A comprehensive series of tests, including dynamic triaxial, monotonic triaxial and unconfined compressive strength (UCS) tests, were carried out on reconstituted landfill waste material buried for over twenty years in a closed landfill site in Sydney, Australia. Waste materials collected from the landfill site were treated with varying percentages of cement, and both treated and untreated specimens were investigated to evaluate the influence of cement treatment. The study examined the dynamic properties of cement-treated landfill waste, including cumulative plastic deformation, resilient modulus, and damping ratio, and also analysed the impact of cyclic loading on post-cyclic shear strength in comparison to pre-cyclic shear strength. The UCS tests and monotonic triaxial tests demonstrated that untreated specimens subjected to monotonic loading exhibited a progressive increase in strength with rising axial strain, whereas cement-treated specimens reached a peak strength before experiencing a decline. During cyclic loading, with the inclusion of cement, a significant reduction in cumulative plastic deformation and damping ratio was observed, and this reduction was further enhanced with increasing cement content. Conversely, the resilient modulus showed substantial improvement with the addition of cement, and this enhancement was further amplified with increasing cement content. The formation of cementation bonds between particles curtails particle movement within the landfill waste material matrix and prevents interparticle sliding during cyclic loading, leading to lower plastic strains and damping ratio while increasing resilient modulus. Post-cyclic monotonic testing revealed that cyclic loading caused the partial breakage of the cementation bonds, resulting in reduced shear strength. This reduction was higher on samples treated with lower cement content. Overall, the findings of the research offer crucial insights into the possibility of cement-treated landfill waste as a railway subgrade, laying the groundwork for informed design decisions in developing transport infrastructure over closed landfill sites while using landfill waste materials available on site.

This research explores the use of cup lump rubber (CLR), an agricultural by-product, as a component in controlled low-strength material (CLSM) for pavement applications in road construction. Two distinct CLSM mixtures were developed: one based on cement and the other on alkali activation. The study evaluated the workability, mechanical properties, and microstructures of both CLSM formulations. Key fresh properties, including slump flow, setting time, and bleeding, were analysed to assess their impact on the self-compaction process. Mechanical characteristics such as unconfined compressive strength, resilient modulus, and wave velocities were also measured. Some CLSM mixtures, both cement-based and alkali-activated, were found to meet the requirements for soil cement bases and subbases. Notably, the resilient modulus values showed significant improvement after 28 days, with certain mixtures achieving subbase-quality gravel standards. The study concludes by recommending the use of both cement-based and alkali-activated CLSMs in pavement design, highlighting their potential to enhance the field of pavement engineering.

Offshore wind turbines (OWTs) are subjected to prolonged external loading, including loads induced by wave action. The soil undergoes bi-directional coupled shear, due to this low-frequency and long-duration loading, the cumulative deformation of the offshore foundation is observed to increase, which poses a threat to the functional reliability of the offshore wind turbines. The soil around the piles is distributed with clay layers. Due to the complex mechanical properties of clay, bi-directional cyclic loading tests are performed to research the drainageinduced deformation characteristics of clays in this paper. Based on these test results, the variation of hysteresis loops of stress-strain, resilient modulus, and the cumulative strain are found to exhibit a strong correlation with both the cyclic stress level and the confining pressure. The stress-strain hysteresis loops and resilient modulus have significantly different trends at higher or lower cyclic stress levels. Then an empirical model that uniformly reflects the strain-hardening and softening characteristics, and an empirical model reflects the characteristics of cumulative strain development in soils is established. Finally, the performance of the permanent cumulative strain prediction model is assessed based on the in-situ test findings from the clay foundation.

Sodium hydroxide (NaOH)-sodium silicate-GGBS (ground granulated blast furnace slag) effectively stabilises sulfate-bearing soils by controlling swelling and enhancing strength. However, its dynamic behaviour under cyclic loading remains poorly understood. This study employed GGBS activated by sodium silicate and sodium hydroxide to stabilise sulfate-bearing soils. The dynamic mechanical properties, mineralogy, and microstructure were investigated. The results showed that the permanent strain (epsilon(p)) of sodium hydroxide-sodium silicate-GGBS-stabilised soil, with a ratio of sodium silicate to GGBS ranging from 1:9 to 3:7 after soaking (0.74%-1.3%), was lower than that of soil stabilised with cement after soaking (2.06%). The resilient modulus (E-d) and energy dissipation (W) of sodium hydroxide-sodium silicate-GGBS-stabilised soil did not change as the ratio of sodium silicate to GGBS increased. Compared to cement (E-d = 2.58 MPa, W = 19.96 kJ/m(3)), sulfate-bearing soil stabilised with sodium hydroxide-sodium silicate-GGBS exhibited better E-d (4.84 MPa) and lower W (15.93 kJ/m(3)) at a ratio of sodium silicate to GGBS of 2:8. Ettringite was absent in sodium hydroxide-sodium silicate-GGBS-stabilised soils but dominated pore spaces in cement-stabilised soil after soaking. Microscopic defects caused by soil swelling were observed through microscopic analysis, which had a significant negative impact on the dynamic mechanical properties of sulfate-bearing soils. This affected the application of sulfate-bearing soil in geotechnical engineering.

Soil suction and the degree of saturation influence the resilient modulus, which should be considered when designing road and railway foundations. To reasonably account for these factors, a suction stress model incorporating both suction and degree of saturation was established for application in transportation design. In this study, the suction stress was considered by categorizing water into bulk and meniscus water and applying cyclic loading to the samples. The soil water characteristic curve (SWCC) was generated using discrete element method (DEM) analysis. Additionally, the resilient modulus was observed to vary with both deviator stress and the degree of saturation. The trends observed in this study are consistent with the results of laboratory tests conducted by other researchers. These findings demonstrated that the water division and cyclic loading algorithm effectively represented the unsaturated soil state. Furthermore, DEM analysis revealed that the suction stress was influenced the resilient modulus, with the resilient modulus increasing as suction stress increased.

Moisture intrusion into the subgrade can significantly increase its moisture content, leading to a decrease in stiffness and strength, thereby compromising the serviceability performance of the pavement. Electro-osmosis has been used as an effective method for reducing moisture content and improving subgrade mechanical properties. However, its impact on mechanical properties has not been well understood. This study evaluated the mechanical behavior of electro-osmosis-treated subgrade soil through laboratory experiments that included bender element and cyclic triaxial tests. The study analyzed the effects of supply voltage and soil compaction degree on electro-osmosis treatment. The results showed that after treatment, the shear wave velocity increased by 26.0 to 59.2%, and the dynamic resilient modulus improved by a factor of three. Increasing the supply voltage and degree of compaction was found to lead to more significant improvements. Further analysis revealed that the reduction in moisture content alone was insufficient to contribute to the improvement. Cementation of colloids generated by the electrochemical reaction between soil particles also contributed to the improvement. It is worth noting that the nonuniform distribution of moisture and colloid in electro-osmosis-treated soils resulted in heterogeneity, with soil close to the anode being the weakest in terms of mechanical strength. Chemical injection or polarity reversal was suggested to enhance the uniformity of distribution and improve the overall treatment effectiveness. Overall, the study highlights the potential of electro-osmosis as a viable method for improving the mechanical properties of subgrade soil, but further research is required to investigate the heterogeneity of the distribution of moisture and colloid.

The premature failure or early deterioration of mine haul roads due to increasing problems of overrutting, potholes, and excessive settlement is a major issue. These problems mainly arise from the mismatch of overburden soil strength and stresses exerted by moving dumpers, inadequate compaction of soil, and improper assessment of the load-deformation characteristics of overburden soil under repeated loading. In the past, several research studies have been conducted; however, most of the studies are related to the geotechnical characterization and stabilization of mine overburden soil. In this study, the deformation characteristics, i.e., plastic and resilient deformations, of an overburden soil extracted during mining operations have been addressed, taking into account the influence of varying compaction densities, cyclic deviatoric stress, and loading frequencies. Compaction density notably affects soil strength, with 5.82% and 16.4% increases in density resulting in 23%-48% and 297%-410% strength gains, respectively. Meanwhile, cyclic deviatoric stress and confining pressure primarily influenced the axial strain behavior of mine overburden soil subjected to cyclic loading. At higher compaction densities, higher resilient modulus values were obtained. For a confining pressure of 48 kPa, increases of 5.82% and 16.4% in compaction density resulted in an increase in the resilient modulus by 32.6%-48.9%, 36.5%-67.6%, and 73%-201.3%, for increasing levels of cyclic deviatoric stress. The plastic deformations obtained were also notably high. Thus, mine overburden soils with high resilient modulus values can still experience premature failure, owing to the significant accumulation of plastic strain under high repeated deviatoric stresses. From the analysis of test results, three-parameter strain models have also been developed as a function of the number of load repetitions and the applied cyclic deviatoric stress to predict the rutting phenomenon in overburden soil at different compaction densities, applied cyclic deviatoric loads, and loading frequencies.

This study investigates the evolution of the dynamic characteristics of a solidified dredge sludge, including the resilient modulus (MR), accumulative plastic strain (epsilon p) and damping ratio (lambda) during long-term traffic loadings considering influences of environmental actions (dry-wet, DW, and freeze-thaw, FT cycles), stress states (confining stress sigma cand deviator stress sigma d) and loading frequency (f). The experimental results indicate that the dynamic characteristics continuously change with increasing loading cycles and the influences of environmental actions, external stress state, and loading frequency are coupled. The resistance of the solidified sludge against traffic loading decreases after both DW and FT cycles, which is manifested by the decrease in the MR and the increase in the lambda and epsilon p. DW cycles induce greater reductions in the dynamic characteristics than the FT cycles. The increasing sigma c improves the resistance of the soil against cyclic loadings, resulting in higher MR and lower epsilon p and lambda. Besides, their rates of change with loading cycles (i.e., delta MR, delta epsilon p and delta lambda) reduce. The MR, epsilon p, lambda, and delta ap increase while the delta MR and delta lambda decrease with the sigma d, indicating that the increase in the cyclic loading level contributes to the accumulation of plastic strain and energy assumption while the resultant densification effect leads to the increase in the MR and decrease in the delta MR and delta lambda. The soil dissipates less energy when loaded under higher f, resulting in higher MR and lower epsilon p and lambda. Results reported in this paper are helpful for better understanding the dynamic responses of solidified sludge under complex loading and environmental conditions.

In cold regions, the performance, safety, and serviceability of engineering facilities overlying on freeze- thaw susceptible soils are being compromised to varying degrees due to the alternate seasonal freezing and thawing cycles (FTCs). FTCs induce temporary and permanent microstructural deterioration of the underlying soils, especially fine-grained soils. In this study, we investigate the shear strength and stiffness behavior of low-compressibility silt subjected to alternate FTCs. Four series (S1 to S4) of unconsolidated undrained triaxial compression tests were performed on moist tamped solid cylindrical soil specimens. The specimens were prepared at four compaction states by changing dry unit weight and moisture content. At each compaction state, unfrozen (normal) specimens and specimens subjected to different number of FTCs were tested at total confining pressures ( 63 ) of 100 kPa, 200 kPa, and 300 kPa. At lower moisture content and increased 63, strain-hardening behavior was more obvious in the stress- strain response. The strain-hardening behavior was subdued with the number of FTCs. Higher moisture content and lower dry unit weight make the silt susceptible to frost action and thaw weakening. Percentage reduction in peak shear strength ranged from 20 to 32% for specimens subjected to 16 FTCs in S1 and S2, 8 FTCs in S3, and 04 FTCs in S4. The reduction in resilient modulus ( MR) with the number of FTCs ranged from 2 to 48% for the four compaction states. The reduction in apparent cohesion value was in the range of 23-64%. After an initial decrease in the range of 16-59%, the angle of internal friction showed a net increase in the range of 8-142%. The current study reveals that low- compressibility silt is susceptible to frost action and thaw weakening. The results show that the S4 with the highest moisture content and void ratio (lowest dry unit weight) aggravates the frost action in the soil.

With continuous increasing of mining activities, some problems, such as environmental issues, occupy a lot of space, and the risks caused by the instability of mine waste depots are far occurred than ever. One possible way to reduce mentioned problems is to stabilize and reuse mine wastes as road construction materials. On the other hand, the most significant parameter for pavement design, either using empirical or mechanistic-empirical methods, is the resilient modulus (Mr) of road materials, which shows the influence of repetitive loading on the stress-strain behavior of materials. To obtain iron ores, it is required to remove the soil resting on the iron ore storage in deeper layers. This soil is typically in the form of alluvium and is known as mine overburdens (MOs). In this study, after identification of the geotechnical characteristics of two types of MO of the Golgohar mine in Sirjan, Iran, these materials were stabilized by using three different percentages of Portland cement (5, 7, and 9%) and were cured for 7 and 28 days, respectively and the resilient modulus were measured using repetitive triaxial loading equipment at different stress levels. Results show that cement stabilization does not enhance the Mr significantly when bulk stress or confining pressure is low. As the bulk stress or confining pressure increase, the Mr of cement-stabilized MOs increases significantly compared to raw MOs. Another justification is that the Mr of cement-stabilized MOs is a function of bulk stress, and deviatoric stress has a negligible effect on the Mr. The comparison between different nonlinear models revealed that the 'Universal' model has the best fit with the measured Mr values of raw and stabilized MOs.