When multiple rigid particles are present, the particles start to interact with each other as the volume fraction of the particles increases. A remarkable strength change has been reported for partial melts. The strength of partial melts abruptly increases when particles start to touch each other and particle-toparticle interaction starts to occur.The volume fraction of such change is known as RCMP in literatures (Arzi 1978, Van der Molen & Paterson 1979). For simulating these situations, physical experiments have been performed for materials with low to high phenocryst fraction (Ildefonse et al. 1992, Park & Means 1997). Numerical models are also developed for systems with relatively high particle fractions (e.g. Tikoff 1994), but these are kinematic models without mechanical consideration. Models based on FEM or FDM can also be used (e.g. Treagus & Lan 2003) to simulate development of magmatic foliation. However, there are two major limitations when we adopt these models:
1 It is known that large strain is necessary for the development of magmatic foliation, but it is technically difficult to sustain large strain in these models.