Soil liquefaction is a major contributor to earthquake damage. Evaluating the potential for liquefaction by conventional experimental or empirical methods is both time-intensive and laborious. Utilizing a machine learning model capable of precisely forecasting liquefaction potential might diminish the time, effort, and expenses involved. This research introduces an innovative predictive model created in three phases. Initially, correlation analysis determines essential elements affecting liquefaction. Secondly, predictions are produced using Convolutional Neural Networks (CNN) and Deep Belief Networks (DBN), verified by K-fold cross-validation to guarantee resilience. Third, Ant Colony Optimization (ACO) improves outcomes by increasing convergence efficiency and circumventing local minima. The suggested EC + ACO model substantially surpassed leading approaches, such as SVM-GWO, RF-GWO, and Ensemble Classifier-GA, attaining a very low False Negative Rate (FNR) of 2.00 % when trained on 90 % of the data. A thorough performance evaluation shown that the model achieved a cost value of 1.133 % by the 40th iteration, exceeding the performance of other models such SVMGWO (1.412 %), RF-GWO (1.305 %), and Biogeography Optimized-Based ANFIS (1.7439 %). The model exhibited significant improvements in convergence behavior, with a steady decline in cost values, especially between the 20th and 50th iterations. Additional validation using empirical data from the Tohoku-oki, Great East Japan earthquake substantiated the EC + ACO model's enhanced accuracy and dependability in mirroring observed results. These findings underscore the model's resilience and efficacy, providing a dependable method for forecasting soil liquefaction and mitigating its seismic effects.

Comprehensive assessment of liquefaction potential is an important aspect of understanding the liquefaction susceptibility and risk of any region. In India, liquefaction potential assessment (LPA) was carried out as a part of seismic microzonation, and a lot of research work has been reported for major cities/regions. A review of LPA for major cities/regions in India was presented in this study for better understanding of the factors considered in the assessment. In addition, a comprehensive LPA considering the susceptibility, probability, and associated seismic risk on existing structures was evaluated for eight sites in Roorkee region, India. The factor of safety against liquefaction (FSL) and liquefaction potential index (LPI) are evaluated using existing standard penetration test (SPT) data. Also, liquefaction probability (PL) and post-liquefaction settlement (SL) are theoretically estimated to frame a comprehensive LPA. This study is the first of its kind to frame a comprehensive LPA considering both the susceptibility indices (FSL and PL) and liquefaction damage indices (LPI and SL). The results indicate that a high risk of liquefaction and surface manifestations are possible for the selected sites for considered seismic scenario. Fines content and the number of borehole layers are critical in influencing the resistance to liquefaction and surface manifestations. Estimation of SL from SPT N number and volumetric strain approach were found in good agreement with the interpretations obtained from the LPI values. It can be stated that for any design of structures against liquefaction, FSL must be higher than 1.20, as this can be evident from the available literature and the presented case study of Roorkee region.

The 2017 Pohang earthquake [the second largest local magnitude (M-L) of 5.4 since 1978] caused significant damage: numerous sand boils and a few building settlements were observed in rice paddies and residential areas, respectively, representing unprecedented case histories of earthquake-triggered liquefaction and cyclic softening. This study evaluated liquefaction triggering and cyclic softening potentials using three in situ tests [standard penetration test (SPT), cone penetration test (CPT), and downhole (DH) test for shear wave velocity (V-S)] and laboratory tests (grain size and soil indices) for the observed sand boils and building settlements. We selected six sites, four of which had sand boils (Sites 1, 2, 3, and 4), and two of which had experienced building settlements that may have resulted from cyclic softening (Sites 5 and 6). The SPT, CPT, and V-S adequately assessed liquefaction triggering [i.e., factor of safety (FS)2 at all depths. The site-specific cyclic stress ratio through the maximum shear stress ratio computed from site response analysis appropriately evaluated the liquefaction triggering and cyclic softening at the considered sites. The results of the soil index test are consistent with the liquefaction and cyclic softening susceptibility criteria for fine-grained soils. We publicly provide the field and laboratory measurements in this study to enrich case history data on liquefaction and cyclic softening induced by intermediate-size earthquakes (e.g., a moment magnitude, M<6), which might significantly contribute to geotechnical earthquake engineering and engineering geoscience communities

Some soil characteristics, such as the shear wave velocity, the shear modulus, the Poisson ratio, and the porosity, affect how clay soils behave. The soil design parameters under loading, such as soil liquefaction induced by dynamic earthquake loading, employ the shear wave velocity and shear module with modest stress. In order to understand the pore saturation, the Poisson ratio and seismic velocity ratio are also utilized. Additionally, one of the most crucial physical characteristics for assessing permeability at the base of any engineering structure, resolving consolidation issues that may arise at the foundation of an engineering structure, and influencing the deformation behavior of soils is soil porosity. Predicting the porosity of clay soils is a crucial first step in tackling engineering and environmental issues that may arise in the soil after an earthquake or not. With the use of dynamic soil metrics such as seismic velocities, shear modules, bulk modules, seismic velocity ratios, and Poisson ratios, the current work aims to estimate soil porosity. Seismic refraction was used by various studies in the past to conduct in-situ geophysical research. The lithological characteristics of the soil (such as the grain size, shape, type, compaction, consolidation, and cementation of the grains) and the physical characteristics of the soil (such as porosity, permeability, density, anisotropy, saturation level, liquid-solid transition, pressure, and temperature), as well as the elasticity characteristics of the soil (such as shear modulus (G), bulk modulus (K), Young modulus (E), Poisson ratio (mu) and Lame constants (lambda) all have an impact on seismic waves passing through a medium.

With respect to geology, most coastal terrains are underlain by problematic soils, some of which are liquefiable in nature and may cause sudden failure of engineering infrastructures. Against this background, this study was carried out to investigate the subsurface geology of some Lagos coastal areas and their engineering implications using geophysical and geotechnical methods. To achieve this purpose, the Multichannel Analysis of Surface Waves, Cone Penetration Test, and Standard Penetration Test were deployed. Surface waves measurements were collected using a 24-channel seismograph to which 4.5 Hz twenty-four vertical geophones were connected via the takeouts of the two cable reels. CPT soundings were carried out with a 10-tons motorized cone penetrometer and boring with SPT were carried out as well. The results of the Multichannel Analysis of Surface Waves measurements showed that the shear waves velocity (Vs) ranges from 160 to 470 m/s. The very loose to loose sand delineated have Vs in the range from 170 to 250 m/s. The tip resistance and sleeve resistance values spanned between 4.0 and 72.0 kg/cm2 and 6.0-94 kg/cm2 respectively. The thickness of the liquefiable sands in the study area varied between 2.5 and 18.0 m. At Ikoyi site, owing to the prevalence of loose silty sand, corroborated by the available borehole data and the Liquefaction Potential Index, it is classified as having a high-risk liquefaction and could be responsible for the periodic damages to structural infrastructures such as roads and buildings. The sediments mapped at Okun-Ajah and Badore sites are mainly saturated loose sands with high likelihood to liquefaction with very-high to high risk severity. The study concludes that the presence of these sediments and other factors that could induce ground motion making the study sites potentially susceptible to liquefaction. Hence, an urgent attention must be given to early monitoring measures to address the trend. Study assesses use of electrical resistivity imaging and seismic refraction (via Multi Analysis Surface Waves) methods for near surface mapping/characterization The study sites belong to the wetland, coastal area of the Dahomey Basin, a part of sedimentary basin with sands deposits, peat, clay and their intercalation The shear waves velocity model integrated with CPT data proved to be useful tool for evaluation of soil liquefaction status with the index suggesting low-high-very high risks

An earthquake measuring 7.5 on the Richter scale that occurred in Palu on 28 September 2018 resulted in liquefaction where the soil lost its bearing capacity due to increased pore water pressure. The liquefaction disaster caused great damage to the Gumbasa Irrigation channel, a large part of which is in the alluvial fan area. This study aims to analyze the potential of liquefaction in irrigation canals in the Sidera village area, Sigi Regency. Using SPT (Standard Penetration Test) data from 2 boreholes with a depth of +/- 20 m, MASW data, and Earthquake Risk Map. Researchers analyzed with the Seed Simplified Procedure approach, The researchers analyzed the Simplified Procedure method proposed by Seed, which uses a stress-based approach that uses the ratio of soil shear strength (CRR) and earthquake-induced soil shear stress (CSR). The results of the analysis using Peak Ground Acceleration (PGA) of 0.43 and groundwater level variations of -2.85 m (borehole BM 53) and -12.5m (Borehole BM 49) show that liquefaction occurs at depths of 4-8 m (BM 53) and 14-17 m (BM 49). The value of the Liquefaction Potential Index (LPI) increases and indicates a high liquefaction potential below the water table with the highest value of 17.88. The analysis shows that liquefaction is closely related to the shallow water table, soil type, and low N-SPT values. The high liquefaction potential requires prevention methods as a form of treatment.