A Comparative Study of the Cracking Effect of Induced Joints of Various Spatial Formations

The use of induced joints is a common cracking control measure used in the design of roller compacted concrete arch dams. Currently, in some projects in which radial twisted joints were used, during the construction period, some cracks appeared around the induced joints while the joints themselves failed to open. From the fracture mechanics point of view, this problem is related to the variations in the spatial formation of the induced joint planes. In this study, we formulated numerical examples involving square plate and cylindrical arch dam with joints of various planar spatial formations and used the virtual crack-closure technique and the Richard brittle fracture criterion to obtain the equivalent stress intensity factor of the joint plane, and we studied the joint plane stress intensity factor based on the variations in the joint plane formation angle. Based on the reciprocal of the normalized stress intensity factor, we obtained the equivalent strength correction coefficient for induced joints of varying plane angles, referred to in this study as the joint plane formation factor ψα, in order to reflect the influence of varying joint plane formations on the induced joint cracking. Our study results show that as the joint plane angle continuously increases, it is more difficult for the induced joints to open, which implies a gradual increase in the equivalent strength of the joint plane. Therefore, in the actual design of rolled concrete arch dams, the straight transverse joint layout should be used for induced joints. If the use of the radial twisted joint layout is necessary, the joint plane angle should not exceed 10°.