Abstract In view of the great differences of the seepage law of the fractured rock with or without filling materials，and that most of the seepage fractures in the engineering rock mass are the shear sliding fractures filled with the original rock broken materials，the research of the influence on seepage discharge caused by the factors such as loading paths，axial compression，confining pressure，fracture depth，particle size of original rock fillings etc.，has important reference value to the selection of the seepage parameters and the stability discrimination of the rock slope. With the experimental study of the fracture seepage aiming at the sandstone with artificial cutting fractures in Yichang area，some conclusions are drawn as follows：(1) The metrical data of seepage discharge do not have the repeatability before filling sand grains are tightly. It is not only under the influence of the axial pressure loading path，but also under the influence of the confining pressure way. The seepage velocity tends to be stable with repeatability after more than four times of loading and unloading cycles under axial pressure and confining pressure. (2) There is a linear relationship between the axial pressure and the seepage discharge of large opening fracture with solid fillings when the fracture depth is less than 2.5 cm，then after the fracture depth reaches 2.5 cm，the relationship becomes nonlinear. And it is mainly because that the increasing fracture depth induces the increment of the change possibility of the sand position and structure. (3) To the fractured rock mass with fillings，the influence of the confining pressure is significant，but to the big opening fracture without fillings，the influence of the confining pressure on the seepage discharge is little，it is because the order of the shape variable of rock mass caused by the confining pressure is too small compared to the wetted cross-section of the fracture with big opening. (4) When axial pressure is less than 0.03 MPa or confining pressure is bigger than 1 MPa，the effect of filling granularity on seepage discharge has the nature of randomness. When axial pressure is more than 0.03 MPa and confining pressure is bigger than 1 MPa，the bigger the sand particle size is，the bigger the corresponding seepage velocity is. At the moment，the bigger the axial pressure is，the more the effect of filling granularity on seepage discharge is. Size relationships and proportions of three different granularity corresponding velocities are stable with the growth of confining pressure.
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Received: 27 July 2009
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