Abstract
In present study, 144 direct shear tests are performed on mated rock joint replicas under constant normal load condition (CNL). For these tests, three natural roughness of joint surface are transferred to the RTV silicon rubber molds. On these molds, mixture of cement, sand, and water in the ratio of 1:1.5:0.45 by weight is poured and joint replicas are made. In this study, the experimental shear strength is corrected with gross contact area (Ac) and incremental dilation angle (i). Further, the peak dilation angle is determined by Barton’s and incremental dilation (dv/dh) approaches and compared. The results showed that Barton’s approach underestimates the peak dilation angle. The roughness quantification of joint surface is done using 3D noncontact type profiler, and morphological parameters of joint surface are determined in each shearing direction as described by Grasselli and Egger (Int J Rock Mech Min Sci 40:25–40, 2003). A new predictive model for joint roughness coefficient (JRC) is developed and Barton’s model is modified. It is observed that modified Barton’s model provides good approximation of shear strength in desired shear direction. Moreover, modified Barton peak shear strength (τPre) is compared with Barton and Grasselli’s experimental peak shear strength, and it is observed that τPre matches closely with Barton’s peak shear strength.
Published Version
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