There has been a growing interest in controlled low strength material CLSM due to its engineering features, such as self-leveling and early strength development, as well as it potential for utilizing industrial waste. Still, the dynamic properties on CLSM are rarely studied. This study evaluates the feasibility of red mud as a partial aggregate replacement in foamed-lightweight CLSM, incorporating high-carbon fly ash and preformed foam. We varied both the red mud contents RMc and foam volume ratio FVR within the mixtures and examined their impact on unconfined compressive strength and dynamic properties including shear modulus G and damping ratio D. The results reveal that the red mud enhances foam stability, leading to more uniform pore structures and increased porosity, which reduces bulk densities. Despite higher porosity, red mud serves as a strong alkaline activator, enhancing geopolymer reactions of high-carbon fly ash and thereby increasing both compressive strength and initial shear modulus G0. Interestingly, increasing FVR had minimal impact on the D, while higher RMcnotably increased D, highlighting its distinct role in energy dissipation. The red mud-incorporated foamed CLSM exhibits strain-dependent normalized shear modulus G/G0 comparable to that of gravel, while its D is 40-100 % higher than gravel or gravelly soil at shear strain of 1.10-5, which corresponds to typical traffic-induced vibration levels. Moreover, theoretical volumetric-gravimetric relationships are introduced to account for the combined effects of FVR and RMcon CLSM behavior. These findings demonstrate that the red mud included foamed CLSM can be utilized as advanced structural backfill material capable of effectively mitigating the vibrations induced by traffic, low-amplitude seismic events, and mechanical sources.

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.

Soil-pile interaction damping plays a crucial role in reducing wind turbine loads and fatigue damage in monopile foundations, thus aiding in the optimized design of offshore wind structures and lowering construction and installation costs. Investigating the damping properties at the element level is essential for studying monopole-soil damping. Given the widespread distribution of silty clay in China's seas, it is vital to conduct targeted studies on its damping characteristics. The damping ratio across the entire strain range is measured using a combination of resonant column and cyclic simple shear tests, with the results compared to predictions from widely used empirical models. The results indicate that the damping ratio-strain curve for silty clay remains S-shaped, with similar properties observed between overconsolidated and normally consolidated silty clay. While empirical models accurately predict the damping ratio at low strain levels, they tend to overestimate it at medium-to-high strain levels. This discrepancy should be considered when using empirical models in the absence of experimental data for engineering applications. The results in this study are significant for offshore wind earthquake engineering and structural optimization.

In this study, a series of resonant column tests was conducted to measure the shear modulus of sand-rubber mixtures at small strain amplitudes (i.e. between 10(-4)% and 10(-2)%), considering different rubber percentages and confining stress levels. The results were then combined with data obtained by dynamic hollow cylinder tests to investigate shear modulus degradation of the mixtures over a wider shear strain range. Based on the test results, a new expression was proposed to improve the prediction of maximum shear modulus of sand-rubber mixtures using the modified equivalent void ratio concept. A new constitutive model was also developed for estimation of strain-dependent shear modulus of the mixtures based on the modified hyperbolic framework. The shear modulus of the mixtures was found to be a function of rubber percentage, confining stress, the modified equivalent void ratio and the relative shear stiffness of rubber and sand. The experimental data and the developed models showed that the shear modulus decreased with rubber percentage and increased with confining stress. Moreover, the reference shear strain of the modified hyperbolic model increased with both rubber percentage and confining stress while its curvature coefficient increased more considerably with rubber percentage compared to the confining stress.

Coral sand is characterized by low cohesion and high porosity, posing a potential liquefaction risk. Thus, coral sand stabilization is necessary in coastal construction projects. Polyurethane, with its excellent toughness, rapid reaction speed, and strong adhesive properties, is an ideal choice for reinforcing coral sand. However, the diffusion range of non-water reacting foamed polyurethane in coral sand is limited. This study explored the use of water-reacting polyurethane (PRP) to solidify coral sand. PRP is known for its high permeability and bonding strength. Despite its potential, the dynamic mechanical properties and reinforcing mechanism of PRP-solidified coral sand, which are crucial for site seismic analysis and seismic design, have not yet been fully understood. Thus, the resonance column and uniaxial compression tests were conducted to investigate the variations in dynamic shear strain, dynamic shear modulus, damping ratio, and uniaxial compressive strength of the solidified material under different confining pressures, PRP incorporation ratios, and mass moisture contents of coral sand. To further investigate the underlying mechanisms of the variations in its mechanical properties, scanning electron microscopy (SEM) and mercury intrusion tests were conducted to analyze the morphology and pore characteristics of the PRP-solidified material. The results show that, at a constant moisture content, increasing the PRP proportion enhanced the dynamic shear modulus, damping ratio, and uniaxial compressive strength of the coral sand. However, excess moisture content reduced these properties. The pore ratio decreased with the increase of PRP and moisture content, with a larger reduction before drying and a smaller one after drying. The tortuosity of the specimens was mainly affected by the incorporation ratio of PRP, which increased with the increase of the incorporation ratio. However, the moisture content of coral sand had a fewer effect on the tortuosity. The permeability gradually decreased with the increase of the PRP incorporation ratio and the moisture content of coral sand. PRP strengthened the coral sand, primarily through its covering, filling, and bonding effects, enhancing the friction and mechanical occlusion. These findings are significant for the applications of PRP in future coastal engineering projects.

This study investigated the small-strain dynamic properties of expanded polystyrene (EPS) lightweight soil (ELS), a low-density geosynthetic material used to stabilize slopes and alleviate the subgrade settlement of soft soil. Resonant column tests were conducted to evaluate the effects of EPS's granule content (20-60%), confining pressures (50 kPa, 100 kPa, and 200 kPa), and curing ages (3 days, 7 days, and 28 days) on the dynamic shear modulus (G) of ELS within a small strain range (10-6-10-4). The results indicate that ELS exhibits a high dynamic shear modulus under small strains, which increases with higher confining pressure and longer curing age but decreases with an increasing EPS granule content and dynamic shear strain, leading to mechanical property deterioration and structural degradation. The maximum shear modulus (Gmax) ranges from 64 MPa to 280 MPa, with a 60% reduction in Gmax observed as the EPS granule content increases and increases by 11% and 55% with higher confining pressure and longer curing ages, respectively. A damage model incorporating the EPS granule content (aE) and confining pressure (P) was established, effectively describing the attenuation behavior of G in ELS under small strains with higher accuracy than the Hardin-Drnevich model. This study also developed an engineering testing experiment that integrates materials science, soil mechanics, and environmental protection principles, enhancing students' interdisciplinary knowledge, innovation, and practical skills with implications for engineering construction, environmental protection, and experimental education.

In this research, we look at the variation of cross anisotropy as a result of the application of vacuum-assisted consolidation in very soft clays that underlie a trial embankment that was built at a site in the former Texcoco Lake, some 11 km north-east of central Mexico City. Cross-anisotropy was evaluated by referring to the cross-anisotropy index, VSH/VSV. It was used shear waves propagated horizontally (VSH) from cross-hole tests, and shear waves transmitted vertically (VSV) from seismic dilatometer and suspension logging tests. These tests were performed two months after the vacuum pumps were shut down thus, the changes induced by the vacuum-assisted consolidation of soil properties were observed from the shear wave velocities measurement. Moreover, the VSH/VSV ratio was evaluated from resonant column tests performed on soil specimens retrieved from a site near the trial embankment. These samples were trimmed horizontally and vertically and tested in the resonant column device. Field and laboratory test results showed that cross-anisotropy of the studied soft lacustrine soils is barely affected by the stress state variation induced by vacuum-assisted consolidation or by loading direction, as observed in the resonant column tests. Laboratory tests also showed that the VSH/VSV is related to the liquidity index through an empirical equation that can be used to estimate fairly well field values of VSH/VSV.

In this paper, the resonant column tests were utilized to examine the small-strain stiffness and attenuation of clay-gravel mixture (CGM) under various effective consolidation pressures and freeze-thaw cycles, on the basis of investigating the electrical resistivity variation trend of CGM samples undergoing various freeze-thaw cycles. It is shown that the resistivity of CGM tends to stabilize when the freeze-thaw cycles (N) reach 9, and, thus, the samples after 0, 3, 6, 9, and 12 cycles were selected for resonance column testing. The results show that, once N > 9, the decay in dynamic shear modulus demonstrates a weakened association with Nand the stiffness degradation effect of freezing-thawing would be weakened and inhibited by high effective consolidation stress. Additionally, a mathematical model was constructed to predict the maximum dynamic shear modulus (Gmax) in the basis of freeze-thaw cycles and effective consolidation stress. Microscopic analysis results suggest that the freeze-thaw effect on CGM lies in the development of soil aggregates and porosity variation within the fine-grained soil. Compared to gravel soils and frozen soil, the cementation of matrix soil and the effect of blocky structure are considered as fundamental reasons for the improved small-strain stiffness and reduced vulnerability to freeze-thaw cycles of CGM.

Biocemented soils present a promising sustainable alternative to traditional Portland cement and asphalt in road embankment construction and remediation. However, the cyclic loading experienced by transportation infrastructures like roads over extended periods explicitly leads to performance degradation. Biocementation, achieved through Microbially Induced Calcite Precipitation (MICP) using ureolytic bacteria or Enzyme-Induced Calcite Precipitation (EICP) with urease enzymes, precipitates calcium carbonate (calcite) as a bonding agent within the soil matrix. Despite the environmental appeal of biocemented soils, their durability under cyclic and repeatable loads remains relatively unexplored. This paper investigates the modulus degradation of biocemented sand subjected to cyclic loading, considering various strain amplitudes and confinement levels. The experimental program involves subjecting two distinct specimens-one uncemented and the other cemented-to three confinement levels (50, 100, and 200 kPa). Each specimen undergoes incremental torque amplitudes to elucidate stiffness behavior across a spectrum of strain levels. Additionally, resilient modulus estimates are obtained for different strain levels, and a critical strain threshold is identified. The primary objective of this research is to unveil fatigue susceptibility criteria, offering crucial insights into the performance of biocemented soils. By doing so, this study contributes to the advancement of sustainable and durable infrastructural solutions, particularly in the context of road construction and maintenance.

In geotechnical engineering, the small-strain shear modulus and its attenuation characteristics are pivotal for analyzing and evaluating soil vibration responses to various engineering construction projects. This study conducts the resonant column test on undisturbed fissured clay samples, exploring the impacts of fissure inclination and confining pressure on the shear modulus in small-strain range. Results indicated that the shear modulus and its attenuation behavior in undisturbed fissured clay are substantially affected by both the fissure inclination angle and the confining pressure. With constant confining pressure, the shear modulus increases as the fissure inclination angle grows, reaching its maximum value at a fissure angle of 90 degrees. In addition, as the confining pressure rises, there is a notable increase in the shear modulus and a corresponding reduction in the decay rate. Through the threshold strain, the elastic deformation of the specimen increases as the fissure inclination angle increases, and the confining pressure increases the ability of the fissured soil to deform at small strains elastically. Based on the acquired data, this research analyzes the relationship between the fitting parameters A and N and the fissure angle in the context of the Harding-Drnevich formula. Consequently, a mathematical model based on the fissure inclination angle and the effective confining stress was established to predict the maximum dynamic shear modulus (Gmax) and decay attributes of undisturbed fissured clay. Additionally, the study offers a comparative analysis of the maximum shear modulus and its attenuation features in clay with varied degrees of fissure development. The stiffness anisotropy is related to the orientation of particles and the normalized decay rate of the fissured clay has a certain relationship with the fissure density.