A new model for TBM performance prediction in blocky rock conditions

The term "blocky rock conditions" is generally associated with face instabilities in blocky/jointed rock masses. These events are generally promoted by unfavorable rock mass structural conditions, in terms of joint frequency and orientation, and acting stresses. As a result, rock blocks are formed and then detach from the excavation face which becomes "blocky", with a markedly irregular and uneven profile. This condition may have a paramount effect on TBM tunneling, leading to a high maintenance frequency and a low TBM advancement rate. Based on the TBM performance data recorded during excavation of tunnels in blocky rock conditions, a TBM performance prediction model has been developed. The model is based on the Field Penetration Index for blocky rock conditions, FPIblocky, which was previously introduced to analyze the TBM performance in blocky grounds at the Lotschberg Base Tunnel. Through a multivariate regression analysis, a new expression has been introduced to predict the FPIblocky based on the volumetric joint count (J(v)) and the intact rock uniaxial compressive strength (UCS). An attempt has also been made to quantify the downtimes that may occur in blocky rock conditions and to estimate a reliable value of TBM daily advance. (C) 2014 Elsevier Ltd. All rights reserved.

[1]  Jamal Rostami,et al.  TBM Performance Analysis in Pyroclastic Rocks: A Case History of Karaj Water Conveyance Tunnel , 2010 .

[2]  Vincent Labiouse,et al.  Brittle Rock Failure in the Steg Lateral Adit of the Lötschberg Base Tunnel , 2009 .

[3]  E Farrokh,et al.  Down time analysis of hard rock TBM case histories , 2013 .

[4]  Daniele Peila,et al.  Ground probing and treatments in rock TBM tunnel to overcome limiting conditions , 2009 .

[5]  Jamal Rostami,et al.  Developing new equations for TBM performance prediction in carbonate-argillaceous rocks: a case history of Nowsood water conveyance tunnel , 2009 .

[6]  Matteo Berti,et al.  TBM performance estimation using rock mass classifications , 2002 .

[7]  Andrea Delisio,et al.  Review of the TBM performance in blocky rocks with potential face stability issues , 2013 .

[8]  Jian Zhao,et al.  Numerical modelling of the effects of joint spacing on rock fragmentation by TBM cutters , 2005 .

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

[10]  Qiuming Gong,et al.  In situ TBM penetration tests and rock mass boreability analysis in hard rock tunnels , 2007 .

[11]  Jian Zhao,et al.  Development of a rock mass characteristics model for TBM penetration rate prediction , 2009 .

[12]  Jian Zhao,et al.  A new hard rock TBM performance prediction model for project planning , 2011 .

[13]  Bernhard Maidl,et al.  Hardrock Tunnel Boring Machines , 2008 .

[14]  R. Ribacchi,et al.  Influence of Rock Mass Parameters on the Performance of a TBM in a Gneissic Formation (Varzo Tunnel) , 2005 .

[15]  Jian Zhao,et al.  Analysis and prediction of TBM performance in blocky rock conditions at the Lötschberg Base Tunnel , 2013 .

[16]  P. Kaiser.  ROCK MECHANICS CONSIDERATIONS FOR CONSTRUCTION OF DEEP TUNNELS IN BRITTLE ROCK , 2006 .

[17]  J. C. Jaeger.  Shear Failure of Anistropic Rocks , 1960, Geological Magazine.