having observed the costly failures of different cutoff walls, that had been constructed according to the mix design specified by reputable consultants in iran, a research programme was conducted to study the effects of constituent materials on the properties of plastic concrete. the main properties, such as compressive strength, biaxial and triaxial strains, permeability, and modulus of elasti...

in the construction process of a plastic concrete cut-off wall, concreting is usually performed using the termie pipe method. in this method, concreting is performed from the lowest point in the excavated trench (containing the slurry) using a funnel and the pipe connected to it. the concrete poured in the funnel gradually settles in the panel through the termie pipe which is beneath the slurry...

Abstract:   A two-dimensional fully implicit finite difference model, which can be easily extended to three dimensions, is developed to study the effect of cut-off walls on saltwater intrusion into the aquifers. This model consists of a coupled system of two nonlinear partial differential equations which describe unsteady density-driven groundwater flow and solute transport. The numerica...

O ne of the most intriguing events in the history of life on earth is the evolution of self-replicating cells. Indeed, it is dazzling to even think about the complexity of the evolutionary changes required to go from a random mixture of molecules to highly organized bacterial cells that are capable of replicating themselves. A predominant theory is that RNA may have formed the basic genetic ele...