139 Study on the Ultimate Bearing Capacity of Layered Foundation Rock Masses with Distinct Element Method

Evaluating the bearing capacity of a surface footing resting on a rock mass is a complex problem. This may be attributed to the fact that rock masses are discontinuous, inhomogeneous and anisotropic media. As a traditional method, the rock masses are considered as equivalent homogenous and isotropic continuum. And the ultimate bearing capacity of foundation rock mass is calculated with limit equilibrium theory. However, this method can't represent the real mechanical behaviors of foundation rock masses. In practices, it is needed that values of ultimate bearing capacity of foundation rock masses should be more precise. Then, a Distinct Element Method is adopted to research the stress-displacement characteristics of strip footings on horizontal and vertical layered rock masses. The numerical results of ultimate bearing capacity are discussed. And the effects of the terrane thickness on the ultimate bearing capacity are analyzed. The results show that, for isotropic foundation rock masses, the numerical result of ultimate bearing capacity with the distinct element method is approximate to the mean value of its limit equilibrium upper and lower bounds; the ultimate bearing capacity of horizontal layered foundation rock masses are lightly affected by terrane thickness, and shear failure mainly appear in foundation rock masses; but the ultimate bearing capacity of vertical layered foundation rock masses are affected strongly by terrane thickness, and with the terrane thickness reducing, the failure model of foundation rock mass is gradually changed from shear failure to uniaxial compression failure.