Incipient plane-strain failure of a rectangular block under gravity

We consider the problem of the incipient plastic failure of a two-dimension al rectangular block of yield stress material under plane strain conditions and gravitational loading. The block is assumed to behave as a perfectly r igid-plastic material obeying the Tresca yield condition. There is no tract ion on the vertical sides and horizontal top, and the traction at the base is determined via a modifed Coulomb-type friction. We use slip-line field t heory to calculate the stress field. Our analysis establishes the dimension s of the block which give incipient failure and also suggests a way of dete rmining the yield stress. Furthermore, we show that the precise value of th e coefficient of friction on the base can be unimportant in certain situati ons. (C) 2000 Elsevier Science Ltd. All rights reserved.