Mechanical characteristics and numerical simulation of powdered crystalline dolomite under the effects of environmental humidity

To reveal the effect of pillar(core)in strength parameters, deformation characteristics and energy evolution by environmental humidity values, the powder-crystal dolomite pillar from the-850 m middle section of the Chashanling mine was cored and produced into standard specimens. Based on the self-built confined space stable humidity condition platform, the system simulation of on-site humidity was successfully carried out via steam method. The porosity, mass and size of the specimens were measured under dry, 80%,90% and 100%RH conditions for 60 d respectively. Uniaxial compression tests were performed, combined with scanning electron microscopy and nuclear magnetic resonance techniques to analyze the microstructure change laws and mechanical parameters such as strength and deformation response characteristics. The results show that:(1) Increased environmental humidity causes dense and regularly arranged mineral particles to lose cements and develop blurred interlayer interfaces. Higher porosity with loss of mineral particles from softened contact surfaces leads to loss of specimen mass and reduction of size.(2) Environmental humidity determines the limited failure mode of the specimen under loading. From tensile failure under dry conditions to mixed shear/tensile failure under 100%RH,the macroscopic crack development on the specimen surface tends to increase with humidity value.(3) Due to the “damage-linkage-invasion” effect of high-humidity expanding from the periphery to the center, the friction between dolomite fractures and mineral grains, as well as parameters such as elastic modulus and peak strength decrease, while Poisson's ratio and peak point strain increase, which accelerates the instability and deformation of dolomite pillar.(4) Numerical simulation of humidity field water vapor corrosion was conducted based on experimental data using particle flow software, and the interaction between micro-crack development characteristics and energy evolution of the model specimens under loading was analyzed.