No abstract

The calculation of the long-term dynamic bearing capacity arises from the need to consider the generation of maximum pore-water pressure developed from a cyclic load. Under suitable conditions, a long-term equilibrium situation would be reached, when pore-water pressures stabilized. However, excess pore-water pressure generation can lead to cyclic softening. Consequently, it is necessary to define both the cohesion and the internal friction angle to calculate the dynamic bearing capacity of a foundation in the long term, being necessary to incorporate the influence of the self-weight of soil and therefore the width of the foundation. The present work is based on an analysis of the results of cyclic simple shear tests on soil samples from the port of El Prat in Barcelona. From these experimental data, a pore-water pressure generation formulation was obtained that was implemented in FLAC2D finite difference software. A methodology was developed for the calculation of the maximum cyclic load that a footing can resist before the occurrence of the cyclic softening. The type of soil studied is a contractive cohesive soil, which generates positive pore-water pressures. As a numerical result, design charts have been developed for long-term dynamic bearing capacity calculation and the charts were validated with the application of a real case study.

The bearing capacity in soft soils under cyclic loading has not been widely studied as the static bearing capacity. In soft saturated soils under cyclic load, the phenomenon of cyclic softening occurs, this consists of an increase in the generation of pore-water pressure due to the cyclic load and a decrease in effective soil stresses. The purpose of this work was to propose a methodology for calculating the bearing capacity in soft soils under cyclic loading. The research is based on the results of monotonic and cyclic simple shear tests carried out with samples from the PRAT port of Barcelona. From an analysis carried out on all the experimental data, an equation for the generation of pore-water pressure is proposed. This formulation was implemented in the FLAC2D finite difference software and is part of the methodology. The methodology of the proposed calculation process consists of 6 stages and verification under two criteria. This process is iterative in case of not meeting any of the two verification criteria. Under this methodology of the calculation process, charts are proposed to calculate the bearing capacity of soft soils under cyclic loading. This application takes into account the properties of the soil, the static bearing capacity (P he), and the effective load outside the foundation (q). Also, an analysis of the parameters that most influence the bearing capacity of soft soils under cyclic loading was carried out.

RESUMO: Las presas de enrocado con pantalla de hormigón (CFRD) son muy frecuentes en la actualidad. Sin embargo, algunas variables; por ejemplo la topografía, el clima, las filtraciones, o la posibilidad de uso de distintos materiales, hace que se estudien otros tipos de presa. Un tipo es la presa de enrocado con núcleo de asfalto (ACRD). La geometría de los dos tipos de presa sigue recomendaciones derivadas de la práctica. Los parámetros geométrico que se emplean, son aquellos que han mostrado un buen resultado. Los conceptos de modelación tenso-deformacional de los perfiles transversales se han empezado a utilizar recientemente. En ambos casos, el elemento de "impermeable" es una barrera de dimensiones transversales reducidas. Se presenta un análisis comparativo del comportamiento de estos dos tipos de presas. Se han utilizado secciones típicas, junto con un modelo de elementos finitos de uso convencional en la solución de estos problemas geotécnicos. Se ha evaluado el comportamiento de la presa en puntos característicos. El enrocado ha sido representado según modelos constitutivos de rigidización, para una mejor interpretación del comportamiento. Se tomaron en cuenta dos condiciones de evaluación (fin de construcción de la presa y estado de régimen). Las modelaciones se efectuaron para tres alturas (30m, 60m y 100m).