Abstract Dynamic soil parameters such as the shear modulus suffer degradation while damping in soil increases under dynamic loading. These can be determined from various tests such as element tests, field tests and centrifuge experiments. Most of the studies about dynamic soil characterization have focused on evaluating these parameters assuming horizontal ground conditions without considering the effect of static shear stresses induced by ground inclination. This paper presents a dynamic centrifuge test conducted on a layered gentle slope comprising clay and sand, to obtain experimental data in terms of shear modulus and damping for various shear strains. Particle Image Velocimetry (PIV) was employed to measure the displacements and to calculate accelerations due to seismic loading at various depths throughout the slope model. The results suggest that the static shear stress caused by the profile inclination causes a more pronounced degradation of the shear modulus when compared to flat ground conditions. Moreover, the damping during the centrifuge test exhibited larger values than expected, following a similar behavior observed in other experimental programs. The strain rate analysis revealed the mobilization of shear stresses higher than the monotonic shear strength for the clay layers during the seismic shaking. experiments sand strains PIV (PIV model Moreover expected programs shaking

Abstract The anchoring of floating platforms is one of many processes in the oil industry that requires innovative strategies. In this respect, there is interest in developing techniques that improve the shear strength of soft soils in order to increase the bearing capacity of offshore foundations anchored in these soils. Normally consolidated clay soil is known to undergo thermal consolidation when submitted to temperature cycles. The present study aimed to assess the impact of a temperature cycle on soft kaolin clay using a reduced-scale physical model submitted to heating at maximum temperatures of 85 °C and 65 °C, followed by cooling. Variables such as pore pressure, temperature at different soil depths and displacement were monitored during the thermal cycle to better understand the phenomenon. The strength profile before and after heating was determined via T-bar tests conducted in different positions in relation to the heat source. The temperature variation increased the undrained shear strength of the soil directly proportional to the temperature applied and inversely proportional to the radial distance from the heat source, reaching improvements of 123%. In this respect, it is believed that applying a temperature cycle to normally consolidated soft clayey soil can improve the pullout capacity of offshore foundations.

Resumen Brasil se encuentra en una región intra-placa de baja a moderada sismicidad, esto quiere decir que hay una limitada disponibilidad de registros de acelerogramas representativos de la región. Parte de un estudio de respuesta local o del diseño sísmico de estructuras requiere del uso de registros aceleración-tiempo que sean compatibles con un espectro de diseño. El presente trabajo tiene como objetivo la aplicación de metodologías para obtener acelerogramas representativos de la región sudeste brasilera, en particular en la región offshore de la cuenca de Campos. Se utilizó la información del análisis probabilístico del riesgo sísmico desarrollado para la región de interés en este estudio para obtener el espectro de respuesta de diseño y para definir los escenarios sísmicos que generan mayor influencia. Adicionalmente, se utilizó la información de acelerogramas registrados a partir de dos sismos relativamente recientes ocurridos en la región sudeste brasilera, para la aplicación de una de las metodologías de obtención de acelerogramas sintéticos.

Abstract Brazil is in an intraplate area of low to moderate seismicity, this means that few or no records of strong ground motions are available. Part of the site response analysis and seismic design of structures require the use of acceleration time-histories compatible with a specified target response spectrum. This study aims to utilize methodologies based on the use of existing earthquake records from a well-known database and synthetic accelerograms to obtain ground motions representative of the Brazilian Southeast Region, particularly in the offshore Campos Basin. Information from a probabilistic seismic hazard assessment performed in the interest area was employed as input to the methodologies applied in terms of target response spectrum and the dominant earthquake scenarios. Besides, the acceleration time-histories of two relatively recent earthquakes that occurred in the Brazilian Southeast were used to apply one of the approaches to obtain a synthetic spectrum compatible accelerogram.