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Abstract The geological strength index(GSI) system concentrates on the description of two factors，rock structure and block surface conditions，which has been widely used in the estimation of strength parameters and deformation parameters. The guidelines given by the GSI system are for the estimation of the peak strength parameters of jointed rock masses. There are no guidelines given by the GSI，or by any other system，for the estimation of the rock mass?s residual strength that yield consistent results. In order to make up the paucity of research，on the basis of GSI system，in this paper，using the GSI quantitative evaluation method by means of adjusting the peak GSI to the residual with two factors：residual block volume and residual joint condition factor . Firstly，according to rock mass index(RMi)，methods to obtain the rock block volume and joint condition factor values are discussed. Then，on the basis of and ，the accessor method for and are probed. Finally，calculating the value by and ，to determine the residual strength parameters by generalized Hoek-Brown criterion. The proposed method for estimating rock mass?s residual strength is validated using in-situ block shear test data from two tunnels and data from back-analysis of rock slopes，so as to provide a new idea to obtain the residual strength parameters of the jointed rock masses.
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Received: 07 December 2012
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2013, Vol. 32 
