This paper presents a procedure on how photogrammetry by simple means can be used to create a joint surface profile using standard off-the-shelf equipment. The results are presented as a step by step instruction ranging from imaging of a rock sample to validation of the acquired data to preparation of a numerical model. Imaging is performed using a camera with a fixed lens in combination with the photogrammet-ry software 3DM CalibCam and 3DM Analyst. Surface data validation is carried out by means of laser scan in order to create a reference surface for local coordinate comparison to the photogrammetry data terrain model (DTM). The photogrammetry data is proven to be accurate on a scale smaller than one millimetre and a numerical shear-box model is prepared using the profiles as input. Surface evaluation show no clear indication that any part of the surface would be less accurately imaged due to directional bias as the areas of deviation are evenly spread across the sample. Profiles derived from photogrammetry are related to JRC. Calibration of the shear-box model is on-going; no numerical results are included in this paper.


An indisputable fact in rock mechanics is that there is a major influence from joint roughness on the shear strength of unfilled joints; a more debated subject is how to evaluate the roughness and relate it to the magnitude of the shear strength. The most common way to incorporate the joint roughness is to use the Joint Roughness Coeffi-cient (JRC) published by N. Barton in 1973 (Tatone & Grasseli, 2010), (Asadollahi & Tonon, 2010) which is a given a value between 0 and 20 depending on the resemble-ance to one of the Barton standard profiles, either by visual estimation or the use of a comb profilometer (Barton & Choubey, 1977).

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