Abstract: The fractal structure is a common phenomenon of soil. Through analyzing influence domain(Voronoi domain) of the fractal structure connection point, the bearing capacity of particle connection is converted to stress intensity. Some beneficial results are obtained. Values of fractal dimension of particle system structure influence soil strength obviously. The particle of basic unit is more, the ring from the particle is longer, the space for the ring is larger; it is more instable in mechanical property, the strength is lower. The stage number of fractal structure determines the size of the maximum pore. The stage number of fractal structure is more, the size of the maximum pore is larger, the equivalent stress intensity is lower. The couple stress intensity is inversely proportional to the area of basic structure unit (two-dimensional). That is to say, the basic structure unit is larger, the couple stress intensity is lower. Therefore, it can be concluded that the particle is larger, the couple stress intensity is lower when other conditions are same.

Key words: fractal, particle structure, stress intensity