Abstract:As for the Wuyi Hydraulic Project on the Dina River in Xinjiang Uygur Autonomous Region of China,the study shows that an arch dam will have a larger economical advantage over an earth dam for the spillway;and drain holes can be emerged into the dam body. No more separate constructions such as floodway,which is a necessary part for earth dams,are required. However,another key issue appears in the determination of the possibility for building an arch dam on sandy gravel:the deformation of the dam in both vertical and horizontal directions;and the corresponding stress distribution in the some situations can exert a great threat to the arch dam safety. The stress-displacement relation of sandy gravel has the two features as follows:(1) the irrecoverable deformation cannot be ignored even in lower stress status;and (2) the tangent deformation modulus is varied under the different stress conditions. Some in-situ tests have been carried out in the adits at different elevations of the dam site;and a nonlinear constitutive model is derived analyzing the effect of stress on rock deformation moduli. This model is capable of simulating the stress-deformation relation;and it can be applied to the assistant in the project layout and design by considering the stress and deformation in the dam body. As an example,this nonlinear model is compared with the linear-elastic model in low stress status,which is corresponding to low mountains at both ends of the dam. It is found out that,by using the nonlinear model,the deformations reduce both in vertical direction and along river direction. However,little change is found in the stress along the dam axial direction. In this case,certain measures can be taken to improve the problem:enlarging the dam bottom locally,mounting concrete piers at both sides of the downstream dam abutment,and setting up artificial short joints and so on.