Abstract: Mudstone is sensitive to moisture, especially under loading coupled effect, its mechanical properties may decrease dramatically. The compression tests were carried out under loading and drying-wetting cycle joint effect to reveal the evolution process of mudstone performance with environment and loading influence. The compacted samples swelled when immerged into water for the first time. But, they would be compressed during drying-wetting cycle process subsequently. Then, pore size analysis testing was performed on compacted mudstone, the pore size distribution curves had two peaks, which corresponded to diameters 0.3 μm and 10 μm, respectively. Pore volumes reduced for drying-wetting cycle and loading joint effect, which was more obviously for large size pores. And, based on swelling testing, compression test and pore size distribution curves, one model about pore-moisture-loading interaction was established. The whole pore volume includes two parts, inter-volume and extra-volume of agglomerate. On the basis, the crushing-filling procedure of mudstone agglomerate was analyzed under drying-wetting cycle, and the mechanism of interaction between mudstone pore-moisture-load was revealed. This research can provide some theoretical references for mudstone subgrade construction.

Key words: mudstone, drying-wetting cycles, pore size distribution, compressive property