Abstract：Failure criteria of rock-soil-concrete are briefly discussed. Estimation is made on the strength parameters of rock，soil and concrete，which is necessary for finite element simulation in flexible pile foundation, excavation whose active and/or passive soil may be reinforced，slope with gravity retaining wall and landslide. The formulae，which can be used to calculate uniaxial tensile strength，uniaxial compressive strength，cohesion and internal friction angle of rock-soil-concrete，are derived from four cases which may be combined respectively with the states of two-dimensional and three-dimensional stresses with failure criterions of Mohr-Coulomb’s inclined line and Mohr’s parabola. Finally the error analysis is discussed.
