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Abstract The mechanical and flow characteristics of rock joint are closely associated with its three-dimensional topography. For a single rock joint，the roughness and waviness of its surface is of paramount importance to flow；and the flow characteristics are related not only to the topography of a single joint surface，but also to the composite topography of the upper and lower joint surfaces. Different contact condition results in different composite topography. The analysis of joint composite topography is the basis of research on flow in a single rock joint. In order to compute the three-dimensional composite topography effectively，the conditions for determining stable contact of two joint surfaces are presented；and the contact algorithm based on determinant conditions is introduced. The Visual C++ programming language is adopted to provide a procedure for three-dimensional composite topography calculation. By using the procedure，the composite topography of joint under different contact conditions can be calculated conveniently with the surface topography data derived from TJXW–3D portable rock surface topography laser scanner developed by Tongji University. Then the fresh marble tension joint is taken as an object；and different contact conditions are formed by dislocating the upper joint surface from the lower joint surface for 1，2，3，4，5 mm respectively after scanning the joint surfaces by TJXW–3D topography scanner. Based on topography data，the composite topography parameters under different contact conditions are calculated by the procedure proposed above；and the influence of different contact conditions on joint composite topography is discussed，which provides a foundation for researches on the relations between three-dimensional composite topography and the mechanical and flow properties of joint under different contact conditions.
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Received: 05 February 2010
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2010, Vol. 29 
