This article presents a model preparation methodology for simulating the seismic behavior of a gentle slope in clay with the presence of a soft, weak layer employing centrifuge testing. The model consisted of a three-layered slope of relatively soft clay with a 3° inclination, representative of Brazilian marine subsoils. In-flight characterization of the undrained shear strength and shear wave velocity profiles were achieved through T-bar penetrometer and air hammer tests. The model was subjected to a series of earthquake simulations at different amplitudes, and the response was tracked with accelerometers and displacement transducers. Additional data were obtained using a particle image velocimetry (PIV) methodology also described in this work. The results show that the proposed model preparation methodology enables the simulation of the strength contrast between the weak and relatively stronger surrounding layers using a laminar container. The additional displacement and acceleration data obtained from the PIV were in good agreement with the corresponding displacement transducer and accelerometer measurements. From the spectral analysis, a shift in the fundamental period was observed as the strain amplitude was increased, suggesting that strain rate effects mobilize higher stresses and a strength rate correction should be considered for the calibration of numerical models and comparison with existing methods for calculation of dynamic displacements in slopes.
The offshore Campos Basin, located in Southeastern Brazil represents an important area in the Brazilian economy as it is one of the most prolific oil-producing basins in the country. With the development of offshore infrastructures in this region, structural design and location must consider different geohazards. This paper addresses the seismic response of gentle submarine slopes subjected to small-to-moderate-sized earthquakes, representative of the Brazilian seismic conditions. The seismic analyses employed numerical modeling, with a nonlinear constitutive model.A set of bedrock ground motions representative of the offshore Campos Basin seismicity was obtained, employing a Uniform Hazard Response spectrum for the region and earthquakes from the Pacific Earthquake Engineering Research (PEER) database. Numerical modelling results showed that, even for small slope angles and moderate earthquakes, there is an accumulation of permanent displacements and shear strains in the downslope direction can affect the stability and performance of existing offshore infrastructures. The findings of this research provide a valuable reference for the prediction of seismic displacements, shear strains and seabed amplification or attenuation of earthquakes on gentle slopes in deep-water deposits similar to those found in the offshore Campos Basin.
This paper presents the experimental results and analysis from two centrifuge experiments that simulated the seismic response of a gentle slope in soft clay. The two models consisted of a three-degree and a six-degree slope in soft clay, respectively, which are representative of typical slopes found on marine seabeds on the continental margins. The models were built in a laminar container in order to reproduce infinite slope boundary conditions. In-flight characterization investigations consisting of T-bar tests and air hammer tests were performed to obtain undrained shear strength profiles and shear wave velocities at various depths, respectively. A suite of earthquakes was
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.