Previsão do comportamento da argila mole da Baixada de Jacarepaguá: o efeito da submersão do aterro e do adensamento secundário.

Abstract

The clay found in Barra da Tijuca, Rio de Janeiro, is known to be very soft and also to have very low specific weight. After 17 years from the execution of a landfill on a clay deposits in the region, piezocone and SPT tests were performed to verify the current soft layer thickness. The original layer thicknesses have been determined from vane and SPT tests at the time of construction of the landfill. It was then possible to determine the settlement that has actually occurred. The primary settlement was calculated through the compressibility parameters previously known. A correction on the calculation result was applied due to the submersion effect. A new methodology for calculating this effect was developed in this work, considering the submersion of the landfill occurring gradually, throughout the mathematical development. From the difference between the total settlement observed in the tests and the estimated primary settlement, the magnitude of the secondary settlement was determined. Thus, it was possible to estimate the secondary OCR. This parameter arises from the theory that considers the secondary settlements occurring with the variation of the effective stresses, but, in this case, horizontal stresses. The main conclusions of this research indicate that the value of secondary OCR is greater than that already known for the Sarapuí clay, which formed the basis for this theory. In addition, the proposed calculation of the effect of submersion proved to be quick and easy to apply and provided results similar to those obtained by the usual methods.