Abstract:Description of fracture surface of rock is the base of evaluating its mechanical behavior. Ways to determine the fractal dimensions of a fracture surface are essential for a better understanding of its complete topographic characteristics. Triangular prism surface area method,projective covering method and cubic covering method are three widely used methods at present. Both the triangular prism surface area and projective covering methods cannot avoid the problem of approximate estimation of the real area surrounded by four points on the fracture surface,because the four points considered seldom lie on a plane. Such approximate calculations will certainly result in error. However,the cubic covering method can assure that every step is accurate. Therefore,it can be regarded as a reliable method for direct determination of the fractal dimension of a fracture surface. In this paper,a laser profilometer is employed to measure the topography of a rock fracture surface. Based on cubic covering method for the fractal dimensions of a fracture surface of rock,a new method named improved cubic covering method is proposed. Cubic covering method and improved cubic covering method are applied to computing fractal dimensions of the same fracture surface of rock. The results show that the improved cubic covering method not only has the advantage of the cubic covering method,but also has more convenient computing process.