Abstract:The one-step cemented backfill provides support for two-step pillar mining. The backfill changes from triaxial stress to uniaxial stress, and its stability is very important to Stope Safety. In this paper, the stress-strain curves, strength characteristics, energy consumption characteristics, and failure modes of cemented backfill under single (uniaxial) and twice (triaxial plus uniaxial) compression with different cement-sand ratios are compared and analyzed. The results show that single filling has a more obvious compaction stage and higher linear elastic stage than twice filling. Increasing confining pressure makes the compaction stage decrease, linear elastic stage,and yield stage extend,and elastic modulus increase; The lime sand ratio of 1:12 directly enters the stage of linear elastic deformation, but the level of low confining pressure is higher than that of high confining pressure. The peak strength of 1:12 decreases with the increase of confining pressure, increases first and then decreases at 1:8, and increases with the increase of 1:4; The results show that the confining pressure has little influence on the strength of 1:4 and 1:12 backfill, and the strength ratio is 26.05%~58.79%, while the strength ratio is 89.92% and 93.51% at 1:8. The results show that the energy value of backfill decreases with the decrease of twice compression and cement-sand ratio, and the proportion of total energy before peak increases and the strain energy before peak increases slowly with the increase of confining pressure; 1: 4 and 1:8, increase the confining pressure to improve the pre-peak energy storage limit, and 1:12 first decreases and then increases. The results show that the cracks are parallel and vertical. The secondary compression increases the degree of fragmentation of the filling body, increases the confining pressure, and maintains integrity. The secondary compression failure path of the sample occurs along the first path, and the failure position occurs at the upper part.