Vertex Models and Random Labyrinths: Phase Diagrams for Ice-type Vertex   Models
  We propose a simple geometric recipe for constructing phase diagrams for a general class of vertex models obeying the ice rule. The disordered phase maps onto the intersecting loop model which is interesting in its own right and is related to several other statistical mechanical models. This mapping is also useful in understanding some ordered phases of these vertex models as they correspond to the polymer loop models with cross-links in their vulcanised phase. 
Kirill Shtengel and L. Chayes