Study On The Stress Field And The Time-Dependent Deformation Of Roadway Surrounding Rock

With the increase of mining depth and mining intensity, the mining conditions are getting worse and worse. For example, high ground pressure, high confined water, various complicate geological structure, and so on, made the roadway maintenance and the deformation control of surrounding rock becoming more and more difficult and the rheological property of rock mass are becoming more and more obvious. So the study on time-dependent of the rockmass structure deformation becomes a hot issue concerned widely in deep geotechnical engineering. In this paper, According to the problem of the forced and stability characteristics of roadway and its support in deep coal mine, the stress field and the deformation field of the roadway surrounding rock are studied by the following aspects such as the experiment on the time-dependent deformation under pressure for broken rock, the theoretical analysis of the stress field under local supporting, the analysis on the elastic-plastic stress field and the visco-elastic deformation of roadway surrounding rock under the water flow, and the numeric analysis on the stability of roadway surrounding rock. The main research results and innovative points are as follows:(1) Based on the experiment of the time-dependent deformation of the broken rock under pressure, the time-history curves of the porosity and its variation rate, the pore pressure-time curves at every stress level under water flow and the curves of rock porosity-porosity variation are obtained. From these curves the effects laws of the lithology, the moisture state and the water flow on the property of time-dependent deformation are given.(2) Using the mathematical theory of the natural boundary element method and the elasticity theory, the boundary integral formulas for the stress functions of roadway surrounding rock with not any support, whole balance support, local support and local weak support on the deep roadway boundary are derived respectively, moreover, from the integral formula the analytic or semi-analytical solutions to the stress of surrounding rock are obtained.(3) Making using of the elastic-plastic theory, the laws of the stress field, plastic region distribution of surrounding rock and the boundary displacement of the roadway changing with the pore pressure are obtained. Using a K-V creep model, the visco-elastic deformation of surrounding rock- supporting system under the whole balance supporting is studied and the changing laws with time of the interactive force between the surrounding rock and liner supporting, the boundary displacement of the roadway and the radial displacement of the roadway surrounding rock under the water flow are obtained respectively.(4) Using numerical simulation methods, the stress field of the surrounding rock and the time-dependent properties such as the plastic distribution and the displacements of the roof, floor and two sides under the whole weak supporting and the local weak supporting are studied, accordingly, the effects of the lateral pressure coefficient, local supporting force and its area on the stability of the surrounding rock are investigated. In the same time, under the flow of the confined water in the floor, the changing laws with the pore pressure for the stress field of the surrounding rock under the local supporting, flow velocity, the plastic distribution and the deformation of the surrounding rock are also obtained.The research results can provide a reference for the deformation analysis and stability control of the deep soft rock roadway with high ground pressure.