Liquefaction of sands is a result of excess pore water pressure generation due to the contractive tendency of the soil skeleton under undrained cyclic shearing. Proper characterization of the excess pore water pressure plays an important role in liquefaction analyses. In this paper, we present results from a series of cyclic triaxial tests on silty sands with different fines contents. Based on these results, we put forward two pore water pressure models (a stress-based model and an energy-based model) to characterize the pore pressure built-up, where the model parameters are calibrated regarding different fines contents, packing densities, confining pressures, and loading amplitudes. The methods for characterizing the model parameters are also discussed.

This study aims to raise awareness of liquefaction risks in densely populated areas of Chiang Rai, following the occurrence of liquefaction in remote areas of northern Thailand in 2011. These urban areas primarily consist of sandy soil layers, which are susceptible to liquefaction. To assess the liquefaction potential, this research conducted Standard Penetration Tests at newly installed boreholes located in the central Chiang Rai province. The liquefaction potential was estimated using the simplified procedure analysis and finite element method. The study considers two earthquake cases associated with 10% and 2% probabilities of exceedance in a 50-year period. Overall, both analysis approaches consistently indicate the potential for liquefaction in Chiang Rai, particularly within shallow layers of loose sand. Additionally, the variation in the type and sequence of soil deposits were found to significantly influence the liquefaction hazard. By incorporating geotechnical data from the boreholes, this study significantly enhances the accuracy of estimated liquefaction potential values for these urban areas.

A new liquefaction potential evaluation method using both Standard Penetration Test (SPT) and shear wave velocity (V_s) data is proposed in consideration of the effects of density and soil fabric on liquefaction characteristics. Through a series of chamber tests, it has been confirmed that for specimens created under the same density and confining stress level but of different soil fabric as reflected from V_s values, the measured SPT blow counts (N-value) did not change with different V_s at the given relative density. In our proposed evaluation method, the cyclic resistance ratio, CRR is first estimated from existing SPT-based approaches, and taken as a reference field resistance representing mainly density effect. A corresponding normalized V_s value could be back-calculated from V_s-based triggering at the same CRR. To account for the soil fabric influence, the implied V_s is compared to the field measurement and a revised in-situ CRR is determined through a previously proposed empirical V_s-CRR relationship where the relative density is normalized. The applicability of the new method is demonstrated through liquefaction case histories collected in Japan and from an open source global database.

This article compares two lateral confinement methods, wire reinforced membrane (WRM) and stacked rigid rings (SRR), used in the ASTM D6528 and D8296 standards for conducting the direct simple shear and the cyclic direct simple shear tests on soil samples in the laboratory. A series of undrained strain-controlled cyclic direct simple shear tests on Jumunjin sand with medium density was conducted using the WRM and SRR confining methods at various strain levels of 0.1%, 0.2%, and 0.5% to compare the excess pore pressure (EPP) generated after each cycle during the testing process. The study found that the effect of the confinement method on EPP generation is negligible at low shear strain levels of 0.1%, but as the shear strain level increases, the difference between the two methods becomes more pronounced. The EPP generated using the WRM method is slightly smaller than that produced by the SRR method at a shear strain level of 0.2%, and significantly smaller at a shear strain level of 0.5%. However, the difference between the two methods gradually decreases as the number of cycles increases. The study concludes that the sample confined with the WRM method had a higher liquefaction resistance than the SRR method. The difference between the two methods gradually decreased with an increase in cycles, and the magnitude of the shear strain level was a crucial factor affecting the difference between the two methods, with larger shear strain levels resulting in greater differences.

For undrained test results involving coarse materials where membrane penetration is inevitable, several correction methods have been proposed. In this study, the applicability of a pore pressure generation model, which is based on volumetric strain evolution under constant cyclic stress ratio and elastic modulus of the soil, is validated to directly estimate the liquefaction strength of gravelly soil without conducting undrained tests and applying empirical corrections. The results show that the elastic modulus of the gravelly soil can be estimated by obtaining the volumetric strain due to membrane penetration, and that volume of membrane penetration has no effect on the evolution of plastic volumetric strain. The estimated pore pressure buildup and liquefaction strength curve by the model agreed well with the undrained test results.

Reducing the liquefaction potential of a soil caused by earthquake has been increasingly investigated. One of the liquefaction mitigation methods is to generate excess pore water pressures in the liquefiable soils. The goal of this study is to investigate the liquefaction characteristics of porous material (PM) and its application in improving the liquefaction resistance of saturated sandy soil. Samples were prepared under loose state and tested under undrained stress-controlled conditions. A series of cyclic triaxial tests were conducted on various conditions such as loading frequency (f) and height-to-diameter ratio (H/D). For the investigation of liquefaction mitigation of fine sand, a comparative study was conducted on the same gradation of PM and coarse sand specimens. The experimental results showed that the effect of the f on the cyclic resistance ratio (CRR) of PM was negligibly minor under f between 0.05 and 1 Hz, regardless of the sample size. Under the same testing conditions, an ignorable effect of specimen sizes on CRR of PM was found under various H/D ratios between 1.6 and 2.8. For the application of PM in geotechnical engineering, while PM specimens have the greatest liquefaction resistance value compared to fine sand and coarse sand, fine sand mixed with 30 % PM, by weight has more resistance than the same gradation of fine and coarse sand mixture by approximately 14 %.

Liquefaction assessments commonly utilize subsurface geotechnical data, such as the standard penetration test (SPT), cone penetration test (CPT), or shear wave velocity (Vs) measurements, to characterize the soil’s resistance to liquefaction. Recently, liquefaction assessment utilizing geospatial data has been gaining attention due to the broader accessibility of data needed, such as digital elevation models (DEM) and other mapped characteristics that can influence liquefaction susceptibility, such as geology and geomorphology. The accessibility of these data makes this method easier to apply. The authors aim to develop a methodology that combines these two sets of data to provide a liquefaction assessment procedure for a vast area that can use easily accessible geospatial data along with subsurface geotechnical data to provide greater detail in the assessment of a site. Prior to developing this hybrid geotechnical-geospatial method, an investigation into the candidate representative geotechnical data (RGD) to be used alongside the geospatial data needs to be undertaken. The study details the exploration of various candidate RGDs that will transform the 3D subsurface geotechnical data – CPT data in this study – into a single parameter that characterizes the site’s vulnerability to surficial liquefaction manifestation (SLM). This transformation will allow it to be assigned to a site with a 2D coordinate along with other liquefaction-related inputs. The authors found that the normalized and clean sand equivalent of cone tip resistance can be averaged with a depth-based inverse weight function to exhibit a satisfactory correlation with SLM and pass the preliminary check for linearity as part of the requirements prior to model development. Certain liquefaction manifestation indices and modified versions of the critical zone thickness also correlate well with SLM but require transformation before they can be used in the model development.

Uncertainty caused by the inherent variability of soil properties assumes a pivotal role in the prediction of soil dynamics. The primary objective of this study is to establish a methodological framework for quantifying statistical estimation errors that are associated with geotechnical investigation aspects (such as investigation number and location) within the context of liquefaction analysis. This objective presents a significant challenge due to the considerable number of analytical parameters involved in the targeted liquefaction analysis, with a substantial portion of them remaining unobservable. Within this research, we assemble sets of parameters from historical cases that have been analyzed by experts, thereby elucidating the statistical attributes inherent in these analytical parameter sets through fundamental statistical techniques. This encompasses the scrutiny of correlation structures among parameters and their subsequent classification into distinct clusters. Furthermore, we endeavor to integrate the statistical attributes of analytical parameters into the liquefaction numerical analysis through the application of simple Bayesian estimation.Subsequently, through the utilization of a basic one-dimensional vertical seismic response analysis as an illustrative example, we investigate the propagation of uncertainty into the seismic response analysis. Building upon the previously discussed findings, we provide evidence that the statistical characteristics of analytical parameters, along with the observational components in analytical parameters, give rise to substantial variations in the dynamics of liquefaction.

On November 9, 2022, two earthquakes of magnitude 5.5 and 5.2 respectively, struck off Italian Adriatic coast with a one-minute delay, but caused no serious damage or injuries. The epicenter of the quake was 35 km offshore from Pesaro, a seaside city in the eastern Marche region, at a depth of 7 km. The two earthquakes ruptured a well-known fault in the buried thrust front of the Northern Apennines. The size and architecture of these faults suggest they could generate even larger earthquakes. Even though no relevant damage observations have been reported after the event as verified by an ad-hoc on-site reconnaissance, 4 recording stations located among the cities of Ancona and Senigallia recorded a horizontal peak ground acceleration higher than 0.1 g. This value is usually adopted as a threshold to discriminate the triggering of seismic-induced soil liquefaction, as well as a magnitude of 5 is considered the lower value able to trigger liquefaction. Moreover, parts of the Marche and Emilia Romagna coast are characterized by saturated granular soil deposits and experienced in the past several liquefaction manifestations. Reports of such historical earthquakes often mention local hydrogeological alteration, surface manifestations/deformation, and liquefaction phenomena (e.g., Rimini’s earthquakes, 1875 and 1916, and the Senigallia’s earthquake, 1930). Therefore, the seismic event of the 9th of November 2022 represents an interesting case study to assess the effectiveness of current soil liquefaction methods based on semi-empirical charts for correctly predicting the non-occurrence of soil liquefaction manifestations. The study assesses the safety against liquefaction for the considered seismic event at a specific site of Senigallia where liquefiable deposits have been detected and adequate soil characterization is available through in-situ tests.