Experiences in Large Slope Stability Problems Under Complex Geology

This article presents a brief summary of the origin of metamorphic rocks, specially schist and the presence of shear or gouge zones in metamorphic rocks, as defects that induce weakness characteristics to the rock mass and that depart substantially from the traditionally evaluation of joints and discontinuities, turning eventually into failure surfaces that govern the stability conditions of surface works. The effect these weak zones inflict into the metamorphic rock mass, especially to schist, causing significant slope stability problems, is illustrated through three case histories. The presence of such defects in the rock mass, detected and analyzed by means of exploratory holes drilled from the surface, can be hardly anticipated during the design stage as far as location, dip direction and geotechnical characteristics, given their erratic alignment within the rock mass, and their disguise during the drilling processes when the clay infill is washed away by the drill water, making their recognition and readiness for lab test sampling even more difficult. Special care of these geologic features, often present in metamorphic rocks, must be taken through: 1) direct exploration –such as galleries–, 2) the elaboration and interpretation of adequate geological models and corresponding sensitivity analyses of shear strength parameters of the established failure surfaces and 3) sound decision making and implementation of stabilization measures based on engineering judgment

On Certain Divisibility Property of Polynomials

We review the definition of D-rings introduced by H. Gunji & D. L. MacQuillan. We provide an alternative characterization for such rings that allows us to give an elementary proof of that a ring of algebraic integers is a D-ring. Moreover, we give a characterization for D-rings that are also unique factorization domains to determine divisibility of polynomials using polynomial evaluations

Recent Experience on Design, Construction and Performance of CFRD Dams

The inherent features of concrete face rockfill dams and the trend of building higher dams have been recently questioned by three recent incidents where major dams have experienced significant cracking in the central portion of the dam after the first filling. The incidents include the dams of Mohale in South Africa, and Barra Grande and Campos Novos in Brazil, the last one being the highest dam of its type built in the world. The design and development of CFRD dams, have been based primarily on precedent and empiricism, however, these recent incidents have shown that the extrapolation of precedent with the current procedures can have serious consequences. This paper present the recent behavior of some of these high dams, as well as the development of numerical analyses (FEM) capable of reproducing observed behavior. It also discuss the design features that are being considered to avoid this unacceptable observed behavior, and the numerical simulations that have been performed to validate these design features for the Porce III hydroelectric project