抄録
This paper introduces a method for calculations of minimum total safety factors of slopes by means of the elasto-plastic FEM, considering tension cracks. Soils are assumed as elasto-plastic materials which obey the Mohr-Coulomb equation as the yield condition (or failure condition) and the Drucker-Prager equation as the flow rule.
The procedure of calculations is as follows. First, the shear strength of soils is assumed as τf=c'/F+σ'tanφ'/F. The initial value of F is taken so small that the initial state of a slope is almost elastic. Next the value of F is increased step by step, and finally the ultimate value of F where slope failure occurs, is determined as the minimum total safety factor of the slope. If large tensile stresses occur in the slope, the above procedure is repeated again after thin elements with small strength and low Young's modulus are inserted into the places where tension cracks are assumed to appear.
It is shown that the method presented here can take account of tension cracks as well as pore water pressures properly which always reduce the safety factor of slopes.
