Moderate-size earthquakes, and the presence of water saturated soil in the near surface can trigger the liquefaction geohazard causing buildings to settle / tilt or collapse, damaging bridges, dams, and roads. A number of paleo-seismic research have focused on the Himalayan area as a potential site for liquefaction. The present study site is in the south of the tectonically active Himalayan foothills and lies in earthquake Seismic Zone III. Therefore, the region can experience earthquakes from nearby regions and can potentially damage civil infrastructures due to liquefaction. The objective of this paper is to determine the susceptibility of alluvial soil deposits to liquefaction for seismic hazard and risk mitigation. Liquefaction geohazard study of alluvial deposits was carried out using shear wave velocity (Vs) profiling. Preliminary assessment of the soil is made by building the average shear wave velocity map up to 30 m depth (Vs30) and by constructing the corrected shear wave velocity (V-s1) maps. It was observed from the Vs30 map that a major portion of the studied area lies in Site Class CD and only a small portion lies in Site Class D. Moreover, it is also noticed from the V(s1 )map that a smaller of the area has V(s1 )lower than the upper limit of V-s1(& lowast; )(215 m/s) below which liquefaction may occur. The region showing lower values of V(s1 )is further examined for liquefaction hazard as per the guidelines given by Andrus et al. (2004). Resistance of the soil to liquefaction, stated as cyclic resistance ratio (CRR), and the magnitude of cyclic loading on the soil induced by the earthquake shaking, stated as cyclic stress ratio (CSR) are computed for the area. Several maps of factor of safety (FS) for different depths are prepared by taking the ratio of CSR and CRR. When FS < 1, the soil is considered prone to liquefaction. Furthermore, susceptibility of soil to liquefaction against different peak horizontal ground surface acceleration (PHGSA) and varying depth of water table is also evaluated in terms of factor of safety. It is observed from this study that for lower levels of PHGSA (up to 0.175 g) the soil can be considered safe. However, the soil becomes more vulnerable to liquefaction when PHGSA is above 0.175 g and with rising water table. The comparison of the factor of safety (FS) obtained using the SPT-N method and the Vs-derived approach shows consistent results, with both methods confirming the absence of liquefaction in the studied soil layers.

This study aims to assess the effectiveness of inter-storey isolation structures in reducing seismic responses in super high-rise buildings, with a focus on analyzing the impact of soil-structure interaction (SSI) on the dynamic performance of the buildings. Utilizing the lumped parameter SR (Sway-Rocking) model, which separately simulates the overall displacement of the super high-rise structure and the rotational motion of the foundation, the dynamic characteristic parameters of the simplified model are derived. The natural frequencies of the system are calculated by solving the equations of motion. The study examines the influence of parameters such as soil shear wave velocity and structural damping ratio on the dynamic response of the structure, with particular emphasis on displacement transfer rates. The findings indicate that inter-storey isolation structures are highly effective in reducing displacement responses in super high-rise buildings, especially when considering SSI effects. Specifically, for high-damping inter-storey isolation structures, modal frequencies decrease as soil shear wave velocity decreases. In non-isolated structures, the damping ratio increases with decreasing soil shear wave velocity, whereas for isolated structures, the damping ratio decreases, with a more pronounced reduction at higher damping ratios. Increasing damping significantly reduces inter-storey displacement and damage indices. However, under low shear wave velocity conditions, inter-storey isolation structures may experience increased displacement and damage.

This paper proposes a performance-based damage assessment procedure for reinforced concrete (RC) box tunnels subjected to earthquakes, employing a pseudostatic approach and a ductility-based damage index that incorporates the relative stiffness between the structure and surround soil, widely denoted as flexibility ratio (F). Distributed plasticity frame elements and discretized spring elements were used to model tunnel structures (slabs, walls, and columns) and the reactions of surrounding soil, respectively. Two damage-state descriptors were investigated: one based on the number of yielding in the tunnel members and another on the material state. Results show that the number-of-yielding based descriptor captures global structural capacity only for specific F ranges, while drift ratio lacks consistency as a damage index across all F ranges. In contrast, the material-state descriptor and damage indexes based on curvature ductility provide effective capacity estimation and are independent of F. Therefore, combining both descriptors is recommended for seismic performance evaluation of RC box tunnels. Additionally, higher F leads to brittle failure due to better load distribution and increased yielding before the strength degradation, while lower F results in concentrated damage with less yielding. These findings highlight the necessity of seismic design considering flexibility ratio for earthquake-resistant tunnels.

The integration of industrial and biogenic waste materials in soil stabilization provides an environmentally sustainable alternative to conventional binders. This study evaluates the influence of mussel shell powder (MSP) on both untreated, cemented, and recycled soils, where the recycled soil was initially stabilized with calcium carbide residue, cured for one year, ground into powder, and then re-treated with MSP. Unconfined compression, ultrasonic pulse velocity, and direct shear tests were conducted to assess the strength, compaction, and shear behavior of MSP-stabilized pure, recycled, and cemented soils. The results indicate that MSP addition reduced plasticity and improved soil workability. In recycled soils, 5% MSP provided optimal strength enhancement, while in cemented soils, 20% MSP was required for significant strength gains due to its role in secondary cementation. Freeze-thaw tests demonstrated that MSP-treated soils exhibited up to a 40% reduction in strength loss compared to untreated samples, improving durability in cold climates. The ultrasonic pulse velocity measurements showed strong correlations with unconfined compressive strength, confirming its potential as a nondestructive assessment method for stabilized soils. These findings highlight the potential of MSP as a sustainable stabilizer for improving soil mechanical properties, durability, and resistance to freeze-thaw cycles.

Improving the fracture toughness of agricultural soil-engaging components can mitigate the detrimental effects of hard particles in the soil while maintaining the wear resistance of the components, thereby improving the service performance. The wear resistance of the parts can be improved by surface treatment, but the surface toughness after treatment still needs to be further improved. In this study, WC10Co4Cr@YSZ (Yttria Stabilized Zirconia) core-shell structured composite powder was synthesized by modifying commercial WC10Co4Cr powder using the sol-gel method, and WC10Co4Cr coatings were prepared using the powders before and after modification. The microstructure of the powder and coatings were characterized. The mechanical properties and wear resistance of the coatings were evaluated through microhardness, nanoindentation, and friction testing. The hardness of the YSZ-modified composite coating was comparable to that of the unmodified coating, yet it exhibited lower porosity and twice the fracture toughness. Wear test results indicated that the coating's wear loss was greatly reduced compared with the substrate. In addition, the wear rate of the YSZ-modified coating was 71.11 % lower than the unmodified coating, demonstrating its exceptional wear resistance. The findings show that incorporation of YSZ into the coating system further enhanced wear resistance. The strengthening mechanisms resulting from the YSZ inclusion include the pinning effect, which controls the size and distribution of the WC grains, the shell structure that prevents overheating, and the improved fracture toughness of the coating. This work provides a new way to extend the service time of agricultural soil-engaging components.

In this study, the role of zeolite and polyvinyl alcohol (PVA) fibers on the durability of cement-stabilized clayey sand soil under freeze-thaw and wet-dry cycles was investigated. Laboratory tests, including unconfined compressive strength (UCS), scanning electron microscope (SEM), and ultrasonic pulse velocity (UPV), were performed to evaluate the effect of zeolite replacement ratio and fiber content on the durability and mechanical characteristics of the stabilized soil. The results showed that the mechanical properties of cemented samples decreased significantly under wet-dry cycles compared to freeze-thaw cycles. The optimal zeolite replacement ratio to achieve the most appropriate durability behavior of cement-treated clayey sand was 20%. Compared to the unreinforced samples, the samples with 0.8% fibers showed a lower reduction in UCS and mass loss under wet-dry and freeze-thaw cycles. The reduction in UCS was limited to 13% and 15%, respectively. The mass loss was limited to 5.2%, which indicates the positive effect of fibers in improving the durability of soil. Samples containing zeolite and fibers had lower mass loss in wet-dry and freeze-thaw conditions than samples without zeolite and fibers. Finally, the SEM microstructural observations justified the results of the durability tests.

Geohazards such as slope failures and retaining wall collapses have been observed during thawing season, typically in early spring. These geohazards are often attributed to changes in the engineering properties of soil through changes in soil phase with moisture condition. This study investigates the impact of freezing and thawing on soil stiffness by addressing shear wave velocity (Vs) and compressional wave velocity (Vp). An experimental testing program with a temperature control system for freezing and thawing was prepared, and a series of bender and piezo disk element tests were conducted. The changes in Vs and Vp were evaluated across different phases: unfrozen to frozen; frozen to thawed; and unfrozen to thawed. Results indicated different patterns of changes in Vs and Vp during these transitions. Vs showed an 8% to 19% decrease for fully saturated soil after thawing, suggesting higher vulnerability to shear failure-related geohazards in thawing condition. Vp showed no notable change after thawing compared to initial unfrozen condition. Based on the test results in this study, correlation models for Vs and Vp with changes in soil phase of unfrozen, frozen, and thawed conditions were established. From computed tomography (CT) image analysis, it was shown that the decrease in Vs was attributed to changes in bulk volume and microscopic soil structure.

An experimental study was conducted to evaluate the effects of crumb rubber (CR) on mechanical properties of roller compacted concrete (RCC) for use in pavements. In the experiment, proportions of 0%, 10%, 20% and 30% by volume (vol) CR, were incorporated into RCC as sand replacement material. Mixtures were made at cement contents of 275 kg/m3 (11%) and 201 kg/m3 (8.6%). The water content quantities used to prepare RCC mixtures, were determined from the moisture-dry density relationship obtained based on the soil compaction approach. Various mechanical properties were measured comprising compressive strength, splitting tensile strength, ultrasonic pulse velocity, static and dynamic moduli of elasticity. Also measured were pore-related physical tests consisting of water absorption and volume of permeable pores. It was found that cement content has significant influence on the amount of CR that can be suitably utilized in RCC mixtures. The RCCs prepared at the adequate cement content of 275 kg/m3, exhibited suitable performance for all mixtures containing up to 20% vol CR content. Results showed that the standard relationships between compressive strength, static and elastic moduli as established for normal concretes, are also applicable to RCCs.

Stabilizing problematic soils with new materials can reduce environmental problems and improve mechanical properties. This research uses the results of various tests, such as unconfined compressive strength (UCS), indirect tensile strength (ITS), ultrasonic pulse velocity (UPV), direct shear test, and standard Proctor compaction, to evaluate the effect of curing time and the nano aluminum oxide contents on the mechanical and shear characteristics of clay soil stabilized with cement and nano aluminum oxide. This research showed that the optimal content of replacing cement with nano aluminum oxide to stabilize clay soil is 0.9% by weight of cement. Adding the optimal content of nano aluminum oxide to cement-stabilized clay soil increased UCS and ITS by 28% and 51%, respectively. Also, the drained internal friction angle and cohesion increased by 17 and 25%, respectively. The results of UPV non-destructive testing can also be used to predict the mechanical characteristics of stabilized clay. By reducing cement consumption and enhancing soil stabilization, this research contributes to Sustainable Development Goals (SDGs) by promoting resource efficiency, lowering environmental impact, and supporting durable infrastructure development.

Conventional triaxial apparatus has limited capabilities for advanced testing of frozen soils, such as loading under controlled temperature and volume change measurements. To bridge this gap, in this paper, we presented a novel ultrasound-integrated double-wall triaxial cell designed specifically for stress and strain-controlled, as well as temperature-controlled testing of frozen soils. Monitoring pore ice content during triaxial tests in frozen soils poses a significant challenge. To overcome this hurdle, we developed an in-cell ultrasonic P wave measurement setup, which was integrated into the triaxial device to monitor freeze advancement at any stage of the test. We proposed a three-phase poromechanics-based approach to estimate the pore ice content of frozen soil samples based on the P-wave velocity. A series of creep tests under different freezing temperatures have been undertaken for frozen soil samples to investigate the effect of ice content and temperature on the volumetric deformations of frozen soils during creep tests. Our study demonstrates the potential of the proposed ultrasound-integrated double-wall triaxial apparatus for creep tests of frozen soils.