Testing on fluid-solid coupling characteristics of fractured coal-rock mass considering regional geostress characteristics

A displacement back method was used to analyze regional geostress characteristics in this research. A new mechanical experimental system was adopted to provide a mechanism on spatio-temporal evolution of internal crack in both coal-rock masses. A simulation model on the fluid-solid coupling of fractured coal-rock mass was built up for un- covering the fluid-solid coupling characteristics with considering the regional geostress characteristics. The authors also offered in-situ geostress monitoring to verify the accuracy of the displacement back method. The values of both vertical geostress and minimum horizontal principal stress remained stable. The maximum horizontal principal stress increased suddenly at local region due to excavation disturbance. DR scanning images of internal cracks with various loading val- ues were offered by digital X-ray system. It showed that the main cracks in the coal-rock masses was propagating con- tinuously when the external loading remained growing. Shapes of crack field in both coal and rock mass were conjugated type and X type. Crack-field data being vectorization processing needed to import in fluid-solid coupling model. The authors got the traits of all seepage parameters in different experimental settings. The traits indicated the fluid-solid coupling characteristics of fractured coal-rock mass. Essential reason for resulting in the propagation and connection of external micro-cracks is increscent external loadings,which leads the macroscopic fracture of the coal-rock mass and value increment of porosity and permeability. Transport process of maximum velocity region represents the distribution characteristics of induced cracks. Crest value of flow velocity is at the main crack and in direction proportion to water inject pressure. Tiny crack has larger hydraulic gradient and the value of flow velocity here is also greater than the one at other position. The features of outlet area velocity indicate the maximum value of flow velocity at the exit lies in two sides of the model and increase with the increment of loading value.