Earthquake-induced Liquefaction Research Articles

Estimation of historical earthquake-induced liquefaction in Fraser River delta using NBCC 2020 GMPEs in deterministic and probabilistic frameworks

Paleo-liquefaction features of sand dykes and sand blows were identified in the 1990s at multiple host sediments in the Fraser River delta in southern British Columbia all younger than 3500 BP. These paleo-liquefaction sites could be linked to Cascadia subduction earthquakes. Empirical magnitude-bound relationships are often used to estimate paleo-earthquake magnitudes. To determine the lower bound magnitude of Cascadia interface earthquakes that could have generated the paleo-liquefaction features, we use ground motion prediction equations for interface earthquakes from the sixth Canadian seismic hazard model of the 2020 National Building Code of Canada. We estimate the minimum M and its peak ground acceleration ( amax) of an interface earthquake required to initiate paleo-liquefaction in the study region. Starting with three full-rupture deterministic scenarios of varying source-to-site distance, we determine the minimum M required from Cascadia subduction zone interface mega-thrust earthquakes to induce liquefaction in the Fraser River delta spans 8.0–8.9 with a corresponding amax range of 0.09–0.13 g. We also perform a back-calculation paleo-liquefaction analysis in a probabilistic framework to incorporate aleatory uncertainties (cone penetration resistance, groundwater table, and amax) and epistemic uncertainties (liquefaction simplified model) via the Monte Carlo simulation. The developed probabilistic methodology is also applicable to a forward liquefaction assessment and other liquefaction sites globally. The median M from this probabilistic paleo-liquefaction for the four investigated sites lies between 8.8 and 9.0. Our probabilistic results also reveal that Cascadia interface earthquakes with M > 8.9 lead to a 31%–57% probability of liquefaction triggering in the Fraser River delta. In addition, we developed deterministic and probabilistic magnitude-bound curves specific to Cascadia interface earthquakes and representative site class E conditions. These curves provide more accurate magnitude estimations for predicting seismic-induced liquefaction from Cascadia interface earthquakes for sites in the Pacific Northwest than empirical bound curves.

Probabilistic-based seismic fragility assessment of earthquake-induced site liquefaction

As a very complex and uncertain problem, seismic liquefaction is affected by many factors, such as earthquake intensity, site conditions, soil properties, etc. During the past half a century, the state-of-the-art in analysis and evaluation of earthquake-induced soil liquefaction and its consequences as well as the state-of-the-practice in improving seismic stability to resist liquefaction have been made much progress. However, the fragility analysis and assessment for seismic liquefaction of sites have not been paid enough attention to. In this paper, the concept of seismic liquefaction fragility for building sites is proposed. The soil resistance to liquefaction and liquefaction possibility are expressed as a fragility function of ground motion intensity, which can be used to describe minor, moderate and severe liquefaction potential under different ground motion intensity. Combined with the existing research results of seismic liquefaction evaluation, the analysis method of liquefaction fragility is given. Taking a specific site as an example for liquefaction fragility analysis, it is found that taking the calculated exceedance probability of different liquefaction levels as the observation value, the liquefaction fragility function follows both lognormal distribution and log-logistic distribution. With the increase of liquefaction level, the median value of liquefaction fragility function increases, while the site liquefaction fragility curve moves to the right, which shows that the ability of the site to resist more severe liquefaction is increasing. When convolved with the analysis results of liquefaction triggering and hazard, the liquefaction fragility function can be a much efficient tool for seismic liquefaction risk analysis of specific sites.

Liquefaction triggering and post-triggering behavior of biocemented loose sand

Biocementation is a biomediated ground improvement technique that can improve the engineering behavior of granular soils. The process has received significant attention as an earthquake-induced liquefaction mitigation technique; however, critical gaps have remained in our understanding of how liquefaction behaviors may shift with differences in loading magnitudes and cementation levels. In this study, direct simple shear tests were performed to examine the undrained shearing behaviors of biocemented loose Ottawa F-65 sand prepared to varying cementation levels corresponding to Vs increases up to 523 m/s. Significant increases in liquefaction triggering resistances were observed with added cementation across a broad range of loading magnitudes (CSR = 0.1–1.75) and exceeded improvements obtainable through densification alone. Following triggering, modest improvements in post-triggering strain accumulation and reconsolidation behaviors were observed that could be primarily attributed to the densification of specimens from added mineral solids at low cementation levels (Δ Vs < 150 m/s). At higher cementation magnitudes, however, post-triggering behavioral enhancements exceeded those that would be expected from densification alone. Outcomes from this study improve our understanding of the liquefaction behaviors of biocemented soils, the metrics by which these behaviors can be effectively characterized, and the mechanisms responsible for behavioral enhancements, ultimately furthering our understanding of how the technology may be employed for liquefaction mitigation.

Biomediated control of colloidal silica grouting using microbial fermentation

Colloidal silica grouting is a ground improvement technique capable of stabilizing weak problematic soils and achieving large reductions in soil hydraulic conductivities for applications including earthquake-induced liquefaction mitigation and groundwater flow control. In the conventional approach, chemical accelerants are added to colloidal silica suspensions that are introduced into soils targeted for improvement and the formation of a semi-solid silica gel occurs over time at a rate controlled by suspension chemistry and in situ geochemical conditions. Although the process has been extensively investigated, controlling the rate of gel formation in the presence of varying subsurface conditions and the limited ability of conventional methods to effectively monitor the gel formation process has posed practical challenges. In this study, a biomediated soil improvement process is proposed which utilizes enriched fermentative microorganisms to control the gelation of colloidal silica grouts through solution pH reductions and ionic strength increases. Four series of batch experiments were performed to investigate the ability of glucose fermenting microorganisms to be enriched in natural sands to induce geochemical changes capable of mediating silica gel formation and assess the effect of treatment solution composition on pH reduction behaviors. Complementary batch and soil column experiments were subsequently performed to upscale the process and explore the effectiveness of chemical, hydraulic, and geophysical methods to monitor microbial activity, gel formation, and engineering improvements. Results demonstrate that fermentative microorganisms can be successfully enriched and mediate gel formation in suspensions that would otherwise remain highly stable, thereby forgoing the need for chemical accelerants, increasing the reliability and control of colloidal silica grouting, enabling new monitoring approaches, and affording engineering enhancements comparable to conventional colloidal silica grouts.

Soft Computing to Predict Earthquake-Induced Soil Liquefaction via CPT Results

Earthquake-induced soil liquefaction (EISL) can cause significant damage to structures, facilities, and vital urban arteries. Thus, the accurate prediction of EISL is a challenge for geotechnical engineers in mitigating irreparable loss to buildings and human lives. This research aims to propose a binary classification model based on the hybrid method of a wavelet neural network (WNN) and particle swarm optimization (PSO) to predict EISL based on cone penetration test (CPT) results. To this end, a well-known dataset consisting of 109 datapoints has been used. The developed WNN-PSO model can predict liquefaction with an overall accuracy of 99.09% based on seven input variables, including total vertical stress (σv), effective vertical stress (σv′), mean grain size (D50), normalized peak horizontal acceleration at ground surface (αmax), cone resistance (qc), cyclic stress ratio (CSR), and earthquake magnitude (Mw). The results show that the proposed WNN-PSO model has superior performance against other computational intelligence models. The results of sensitivity analysis using the neighborhood component analysis (NCA) method reveal that among the seven input variables, qc has the highest degree of importance and Mw has the lowest degree of importance in predicting EISL.

A multi-phase biogeochemical model for mitigating earthquake-induced liquefaction via microbially induced desaturation and calcium carbonate precipitation

Abstract. A next-generation biogeochemical model was developed to explore the impact of the native water source on microbially induced desaturation and precipitation (MIDP) via denitrification. MIDP is a non-disruptive, nature-based ground improvement technique that offers the promise of cost-effective mitigation of earthquake-induced soil liquefaction under and adjacent to existing structures. MIDP leverages native soil bacteria to reduce the potential for liquefaction triggering in the short term through biogenic gas generation (treatment completed within hours to days) and over the longer term through calcium carbonate precipitation (treatment completed in weeks to months). This next-generation biogeochemical model expands earlier modeling to consider multi-phase speciation, bacterial competition, inhibition, and precipitation. The biogeochemical model was used to explore the impact of varying treatment recipes on MIDP products and by-products in a natural seawater environment. The case study presented herein demonstrates the importance of optimizing treatment recipes to minimize unwanted by-products (e.g., H2S production) or incomplete denitrification (e.g., nitrate and nitrite accumulation).

Numerical modelling of a tunnel adjacent to a surface structure in liquefiable ground

Earthquake-induced liquefaction is likely to cause uplift displacements of underground structures and excessive settlements of surface structures. While these two phenomena have been investigated separately in the literature, the case of a shallow tunnel buried adjacent to a surface structure in liquefiable ground has not yet been thoroughly studied. In this paper, the OpenSees platform is employed to numerically model two centrifuge tests on the structure–soil–structure interaction in saturated Hostun sand. The PM4Sand constitutive model is calibrated to capture the non-linear behaviour of the liquefiable ground. Overall, the numerical simulations are in good agreement with the centrifuge test data. The excess pore pressure build-up, the acceleration response of the Hostun sand ground, the uplift of the tunnel and the settlement of the surface structure are simulated with adequate accuracy. Then, the validated numerical models are used to investigate further the structure–soil–structure interaction in liquefiable ground, with a special emphasis placed on the variation of the relative density of the sand, and a parametric analysis is conducted on the responses of the tunnel and the surface structure.

The Effect of Irregular Seismic Loading and Soil Density on the Liquefaction Behavior of Saturated Sand

Structures located on sandy soils can be significantly damaged by earthquake-induced liquefaction. A series of stress-controlled cyclic triaxial tests under harmonic and irregular loading under various soil densities 30%, and 50%, was conducted to evaluate the effects of irregularities and relative densities on the liquefaction characteristics of saturated sand. The irregular actual ground motions time histories obtained from six stations of the 1999 Chi-Chi Earthquake and harmonic sinusoidal cyclic loading time histories were applied to Firoozkooh #161 sand specimens, and the results were compared in terms of the type waveforms loading and relative densities. Based on the stress and energy method, the Correction coefficient is calculated for a variety of densities and types of irregular loading. The present results reveal that it is not precise to assume a single correction coefficient for all records, regardless of the complicated time-domain characteristics of ground motions. Furthermore, the results indicate that the relative soil density and the type of irregular loading influenced sand's pore pressure generation and liquefaction potential.

Assessment on earthquake-induced liquefaction around a hybrid monopile foundation for offshore wind turbines with a transition layer model

Offshore wind turbines are currently being developed to have a large size. A hybrid monopile foundation, which is composed of a single pile and a wheel, is advantageous in terms of bearing capacity and liquefaction resistance in liquefiable soil. In this study, the seismic response of a hybrid monopile foundation was investigated using a verified numerical model. Earthquake-induced liquefaction around the foundation was assessed by considering the influence of the foundation dimensions. In the numerical model, a pile-soil contact element was proposed using a transition layer model that effectively buffered the pile-soil interactions. The soil characteristics were evaluated based on the distribution of excess pore water pressure. The liquefaction resistance of the shallow layer was improved by the wheel, and the pile length had a negligible influence on the seismic response. Larger wheel diameter and thickness demonstrated a more pronounced improvement in the anti-liquefaction ability. The influencing zone was determined based on the liquefiable area and had a conical shape under the wheel. This study quantitatively investigated the liquefaction characteristics of a hybrid monopile foundation and provided insights into the numerical calculation of dynamic pile-soil interactions.

Centrifuge Modelling of Vertical and Horizontal Drains to Mitigate Earthquake-Induced Liquefaction

This paper reports the results of dynamic centrifuge tests carried out on sandy models alternatively equipped with vertical or horizontal drains. The main aim of the experimentation was to investigate the use of horizontal drains to mitigate the liquefaction susceptibility of sandy deposits and to validate their applicability as a remediation technique applicable in urban and industrial areas to protect existing buildings from liquefaction. The assessment and validation were carried out by comparing the seismic behavior of models treated with horizontal drains with that of the untreated model and models equipped with vertical drains.

Seismic responses of suction bucket foundation in liquefiable seabed considering spatial variability

The abundant wind energy happens to be distributed along the seismic regions with potential liquefaction. Offshore wind turbines have to be built in these regions for high power generation efficiency. The earthquake-induced liquefaction affected by the natural variability of the seabed makes the safety assessment of suction bucket foundations a challenge. The seismic responses of the laterally-loaded suction bucket foundation in spatially variable soil modeled by an advanced constitutive model were investigated using an FE- FD method. The SPT-(N1)60cs was considered a random variable and the seabed was modeled as a non-Gaussian random field by the Cholesky decomposition technique. The seismic responses were described by the Monte Carlo simulation and the FE-FD method. Statistics of the tilt and the liquefaction potential index influenced by the coefficient of variation and the scale of fluctuation were investigated. The stochastic model was compared with the deterministic model. The liquefaction mechanism and failure mechanism of the suction bucket foundation in random soil were investigated. The tilts and liquefaction may be underestimated without considering the soil spatial variability. Safety factors were introduced into the calculation of the failure probability of the suction bucket foundations. The simulations provide insight into the nonlinear behavior of suction bucket foundations considering the liquefaction of spatially variable soil.

Shallow foundations subjected to earthquake-induced soil liquefaction resting on deep soil mixing columns

Shallow foundations subjected to earthquake-induced soil liquefaction resting on deep soil mixing columns

Geospatial data-driven assessment of earthquake-induced liquefaction impact mapping using classifier and cluster ensembles

A 5.4 ML earthquake occurred on November 15, 2017, in Pohang, South Korea. This earthquake was the second largest recorded earthquake in South Korea and had detrimental effects on the ground and infrastructure. Among all the ground deformations, hundreds of liquefaction-induced sand boils and ground failures observed near the epicenter were major issues. However, whether subsurface characteristics and liquefaction vulnerability indices trigger regional liquefaction manifestations and how local liquefaction occurs as a consequence remains elusive. In this study, we present a novel data-driven model for the analysis of site-specific liquefaction triggering that considers the spatial uncertainties of principal liquefaction vulnerability indices. This is achieved by establishing an advanced artificial intelligence technology that assembles optimization-oriented, supervised, and unsupervised machine-learning models. The phased decision-making process could develop unified liquefaction hazard zonation based on the clustering ensemble methodology and help identify feasible liquefaction impact mapping procedures via the optimized classification of their performance evaluation with liquefaction inventory. The alternative three-phase approach, depending on the feasibility of geo-data and geospatial modeling, consists of three zonation methods (macro-, micro-, and nano-zonation) based on a 3D grid network, which assigns the best-fitting machine-learning model. The resulting liquefaction impact map, which has a high resolution and is assigned nano-zonation-based clustered liquefaction indices, can assist in site-specific decision-making to zonate liquefaction-induced ground displacement.

Addressing complexities in MPM modeling of calibration chamber cone penetrometer tests in homogenous and highly interlayered soils

Cone penetrometer tests (CPTs) are used to characterize soil for a variety of geotechnical engineering applications, including earthquake-induced liquefaction triggering assessment. Numerical modeling of CPTs is frequently used to better understand soil behavior, soil-penetrometer interaction, and engineering estimates made from CPT data. However, calibrating and validating numerical CPT simulations with experimental calibration chamber (CC) data can be challenging. Specifically, uncertainties in the interpretation of laboratory strength and compression data compound with uncertainties in the CC testing and the assumptions made when developing the numerical model. This article provides a comprehensive review of uncertainties in the calibration and validation of CPT numerical simulations performed in homogenous sand, homogenous clay, and layered sand-clay soil profiles, comparing numerical results with well-documented experimental calibration chamber tests performed at Deltares. In particular, the Material Point Method (MPM) is used to perform the numerical analyses. A framework is presented to assess how uncertainty in the numerical model output is attributed to each input parameter. It is demonstrated that uncertainties can be explored numerically. Finally, recommendations for future experimental and numerical studies of CPTs are provided.

Liquefaction assessment based on numerical simulations and simplified methods: A deep soil deposit case study in the Greater Lisbon

The accurate estimation of earthquake-induced liquefaction damage requires detailed ground response analysis, which does not generally consider liquefaction. This paper presents a well-documented pilot site where different approaches to estimate surface ground motion were compared. A simplified stress-based method and non-linear dynamic effective stress numerical analyses were used to identify liquefaction. HVSR curves were used to validate the numerical analyses and laboratory test results were employed to calibrate an advanced constitutive model capable of reproducing liquefaction stress-strain behaviour and pore water pressure generation.1D non-linear elastic numerical analysis evidenced high shear strains in weak soil layers where liquefaction may occur. When PM4sand model was used to simulate liquefaction behaviour in sandy layers, 1D and 2D model responses were rather similar, since liquefaction occurs predominantly at a sandy layer that extends across the valley. Therefore, 1D horizontally infinite layers seems to be a good approximation of the 2D response of this valley.

Enhancing the seismic performance of piles in liquefiable soils by slag powder

Case studies show that earthquake-induced soil liquefaction can cause large lateral deformation of piles, leading to bridge damage. In this study, an iron and steel manufacturing by-product, slag powder, was utilized for the first time to mitigate soil liquefaction, thereby reducing the lateral deformation of piles during earthquakes. First, the liquefaction resistance of soil improved by slag powder was analyzed by cyclic triaxial tests. The results indicate that as the slag powder content increased, the soil liquefaction resistance increased. When the cyclic stress ratio is 0.2, the number of liquefaction cycles of the reinforced soil increases by 30 compared with that of the unreinforced soil. Second, a numerical modeling method of slag powder reinforced sand was proposed and validated by the cyclic triaxial test results. Third, the seismic response of piles in liquefiable soils enhanced by slag powder was evaluated using finite element analyses, and slag powder was determined to be effective in decreasing the lateral deformation of piles in liquefiable soils, the maximum displacement of the pile was reduced by 45 %. Last, an empirical formula that can easily evaluate the mitigation effect of slag powder on the lateral deformation of piles is proposed and verified by the results of finite element analysis.

Sea-level fluctuations control the distribution of highly liquefaction-prone layers on volcanic-carbonate slopes

AbstractUnderstanding and quantifying the hazards related to earthquake-induced submarine liquefaction and landslides are particularly significant offshore of tropical volcanic-carbonate islands, where carbonate production competes with volcanism to create highly contrasted lithological successions. To improve the detection of liquefaction-prone layers, we analyzed physical properties and mineralogy and performed 70 dynamic triaxial tests on 25 sediment cores offshore of the eastern side of Mayotte (Comoros archipelago in the western Indian Ocean) in an area that has experienced significant seismicity since 2018. We found that the main parameter controlling the liquefaction potential offshore of Mayotte is the presence of low-density layers with high calcite content accumulating along the slope during lowstands. This phasing with sea-level fluctuations implies a significant recurrent geohazard for tropical volcanic-carbonate islands worldwide. Furthermore, the relationship we found between the cyclic resistance of sediment and its density and magnetic susceptibility represents a time-effective approach for identifying the hazards related to earthquake-induced liquefaction.

Assessment of earthquake-induced liquefaction susceptibility using ensemble learning

Assessment of earthquake-induced liquefaction susceptibility using ensemble learning

Impacts and causative fault of the 2022 magnitude (Mw) 7.0 Northwestern Luzon earthquake, Philippines

At 00:43 UTC on 27 July 2022, a 15-km deep major earthquake with magnitude (Mw) 7.0 struck Northwestern Luzon, Philippines. The strongest ground shaking felt was at PHIVOLCS Earthquake Intensity Scale (PEIS) VII (destructive), equivalent to Modified Mercalli Intensity (MMI) VII, in Abra and along the coastal areas of Ilocos Sur. More than a thousand landslides, rockfalls and tension cracks were mapped, near the epicentral region, in the northwestern part of the Central Cordillera. Most of the landslides were shallow-seated, many of which were situated along road cuts. Liquefaction manifested as lateral spreads, sand boils, fissures, ground subsidence, and localized swelling was documented along the coastal areas of Ilocos Sur and river channels in Abra and Ilocos Sur. Sea level disturbance was also observed in some coastal areas of Ilocos Sur and La Union. Damages to buildings and infrastructures were documented in areas that experienced PEIS VI (very strong), equivalent to MMI VI and PEIS VII (destructive). Earthquake data, including hypocentral location, aftershock distribution, focal mechanism solutions and strong motion data, and InSAR observation indicate that the earthquake was generated by an almost north-south striking reverse left-lateral oblique fault that is gently dipping to the east. There is no clear indication of a surface rupture based on InSAR analysis and field investigation. The spatial distribution of geologic impacts, such as earthquake-induced landslides and liquefaction, is strongly controlled by the causative fault, the direction of rupture propagation and geology. Peak ground acceleration (PGA) records show a unidirectional rupture propagation and are congruent with the spatial distribution of earthquake impacts. Although earthquake parameters, deformation analysis and field data suggest that the Abra River Fault is the probable causative fault, the derived geometry and kinematics from the seismotectonic analysis challenge our existing understanding of the nature of the Abra River Fault, as well as the other segments of the Philippine Fault. The need to understand these earthquake sources in the country is needed for a better seismic hazard and risk assessment.

Effects of Earthquake-Induced Liquefaction on a Group of Piles in a Level Ground with Sloping Base Layer: a Physical Modeling

Effects of Earthquake-Induced Liquefaction on a Group of Piles in a Level Ground with Sloping Base Layer: a Physical Modeling