A NEW PROPOSAL OF EVALUATION SYSTEM FOR TUNNEL FACE BASED ON THE ANALYSIS OF THE OBSERVATION RECORDS

Abstract

This paper proposes a new evaluation system for the condition of rock mass at a tunnel face as follows: 1) the condition of rock mass is evaluated from the strength of rock mass and the condition of ground water and stress, 2) the strength of rock mass is scored by a weighted mean of the rank which corresponds to the rock strength, degree of weathering, and frequency and openness of fractures, 3) the score is adjusted by the rank which corresponds to the ground water inflow and that calculated by the ratio of strength and vertical load of the rock mass. This new system is found to be more effective than the current appraising method for the support determinations.