A semi-empirical analysis on bearing ability of lunar regolith

The bearing ability of lunar regolith, in particular the so-called stress-sinkage relationship, is crucial for the designing of large lunar vehicles, which is needed for the architecture and mining missions on the Moon. In this work, we analyze the bearing ability of lunar regolith by a semi-empirical model on the packing of solid grains. Our model suggests that the lunar regolith with coarser grains shows better bearing ability. By comparing with the stress-sinkage data of lunar boulder tracks, we also date the fragmentation of regolith grains with the increase of normal stress on the lunar surface. According to this phenomenon, the stress-sinkage relationship of lunar regolith is controlled not only by the intergranular interactions, but also by the compressional fragmentation of regolith grains. In particular, the fragmentation of lunar regolith takes place drastically when the normal stress on the lunar surface increases from zero to ∼ 50 kPa, but turns to be not significant for the further increase of this normal stress. The small radius of fragmented regolith grains is likely to be the predominant reason for the weak bearing ability of lunar regolith under heavy loads. Based on this point, the bearing ability of lunar regolith can be enhanced by suppressing the compressional fragmentation of regolith grains, which would be achieved via the mixing with other coarser solid grains consisting of more ductile materials.