Response Analysis Of Deformation Of Roadway Surrounding Rock-Seepage Of Water Coupled System Under The Condition That Coal Seam Is Main Aquifer

Coal measure strata of coal bed aquifers are very rare and were first found in Xiaojihan Coal Mine of Yuheng Coal in western China. Due to large amounts of water in coal, it is easy to incur mine water disasters. How to predict water inflow in water-bearing coal roadways has become a major problem for roadway excavation and coal mining. The analysis of dynamic response of the surrounding rock deformation-unsaturated water seepage coupling system is one of the key scientific issues that need to be addressed urgently. On the basis of investigating the formation mechanism of coal measure strata of coal bed aquifers, this paper uses a combination of experiment, actual measurement, theoretical analysis, numerical simulation and other methods to deeply study the water burst law of roadways, with the innovative achievements as shown below:(1) Based on the analysis of geological conformation movement, this paper studies the water-bearing structure characteristics of shallow-buried loose sand bed-thick bedrock-coal bed in Xiaojihan Coal Mine area, and reveals the formation mechanism of coal bed aquifers in Xiaojihan Coal Mine by employing the geology theory.(2) The tensile strength, cohesion, internal friction angle, elasticity modulus, Poisson’s ratio, permeability, the β non-Darcy flow factor coefficient, acceleration coefficient, among many others, of Xiaojihan coal measure strata are obtained through the mechanical properties and permeability tests of water-bearing coal bed. In addition, by making a quantitative analysis of the porosity, permeability parameter and internal friction angle of coal beds, it further reveals the mechanical characteristics of coal bed aquifers.(3) It discusses the failure modes and failure conditions of coal bed aquifers, and establishes the flow rule after shear yielding based on the D-P criterion. Besides, by using the relationship between the strain vector and the strain tensor, the plastic potential is constructed, and the flow rule after tensile fracture is established as per the Lagrange equation. Further, this paper presents the conditions for transforming the failure conditions.(4) It builds a system dynamics model for deformation of surrounding rocks in roadways(coal bed aquifers, water-resisting layer, and phreatic aquifer)-unsaturated water seepage coupling, designs the system response calculation method according to the Lagrange rapid analysis method, and also utilizes the Fortran language to compile the response computing program. Besides, a numerical example is used to verify the convergence and numerical stability of the algorithm.(5) By calculation and analysis of deformation of surrounding rocks in roadways-seepage coupling response in pilot production working faces in Xiaojihan Coal Mine 11203, this paper acquires the influence rule of coal cohesion, coal internal friction angle, and coal tensile strength on the water level and water inflow of roadways. Combined with practical engineering test data, it verifies the feasibility of predicting roadways’ water inflow.