Under the new regulatory requirements for nuclear power plants, the increase in standard ground motion has underlined the need to evaluate the effects of liquefaction on Pleistocene sands, conventionally regarded as non-liquefiable soils. One characteristic of Pleistocene sand is age-related cementation. However, only a few comprehensive studies have been conducted on the degree of cementation required to assess the effects of liquefaction. In this study, various element tests, such as unconfined compression tests, drained monotonic and undrained cyclic hollow torsional shear tests, and cyclic triaxial tests, were conducted using sand with cement to investigate the effect of cementation on the seismic behavior of sandy soils. When sand is properly cemented, shear failure occurs before the excess pore water pressure ratio reaches one under undrained cyclic loading, and liquefaction does not occur such that the effective stress reaches zero. The effect of cementation is observed not only in the cyclic resistance ratio but also in the maximum excess pore water pressure ratio during undrained cyclic loading, unconfined compression strength, dynamic strength to static strength ratio, and shear modulus dependence on confining pressure. These indices can be used as criteria to determine whether the effects of liquefaction should be considered.

The use of “simplified procedures” for the study of lateral spreading could be misleading, and it is debatable whether or not lateral spreading case histories should be included in liquefaction triggering databases. In this context, the 2010-2011 Canterbury Earthquake Sequence (CES) provides several examples of liquefaction and lateral spreading, as identified by the post-earthquake reconnaissance campaigns. Major to moderate lateral spread displacements were observed in the proximity of the Avon River in Christchurch (New Zealand), within about 100-200 m from the fluvial axis and with maximum crack widths of over 200 mm. This paper documents the results of a series of seismic dilatometer tests (SDMT) performed along a section that crosses the Wainoni suburb from the Avon River, where lateral spreading was severe, to farther from the river, where liquefaction features were relatively minor during the CES. Profiles of the SDMT parameters, especially of the horizontal stress index (K_D), show significantly higher values when the sounding is close to the river but insignificant changes at greater distances from the river. Increases in K_D may be related to an increase in the lateral stress in the subsoil induced by compression of the lateral spread mass near the river. Because the flat dilatometer test (DMT) is more sensitive to changes in lateral stress than other in-situ tests, this increase in lateral stress during lateral spreading may not have been recognized using other test methods. Although post-liquefaction in-situ testing is commonly used to develop liquefaction triggering databases, the observed increase in K_D suggests that the DMT-based triggering curves should only include post-liquefaction case histories with no lateral spreading. Similar precautions may be necessary for other in-situ tests after additional research.

In this study, model vibration experiments were conducted in a gravity field to evaluate the effect of an impermeable layer on the flow deformation of the ground based on the strain distribution. A saturated sloping ground was shaken and photographed using a high-speed camera, and the shear and volumetric strains generated in the ground were determined through image analysis. In the experiment, sand eruptions occurred only in the presence of impermeable layers, and the ground below the impermeable layers exhibited expansion behavior near the locations where sand eruptions occurred. Furthermore, the shear and volumetric strains tended to differ in terms of the location of the maximum values and the shape of the depth distribution, depending on the presence of impermeable layers and the effect of sloshing.

Liquefaction is a phenomenon which tends to cause damage to buildings and structures founded on liquefiable soils. However, existing probabilistic liquefaction-induced lateral spread hazard analysis (PLLSHA) is based on empirical lateral spread (LS), in which the spatial variability of soil parameters is ignored in liquefaction hazard evaluations. This paper thus proposes a PLLSHA method which can consider the spatial variability of soil parameters. The response spectrum matching method was used to select 15 ground motions from NGA-West2 database under the earthquake scenario with magnitude of 7.0 and rupture distance of 10 km. Based on the Cholesky midpoint method, random fields for the relative densities of the liquefiable layer with different mean values, coefficients of variation, horizontal and vertical correlation lengths were generated and then embedded into the sloping grounds containing liquefiable layers. A set of random variables for relative densities of the sloping ground is also generated for comparative purpose. The finite element software OpenSees is used to establish the two-dimensional sloping ground model and conduct several dynamic response analyses based on the ground motions selected. The mean LS on surface ground are monitored and recorded as indicators of liquefaction consequence for analysis. An assumed site source with variable magnitudes and 10 km from sloping ground is used for conducting the PLLSHA. Result shows that the spatial variability of relative density of soils has a great influence on the liquefaction hazard results. Specifically, the liquefaction-induced LS hazard would be greater when the mean value of the relative densities or vertical correlation lengths are smaller, as well as when the coefficient of variation or horizontal correlation lengths are larger. When a random variable model is utilized, the liquefaction-induced LS hazard is significantly overestimated. This study would provide a theoretical reference for lateral spread hazard analysis of liquefiable soil layers exhibiting strong spatial variability.

During the Petrinja earthquake sequence in December 2020, numerous liquefied sand ejections came to the surface along the Kupa, Sava and Glina rivers in Quaternary alluvial sediments. In October 2022, we performed field investigation in the epicentral area, involving geotechnical and geophysical techniques, at different sites with sand ejecta or lateral spreading along the Kupa river to specify the geometries of the various subsurface sedimentary layers and in particular the liquefied zones in depth. For all sites, the sandy ejecta most likely originates from sandy point bars buried under silty layers and located preferentially in the convex parts of meanders. This paper presents and discusses models to highlight the different geometries obtained by geophysics or built from geotechnical soundings for one site located on the eastern edge of an abandoned former meander of the Kupa River.

This study investigates the impact of liquefaction-induced lateral load demand on piles, focusing on the relationship between geometric boundary effects, such as sidewall effects, and drag force experienced by the pile. By modeling liquefied soil as fluid, this study explores pile response during liquefied soil flow and quantifies the influence of sidewall effects on the drag force calculation. The study uses a numerical software, COMSOL, to conduct analyses for investigating pile–soil interaction under Newtonian flow assumptions and laminar flow conditions to consider the conversion of drag force from unbound to bounded conditions under different Reynolds numbers, Re, and the separation of boundary effects, which is considered in apparent viscosity, and intrinsic viscosity. The proposed method approach is validated through comparisons of numerical and experimental results, correcting drag forces for different width and length-to-diameter ratios within a specific Re range. The study suggests a better correction procedure to accurately calculate drag forces for embedded piles during soil liquefaction, enhancing the understanding of pile behavior.

Following the September 4th 2010 Mw7.1 and February 22nd 2011 Mw6.2 Earthquakes in Canterbury, New Zealand, liquefaction-induced lateral spreading was observed along the Avon and Heathcote rivers. Detailed field measurements following the events provide a benchmark to evaluate the efficacy of lateral spreading prediction models under real world conditions. This paper presents the development of 2D effective stress finite difference models in FLAC2D of two transects along the rivers, and compares numerical results to observed displacements for the two major seismic events. The liquefiable soil was modelled with the PM4Sand model, and an automated calibration procedure was developed to determine the model inputs based on CPT results. The displacements during the earthquake excitation and post-shaking during pore pressure dissipation were quantified. Overall the simulations show reasonably consistent ground displacements at the channel free-face for both events and both transects, though recognising significant uncertainties in the simulations and field measurements. The results of the numerical simulations highlight the importance of both geometric (notably the channel width) and soil properties as key factors that influence lateral spreading displacements. The simulation results provide some confidence that detailed finite difference models can reasonably capture the expected level of ground movement during a lateral spreading event.

Case histories have reported significant damage to structures during earthquakes due to permanent ground displacements (PGDs) arising from liquefaction-induced lateral spreading. The empirical model by Youd et al. (2002) is classical and has been widely adopted in practice over two decades owing to its simplicity. However, the suitability of this model for M>8 earthquakes is at stake, as it is largely based on datasets with M<8 earthquakes. Zhang and Zhao (2005) proposed another empirical model to compute PGDs that accounts for the underlying mechanism and different tectonic source type responsible for earthquake of a given magnitude; accordingly, the outcomes from this model differentiates between crustal and subduction earthquakes. The authors in their recent work developed probabilistic lateral spread displacement hazard curves by implementing Youd et al. (2002) and Zhang and Zhao (2005) models using the Openquake opensource platform, where the users are provided with a choice of using hazard curves based on the model of their preference. Based on the initial comparison of the hazard curves, it has been observed that both the models show similar trends for all the geographic locations considered in the study. However, the annual probability of occurrence reported by Zhang and Zhao (2005) model were found to be significantly higher than those predicted by Youd et al. (2002), for a given level of expected lateral spread displacement. This apparent conservatism of the predictions based on Zhang and Zhao (2005) motivated the authors to perform a comparative assessment in order to understand the underlying reasons for the differences in the outcomes and comment on the applicability of the models. In view of this, Openquake analyses were performed considering some selected geographic locations in Canada, and the findings from this work are presented herein.

This study presents the results of continuously measured ground acceleration and pore water pressure at a liquefaction-prone site in reclaimed land in the Tokyo Bay area. The site was monitored over the past two years since November 2020, recording earthquakes, including one with a maximum horizontal acceleration of 162.7 Gal, leading to an excess pore water pressure increase of 19.4 kPa. This study also proposes an influence index of acceleration on pore water pressure for liquefaction assessment. We calculated the new index I_pw, which successfully explained the impact of seismic motion on the rise of excess pore water pressure. Additionally, it was validated by applying I_pw to a series of shaking table tests under a 1G condition. As a result, the validity of the index I_pw with the seismic duration threshold determined by the acceleration level was confirmed as a case study.