GENERALIZED DAMAGE MODEL FOR ASPERITY AND SHEAR STRENGTH CALCULATION OF JOINTS UNDER
CYCLIC SHEAR LOADING
LIU Bo，LI Haibo，LIU Yaqun，XIA Xiang
(State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，
Chinese Academy of Sciences，Wuhan，Hubei 430071，China)
Abstract：Degradation mechanism of the shear strength of rock joints under cyclic shear loading and corresponding analysis model are bases for accurate assessment of rock engineering safety under seismic load. Joint specimens with three kinds of joint wall strengths and five kinds of asperity angles were prepared，then a series of cyclic shear tests were performed under four normal stress levels. Test curves，destruction process of tooth-asperity and the residual form of tooth-asperity were discussed according to test results. And further，a generalized damage model for residual form of tooth-asperity is proposed. Using the proposed model，the mathematical relationships between snipped rate of tooth-asperity，dilation rate，angle of base friction and average dilation angle were established separately. In addition，an empirical formula of the average dilation angle was given according to the cyclic shear experimental results. Thus，the cyclic shear strength calculation formula was established based on the average dilation angle formula and Ladanyi-Archambault shear strength formula. Finally，calculation results of cyclic shear strength were compared with test results. It is indicated that，the calculation results have good agreement with the test results，but there exists certain deviation for the high angle joints specimens.
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2013, Vol. 32 
