. However, interdependencies between PPN components increase the potential for risk cascading propagation and amplify the impact of certain risks into the collapse of the entire PPN. To maintain PPN robustness and controllability, it is necessary to study the risk cascading propagation process in PPN. First, the PPN is constructed based on a scale-free network generation algorithm. Second, a risk cascading propagation model of the PPN is developed using a load capacity model. Four different mixed strategies are proposed to explore the effect of risk cascading propagation on the PPN, and a numerical simulation is applied to examine the robustness and controllability of the PPN under different strategies. The results show that the nonlinear load capacity model with the initial residual capacity redistribution principle provides optimal robustness against risk cascading propagation. When the management capacity redundancy reaches a certain value, PPN has better risk cascading propagation controllability, regardless of the mixed strategy. These results provide a basis for managers to protect against risk cascading propagation and improve PPN robustness and controllability in a specific context. The proposed model can also enrich project portfolios and risk management theory. • The risk cascading propagation model of project portfolio network is proposed. • Different risk triggering scenarios are considered in the proposed model. • The definition of component load, including initial, risk and extra loads, is given. • Different mixed strategies are developed to maintain the network characteristics. [ABSTRACT FROM AUTHOR]