The frequency and intensity of natural disasters, including avalanches, mudflows, and landslides, have increased significantly in recent years due to climate change and global warming. In order to mitigate the catastrophic effects of these events, it is essential to construct suitable protective structures in areas at risk. However, the design and dimensioning of protective structures is a complex task that requires advanced numerical simulation techniques. This work will present partitioned coupling strategies to simulate the complex interaction of gravity-driven mass flows impacting protective structures. Due to the large strains developed in the granular mass flow, the Material Point Method (MPM) is used to discretize the physical problem. Thus, the flowing material is represented by Lagrangian particles, while the governing equations are solved on the computational background grid. However, due to this discretization, the imposition of boundary conditions is a complex task. In particular, moving boundaries, which are required for partitioned coupling with other numerical methods, are crucial since they cannot be imposed at the nodes of the computational background grid. Moreover, an interface description is required for the coupling strategies. For this purpose, boundary particles are introduced, which provide an adequate description of the boundary position during the computation and are used to weakly enforce boundary conditions on the MPM model. To investigate highly flexible protective structures being impacted by gravity-driven mass flows a partitioned coupling strategy of the Finite Element Method (FEM) and MPM is derived, which allows to combine the strengths of FEM for accurate and efficient modeling of the complex structures while MPM is advantageous for simulating the large strain event of flowing masses. For this coupling strategy, a Neumann condition is introduced in the FEM partition, while in MPM the weak imposition of essential boundary conditions along the shared interface is required. For this purpose, either the Penalty or Lagrange multiplier method is used to weakly enforce the essential interface condition. Various examples of increasing complexity are systematically evaluated to assess the accuracy of the developed methodology, and its ability to model the impact of a gravity-driven mass flow into highly flexible protective structures will be demonstrated.