Stress-strain state of earth dams with a clay cement-concrete diaphragm

Abstract

The purpose of this research is to calculate stress-strain state of an earth dam with a "diaphragm wall" along the axis of the dam and coupling "diaphragm wall" with a rock bed. "Diaphragm wall" is a vertical clay cement-concrete diaphragm made of secant piles, which elastic modulus varied during the calculation 60 ÷ 120 MPa. The numeric modeling of the stress-strain state was carried out at the elaboration of structure variants for the earth dam of the Nizhne-Bureyskaya Hydro Power Plant (HPP) height about 40 m. Evaluation and analysis of working capacity of the cement-clay concrete diaphragm were carried out on the basis of computational modeling results, which were obtained using the finite element method (FEM). A specialized computer program was used for this calculation, developed at the Hydraulics and Hydraulic Engineering Department of the Moscow State University of Civil Engineering (MGSU). The modeling was carried out in flat setting. In the modeling were included a staged constructing of the earth dam and staged applying loads. There was considered also two variants of presence of friction between ground and liquid clay cement concrete. At the first variant, friction was taken close to zero at the beginning of the calculation and was increased at following stages, and at the second variant, maximum possible friction was taken at all stages of the calculation. For these two variants of the calculation were modeled two variants of embedding the clay cement-concrete diaphragm into the rock bed - rigid and compliant. In this research are shown all results of the modeling of the stress-strain state of the earth dam: the distribution of stresses in the earth dam and in the "diaphragm wall" and also vertical and horizontal displacements in the diaphragm for all described variants. Conclusions were done as a result of this research about effect of construction variants at results of the calculation. All modeling results were analyzed. Recommendations were given for the structure of impermeable diaphragms.