Tunnel Stability Research On Goaf

Shanxi province is rich of coal with coal distribution in most part of it. Lots of goafs was left after the lasting excavation activites. These have increased the difficulty and cost of additional to the highway construction in Shanxi Province. With the rapid development of haighway engineering, some of highway tunnels, cutting through the coal strata and gob, is inevitable. And at present, there is few production about tunnels that cutting through the coal strata and gob, most research is based on the experience and investigation and there are not much the systemic research. So, the research on the stability and deformation rules of the tunnel on goaf has important theoretics significance and practicality value .In this paper, Take Shi Pogou tunnel of Lijun highway in Shan xi province for example, adopt numerical simulation to analysis the stability of Shi pogou tunnel,and the following works has been finished:Firslty, according to the information on drilling and geophysical surveying, based on the tunnel surrounding rock classification , evaluated the stability of engineering geology about the Shi pogou tunnel and the slope of the tunnel entrance;Secondly, according to the mining subsidence theory, calculated both surface movement and deformation which caused by the seam mining below Shi pogou by the probability-intergral method;Thirdly, based on the non-linear theory and the date of construction stratigraphic borehole, The three-dimensional geologic model and numerical calculation model of Shi pogou tunnel is built by using the finite element software ANSYS;Fourthly, the original tunnel stress is calculated by FLAC3D; According to the order of the construction sequence, the coal seam’s excavation of the Tongde coal mine which below the Shi pogou tunnel is simulated; The deformation response curve of dynamic recovery and construction process can be drawn by the history monitor points setting in a specific section. These curves which depend on the different surface geology conditions and tunnel structure revealed the complex displacement and nonlinear deformation response characteristic of goaf overlying rock mass. Compatible, through displacement cleared after goaf treatment, the law of surface and tunnel displacement and deformation is simulated, which is only caused by the tunnel excavation.