Affect of Water Content and Compaction Degree on Mechanical Characteristics of Backfill in Coal Mine

Taking the backfill in a mining area as research object, using direct-shear test and compression test, we measured shear strength and compression index of soil samples with different water content and compaction degree, and analyzed the variation laws of shear strength and compressive properties due to different water content and compaction. The experimental results show that the value of cohesion has no obvious change as water content increases when the water content was not greater than the optimal moisture content; but, under the high pressure degree, there is a water content value that makes the cohesion of soil reach the peak, and the friction angle has little change with the change of water content; the cohesion has an exponent increase with the increasing of dry density, but the friction angle increases linearly with the increasing of compaction degree; the compaction degree increases with the increasing of water content, and the effect of the compressibility on compaction degree is opposite to that of water content.