Centrifuge modeling of pore pressure buildup in a sand deposit as a result of shaking is evaluated by comparison with a large-scale experiment. In large-scale Test SG-1, a 5.6-m-thick, mildly sloping deposit of hydraulic fill clean Ottawa sand of Dr=40%, was subjected to 5 s of low-intensity base shaking (<0.02g) that induced excess pore pressures short of liquefaction. Three centrifuge experiments using various soil deposits and saturation fluids were conducted and compared with the large-scale test. One of these centrifuge simulations used the same Ottawa sand and Dr=40% of the prototype, a viscous pore fluid, and dry pluviation deposition, which created a soil fabric stiffer than the prototype. The other two centrifuge simulations used silty sand saturated with water. The pore pressure buildup in one of the silty sand tests was in good agreement with the prototype, while the other two centrifuge deposits did not develop any excess pore pressure. The various responses in the four tests are expla...

This paper examines in detail the mechanics of lateral spreading observed in a full-scale test of a sloping saturated fine sand deposit, representative of liquefiable, young alluvial and hydraulic fill sands in the field. The test was conducted using a 6-m tall inclined laminar box shaken at the base. At the end of shaking, nearly the whole deposit was liquefied, and the ground surface displacement had reached 32 cm. The presented analysis of lateral spreading mechanics utilizes a unique set of lateral displacement results, DH , from three independent techniques. One of these techniques—motion tracking analysis of the experiment video recording—is especially useful as it produced DH time histories for all laminar box rings and a complete picture of the lateral spreading initiation with an unprecedented degree of resolution in time and space. A systematic study of the data identifies the progressive stages of initiation and accumulation of lateral spreading, lateral spread contribution of various depth ran...

In this research, two components were developed jointly: On the one hand, an experimental plan was created to obtain specific variables of the concrete and serve as a reference for the second model, a numerical and computational type created to address the variability in parameters, such as the elasticity and flow of coarse aggregate and mortar. The experimental work reproduced a specific gradation with a 1” nominal maximum size TMN on spheroidal-shaped particles. To address the diversity of limestone in the national territory, rocks were extracted from five calcareous areas of the country, which were transformed through different activities from lamination and turning with different bits to being carved into spheres until the reference gradation formed. The next stage consisted of determining the mechanical and stress–strain properties of both the mortar and coarse aggregate. In the case of mortar, the compressive stress was obtained from 50 mm × 50 mm × 50 mm cubes and the modulus of elasticity from 100 mm × 200 mm cylinders; for the coarse aggregate, the compressive stress was obtained through tests on cylinders of the calcareous rock used to form the spherical aggregate particles. The materials were mixed according to a previous proportioning for f′_c = 28 MPa and cast in cylinders of 100 mm × 200 mm. Finally, the compressive stress and the modulus of elasticity in these specimens were determined. Separately, a computational model was created to reproduce the experimental model with the same type of materials and load conditions and thereby estimate the compressive stress and modulus of elasticity of the tested material. This model was developed based on finite elements simulating concrete under a two-phase model, in which the coarse aggregate phase was arranged with spheroidal particles that were assembled with the mortar paste, thus finally reproducing a concrete cylinder of 100 mm × 200 mm. Material properties, taken from experimental work, were assigned to these materials. Initially, work was carried out in the elastic range, obtaining, as a result, the modulus of elasticity E_c, and then the specimen was brought to failure, obtaining, as a result, the maximum compressive stress f′_c. To attend to the influence of the effect of the mesh size for modeling on the numerical results of both parameters, several simulations were carried out in which mesh sizes of 4.0, 3.5, 3.0, and 2.5 mm were established for the mortar and the coarse aggregate, respectively, for carrying out the modeling. The results in the computational model showed that the compressive stress turned out to be more sensitive than the modulus of elasticity to the variation in the size of the mesh. For the first, the differences between the 4 mm mesh and the 2.5 mm mesh reached 3%, but for the second, the difference only reached 1% between the results for the same meshes. When the results between the experimental and computational models were compared, we found that the experimental values had the best closeness with results in the 2.5 mm mesh.

Accurate estimation of shear wave velocity is necessary in most geotechnical earthquake engineering applications. This paper details two different methodologies implemented for the estimation of the shear wave velocity profile of soil deposits. The first implemented method employs bender elements, whereas the second relies on a system identification technique and the use of acceleration recordings. In order to compare the two techniques, two centrifuge experiments were conducted using saturated Ottawa F#55 sand in a one-dimensional laminar container. The sand was deposited at void ratios 0·723 and 0·625, respectively. Shear wave velocity profiles obtained using both techniques were compared. These profiles were also compared to those documented in the literature. The results agree well with each other and with the values from the literature. The matching results support the validity of using both methods as a means of estimating the shear wave velocities in centrifuge models as well as in full-scale testing.

Swelling behavior of clays is of great importance for numerous engineering applications due to the prevalence of expansive clays around the world. Expansive clays are present in Mexico City, United States, Australia, Africa and South America, among others. In some cases, these types of clays could present swell pressure values greater than 400 kPa. In this technical note, correlation equations are developed to estimate the swell pressure of clays using laboratory tests performed on swelling clays in the city of Barranquilla, Colombia. Correlations are based on Atterberg limits and water content among other soil properties. Equations with statistically significant coefficients were selected and compared with equations found in the literature. Developed correlations evidenced that swell pressure decays quickly as water content increases. It was found that for the studied soils, Atterberg Limits did not present statistical significance in the estimation of swell pressure. Correlaciones empíricas para la determinación de la presión de expansión de arcillas expansivas en Barranquilla, Colombia ResumenEl comportamiento expansivo de las arcillas presenta vital importancia alrededor del mundo, ya que este tipo de arcillas se encuentras en diversas y extensas zonas del planeta. Arcillas con este tipo de comportamiento se encuentran presentes en diversas regiones del mundo como la ciudad de México, los Estados Unidos, Australia, algunas zonas de África y Sudamérica, entre otras. Este tipo de arcillas pueden presentar en algunos casos presiones de expansión superiores a los 400 kPa. En la presente nota técnica se desarrollan correlaciones para estimar la presión de expansión de arcillas con base en ensayos de laboratorio practicados a arcillas con comportamiento expansivo presentes en la ciudad de Barranquilla, Colombia. Las correlaciones desarrolladas se basan en los límites de Atterberg y contenido de humedad, entre otras propiedades de los suelos. Se seleccionaron aquellas ecuaciones que presentaban coeficientes estadísticamente significativos y se realizaron comparaciones con correlaciones presentes en la literatura. Las correlaciones mostraron que la presión de expansión decae rápidamente a medida que el contenido de humedad aumenta. Además, se observó que para los suelos estudiados los límites de Atterberg no son estadísticamente significativos para la estimación de la presión de expansión.