With the development of Chinese social economy, more and more coal resource is required. So, it is very important to mine the "three under" (under buildings, under railway and under water) pressure coal when coal mine resources is increasingly scarce today. The traditional "three under" pressure coal mining process will cause certain degree of the surface environment destruction, and filling mining method not only can ensure the efficient production but also can effectively reduce the damage of the surface environment. But the creep properties of overlying strata will be affected by the groundwater seepage among the filling mining, and which finally affect the long-term stability of the engineering. Therefore, study about effect of seepage on creep of overlying strata in filling mining process has important theoretical significance and strong application value.
In this paper, we derives the stress equilibrium equation of the rock under the action of stress and water pressure according to the equation of hydrostatic equilibrium, the principle of effective stress, and the geometric equations based on the general solution of the Burgers model in the classic rheology. Meanwhile seepage field control equation has been acquired according to the Darcy's law and the seepage field equation of continuity. Finally the seepage-creep coupling mathematical model is founded. We study the change of overlying strata creep under different mining methods and different pore water pressures on the computing platform of Comsol Multiphysics to validate the founded model. The results can forecast surface subsidence in mining "Buildings, Railways and Water Bodies" pressed coal.
