With the rapid development of infrastructure in western China, numerous arch bridges have been constructed as vital transportation hubs spanning river canyons. Understanding the impact of canyon topography on the seismic response of long-span half-through arch bridges crossing canyons is essential. This study first establishes a seismic input method for oblique P-wave and SV-wave incidence, based on the viscous-spring artificial boundary theory, which transforms ground motions into equivalent nodal loads on artificial boundaries. The feasibility of this proposed method is systematically validated. Subsequently, parametric investigations are carried out to explore the effects of seismic wave incidence angle, canyon depth-to-breadth ratio and soil elastic modulus on the ground motion amplification characteristics in V-shaped canyons under oblique P-wave and SV-wave excitations. Finally, dynamic response patterns of the arch ribs and the stress-strain relationships at critical structural components are thoroughly analyzed. Key findings reveal that SV-waves induce significantly different ground motion amplification effects compared to P-waves, with the wave incidence angle and canyon width-to-depth ratio being crucial influencing factors. The connection between the arch footings and the concrete cross braces constitutes the most vulnerable region, frequently exhibiting maximum stresses that exceed the yield strength of C40 concrete under multiple scenarios. Notably, when the depth-to-breadth ratio (D/B) is 0.75, the peak stress at the arch footings reaches 5.18 x 10(7)kPa, surpassing the yield stress threshold of C40 concrete. These findings highlight the need for special seismic fortification measures at these critical connections during bridge design. This research offers valuable insights into the seismic design of long-span arch bridges in complex topographic conditions.

Previous earthquakes reveal that the sedimentary V-shaped canyon (SVC) may result in severe damage of canyon-crossing bridges (CCBs). The seismic response of CCB is affected by various parameters, including sedimentary soil characteristics and fault rupture mechanisms. However, these influential parameters of SVC on the seismic response of CCB have not been sufficiently studied in the existing literature. Thus, this study aims to identify the most influential factor on the seismic response of bridges across SVC using parametric analysis. For this purpose, the spectral element method (SEM) is adopted to simulate the wavefield of SVC considering the fault dynamic rupture. The characteristics of ground motions in the Forward region (FR) and the Middle region (MR) are investigated. The sensitivity of ground motions recorded in SVC to four main influential factors (i.e. shear wave velocity of sedimentary soil Vs, the ratio of sedimentary soil depth to canyon depth d/D, layer sequence O, and fault-to-canyon distance Rrup) is numerically evaluated. Furthermore, the parametric analysis is performed to estimate the impact of these influential parameters on the seismic response of a CCB. The results reveal that the amplitudes of pulse-type ground motions in the illuminated side of SVC increase with the decrease of Vs. As the Vs decreases from 2300 m/s to 400 m/s, the residual deformations of four bearings increase by 293 %, 93 %, 451 %, and 292 %, respectively. When the d/D is 0.3, the velocity pulse ground motions in SVC have the largest PGVs. The base shear of the piers in the case of d/D = 0.3 increases by more than 77.3 % compared to that without considering the sedimentary soil (d/D = 0). The inverted sequence may result in larger seismic responses of bearings and piers compared to normal sequence. Rrup has the most significant effect on the seismic response of CCBs. The higher-order effect and additional plastic hinges are more noticeable when Rrup is less than or equal to 7.5 km.

This work explores the development of a renewable, carbon-neutral, light-colored UV-shielding film to protect photosensitive pesticides from solar radiation, as these chemicals are easily degraded under UV light, substantially reducing their efficiency and causing soil and water pollution. The abundant benzene rings in lignin and phenolic hydroxyls in tannin boosted the co-self-assembly of lignin and tannin into composite nanospheres by the simultaneous pi-pi stacking and H-bonding interactions between these two biopolymers. These lignin-tannin (LT) composite nanoparticles were used as natural UV-shielding additives to coat a poly-vinyl-alcohol (PVA) film, endowing the PVA-LT film with an excellent UV-shielding ability (>95 % efficiency) due to the strong pi-pi stacking and concentrated phenolic hydroxyls. Typical photosensitive pesticides covered with the PVA-LT film significantly increased their remaining rate by 1.5 times compared to those under the uncoated film. Besides, intensive intermolecular hydrogen bonds were generated between PVA and the abundant phenolic hydroxyl groups exposed on the hydrophilic shell of the LT coating, enhancing the mechanical properties and water vapor retention of the composite film. Our biodegradable composite film derived from natural plant extracts not only protected photosensitive pesticides from UV irradiation but also allowed the transmission of visible light to guarantee the photosynthesis process of crops.

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.

The waterfront sheet -pile wall, retaining the saturated backfill, is susceptible to seismic damage due to the unbalanced forces between the backfill and toefill sides. In light of this concern, three dynamic centrifuge model tests were conducted at Zhejiang University under the framework of LEAP-RPI-2020. The centrifuge models, consisting of a dense layer and an overlying medium -dense layer, were fully saturated and retained by a cantilevered sheet -pile wall. This study aims to elucidate the dynamic responses of this soil -wall system subjected to varying shaking intensities, including acceleration responses, excess pore pressure ratios (r(u)) and shear strains in model soils, ground deformations and wall rotation. The results provide valuable insights into the liquefaction responses of the soil under mild to severe rotation of the sheet -pile wall. The mechanism of flow liquefaction triggered with r(u) < 1 was revealed by cyclic triaxial tests, which is defined as fluidization in this study. It qualitatively explains the phenomenon that the peak r(u) cannot reach unity in the vicinity of sheet -pile wall within the backfill. Furthermore, the efficacy of V-s -based liquefaction characterization model was examined in the saturated backfill, and the discrepancies mainly resulted from (1) the ignorance of fluidization in the traditional liquefaction criteria (i.e., r(u) = 1); and (2) an overestimation of the cyclic shear stresses in soils adjacent to sheet -pile wall.