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The Niigata M7.5 Earthquake of 1964 remains uniquely important among field case histories for understandingliquefaction triggering and manifestations. Much has been written about the Kawagishi-cho strong motion record, theNiigata case histories of seismic-soil liquefaction triggering, and the post-triggering lateral spread displacements. Thispaper explores a new and different perspective on the disaster - the geologic setting and geomorphic processesreworking Holocene sand units that ultimately create the most severe liquefaction effects during the earthquake. Acrossthe city, liquefaction was most pronounced in fluvially-reworked sands derived from three aeolian and barrier islanddune fields upriver and along the coastline. The largest source of beach and aeolian sand material that liquefied in1964 is a mid-Holocene maximum transgressive barrier island that deposited fifty–sixty meters of sand along the thencoastline five-eight-thousand years ago. Tectonic-downwarping and -subsidence of the Echigo Plain has allowed fordelta-progradational processes to build out a thick sedimentary prism beneath the current location of Niigata City.Within this prism, the Shinano and Agano Rivers have eroded and fluvially-redeposited these barrier island sands, andthose of a closer-in two-three-thousand-year beach-ridge deposit, beneath districts of the city. Most recently, forhuman-placed fills the materials are sourced almost entirely from modern coastal beach-ridge and sand dune depositsfronting the Sea of Japan. More than any other factors, these geologic conditions and geomorphic depositional historiescontrolled the locations and severity of soil liquefaction during the 1964 event. Today, these geologic units persist asa future risk to infrastructure of Niigata City.

This study investigates the impact of nearby structures on the cyclic settlement mechanisms of shallow foundations in liquefiable soils using a numerical model based on Biot's porous media theory. The model predicts excess pore water pressure and settlement by coupling equilibrium and continuity equations, solved using an implicit time integration scheme. Soil nonlinearity under cyclic loading is represented using generalized plasticity, boundary surfaces, and non-associated models. Three scenarios are simulated to study the effect of spacing between light and heavy foundations and variation in acceleration intensity. Results show that as spacing between foundations increases, lateral displacement and settlement decrease. Excess pore water pressure generation also decreases with increased foundation spacing. Soil just below the foundation exhibits maximum settlement, decreasing with depth. When input acceleration increases from 0.1 g to 0.15 g and 0.2 g, settlement increases by 40%–55% and 90%–110% respectively for both light and heavy foundations, regardless of spacing. Excess pore water pressure also increases sharply with higher acceleration intensity. The findings highlight the importance of considering foundation-soil-foundation interaction effects in liquefaction-prone urban settings and provide insights for designing resilient shallow foundations. The advanced numerical modeling approach offers engineers a more informed way to mitigate liquefaction risk and build safer, more durable structures in earthquake-prone areas. [ABSTRACT FROM AUTHOR]

The response of partially saturated granular cargoes during maritime transportation has resulted in the capsize and sinking of 27 bulk carriers at sea and the loss over 90 seafarers' lives in the last decade. The partially saturated granular material response to energy imparted during cargo loading, ship engine vibrations and vessel rolling motions from sea states causes a change in state of the granular cargo, which can lead to vessel instability and ultimately capsize. However, the mechanisms driving the response of partially saturated granular cargos within a bulk carrier hold are not well understood. This paper presents results from an experimental study of rolling table centrifuge model tests on a partially saturated silica sand to contribute to improved understanding of the response of granular cargoes during maritime transport. Observed settlement, pore pressure, moisture content and density changes during and/or following a sequence of large amplitude rolling motions are presented. The results indicate that for the conditions considered, a progressive upwards migration of pore water during rolling led to creation of a free surface of water above the granular sample that was left in a denser, lower moisture content sample compared to its initial state. Sloshing of free water on top of even a competent cargo during rolling motions of the ship can contribute to loss of ship stability and ultimately capsize. [ABSTRACT FROM AUTHOR]

Mixing discrete flexible fibres into sand may improve its liquefaction resistance during cyclic loading. Here, the benefits are demonstrated by performing undrained cyclic triaxial tests on fibre-reinforced samples in very loose and loose states. The development of a liquified state may be delayed when fibres are present. Here, the strain energy dissipation during loading, and liquefaction development, is focused on. The results show that strain energy continuously dissipates as undrained cyclic loading proceeds. The capacity energy, which coincides with a double amplitude axial strain of 5% or the unity of excess pore pressure ratio ( r u ), whichever occurs first, is increased by the inclusion of fibres. Under the two-way symmetrical cyclic loading, with a cyclic stress ratio of 0.2, the inclusion of fibres with a fibre content of 0.5% leads to the capacity energies of the samples in very loose and loose states increasing by 86.8 and 158.8%, respectively. The generation of pore pressure is closely related to the dissipated energy. The fibres alter the liquefaction responses of a sand skeleton in ways that depend on the applied loading conditions, and this depends on the extent to which the fibres are mobilized in tension during loading. When unities of r u are attained for fibre-reinforced sand samples, their states may vary greatly and remain far from liquefaction. A newly defined pore pressure ratio ( r u ∗) proves to be a better indicator of liquefaction in fibre-reinforced sand. A possible energy-based method, intended for practical use to assess liquefaction resistance of fibre-reinforced sand, and the margin of safety against liquefaction, is also presented. [ABSTRACT FROM AUTHOR]

Stone column installation is commonly employed to prevent liquefaction. Stone columns mitigate liquefaction by means of mainly three mechanisms which are drainage, stiffening and densification. A factor of safety against liquefaction $FS$ FS is used to quantify liquefaction potential. The aim of this study was to assess the efficiency of stone columns as a liquefaction remediation based on twenty four case studies. In these cases, SPT and CPT tests were recorded before and after stone columns installation. It was found that the installation of stone columns considerably increased soil density mainly in clean to slightly silty sand. The average rate of increase in the penetration resistance ${N_{1,60,cs}}$ N 1 , 60 , cs and ${q_{c1Ncs}}$ q c 1 Ncs were about 31.13% to 69.29% and 57.10% to 318.28%, respectively. Furthermore, the cyclic shear stress ratio of reinforced soil can be reduced by 13.5% to 77.5% due to the stiffening improvement of stone columns. Densification and stiffening mechanisms have been investigated through several approaches. Their individual and combined effects have been analysed. Comparative results indicate that considering the densification and stiffening effects in liquefaction analyses improved considerably the performance of stone columns. [ABSTRACT FROM AUTHOR]

Recent earthquakes in New Zealand and Japan showed that pre-shaking histories significantly affected the reliquefaction resistance of soils. In this study, a series of experimental tests was conducted to elucidate the coupled effects of inherent and induced anisotropy on reliquefaction resistance of Toyoura sand, which have not been studied before. Accordingly, loose and dense Toyoura sands were prepared with two different methods: dry deposition and moist tamping. The specimens were sheared cyclically using a hollow cylinder torsional shear apparatus under various cyclic stress ratios up to different residual shear strains (γres) and reconsolidated at different states. The experimental results were assessed from various perspectives, including stress–strain relationships, failure mechanisms, liquefaction/reliquefaction resistance, excess pore water pressure (EPWP) generation and compressibility in conjunction with micromechanical interpretations. It was shown that fabric evolution affects the reliquefaction characteristics of Toyoura sand substantially. Interestingly, a unique correlation exists between EPWP and shear strain accumulation for all tests. An energy-based model was developed to uniquely correlate the dissipated energy with the cyclic resistance based only on residual shear strains; this model shows great promise to develop a unified, energy-based criterion for quantifying the liquefaction/reliquefaction resistance of soils with different fabrics. [ABSTRACT FROM AUTHOR]

The potential for static liquefaction of tailings is a major focus in the design and operation of tailings storage facilities. This research models the behaviour of unsaturated tailings, with a variety of degrees of saturation, addressing the propensity for static liquefaction during monotonic loading. Unsaturated triaxial tests, including constant suction conditions and constant water–air mass conditions, were performed. A bounding surface plasticity model was used to simulate the results. The constant mass condition is relevant to undrained closed-system loading, which may prevail during fast deformation after the tailings becomes unstable, when the air and water in the pore space remain locked inside the tailings. Boyle's law and hydraulic hysteresis were accounted for to model the changes of pore air and water pressures, and suction, with the change in tailings volume. Good agreement was achieved between test results and model simulations. Additional simulations to mimic rising water tables under constant total stress states in the field, situations that may trigger instabilities, are also shown. Results are added to charts which relate peak and post-liquefaction strengths, as well as collapse lines, to measures of initial state, for unsaturated conditions, which may be of use in practice. [ABSTRACT FROM AUTHOR]

This work investigates the soil stabilization impact of adding silica fume and phosphogypsum on the hydro-mechanical behavior of clayey sand. Laboratory tests were performed on natural soil samples containing 5%, 10%, 15%, and 20% of silica fume and 3%, 6%, 9%, and 12% of phosphogypsum by weight of dry soil. The tests included particle size distribution, compaction characteristics, liquid limit, plastic limit, direct shear test, and hydraulic conductivity. The addition of phosphogypsum from 3 to 6% by weight of dry soil improved the engineering properties of the soil, resulting in an increase in the maximum dry density from 15.73 to 16.22 kN/m3. The highest shear strength of 17.91 kPa was obtained with an addition of 6% of phosphogypsum waste by the weight of dry soil. Similarly, a 10% substitution of silica fume in natural soil resulted in the highest shear strength of 20.37 kPa, providing improved resistance against liquefaction. The results show that the addition of phosphogypsum and silica fume stabilizers can be successfully used to treat clayey sand for various construction activities. The research outcomes will help engineers and construction professionals in implementing cost-effective and sustainable solutions for soil stabilization of clayey sand in practical applications. [ABSTRACT FROM AUTHOR]

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As a new type of energy that can meet the requirements of carbon neutrality, biomass has received wide attention in recent years, and its rational and efficient thermal utilization can help reduce greenhouse gas emissions and establish an energy-saving, low-carbon energy system to promote sustainable development. In this paper, the current utilization and research status of plant-based biomass waste is comprehensively summarized from four aspects, namely component properties, industrial thermal utilization means, experiments and theoretical calculations. In addition, this paper summarizes the research progress in several aspects, such as microscopic experimental studies, macroscopic pyrolysis characterization, and multiscale theoretical model construction of biomass waste. However, due to the diversity and heterogeneity of biomass, there are still some challenges to extending the laboratory research results to large-scale industrial production, for which we also provide an outlook on future technological innovations and development directions in this research area. [ABSTRACT FROM AUTHOR]

The objective of this study was to improve the liquefaction efficiency of cornstalk by N-methylmorpholine-N-oxide (NMMO) pretreatment, and NMMO pretreated cornstalk was liquefied in polyols. It also entailed studying the process involve in the liquefaction of NMMO pretreated cornstalk in polyols. The results demonstrated that the chemical composition of cornstalk had little change and the total crystallinity index decreased from 0.510 to 0.165 by NMMO pretreatment. The kinetics along with different pretreatment was estimated by kinetic models at different liquefaction temperatures. Kinetic studies showed that NMMO pretreatment significantly improves the liquefaction efficiency of cornstalk. In comparison with raw cornstalk, NMMO pretreatment led to a decrease in the activation energy of liquefaction reaction. The liquefaction products were analyzed by Fourier transform infrared spectrometer (FTIR), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC) to further explain the liquefaction mechanism of cornstalk pretreated by NMMO. [ABSTRACT FROM AUTHOR]

This case study evaluated the liquefaction risk and application of vibro-compaction for soil improvement in a construction project site on Saadiyat Island, Abu Dhabi, UAE. Abu Dhabi is designated as Zone 0 according to the Uniform Building Code (UBC-97), and we discuss the design criteria for vibro-compaction that were adopted to mitigate the liquefaction risk, the trials conducted to establish the application criteria for vibro-compaction, and the general practices related to vibro-compaction. Specific studies conducted in Abu Dhabi Emirate indicate that the seismicity in the region is low, and the probability of liquefaction is very limited. However, during the pre-project soil investigation phase, the analysis of potential soil liquefaction indicated that certain examined areas have the potential to undergo liquefaction. The liquefaction potential was assessed based on a combination of safety factors obtained for an earthquake with a magnitude Mw = 6 and the corrected cone tip resistance (qc). The acceptability criteria for improved soil are based on cone penetration test (CPT) results. The target qc is accepted as 2.7 MPa and the treatment depth would be a minimum of − 3.5 m. A field trial was conducted to determine the optimal compaction grid spacing that meets the specified acceptance criteria and aligns with the project's design criteria. Based on the trial evaluation, a vibro-compaction grid spacing of 4 × 4 m was appropriate. Consequently, a total of 4125 points at the construction site underwent vibro-compaction. [ABSTRACT FROM AUTHOR]

Driven by the growing energy crisis and environmental concerns regarding the utilization of fossil fuels, biomass liquefaction has emerged as a highly promising technology for the production of renewable energy and value-added chemicals. However, due to the high oxygen content of biomass materials, biocrude oil produced from liquefaction processes often contains substantial oxygenated compounds, posing challenges for direct downstream applications. Catalytic hydrodeoxygenation (HDO) upgrading with hydrogen donors is crucial for improving the quality and applicability of biomass-derived fuels and chemicals. The costs, safety, and sustainability concerns associated with high-pressure gaseous hydrogen and organic molecule hydrogen donors are driving researchers to explore alternative and innovative biomass hydrodeoxygenation approaches without exogenous hydrogen donors. This review offers an overview of the recent developments in catalytic hydro-liquefaction and hydrodeoxygenation methods for biomass valorization without external hydrogen donation, including catalytic self-transfer hydrogenolysis using endogenous hydrogen in biomass structure, in situ catalytic hydrodeoxygenation employing water as the hydrogen donor, and in situ hydrodeoxygenation via water splitting assisted by zero-valent metals. The in situ hydrogen supply mechanisms and the impact of various hydrodeoxygenation catalysts on hydrogen donation efficiency using endogenous hydrogen are summarized in detail in this work. Furthermore, the current obstacles and future research demands are also discussed in order to provide valuable recommendations for the advancement of biomass utilization technologies. [ABSTRACT FROM AUTHOR]

The ongoing transition in the energy sector demands more efficient and reliable energy storage solutions. Our study addresses this need by optimizing the industrial process of liquefied natural gas (LNG) storage, focusing on enhancing thermal performance and energy efficiency. Leveraging a standard LNG storage design, we meticulously evaluated critical supporting variables, modeled key components, and conducted integrated cycle simulations. The primary goal was to minimize the volume of stored gas (achieving a reduction to approximately 1/600th of its gaseous state) while maintaining optimal storage conditions. Our methodology prioritizes insulation over pressure‐bearing factors in large‐scale tanks, aligning with the unique thermal challenges of LNG storage. Simulations were based on methane, which constitutes over 86% of the natural gas in the Middle East, ensuring relevance to the region's resources. The results are promising, with a compression stage reaching a maximum pressure of 2.377, an energy efficiency ratio of 60.71%, and a performance coefficient of 3.188. These findings offer a significant step forward in developing more effective and efficient LNG storage systems, contributing to the broader goal of sustainable energy management. [ABSTRACT FROM AUTHOR]

In this article, a numerical calibration procedure for undrained cyclic triaxial tests is presented to evaluate the liquefaction potential in sand and silt samples from mining tailings in northern Chile. The numerical modeling of an axisymmetric specimen involved two stages: isotropic consolidation using the Hardening Soil Small (HSS) model and a cycling phase employing the UBC3D-PLM model to simulate the onset of liquefaction using the criterion that the excess pore pressure ratio R u should exceed 0.8. The results demonstrate that the UBC3D-PLM modeling calibrated with experimental data from cyclic triaxial tests effectively represents the excess pore pressure in both sandy and silty soils from mining tailings. The accuracy of the modeling decreases when a single set of parameters is applied to the same soil at different cyclic stress ratios (CSR), highlighting the need for specific calibrations for each loading. [ABSTRACT FROM AUTHOR]

Liquefaction can significantly alter the ground response. However, no existing design spectrum accounts for the severity of soil liquefaction. This work aims to develop correction factors that can be used to adjust code-based design spectra to reflect the specific liquefaction susceptibility of a site. The correction factor is derived as the ratio of response spectra calculated by two types of 1D nonlinear site response analyses: effective stress analysis, which can model porewater pressure (PWP) generation, and total stress analysis. We considered seven real profiles and 200 motions in our analysis. Four combinations of soil nonlinear models and PWP generation models are also utilized to account for epistemic uncertainties. Results show that the response spectral ratio for liquefied sites typically falls below one for periods less than 1–2 s and rises above one for longer periods. Meanwhile, the response spectral ratio reflects the overall liquefaction susceptibility influenced by PWP, factor of safety, and liquefiable layer depth, while the liquefaction potential index (LPI) captures their complex interplay. Accordingly, we propose four LPI-dependent factors: three correction factors for peak ground acceleration, 0.2 s spectral acceleration (Sa), and 1.0 s Sa, and a long-period adjustment factor applicable for periods exceeding 1 s. The correction factors linearly decrease with increasing LPI, while the adjustment factor exhibits the opposite trend. A design spectrum for a liquefiable site can be readily constructed by adjusting the code-based design spectrum using the proposed correction factor, as illustrated in the example. This approach is applicable as long as LPI is available from a simplified liquefaction analysis or a liquefaction hazard map. [ABSTRACT FROM AUTHOR]

Liquefaction-induced flow failures, excessive settlements, lateral spreading, and loss of shear strength in granular soils can become massive hazards during earthquakes. Among the various mitigation techniques available, soil reinforcement using dense granular columns can be considered as a very effective technique, and its effectiveness gets further improved by encasing the columns in a geotextile to maintain the integrity of the columns during earthquakes. This paper presents findings from a first-of-its-kind study of simple shear tests on sand reinforced with geotextile-encased granular columns (EGC) to understand the fundamental mechanisms leading to its improved liquefaction resistance and shearing response. The effects of area replacement ratio and grouping action of columns on the overall response are established by performing a series of multi-stage constant volume simple shear tests on unreinforced and EGC-reinforced sands. The area replacement ratio was varied between 4 and 16% in different tests, and the tests with 16% area replacement ratio were conducted on sand with a single column and a group of columns. The particle sizes, encasement tensile strength, and column configurations are carefully chosen to avoid scaling and boundary effects on the test results. The performance of EGCs against liquefaction was evaluated considering all fundamental mechanisms, including the progression of pore pressures, nonlinear hysteretic behaviour, strain energy accumulation, and shear modulus degradation. The potential of EGCs for mitigating the liquefaction and improving the post-liquefaction shear strength of sand was found to improve with the increase in the area replacement ratio. For a specific area replacement ratio, the beneficial effects were more significant when the EGCs were spread into a group of symmetrically placed columns instead of a single column at the centre. The stress concentration on the EGCs due to modulus contrast and additional confinement offered by the EGCs to intervening soil have collectively benefited the shearing response of sand before, during, and after liquefaction. [ABSTRACT FROM AUTHOR]

Under traffic load, earthquake load, and wave load, saturated sand foundation is prone to liquefaction, and foundation reinforcement is the key measure to improve its stability and liquefaction resistance. Traditional foundation treatment methods have many problems, such as high cost, long construction period, and environmental pollution. As a new solidification method, enzyme-induced calcium carbonate precipitation (EICP) technology has the advantages of economy, environmental protection, and durability. Through a triaxial consolidated undrained shear test under cyclic loading, the impacts of confining pressure (σ3), cementation number (Pc), cyclic stress ratio (CSR), initial dry density (ρd), and vibration frequency (f) on the development law of pore water pressure of EICP-solidified sand are analyzed and then a pore water pressure model suitable for EICP-solidified sand is established. The result shows that as σ3 and CSR increase, the rise rate of pore water pressure of solidified sand gradually accelerates, and with a lower vibration number required for liquefaction, the anti-liquefaction ability of solidified sand gradually weakens. However, as Pc, ρd, and f rise, the increase rate of pore water pressure of solidified sand gradually lowers, the vibration number required for liquefaction increases correspondingly, and its liquefaction resistance gradually increases. The test results are highly consistent with the predictive results, which show that the three-parameter unified pore water pressure model is suitable for describing the development law of A-type and B-type pore water pressure of EICP-solidified sand at the same time. The study results provide essential reference value and scientific significance in guidance for preventing sand foundations from liquefying. [ABSTRACT FROM AUTHOR]

Proper consideration of variations in soil properties and their effects is necessary to enhance the seismic safety of structures. In this study, the effect of spatial variations in the cyclic resistance ratio on seismic ground behavior was investigated. Initially, dynamic centrifuge model tests were conducted on sandy ground featuring a 20% mixture of weak zones with low relative density and on homogeneous sandy ground with no mixture of weak zones. Subsequently, an effective stress analysis was performed by modeling the distribution of weak zones in the centrifuge model tests. Finally, after confirming the validity of the parameter settings, several analytical models with different weak-zone distributions were generated and numerically analyzed using random field theory. The results indicate that a local mixing of approximately 20% weak zones has only a limited effect on overall ground behavior. However, differences were observed in the rate of increase and dissipation of the excess pore water pressure ratio and in the residual horizontal displacement. [ABSTRACT FROM AUTHOR]

Large deformation of sand due to soil liquefaction is a major cause for seismic damage. In this study, the mechanisms and modeling of large post-liquefaction deformation of sand considering the significant influence of water absorption in shearing and seismic wave conditions. Assessment of case histories from past earthquakes and review of existing studies highlight the importance of the two factors. Based on the micro and macro scale mechanisms for post-liquefaction shear deformation, the mechanism for water absorption in shearing after initial liquefaction is revealed. This is aided by novel designed constant water-absorption-rate shear tests. Water absorption in shearing can be classified into three types, including partial water absorption, complete water absorption, and compulsory water absorption. Under the influence of water absorption in shearing, even a strongly dilative sand under naturally drained conditions could experience instability and large shear deformation. The mechanism for amplification of post-liquefaction deformation under surface wave load is also explained via element tests and theoretical analysis. This shows that surface wave-shear wave coupling can induce asymmetrical force and resistance in sand, resulting in asymmetrical accumulation of deformation, which is amplified by liquefaction. A constitutive model, referred to as CycLiq, is formulated to capture the large deformation of sand considering water absorption in shearing and seismic wave conditions, along with its numerical implementation algorithm. The model is comprehensively calibrated based on various types of element tests and validated against centrifuge shaking table tests in the liquefaction experiments and analysis projects (LEAP). The model, along with various numerical analysis methods, is adopted in the successful simulation of water absorption in shearing and Rayleigh wave-shear wave coupling induced large liquefaction deformation. Furthermore, the model is applied to high-performance simulation for large-scale soil-structure interaction in liquefiable ground, including underground structures, dams, quay walls, and offshore wind turbines. [ABSTRACT FROM AUTHOR]

The use of fossil fuels has been essential to the development of society, but has also contributed partly to global warming. For example, carbon dioxide emissions from fossil fuels and industries have increased by 60% since 1990, calling for the recycling of modern biomass in the context of a carbon neutral economy. Here we review the hydrothermal conversion of biomass into biofuels, chemicals and biomaterials with emphasis on subcritical water properties, hydrolysis of biomass, steam explosion, fractionation, carbonization, liquefaction, gasification, and fractionation of bio-oil. We observe that hydrothermal conversion of biomass in the presence of water at subcritical conditions produces value-added compounds with high process efficiency. Subcritical water allows rapid reaction rates, low mass transfer resistance, and gas-like diffusivity. [ABSTRACT FROM AUTHOR]

Soil liquefaction response is significantly affected by soil gradation (particle size, angularity, coefficient of uniformity) and density. However, the literature on the factors affecting liquefaction resistance with initial static shear stress (e.g., sloping ground) is more limited and primarily based on clean, poorly graded sands. As a result, the influence of particle size and gradation on the liquefaction potential of soils with initial shear stress is overlooked. In this study, 223 large-size cyclic simple shear tests were conducted on poorly and well-graded sands and gravels to evaluate the effects of soil gradation on the liquefaction resistance with the presence of initial static shear stress. Sandy and gravelly soils with coefficients of uniformity ranging from 1.6 to 42 were tested in a large-scale cyclic simple shear device under constant volume conditions, and the initial static shear stress correction factor Kα values were obtained. The results show that poorly graded sand specimens exhibit flow liquefaction, have a more significant vertical effective stress reduction as the initial static shear stress increased, but also exhibit beneficial effects of initial static shear stress even if loosely packed, mainly due to their more dilative nature. Well-graded sandy soils, on the other hand, did not have as an abrupt loss of stiffness compared to poorly graded sand specimens, but due to their higher coefficient of uniformity may be more contractive, causing more pronounced shear strain development at the last few cycles. Gravel content also affected the void ratio of sand, which influenced the onset of strain softening or hardening during cyclic loading. Dense specimens with initial static shear stress exhibit cyclic mobility, but this may not necessarily provide beneficial effects of the Kα correction factor, especially for higher coefficients of uniformity. The experimental results suggest that the widely used Kα correction factor approaches that were originally suggested based on poorly graded sand may be overoptimistic for both loose and dense soils when considering a broader spectrum of soils such as those encountered in engineering practice. It is proposed that the Kα correction factor should consider not only relative density and initial static shear stress but also particle size and gradation (i.e., determining the gravel content and the coefficient of uniformity), as well as angularity. [ABSTRACT FROM AUTHOR]

The effects of phase shift (δ) between compression and shear waves, and consolidation stress ratio (Kc) on the liquefaction resistance of sand under simultaneous compression and shear wave loading is investigated using a hollow cylinder torsional shear apparatus. The differences caused by prior stress history (assessed using drained versus undrained preshear) highlight the importance of test protocols in undertaking research to explore the effects of complex dynamic loading paths. The liquefaction resistance of sand was highly dependent on the loading path. However, it was not affected much by variations in δ , if the horizontal shear stress ratio (τzθ/σmc′) and the ratio between shear stress increment and normal stress increment (ΔS/ΔN) were held constant. In tests with constant cyclic stress ratio (CSR), an increase in δ decreases the cyclic resistance because the increase in δ causes a reduction in the rate of deviatoric stress increment per degree of principal stress rotation. At a given CSR , for δ≠0 cases, a change in ΔS/ΔN does not affect the liquefaction resistance of sand because the magnitude and pattern of rotation is not affected much by ΔS/ΔN (for the ratios explored in this research). Increasing Kc or static shear stress ratio (αst) increased the cyclic resistance of the tested sand for ΔS/ΔN<1. The rate of increase in cyclic resistance with increasing αst decreases with the increase in ΔS/ΔN and was essentially unchanged for ΔS/ΔN=1. This observation, that the rate of increase in cyclic resistance with αst decreases with increasing ΔS/ΔN , is consistent with the observation in the literature that the cyclic triaxial loading yields higher static shear stress correction factor (Kα) than cyclic simple shear in loose sand. [ABSTRACT FROM AUTHOR]

Evaluation of the liquefaction susceptibility of soils is one of the most important subjects in geotechnical earthquake engineering. The energy-based liquefaction evaluation procedure, with a focus on seismic energy propagation and dissipation in soils, has attracted increasing attention in recent years. This paper presents a systematic analysis of cyclic triaxial test data of three series of silty sands through the energy-based approach. The stress-normalized accumulative dissipated strain energy per unit volume required for triggering liquefaction is used to evaluate the liquefaction potential of sands. It is a function of void ratio, fines content, and sand type. The pore pressure generation with the stress-normalized accumulative dissipated energy per unit volume can be simulated by a one-parameter pore pressure model, and the model parameter is affected by void ratio, fines content, and sand type. Unified characterizations of the stress-normalized accumulative dissipated energy per unit volume required for liquefaction and the fitting parameter of the pore pressure model are proposed in the framework of critical state soil mechanics. [ABSTRACT FROM AUTHOR]

In shallow water regions, ocean waves commonly propagate in the form of cnoidal waves, with the response induced in the seabed obviously being different from that involving conventional linear waves. Computational models of waves and seabeds were established based on cnoidal wave theory and Biot's completely dynamic consolidation theory, respectively. A semianalytical solution for the dynamic response of the multilayered, transversely isotropic (TI), poroelastic seabed induced by cnoidal waves was derived via the scalar potential function and the dual variable and position method. The reliability and accuracy of the developed semianalytical solution was verified against existing solutions and experimental data. This parametric study demonstrated that cnoidal waves have a significant effect on the dynamic response of the seabed compared to linear waves. Also, the induced pore pressure/stresses and corresponding liquefaction potential were significantly affected by the anisotropy and layering of the seabed material. The newly developed solution can serve as a useful tool for estimating the liquefaction potential of a TI and multilayered poroelastic seabed in shallow water. [ABSTRACT FROM AUTHOR]

During the 1886 MW 7.3 Charleston, South Carolina, earthquake, three railroads emanating from the city were exposed to severe shaking. Expansion joints in segmented railroad tracks are designed to allow railroad infrastructure to withstand a few parts in 10,000 of thermoelastic strain. We show that, in 1886, transient contractions exceeding this limiting value buckled rails, and transient extensions pulled rails apart. Calculated values for dynamic strain in the meizoseismal region are in reasonable agreement with those anticipated from the relation between strain and moment magnitude proposed by Barbour et al. (2021) and exceed estimated tectonic strain released by the earthquake by an order of magnitude. Almost all of the documented disturbances of railroad lines, including evidence for shortening of the rails, can thus be ascribed to the effects of dynamic strain changes, not static strain. Little or no damage to railroads was reported outside the estimated 10-4 dynamic strain contour. The correspondence between10-3 and 2 × 10-4 contours of dynamic strain and Mercalli intensity 9 and 8, anticipated from the dependence of each quantity on peak ground velocity, suggests it may be possible to use railroad damage to quantitatively estimate shaking intensity. At one location, near Rantowles, -20 km west of Charleston, a photograph of buckled track taken one day after the earthquake has been cited as evidence for shallow dextral slip and has long focused a search for a causal fault in this region. Photogrammetric analysis reveals that the buckle was caused by transient contraction of <10 cm with no dextral offset. Our results further weaken the evidence for faulting in the swamps and forests south of the Ashley River in 1886, hitherto motivated by the photograph and limited macroseismic evidence for high-intensity shaking. [ABSTRACT FROM AUTHOR]

Fossil fuels are deemed to diminish because of their limited availability, no renewability, and emissions of greenhouse gases and other poisonous materials to the atmosphere and the ecosystem. Renewable energy based on sustainable biomass has occupied an increasing share of the energy system over the past decade. Among several massively cultivated crops worldwide, corn, sugarcane bagasse, and soybean straws are some of the leading agricultural by-products that can generate substantial energy (e.g., biofuels, hydrogen) as vital sustainable energy to substitute non-renewable fossil fuels. This paper aims to review recent progress in renewable energy generation from biomass based on thermochemical techniques-i.e., gasification, pyrolysis, and liquefaction-detailed technical features and their application for extraction energy from biomass. The quality, composition, and productivity of renewable energy extracted from biomass based on existing thermochemical techniques are compared, and their technical dependencies upon the thermochemical processes are discussed. Furthermore, analysis of technical deficiencies of existing methods, and exploration of innovative emerging technologies for high-efficiency and high-quality renewable energy generation from biomass straws. In general, biomass gasification stands out as the most efficient technique for hydrogen production (HP) from biomass due to mature technology, high hydrogen yield, and potential for integration with other presented techniques. [Display omitted] • A detailed review of HP from biomass using thermochemical techniques. • Discussion about gasification, pyrolysis, and liquefication working principles. • Comparison between all types of presented thermal techniques. • Advantages and disadvantages of gasification, pyrolysis, and liquefication. • Overall performance of all thermal techniques presented in this review. [ABSTRACT FROM AUTHOR]

The liquefaction and consequent injection of clastic dykes (injectites) is often associated with the occurrence of large earthquakes. Injectites are most documented in thick unconsolidated sedimentary sequences and less commonly in rocks as a result of localized clastic mud overpressure due to earthquake-induced shaking. This paper documents near-surface clastic dykes injected into Middle-Late Pleistocene travertine deposits following repeated seismic events. The novelty is that there is a clear relationship between the development of the injectites and the activity of seismogenic faults that cut the entire body of the travertine, deposited at least at 45.5 ± 8.5 ka, and the topographic surface. The clastic slurry, derived from the fluidization of silty-sandy continental deposits at the base of, or intercalated with the travertine body, was in geometric connection with the faults. When this occurred, the over-pressured slurry was injected into the fault zone, filling the fractures and assisting their development by over-pressure hydrofracturing and counteracting the frictional forces on the fault. This evidence, in addition to documenting another case of liquefaction and associated emplacement of clastic dykes, has a twofold significance: i) it records the effects of clastic dykes intruded at very shallow depths, up to the surface, within a capable fault zone; ii) it documents a polyphase injection of clastic material into travertine deposits, never before described, induced by repeated liquefaction phenomena following major seismic events, thus highlighting and reinforcing the importance of travertine for the study of active tectonics and earthquake studies. [ABSTRACT FROM AUTHOR]

Post-earthquake scientific investigation is considered as one of the pillars supporting earthquake engineering. On the 6th of February, 2023, two deadly strong earthquakes, which magnitudes were Mw7.8 and Mw7.5, respectively, shook Southern-Central Turkiye, caused significantly large casualties and tremendous economy loss. Through on-site field survey, liquefaction phenomena and liquefaction-induced damage to buildings were observed. The observations are: (1) the consequences of soil liquefaction included sandboils, lateral spreading, ground subsidence and ground failure caused by loss of bearing capacity; (2) in two liquefied areas, lateral spreading was investigated and the spreading displacement ranged from several centimeters to meters, resulting in damage or demolishing of buildings; (3) in Golbasi town, many 6 to 10-story buildings significantly subsided and tilted due to liquefaction-induced loss of ground bearing capacity. Buildings subsided by tens of centimeters to 2 ~ 3 m, and tilted by several degrees to tens of degrees; (4) ground subsidence of tens of centimeters with respect to adjacent buildings was detected. The liquefaction phenomena were compared with those triggered by the 2008 Wenchuan, China, earthquake which maintained similar in magnitude and focal depth. The findings and lessons learnt will enhance the understanding of liquefaction hazard, challenge the current liquefaction countermeasures, and eventually facilitate to improve liquefaction mitigation techniques. [ABSTRACT FROM AUTHOR]

Wave- and current-supported fluid mud on gently sloped continental shelves represents a type of sediment gravity flow capable of rapidly transporting substantial sediment over short periods, significantly contributing to coastal geomorphic evolution. To investigate the dynamics of intertidal fluid mud events, in-situ observations were conducted from May 9 to May 18, 2017, using a seabed tripod system at the lower intertidal flat of the central Jiangsu coast, China. Fluid mud was observed following a medium wind-wave event, with a maximum significant wave height of 0.42 m. The liquefied seabed, loosened by liquefaction, facilitated bed erosion and sediment resuspension. Fluid mud layers, with mean suspended sediment concentrations (SSCs) exceeding 10 g/L, periodically formed during high slack tide, early flood, and late ebb phases. These layers varied in thickness from 4 cm to 20 cm and exhibited strong stratification caused by suspended sediment. Fluid mud disappeared when the bottom turbulence kinetic energy exceeded a threshold of 0.00045 m2/s2 due to an increase in current velocity. The downslope movement of intertidal fluid mud was estimated using a theoretical buoyancy-friction model and validated by observed offshore-directed velocity jets at 0.1 m above the seabed during high slack tide phases. Additionally, onshore winds favored fluid mud formation during early flood phases, while offshore winds favored it during late ebb phases. These observations suggest that fluid mud can form on intertidal flats under conditions where tidal flows and winds align, contributing to a deeper understanding of the formation mechanisms of shallow gravity flows and the improvement of sediment transport models. [ABSTRACT FROM AUTHOR]

The state parameter (ѱ) accounts for both relative density and effective stress, which influence the cyclic stress or liquefaction characteristic of the soil significantly. This study presents a ѱ‐based probabilistic liquefaction evaluation method using six soft computing (SC) techniques. The liquefaction probability of failure (PL) is calculated using the first‐order second moment (FOSM) method based on the cone penetration test (CPT) database. Then, six SC techniques, such as Gaussian process regression (GPR), relevance vector machine (RVM), functional network (FN), genetic programming (GP), minimax probability machine regression (MPMR) and multivariate adaptive regression splines (MARS), are used to predict PL. The performance of these models is examined using nine statistical indices. Additionally, plots such as regression plots, Taylor diagrams, error matrix and rank analysis are shown to assess the SC model's performance. Finally, sensitivity analysis is performed using the cosine amplitude method (CAM) to assess the influence of input parameters on output. The current study demonstrates that SC models based on state parameter predict PL effectively. RVM and MPMR models closely follow the GPR model in terms of performance, which is superior to the other models. Notably, two equations are generated using GP and MARS models to predict PL. The results of the sensitivity analysis reveal the magnitude of earthquake (Mw) as the most sensitive parameter. The outcomes of this research will offer risk evaluations for geotechnical engineering designs and expand the use of state parameter‐based SC models in liquefaction analysis. [ABSTRACT FROM AUTHOR]