Energy release process of surrounding rocks of deep tunnels with two excavation methods

Numerical analysis of the total energy release of surrounding rocks excavated by drill-and-blast (D&B) method and tunnel boring machine (TBM) method is presented in the paper. The stability of deep tunnels during excavation in terms of energy release is also discussed. The simulation results reveal that energy release during blasting excavation is a dynamic process. An intense dynamic effect is captured at large excavation footage. The magnitude of energy release during full-face excavation with D&B method is higher than that with TBM method under the same conditions. The energy release rate (ERR) and speed (ERS) also have similar trends. Therefore, the rockbursts in tunnels excavated by D&B method are frequently encountered and more intensive than those by TBM method. Since the space after tunnel face is occupied by the backup system of TBM, prevention and control of rockbursts are more difficult. Thus, rockbursts in tunnels excavated by TBM method with the same intensity are more harmful than those in tunnels by D&B method. Reducing tunneling rate of TBM seems to be a good means to decrease ERR and risk of rockburst. The rockbursts observed during excavation of headrace tunnels at Jinping II hydropower station in West China confirm the analytical results obtained in this paper.

[1]  Julius Miklowitz,et al.  Plane-Stress Unloading Waves Emanating From a Suddenly Punched Hole in a Stretched Elastic Plate , 1960 .

[2]  M. A. Kayupov,et al.  Studies of the effect of dynamic processes during explosive break-out upon the roof of mining excavations , 1988 .

[3]  Nick Barton,et al.  TBM Tunnelling in Jointed and Faulted Rock , 2000 .

[4]  J. P. CARTERt,et al.  Sudden Excavation of a Long Circular Tunnel in Elastic Ground , 2002 .

[5]  Xu Ze-mi.  Analysis of energy released in process of rock-burst , 2003 .

[6]  Jia Yao-dong,et al.  STUDY ON ROCK MECHANICS IN DEEP MINING ENGINEERING , 2005 .

[7]  Li Li-yun.  CRITERIA FOR STRENGTH AND STRUCTURAL FAILURE OF ROCKS BASED ON ENERGY DISSIPATION AND ENERGY RELEASE PRINCIPLES , 2005 .

[8]  Chen Guoqing,et al.  STUDY ON NEW INDEX OF LOCAL ENERGY RELEASE RATE FOR STABILITY ANALYSIS AND OPTIMAL DESIGN OF UNDERGROUND ROCKMASS ENGINEERING WITH HIGH GEOSTRESS , 2006 .

[9]  Zhou Chuangbing.  STUDY ON IMPACTION OF INITIAL GEOSTRESS FIELD ON VIBRATION OF SURROUNDING ROCK DURING EXCAVATION WITH DRILLING AND BLASTING METHOD , 2008 .

[10]  Ming Cai,et al.  Influence of stress path on tunnel excavation response – Numerical tool selection and modeling strategy , 2008 .

[11]  Jimin Wang,et al.  Preliminary engineering application of microseismic monitoring technique to rockburst prediction in tunneling of Jinping II project , 2010 .

[12]  Z. Shan,et al.  Management of rock bursts during excavation of the deep tunnels in Jinping II Hydropower Station , 2010 .

[13]  Z. Shan,et al.  Behavior of Marble At Jinping II Project--Part 1: Intact Rock , 2010 .