Geosynthetic-reinforced column-supported (GRCS) embankments have increasingly been used in the recent years for accelerated construction. Numerical analyses have been conducted to improve understanding and knowledge of this complicated embankment system. However, most studies so far have been focused on its short-term or long-term behavior by assuming an undrained or drained condition, which does not consider water flow in saturated soft soil (i.e., consolidation). As a result, very limited attention has been paid to a settlement-time relationship especially postconstruction settlement, which is critical to performance of pavements on embankments or connection between approach embankments and bridge abutments. To investigate the time-dependent behavior, coupled two-dimensional mechanical and hydraulic numerical modeling was conducted in this study to analyze a well-instrumented geotextile-reinforced deep mixed column-supported embankment in Hertsby, Finland. In the mechanical modeling, soils and DM columns were modeled as elastic-plastic materials and a geotextile layer was modeled using cable elements. In the hydraulic modeling, water flow was modeled to simulate generation and dissipation of excess pore water pressures during and after the construction of the embankment. The numerical results with or without modeling water flow were compared with the field data. In addition, parametric studies were conducted to further examine the effects of geosynthetic stiffness, column modulus, and average staged construction rate on the postconstruction settlement and the tension in the geosynthetic reinforcement.

The curing of soil specimens treated with a liquid polymer soil stabilizer of styrene acrylic family was studied through an extensive laboratory testing program. First, the effect of different curing environments including air, water and heating on the unconfined compressive strength (UCS) of stabilized sand was studied to identify suitable curing environments. Furthermore, a parametric study was conducted through which the liquid content of the specimens (i.e., polymer + water) was varied and the overall performance of treated specimens of sand and sulfate-rich high plasticity clay was assessed. The optimally treated specimens (i.e., with the best curing environment and optimal stabilizer dosage) were evaluated for their (1) short-term performance, (2) swelling potentials of treated high plasticity clay, and (3) durability after 24 wet–dry or freeze–thaw cycles. The results suggested that heating can significantly expedite the curing; conversely, soaking the specimens in water showed a detrimental effect in terms of the resultant strength. The strongest specimens were achieved when no extra water in addition to the liquid stabilizer was added when treating the soil. As to clay, the liquid polymer showcased excellent performance in reducing the swelling potential but the strength of the specimens was highly decreased by to moisture and freeze–thaw cycles.

A geothermal energy pile is a revolutionary piling technique that combines a pile foundation with a ground source heat pump system that not only supports the structure but also provides heating and cooling for buildings and bridges. The thermo-mechanical behavior of long energy piles in soft clay has rarely been investigated, despite their increasing utilization. A long floating energy pile with a length-to-diameter ratio of 66.7 was evaluated on its own and monitored in service of the supported structure in the city of Kunshan, China. With vertical mechanical loads, the experiment involved alternate cooling and heating cycles, allowing for careful analysis and assessment of the pile’s temperature, stress, and displacement. Temperature-induced stress, axial force, and friction resistance of the pile shaft, as well as the change in displacement of the energy pile throughout building, were all studied. The field observations revealed without any surprise that a longer energy pile outperformed a shorter one in terms of heating exchange capacity with a more homogenous temperature distribution along the pile. Following a quasi-linear relationship with the temperature variation, the thermo-induced additional axial force soared with the larger length-diameter ratio of the pile and may even reach four times that of the pile under pure mechanical loads. Important additional settlements were also observed especially in cooling conditions. The shaft frictions along the long bored energy pile were found to have a complicated distribution, which requires further investigations.

Lignin is a natural copolymer found in plants that is a major waste from bioenergy and paper industries. In this study, comprehensive laboratory testing programs were carried out to evaluate the strength improvements and water resistance of soil after being stabilized by lignin and polymerized lignin. The chemical polymerization of pre-treated lignin involves a process of linking short lignin molecules to form longer ones and consuming hydrophilic functional groups to improve its stability under wet conditions. Various testing combinations were considered, including four lignin or polymerized lignin contents (0, 6, 8, and 10 %) and four lime contents (0, 2, 4, and 6 %). The results show that lignin-stabilized soil will take at least 14 days to reach maximum strength, whereas the minimum curing period is 21 days for soil stabilized with polymerized lignin. The optimum dosage is 8 % when lignin or polymerized lignin is used for soil stabilization. Polymerized lignin can provide approximately 10 to 20 % more strength improvement than lignin; however, lime seems work better with lignin than polymerized lignin when added as a strength booster. The water soaking tests showed that polymerized lignin has better moisture resistance than lignin, and additional lime can further improve the performance of stabilized soil with respect to water susceptibility. However, the strength of specimens cannot fully recover, decreasing slightly after each dry–wet cycle for both specimens treated by lignin and polymerized lignin. The total decrease is about 5∼10 % after two cycles. The temperature and pH value control and oxygen supply approach used in this study will be an important reference for future studies.