摘要：Gradation equation is one way to describe the gradation of coarse-grained soil conveniently,exactly and *** the gradation equation,the influence of gradation on the mechanical behaviors of coarse-grained soil can be expressed quantitatively.A new gradation equation with a parameter is *** basic properties and applicability of the new equation are *** results show that the proposed equation has the applicability to express coarse-grained soil gradation(CSG),and the range of the parameter β is found to be 00.5,the gradation curve is sigmoidal,otherwise the gradation curve is *** well graded gradations,the parameter has the value of 0.13<β<*** CSGs used in domestic and foreign earth-rockfill dams are probed,and the value of the parameterbfalls in the range of 0.18 to *** investigation of the range of β is of value to guide the design for CSG of earth-rockfill dam.