This study investigates the influence of wood pellet fly ash blended binder (WABB) on the mechanical properties of typical weathered granite soils (WS) under a field and laboratory tests. WABB, composed of 50 % wood pellet fly ash (WA), 30 % ground granulated blast furnace slag (GGBS), and 20% cement by dry mass, was applied at dosages of 200-400 kg/m3 to four soil columns were constructed at a field site deposited with WS. After 28 days, field tests, including coring, standard penetration tests (SPT), and permeability tests, revealed enhanced soil cementation and reduced permeability, indicating a denser soil matrix. Unconfined compressive tests (UCT) and free-free resonant column (FFRC) tests on field cores at 28 and 56 days, compared with laboratory specimens and previously published data, demonstrated strength gains 1.2-2.1 times higher due to field-induced stress. The presence of clay minerals influenced the WABB's interaction and microstructure development. Correlations between seismic waves, small-strain moduli, and strength were developed to monitor in-situ static and dynamic stiffness gain of WABB-stabilized weathered granite soils.

This study investigates the liquefaction characteristics of deep soil layers and their subsequent effects on the seismic response of subway station structures, utilizing shaking table tests and inputting seismic waves of varying principal frequencies. Macroscopically, the liquefaction of deep soil strata does not result in surface manifestations such as water spraying and sand bubbling. However, it still induces cracking and damage to the soil surrounding the structure. Analyzing from the perspective of the pore pressure ratio reveals that the ratio under free-field conditions is significantly lower than under structural conditions. Additionally, the pore pressure ratio caused by the Beijing Hotel wave is greater, followed by the Beijing artificial wave, while the Ming Shan wave results in the smallest ratio. In terms of the station structure, the structural acceleration and tensile strain increment induced by the Beijing Hotel wave are the most significant, followed by the Beijing artificial wave, with the least effect from the Ming Shan wave. This indicates that the liquefaction behavior of deep soil layers is primarily influenced by the overlying load and the frequency characteristics of seismic waves. The construction of subway stations reduces the overlying loads on soil layers, increasing the likelihood of soil layer liquefaction. Meanwhile, a lower main frequency of the seismic wave results in a higher degree of liquefaction in the deep soil layers. The seismic response of the station structure is contingent on the frequency characteristics of the seismic wave. The lower the primary frequency of the seismic wave, the higher the seismic response of the station structure. Furthermore, the liquefaction behavior of the deep soil layers also impacts the seismic response of the station structure, particularly the tensile strain response of the top and bottom slabs of the station structure.

Resonance can significantly amplify a structure's response to seismic loads, leading to extended damage, especially in critical infrastructure like nuclear power plants. Thus, this study focuses on the resonance effects of the dynamic interaction between layered soil, pile foundations, and nuclear island structures, which is particularly important given the limited availability of bedrock sites for such facilities. Specifically, this study explores the resonance behavior of nuclear islands under various seismic conditions through large-scale shaking table tests by developing a dynamic interaction model for layered soil-pile-nuclear island systems. The proposed model comprises a 3 x 3 pile group supporting the upper structure of a nuclear island embedded within a three-layer soil profile. Sinusoidal waves of varying frequencies identify the factors influencing the system's resonance response. Besides, the resonance effects are validated by inputting seismic motions based on compressed acceleration time histories. Furthermore, the impact of non-primary frequency components on structural resonance is assessed by comparing sinusoidal wave components. The findings reveal that resonance effects increase as the amplitude of the input seismic motion increases to a certain threshold, after which the effect stabilizes. This trend is particularly pronounced in the bending moment response at the pile head. Additionally, an independent resonance phenomenon is observed in the superstructure, suggesting that its resonance effects should be considered separately in nuclear island design. Similar resonance effects are observed when the predominant frequency of sinusoidal waves closely matches the compressed seismic motions, suggesting that sinusoidal inputs effectively simulate structural resonance during seismic design testing.

This study introduces a simplified analytical method to extract shear wave velocity profiles from seismic waves evoked by explosives, providing a time-efficient solution to the conventional Multichannel Analysis of Surface Waves (MASW) method. Controlled ammonium nitrate emulsion explosions were used at five research sites throughout Thailand with different geological conditions to capture ground motion data through a 16-geophone array during field investigations. This direct analysis evaluates surface wave arrival times in real-time while implementing elastic theory-derived empirical factors for analysis. The proposed method delivers results that match MASW-derived profiles yet require fewer complex procedures and shows Vs30 variations from 4.43 to 38.33%. The simplified method delivered the most accurate results in areas displaying gradual soil property transitions and showed reduced precision when dealing with abrupt soil type or mechanical property shifts. The new method transforms petroleum exploration seismic data into geotechnical applications by delivering dependable shear wave velocity profiles with lower complexity and using fewer resources. It is specifically valuable for limited-budget engineering projects or difficult-to-access locations.

This paper presents a comprehensive method for analyzing prestressed concrete bridges subjected to multiple concurrent dynamic loads, incorporating soil-structure interaction (SSI) and seismic wave propagation effects. The study develops a comprehensive numerical framework that simultaneously accounts for traveling seismic waves, train-induced vibrations, and soil-foundation dynamics. Three-dimensional finite element modeling captures the complex interaction between the bridge structure, foundation system, and surrounding soil medium. The investigation considers the spatial variability of ground motion and its influence on the bridge's dynamic response, particularly examining how different wave velocities and coherency patterns affect structural behavior. Advanced material constitutive models based on damage mechanics theory are implemented to represent both linear and non-linear structure responses under dynamic loading conditions. The analysis reveals that traditional simplified approaches, which neglect SSI, train, and seismic loading combinations, and traveling wave effects may significantly misestimate the structural demands. The results demonstrate how wave passage effects can either amplify or attenuate the combined response depending on the relationship between seismic wave velocity, the frequency content of the ground motion recordings, and the local soil conditions. These findings could contribute to the development of more reliable design methodologies for prestressed bridges in seismically active regions with significant railway traffic.

Cliff-attached structures are structures attached to slopes and connected tightly, which is particularly complex to analyze due to the foundations' unequal grounding and the lateral stiffness' irregularity. In rare earthquakes, seismic waves are usually obliquely incident on the foundation at a certain angle. Therefore, it is not appropriate to consider only seismic waves' vertical incidence, and it is necessary to consider multi-angle oblique incidence. In this paper, based on the theory of viscous-spring artificial boundary and the principle of equivalent nodes at the interface of oblique incidence of ground shaking P-waves, and combined with the dynamic properties related to Buckling-Restrained Brace, the numerical models of slopes and two kinds of cliff-attached structures considering the slope amplification effect and soil-structure interaction are established. The dynamic response of the obliquely incident seismic waves under the action of the cliff-attached vibration reduction structure is studied in depth, and the additional effective damping ratios of the nonlinear energy-dissipated units based on the deformation energy are compared and analyzed. It is shown that under the four oblique incidence angles of incidence (compression waves in the vertical plane) studied in this paper, the seismic dynamic response and damage degree peaked at an angle of incidence of 60 degrees, with a tendency to increase and then decrease with increasing angles of incidence. The ability of an energy-dissipating vibration reduction device to change structural vibration characteristics decreases with an increase in incidence angle. The difference between the total strain energy of the structure in the X-direction (Transverse slope direction) and Y-direction (Down-slope direction) and the total energy dissipation of the dissipative components is obvious, with the X-direction being about 10 times that of the Y-direction.

The effects of phase shift (delta) between compression and shear waves, and consolidation stress ratio (K-c) 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 delta, if the horizontal shear stress ratio (tau(z theta)/sigma(mc)') and the ratio between shear stress increment and normal stress increment (Delta S/Delta N) were held constant. In tests with constant cyclic stress ratio (CSR), an increase in delta decreases the cyclic resistance because the increase in delta causes a reduction in the rate of deviatoric stress increment per degree of principal stress rotation. At a given CSR, for delta not equal 0 cases, a change in Delta S/Delta N does not affect the liquefaction resistance of sand because the magnitude and pattern of rotation is not affected much by Delta S/Delta N (for the ratios explored in this research). Increasing K-c or static shear stress ratio (alpha(st)) increased the cyclic resistance of the tested sand for Delta S/Delta N<1. The rate of increase in cyclic resistance with increasing alpha(st) decreases with the increase in Delta S/Delta N and was essentially unchanged for Delta S/Delta N=1. This observation, that the rate of increase in cyclic resistance with alpha(st) decreases with increasing Delta S/Delta N, is consistent with the observation in the literature that the cyclic triaxial loading yields higher static shear stress correction factor (K-alpha) than cyclic simple shear in loose sand. (c) 2024 American Society of Civil Engineers.

In this study, the segment joint and ring joint of the lining of the straight-jointed tunnel are simplified as an equivalent open cylindrical shell with a small central angle and an equivalent closed cylindrical shell with a small width, and the lining of the straight-jointed tunnel is thus simplified as an equivalent continuous periodic shell (ECPS) described by the cylindrical shell theory. Since the ECPS lining is periodic along the longitudinal direction, the tunnel-soil system can thus be treated as a periodic system, which is referred to as the periodic tunnel-soil system (PTSS) in this study. Based on the proposed ECPS lining model, an analytical method for the tunnel with the ECPS lining (ECPS tunnel) under seismic waves is established in this study. By employing the periodicity condition for the PTSS as well as the wave function expansion method, the representation for the wave field in the soil is established. With the aforementioned cylindrical shell theory and Fourier series expansion method, the convolution type constitutive relation for the ECPS lining and the Fourier space equations of motion are derived. By using the soil-lining continuity condition and aforementioned formulations for the ECPS lining and soil, the coupled Fourier space equations of motion for the PTSS are established, with which the response of the ECPS lining and scattered waves in the soil can be determined.

Earthquakes present worldwide risk to economic and human safety. The 2023 earthquakes in T & uuml;rkiye provided a reminder of the potential for catastrophic consequences with 50,700 deaths and 15.7 million people affected. The ability to predict ground motions and infrastructure damage for earthquakes continues to be a challenging problem for scientists and engineers. Until now, estimates of ground motions have been performed empirically by looking at sparse data from past earthquakes. This approach can provide statistical information on intensity amplitudes but cannot inform site-specific ground motions essential to developing the most effective resilience. Interest has grown in large-scale computational models to simulate earthquakes at regional scale. The U.S. Department of Energy EarthQuake SIMulation (EQSIM) framework was developed for regional-scale earthquake simulations at unprecedented fidelity, taking advantage of emerging GPU-accelerated systems. This article describes the EQSIM workflow and demonstrates regional-scale simulations with the new computational capability available to scientists in their quest to mitigate future disasters.

This paper aims to elucidate the clear visibility of attenuating seismic waves (SWs) with forest trees as natural metamaterials known as forest metamaterials (FMs) arranged in a periodic pattern around the protected area. In analyzing the changeability of the FM models, five distinct cases of metawall configurations were considered. Numerical simulations were conducted to study the characteristics of bandgaps (BGs) and vibration modes for each model. The finite element method (FEM) was used to illustrate the generation of BGs in low frequency ranges. The commercial finite element code COMSOL Multiphysics 5.4a was adopted to carry out the numerical analysis, utilizing the sound cone method and the strain energy method. Wide BGs were generated for the Bragg scattering BGs and local resonance BGs owing to the gradual variations in tree height and the addition of a vertical load in the form of mass to simulate the tree foliage. The results were promising and confirmed the applicability of FEM based on the parametric design language ANSYS 17.2 software to apply the boundary conditions of the proposed models at frequencies below 100 Hz. The effects of the mechanical properties of the six layers of soil and the geometric parameters of FMs were studied intensively. Unit cell layouts and an engineered configuration for arranging FMs based on periodic theory to achieve significant results in controlling ground vibrations, which are valuable for protecting a large number of structures or an entire city, are recommended. Prior to construction, protecting a region and exerting control over FM characteristics are advantageous. The results exhibited the effect of the 'trees' upper portion (e.g., leaves, crown, and lateral bulky branches) and the gradual change in tree height on the width and position of BGs, which refers to the attenuation mechanism. Low frequency ranges of less than 100 Hz were particularly well suited for attenuating SWs with FMs. However, an engineering method for a safe city construction should be proposed on the basis of the arrangement of urban trees to allow for the shielding of SWs in specific frequency ranges.