Numerical analysis and fluid-solid coupling model tests of coal mining under loose confined aquifer

To study the stability of coal mining under loose confined aquifer, fluid-solid coupling model technology is newly developed, and an extensible geomechanical model system under stress and seepage loading is established. Major improvements in the tests are made in terms of similar materials of fluid-solid and advanced measurement methods/techniques. By using the new similar materials of fluid-solid, true reappearance of catastrophe evolution process for the water inrush induced by mining disturbance is obtained, and multivariate precursor information for real time water inrush is collected by means of the fiber bragg grating technology, acoustic emission technique and resistivity tomography technology. A numerical method considering the coupling effect of multi-physics field is adopted in order to know the coupling evolution law of stress field, displacement field and seepage field in the catastrophe evolution process of water inrush and the response characteristics of precursor information for multi-physics field of water inrush are analyzed. Based on the results of model test and numerical simulation, rock stress suddenly decreases after sustainable growth when the water-resistant key strata rupture, and rock displacement suddenly jumps after sustainable growth, but there exits a stable surging segment in which precursor information of water inrush is contained before jumping appears, and rock seepage suddenly decreases after continuous decrease, but there exits an abnormal fluctuating segment in which precursor information of water inrush is contained long before water inrush happens, and rock apparent resistivity and acoustic