Search for: All records

Two centrifuge experiments were conducted at Rensselaer Polytechnic Institute (RPI) to evaluate and assess the validity of the generalized scaling laws. The experiments were performed within the framework of the Liquefaction Experiments and Analysis Project (LEAP) and consisted of testing a saturated sloping deposit subjected to a tapered base input acceleration. The two tested models reflected consistent soil conditions but were built based on different scaling principles. The first model observed the conventional scaling laws for centrifuge physical modeling. The second model reflected the generalized scaling laws. The two tested models exhibited consistent response before liquefaction. The generalized scaling model showed a higher susceptibility to liquefaction and had a higher rate of pore pressure buildup. 

A series of centrifuge tests of a sloping ground were conducted at Rensselaer Polytechnic Institute (RPI). These tests were used to monitor and assess the soil response, in terms of generated accelerations, excess pore water pressure (EPWP) and associated lateral spreading, as a function of variations in the dynamic input motion and soil relative density. This series of tests are part of the Liquefaction Experiments and Analysis Projects (LEAP-2017), an international effort to assess the repeatability and reproducibility of centrifuge experimental results, and verify and validate soil liquefaction numerical tools using the experimental data. 

An analysis is conducted to assess the sensitivity of 17 replicas of a saturated sloping deposit tests conducted within the 2017 Liquefaction Experiments and Analysis Projects (LEAP). A difference analysis is first used to quantify the dissimilarities between recorded input acceleration time histories. This analysis provided a unique decomposition of the differences in terms of phase, frequency-shift, amplitude at 1 Hz, and amplitude of frequency components higher than 2 Hz (2+Hz). A kriging analysis was used to evaluate the sensitivity of the deposit response accelerations to differences in input motion amplitude at 1Hz and 2+Hz and cone penetration resistance. The analysis showed a response that is more sensitive to variations in cone penetration resistance values than to amplitude of the input 1Hz and 2+Hz motion (frequency) components. 

An analysis is conducted to assess the sensitivity of 17 replicas of a saturated sloping deposit tests conducted within the 2017 Liquefaction Experiments and Analysis Projects (LEAP). A difference analysis is first used to quantify the dissimilarities between recorded input acceleration time histories. This analysis provided a unique decomposition of the differences in terms of phase, frequency-shift, amplitude at 1 Hz, and amplitude of frequency components higher than 2 Hz (2+Hz). A kriging analysis was used to evaluate the sensitivity of the deposit response accelerations to differences in input motion amplitude at 1Hz and 2+Hz and cone penetration resistance. The analysis showed a response that is more sensitive to variations in cone penetration resistance values than to amplitude of the input 1Hz and 2+Hz motion (frequency) components. 

An analysis is conducted to assess the sensitivity of 17 replicas of a saturated sloping deposit tests conducted within the 2017 Liquefaction Experiments and Analysis Projects (LEAP). A difference analysis is first used to quantify the dissimilarities between recorded input acceleration time histories. This analysis provided a unique decomposition of the differences in terms of phase, frequency-shift, amplitude at 1 Hz, and amplitude of frequency components higher than 2 Hz (2+Hz). A kriging analysis was used to evaluate the sensitivity of the deposit response accelerations to differences in input motion amplitude at 1Hz and 2+Hz and cone penetration resistance. The analysis showed a response that is more sensitive to variations in cone penetration resistance values than to amplitude of the input 1Hz and 2+Hz motion (frequency) components. 

Constitutive relations used to describe the stress-strain-strength behavior of soils in cyclic loading are known to play a critical role on our ability to predict the response of geo-structures to seismic loading. The extent and intricacies of this role, however, are highly problem-dependent and often difficult to discern from the effects of other ingredients of a numerical simulation. Moreover, realistic assessments of constitutive models and numerical analysis techniques require detailed comparisons of their performances with reliable experimental observations. The experimental data that have been produced in the course of recent Liquefaction Experiments and Analysis Projects (LEAP-2015 and LEAP-2017) provide an opportunity for a more thorough assessment of the capabilities and limitations of constitutive models for sands over a wide range of strains. The LEAP experimental data along with a large number of cyclic element tests are used here to explore the performance of several constitutive models in numerical simulation of soil liquefaction and its effects on lateral spreading of mildly sloping grounds. 

The experimental results of two centrifuge test replicas of a sloping (saturated-soil) deposit are used to assess the predictions of the (open source) software OpenSees. The discrepancy between recorded and computed acceleration time histories is expressed as a unique aggregate of three measures associated with shape, phase and frequency-shift. This decomposition sheds light on the level of consistency between computed and recorded soil accelerations and the likely source of inaccuracies in the used model prediction.