Study On The Law Of Surface Subsidence About Deep Mining By Back Analysis

With the rapid development of our country's economic,the demanding and mining area of various underground resources is increasing, and the mining rate is accelerating. But it also attracts more and more scholars and society concerns that surface subsidence caused by mining,especially mining below the building , the river and the railway.The mining of underground resouces of Nanjing Qixia Mountain belongs to this typical mining below the building , the river and the railway.Under the support by Natural Sciense Foundation for Talented Youngs of Chongqing and the Supporting Program of New-Century Talents by the Ministry of Education,the study on the surface subsidence problem of Nanjing Qixia Moutain caused by deep mining is studied by considering the creep of rock and filling.The main conclusions are summarized as follows:①Surface subsidence monitoring networks established. Laws of surface subsidence were revealed from the numerical results. It can be found that the surface subsidence tend to stability.②Three-dimensional numerical model is established. Surface subsidence caused by mining and filling is obtained.It is shown from the numerical results that surface subsidence induced by mining and filling is much smaller than the measured data. This is because the creep of rock and filling is not considered.③Effects of the creep parameters of rock and filling on surface subsidence is determind by orthogonal design method.It is found that the Kelvin viscosity,Maxwell shear modulus,Maxwell viscosity of Qixia limestone and Qixia sandstone significant affect on the surface subsidence.④Based on Genetic Algorithms program, the displacement back analysis is carried on and the creep parameters is obtained.The creep parameters obtained by the displacement back analysis with those from analogy method,the accuracy of the Genetic Algorithms program was above 85%. This shows that the programm of the Genetic Algorithms has a good optimization properties.⑤The surface subsidence above the the mining area is predicted by using the creep parameters after the civil build is built.From the numerical results,the civil build little affects on surface subsidence in this area.