报告题目: Discontinuum-Equivalent Continuum Analysis of the Stability of Tunnels in a Deep Coal Mine Using the Distinct Element Method 

邀请专家: Pinnaduwa Kulatilake教授,The University of Arizona, USA

报告时间: 2016年6月17日上午8:30-10:00
    报告地点: 1306教室
 
 
   Abstract: Stability studies on two tunnels, a horseshoe shaped and an inverted arch shaped tunnel, in a deep coal mine in China, performed using the 3DEC distinct element code were presented. The rock mass mechanical property values for the tunnel shapes have been estimated through a back-analysis procedure using available field deformation data. The back-analysis has been carried out through a pseudo-time dependent support installation routine which incorporates the effect of time through a stress-relaxation mechanism. The back-analysis indicates that the rock mass cohesion, tensile strength, uniaxial compressive strength and elastic modulus values are about 35%-45% of the corresponding intact rock property values. Additionally, the importance of incorporating stress-relaxation before support installation has been illustrated through the increased support factor of safety and reduced grout failures. The calibrated models have been analyzed for different supported and unsupported cases to estimate the significance and adequacy of the current supports being used in the mine, and to suggest a possible optimization. The effects of supports have been demonstrated using deformations and yield zones around the tunnels, and average factors of safety and grout failures of the supports. The use of longer supports and floor bolting has provided greater stability for the rock masses around the tunnels. Finally, a comparison between the two differently shaped tunnels establishes that the inverted arch tunnel may be more efficient in reducing roof sag and floor heave for the existing geo-mining conditions.