Soil Liquefaction Research Articles

Weighing the Influence of Geological and Geotechnical Factors in Soil Liquefaction Assessments

Weighing the Influence of Geological and Geotechnical Factors in Soil Liquefaction Assessments

Soil liquefaction manifestations at Hatay Airport after the February 2023 Türkiye earthquake sequence

Hatay Airport was shaken by the Mw 7.8 and Mw 7.5 Pazarcık and Ekinözü-Elbistan Kahramanmaraş earthquake sequence on February 6, 2023. Two weeks after these events, Mw 6.3 Yayladağı-Hatay earthquake shook the site again. This paper presents the results of the reconnaissance assessment of soil liquefaction at the site, focusing on mostly three aspects: (a) the seismic response of the Hatay Airport, particularly the surface manifestations of seismic soil liquefaction in the form of soil ejecta; (b) the findings of site investigation studies performed before and after the seismic events, and (c) assessments for soil liquefaction susceptibility. Among the soil ejecta samples collected, three out of five are classified as clayey sand and fall within or near the boundary of the “further studies required” region on the susceptibility charts. The remaining two ejecta samples, composed of low and high-plasticity clay soils with PI values of 31 and 36% fall within the “not susceptible” region. The deviation from the current state of knowledge might be attributed to liquefaction-induced seepage eroding clayey soils to the ground surface or limitations in the current liquefaction susceptibility assessment methods for fine-grained soils, which may not accurately delineate the boundaries between susceptible and not-susceptible zones. Determining the most likely explanation requires additional site investigation studies, including CPT soundings, extending beyond the scope of this reconnaissance study. The documented case history and assessment results are expected to enhance the understanding of seismic soil liquefaction in fine-grained soils and contribute to the development of predictive models based on case histories for assessing liquefaction susceptibility and triggering.

Ground liquefaction caused by 6 February 2023 Kahramanmaraş earthquakes of Türkiye and some assessments on its extent and impacts on built environment

Ground liquefaction caused by 6 February 2023 Kahramanmaraş earthquakes of Türkiye and some assessments on its extent and impacts on built environment

Characterizing undrained behaviour of imperfectly saturated Palar sand

The occurrence of earthquake-induced soil liquefaction poses a significant threat, leading to extensive damage to building foundations and other structures, resulting in substantial economic repercussions. The seismic performance of geotechnical systems is markedly influenced by the saturation level of the soil. This study examines the impact of dynamic response on Palar sand. Cyclic triaxial tests were conducted on partially saturated fine-grained loose sand with a relative density of 35 % and a degree of saturation ranging from 65 % to 75 %. These tests were carried out at a strain rate of 0.1 % and confining pressures of 50 and 75 kPa. The study findings reveal that an increase in back pressure corresponds to a rise in the excess pore water pressure ratio of the sand. Additionally, the sand undergoes liquefaction as the number of cycles increases, and the degree of saturation decreases for different confining pressures at frequencies of 0.75 and 1 Hz. It was observed that soil liquefies more rapidly at lower strain rates with an increase in effective confining pressure. Conversely, at higher frequencies, soil liquefaction occurs in a smaller number of cycles. Comparing the effects of confining pressure and frequency, a damping ratio of 13 % and a shear modulus of 40 MPa were achieved at a frequency of 0.75 Hz and a confining pressure of 50 kPa. The shear modulus of partially saturated sand decreases with an increase in the initial degree of saturation due to specific characteristics of the Palar sand and the loading conditions.

A novel approach to predicting liquefaction-induced settlements using Kolmogorov–Arnold Networks (KANs)

Soil liquefaction refers to the loss of strength and bearing capacity of soil under dynamic loads. Structures built on liquefied soils experience settlement. In this study, the newly developed Kolmogorov–Arnold Networks (KAN) method, an innovative artificial neural network technique, was utilized to predict liquefaction-induced settlement. The KAN method, which extends beyond the traditional Multi-Layer Perceptron (MLP) approach, was compared with the Random Forest method for benchmarking purposes. Using data derived from laboratory and field studies, models were constructed using both methods, and their performances were analyzed. According to the results, the KAN model outperformed the RF model in terms of R2, MAE, MSE, and RMSE metrics. Additionally, the feature importance analysis on the KAN model identified cyclic stress ratio (csr) and corrected SPT blow count (n1_60) as the most significant variables. These results underscore the potential of the KAN method in enhancing predictive accuracy and reliability in geotechnical applications, paving the way for its broader acceptance and implementation in real-world scenarios.

GEOTECHNICAL INVESTIGATIONS FOR SCHOOL CONSTRUCTION

A series of earthquakes that commenced on December 28, 2020, resulted in extensive material damage within a 50-60 km radius from the epicenter, located near the City of Petrinja. Due to the significant structural damage sustained by the building of Petrinja Primary School I, a decision was made to construct a new school building. The construction of the new school began in 2022 and was completed in 2023. This study presents the findings of geotechnical investigations conducted at the site of the new school, which included five static cone penetration tests (CPTu), two dynamic probing heavy tests (DPH), one Marchetti dilatometer test (DMT), and two profiles of multi-channel analysis of surface waves (MASW). The geotechnical investigations resulted in the development of a soil profile consisting of eight distinct zones. Recommendations for the foundation design of the new building have been provided, alongside an assessment of the risk of soil liquefaction. The potential for liquefaction has been identified within zone 4, which comprises clayey sands at depths ranging from 4 to 6 meters.

Predicting strain energy causing soil liquefaction

Liquefaction, which typically occurs in saturated sandy soil deposits, is one of the destructive phenomena that can occur during an earthquake. When the soil reaches liquefied state, it loses a significant amount of resistance and stiffness, which often results in widespread catastrophic damages. Therefore, accurate evaluating the potential of soil liquefaction occurrence is of great importance in earthquake geotechnical designs in regions prone to this phenomenon. The strain energy-based approach is a novel robustness technique to evaluate liquefaction potential. In the current research, 165 laboratory data sets from cyclic experiments were collected and analyzed. A predictive model using gene expression programming (GEP) was proposed to assess strain energy needed for occurrence of soil liquefaction. Assessing physical behavior of developed GEP-based model was conducted through sensitivity analysis. Performance of GEP-based was validated by comparing with a series of centrifuge experiments and cyclic triaxial tests results. Subsequently, after experimental verification of numerical modeling, the strain energy required for soil liquefaction under cyclic loading at different conditions were numerically evaluated and compared with the strain energy calculated by proposed model. Finally, the developed GEP-based model was compared with established strain energy-based relationships. The results indicated high precision of proposed GEP-based model in determination of strain energy required for soil liquefaction triggering.

Integration of multiple observations for validation of mechanisms of earthquake-triggered groundwater level Anomalies: 2016 Taiwan Meinong earthquake

This study analyzes multi-depth groundwater level data and integrated observation data to validate the previously proposed mechanisms of hydrological anomalies triggered by the 2016 M6.4 Meinong earthquake in Taiwan. The main influence area was northwest of the epicenter, which may be due to the blind fault rupture, intensity distribution, and hydrogeological properties. The step changes in groundwater level do not fit the concept of epicentral distance, static stress–strain theory, or the focal mechanism. The distribution of step changes in groundwater level have a pattern similar to that of horizontal peak ground velocity. The results imply that these changes may be driven by dynamic stress–strain, instead of static stress–strain. The minimum horizontal peak ground velocity and acceleration of the Meinong earthquake, which induced obvious step changes in groundwater level and soil liquefaction, are provided. The pressure dissipation ability of an aquifer (e.g., transmissivity) may affect the persistence of groundwater responses. Four wells located near the surface rupture area, which has cemented or partial cemented geological material, showed an obvious step decrease in the groundwater level at a deep depth and all wells showed an increase in the groundwater level at a shallow depth. These decreases and increases of the groundwater level at different depths have different mechanisms, which are discussed in this study. The integrated observations made during the Meinong earthquake show that ground motion and the hydraulic properties might be important factors in hydrological anomalies. The results of this study are an important reference for further studies on earthquake hydrology.

Instability and deformation behaviors of root-reinforced soil under constant shear stress path

Climate change is becoming a greater global challenge, leading to more frequent and intense extreme weather events, which in turn increase mountain hazards like shallow landslides and soil erosion. Ecological slope protection using vegetation has gained in- creasing attention to mitigate natural disasters in recent years. While numerous studies have demonstrated the contribution of root systems to soil reinforcement, the comprehensive impact of roots on soil mechanical response under rainfall scenarios remains elusive. This study investigates the instability and deformation behaviors of root-reinforced soil through constant shear drained (CSD) tests. The role of root characteristics, including biomass, diameter, and length, in modulating the shear strength, instability and deformation behaviors of soils is investigated. The results indicate that the shear strength and stability of root-reinforced soil, as well as the inhibition effect of root on contractive deformation after the initiation of instability, increasing with greater root biomass and length and smaller root diameter. Moreover, due to the potential weak interfaces, fine or stiff long roots appear to increase the likelihood of volumetric dilation in root-reinforced soil at the later stage of unstable deformation. However, this dilatancy can be effectively resisted by increasing root planting density to form the root network. Furthermore, our experiments suggest that herbaceous vegetation with finer and longer roots is more effective in mitigating static liquefaction of soils induced by rainfall infiltration. This study helps develop a predictive constitutive model for root-reinforced soils and supports future bioengineering slope design.

Ground failures and foundation performances in Adıyaman–Gölbaşı following the 6 February 2023 Kahramanmaraş–Türkiye Earthquake Sequence

The 6 February 2023 Kahramanmaraş–Türkiye earthquake sequence (M7.8 and M7.6) presents an exceptional opportunity to investigate both the effects of local soil conditions on damage patterns under strong shaking conditions and the performance of building foundations in areas that experienced ground failure. The significant ground failure and structural damage in Adıyaman–Gölbaşı triggered an intensive series of detailed reconnaissance and field surveys. This article aims to present the resulting database of observations on ground failures, building, and foundation performances. The field reconnaissance of ground failures and their effects on building performances involved aerial and walk-down surveys, including high-quality photographs taken across the town. In addition, data on building damage statistics compiled by the Ministry of Environment, Urbanization, and Climate Change were accessed and analyzed. The subsurface characteristics of the town were characterized using available data from pre-earthquake site investigation campaigns employed for town planning purposes. It is concluded that the ground failures in the town primarily resulted from soil liquefaction and cyclic softening. Most of the poor building and foundation performances and ground failures were documented in the northern part of Atatürk Boulevard, closer to the lake of Gölbaşı, where soil site characteristics were unfavorable. This revealed once again the significant effects of local soil site conditions, particularly soil liquefaction, on the intensified ground failures, foundation, and structural damage levels.

Evaluación de los efectos secundarios tras el sismo del 18 de enero de 2021 (Mw 6,5) en San Juan, Argentina: determinación de la intensidad sísmica a través de la escala ESI-2007

This study focuses on evaluating the numerous secondary effects, such as mass wasting and soil liquefaction, caused by the Mw 6.5 earthquake that occurred on January 18, 2021, in the province of San Juan, Argentina. The epicenter was located on the eastern flank of the Las Osamentas range. Although it caused significant damage to buildings and cultivated areas, there were no fatalities. The aim is to identify and describe these secondary effects and determine the seismic intensity of the event using the INQUA’s (International Union for Quaternary Research) 2007 ESI (Environmental Seismic Intensity) scale. Field assessments were conducted shortly after the earthquake, documenting liquefaction and mass wasting structures through direct observations, digital photographs, GPS (Global Positioning System) localization, and data inventory, among other methods. This procedure validates a protocol for future applications in estimating seismic intensities for sparsely populated areas. Additionally, the study seeks to confirm the scientific and cultural importance of these ephemeral structures as assets that could be protected, therefore contributing to regional development.

Developing Soil Liquefaction Analysis Program created on Visual Basic Analysis in MS Excel based on the 2018 Turkish Seismic Code

Developing Soil Liquefaction Analysis Program created on Visual Basic Analysis in MS Excel based on the 2018 Turkish Seismic Code

Machine learning approach for evaluating soil liquefaction probability based on reliability method

Machine learning approach for evaluating soil liquefaction probability based on reliability method

Wave-induced sloping seabed residual response around a buried pipeline

Most studies of the wave interaction with pipeline were conducted on a flat seabed. This paper presents the results from the numerical modelling simulation to investigate the wave induced response around a half-buried pipeline on a sloping seabed. The numerical model is validated using the experimental data of the wave-pipeline-seabed interaction. The validated model is then applied to simulate the wave generated pore pressure distribution around the pipeline buried in the sloping seabed. Effects of the pipeline buried depth, the pipeline position and the slope gradient on the wave generated residual pore pressure as well as the potential soil liquefaction within the sloping seabed are simulated and analyzed. Results demonstrate that the pipeline location on the sloping seabed can significantly affect the residual pore pressure within the sloping seabed. This is particularly true when the pipeline is placed at the junction between the flat seabed and slope.

An analytical solution to the soil’s dynamic response induced by wave interaction with a marine current characterized by a non-uniform vertical profile

In this work, we obtain an analytical solution to the soil’s dynamic response induced by wave interaction with a marine current with a prescribed non-uniform vertical profile. The control volume used to analyze the present problem is divided into a water region and another composed of a poroelastic soil region. The governing equations for the water hydrodynamics are presented in its dimensionless version and they are simplified for the limit of linear water waves. The velocity field in the water region is determined from the continuity equation and the “inviscid Orr-Sommerfeld linear equation”. We obtain a dispersion equation for wave-current interaction. For modeling the soil’s dynamics response, we adopt the u-p approximation. Considering a characteristic criterion for soil liquefaction, the maximum liquefaction depth is obtained as an eigenvalue problem. The analytical estimations, valid for the limit of linear water waves, provided by the present analysis show that, marine currents traveling in the same direction to the wave propagation induces larger values of the liquefaction depth than those obtained for currents opposite to wave propagation. As a first approximation, the present analysis may help understand the dynamic response of poroelastic soil induced by the wave-non-uniform marine current interaction.

Study on the Effect of Liquefiable Overburden Foundations of Rockfill Dams Based on a Pore Pressure Model

China’s southwestern region boasts abundant hydropower resources. However, the area is prone to frequent strong earthquakes. The areas surrounding dam sites typically have deep overburden, and the liquefaction of saturated sand foundations by earthquakes poses significant safety risks to the construction of high dams in the southwest. The effects of liquefaction and reinforcing measures on the foundations of rockfill dams on liquefiable overburden under seismic action are currently the subject of somewhat unsystematic investigations. The paper utilizes the total stress and effective stress methods, based on the equivalent linear model, to perform numerical simulations on the overburden foundations of rockfill dams. The study explores how factors such as dam height, overburden thickness, liquefiable layer depth, liquefiable layer thickness, ground motion intensity, and seismic wave characteristics affect the liquefaction of the overburden foundations. Additionally, it examines how rockfill dams impact the dynamic response, considering the liquefaction effects in the overburden. The results show that although the total stress method, which ignores the cumulative evolution of pore pressure during liquefaction, can reveal the basic response trend of the dam, its results in predicting the acceleration response are significantly biased compared to those of the effective stress method, which comprehensively considers the cumulative changes in liquefaction pore pressure. Specifically, when the effect of soil liquefaction is considered, the predicted acceleration response is reduced compared to that when liquefaction is not considered, with the reduction ranging from 4% to 30%; with increases in the thickness and burial depth of the liquefiable layer, the effective stress method considering liquefaction significantly reduces the predicted peak acceleration; the effect of liquefiable soil on the attenuation of the speed response is more sensitive to the low-frequency portion of the seismic wave. The study’s findings are a significant source of reference for the planning and building of rockfill dams on liquefiable overburden.

Stone column strategies for mitigating liquefaction-induced uplift of tunnels

Tunnels embedded in liquefiable soil are frequently subjected to uplift and sustain serious damage during major earthquakes. Mitigation methods to prevent the flotation of these tunnels must be developed and implemented in the natural environment. For this purpose, this study proposes a new method that uses stone columns to enhance soil drainage and mitigate soil liquefaction around tunnels. A circular tunnel in liquefied soil is simulated using a 2D finite element model, PLAXIS 2D, and subjected to a sinusoidal input motion. The tunnel's pre-construction and post-construction scenarios are examined. Parametric studies are carried out to investigate the effect of changing several parameters, such as the distance between stone columns and tunnel springing, the diameter of stone columns, the spacing between stone columns, the number of stone column rows, and the stone column arrangement patterns on the effectiveness of liquefaction mitigation. The study reveals that liquefaction mitigation is enhanced by using stone columns closer to tunnel springing, with larger diameters, less spacing, and more rows of stone columns that are arranged in a square pattern. It also emphasizes the importance of timely implementation of stone columns for maximum benefit.

Escape routes and safe points in natural hazards. A case study for soil

The scope of this work was to develop soil liquefaction and landslide hazard maps, by computing Peak Ground Acceleration (PGA) for a return period of 475 years, to outline safe points and escape routes designed for schools situated in the drainage basin of Xerias River at northeastern Peloponnese, Greece. The school locations were spatially correlated with each geohazard map to assess the potential hazards to schools within the study area. Web maps illustrating safe and unsafe areas for both geohazards were developed though the GIS online platform for the town of Corinth and four settlements of the study area, where schools exist. Safe points were identified, and routes for evacuation from schools to these locations were mapped using the shortest paths on the existing road network for each geohazard. All the data was integrated into the GIS application available to the public. The findings indicated that 75% of the schools in the study area are situated in areas susceptible to soil liquefaction and landslide hazards. The northern part of the town of Corinth, which includes 62% of the town's schools, is situated in unsafe areas to soil liquefaction. Unsafe areas for landslides are located in the central and northern section of the town, encompassing 35% of the schools. The school buildings in one settlement within the study area are situated in safe areas for both geohazards. The schools in the remaining settlements are sited in areas considered unsafe due to either liquefaction or landslides hazard. A total of 12 safe points were proposed for soil liquefaction hazard and 17 for landslide hazard across all the studied urban areas. The suggested escape routes for both geohazards range from 200 to 1094 m, distances that teachers and students can easily walk. The proposed method can rapidly and effectively identify safe locations and evacuation routes, facilitating authorities in planning for evacuations.

Enhancing sand liquefaction resistance through microbial-induced partial saturation: An experimental study

The liquefaction potential of saturated sand can be significantly reduced by inducing partial saturation in the soil. Conventional soil liquefaction mitigation methods, namely soil densification, drainage, cementing, and groundwater lowering, pose environmental concerns and are challenging to apply to pre-existing structures. However, the microbially induced partial saturation (MIPS) method is emerging as a novel and eco-friendly approach to mitigate liquefaction. The MIPS method involves microbial denitrification, which produces nitrogen gas and results in a desaturating effect in the saturated soil. The current study conducted a series of stress-controlled undrained cyclic triaxial tests on saturated sandy soil and microbially-desaturated sandy soil under different relative densities and loading conditions. In addition, the study systematically analyzed the effects of temperature and pH on bacterial activity and the denitrification process. Batch experiments were conducted to establish a relationship between the initial nitrate concentration in the bacterial media and the resulting desaturation.Comprehensive analyses of cyclic resistance curves were performed to gain a thorough understanding. Additionally, the study conducts detailed analyses of the accumulation of excess pore pressure and the resulting axial strains and deformation patterns in both treated and untreated sand. This study demonstrates that the MIPS treatment considerably enhances the liquefaction resistance of treated sand.

The Importance of seismic microzonation under the threat of an earthquake of the north anatolian fault in nilüfer, bursa, turkiye

The Nilüfer district experienced the most recent urbanization among the central districts of Bursa in South Marmara region with the completion of rapid construction. Since 358 BCE, many destructive earthquakes were reported on the branches of the North Anatolian Fault (NAF) which caused extensive damage to buildings and loss of life near Bursa city. Besides some studies conducted to define the soil behavior in the vicinity of Bursa, a seismic hazard study in Nilüfer is still lacking. We, therefore, carried out a microzonation study including the following steps. First, an earthquake hazard analysis was conducted and the peak ground acceleration (PGA) values were determined for an expected earthquake. In the next step, MASW (Multi-Channel Analysis of Surface Wave) measurements conducted at 54 points in 28 neighbourhoods of Nilüfer district were evaluated. Soil mechanical parameters were determined at 11 boreholes to assess the liquefaction potential. It was found that almost half of the study area suffers from low damage considering only the vulnerability index (Kg) index, which depends on the site effect. Therefore, in addition to the Kg values, we created a microzonation map using the results of soil liquefaction, settlement, changes in groundwater level, and the average values of spectral acceleration. The study area is classified by four damage levels changing from low to high. Using only the Kg index could not quantify the potential damage level in the study area, thus we showed that the districts of Altınşehir, Hippodrome, Ürünlü and Alaaddinbey, Ertuğrul, 29 Ekim, 23 Nisan, Ahmetyesevi and Minareliçavuş were identified at potentially high-risk damage zones. The results of this study clearly showed that considering the Kg index, which depends only on the local site effect, may lead to inadequate damage values.