ENGINEERING CLASSIFICATION OF ROCK MASSES AND ITS POTENTIAL USE FOR EVALUATING THE RELIABILITY AND SAFETY OF TUNNELS CONSTRUCTED BY POWERED TUNNEL-DRIVING COMPLEXES

摘要

Numerical parameters are cited forthe stress state of a tunnel linintr and tunnel/rock-mass system as a whole. Engineering classifications of rock masses (ECRM), which, in the general case, are a technique that permits prediction of rock-mass interaction with an underground structure on the basis of a general characteristic of the rock with no direct calculations of the stress states, are used in underground-construction practice. The fundamental practical advantage of ECRM consists in the possibility of planning design solutions for a structure (assess the required thickness of the lining, the limiting span of the tunnel without the lining, the spacing and length of anchors, etc.), or assessment of effective characteristics of the rock mass on the basis of initial information (beginning with visual analysis of drill-hole tilt, even under field conditions). Its exceptional on-going adaptability in acquiring results makes ECRM particularly valuable tools for rough design, investment acquisition, and the solution of engineering-safety problems.