Topological Interlocking Structures (TIS) are assemblies of interlocking building blocks that hold together solely through contact and friction at the block interfaces and thus do not require any connective elements. This salient feature makes them highly energy-absorbent, resistant to crack propagation, geometrically versatile, and reusable. It also gives rise to failure mechanisms that, differently from ordinary structures, are governed by multiple contact interactions between blocks and frictional slip at their interfaces. Commonly-used modeling tools for structural analysis struggle to capture and quantify these unusual failure mechanisms. Here, we propose a different approach that is well-suited for modeling the complex failure of slab-like TIS. It is based on the Level-Set-Discrete-Element-Method, which was originally developed for granular mechanics applications. After introducing the basic assumptions and theoretical concepts underlying our model, we show that it accurately captures the slip-governed failure of slab-like TIS panels as observed in the literature, that it can closely estimate the force–displacement curves, and that it is can be used to explore important features governing the structural mechanics of TIS. The theoretical foundation, together with the results of this study, provide a proof-of-concept for our new approach and point to its potential to improve our ability to model and understand the behavior of interlocked structural forms.