Basal reinforcement of embankments and supporting with piles is one of the most recent solutions for rapid embankment construction on soft foundation soils. This paper uses the Particle Image Velocimetry (PIV) to evaluate the performance of unreinforced and reinforced embankments over soft foundation soils in terms of maximum settlement at the embankment base, lateral displacements of the embankment toe and the strains in the reinforcement layer using the digital images captured during the centrifuge model tests at 40g. The reinforcement consisted of a single layer of a scaled-down model basal geogrid and additional support from end-bearing or floating piles. The paper examines the effect of varying embankment heights on the geogrid strains and deformation characteristics of subsoil under rapid embankment construction over unreinforced and reinforced soft foundation soil with varying support conditions. The unsupported reinforced embankments showed a peak geogrid axial strain near the toe, whereas it peaked near the mid- of the embankment for pile supported reinforced embankments. The study also investigates the failure mechanisms of unreinforced and reinforced embankments, with and without pile support, using shear strain contours derived from PIV analysis. The paper underscores the efficacy of PIV as a tool for visualising the deformation behaviour and failure mechanisms in soil during centrifuge model studies. Additionally, the research provides insights into the operation of an in-flight sand hopper used for embankment construction in centrifuge model studies. Post-investigation studies contribute to understanding the potential failure mechanisms in embankments supported by end-bearing and floating piles. Overall, this paper showcases the practical application of PIV in studying the challenges related to rapid embankment construction on soft foundation soils.

To reuse industrial solid wastes and waste clay with low liquid limit, a kind of soil solidification material by using cement, quicklime and industrial solid wastes such as ground granulated blast -furnace slag (GGBS), silica fume (SF) was developed in this study. Response surface methodology (RSM) based on central composite design (CCD) was used to design the experiment and optimize the mix ratio of GGBS, quicklime and SF under certain cement content conditions (i.e., the content ratio of cement, GGBS, quicklime, and SF was 5: 9.14: 1.7: 2.13). A soil solidification agent named O-QGS was developed to solidify waste clay with low liquid limit. To clarify the solidification mechanism of solidified soil, a series of laboratory experiments such as UCS test, water stability test, and scanning electron microscopy (SEM) test were carried out to capture the mechanical properties, water stability, and microstructure of O-QGS solidified soil and cement solidified soil. For practical purpose of O-QGS, a method for forming prefabricated pile by using O-QGS solidified soil was developed, and a method for strengthening soft foundations with prefabricated O-QGS solidified soil pile was proposed. Based on the results of load tests, the bearing capacity of prefabricated O-QGS solidified soil pile and cement high-pressure rotary jet grouting pile, as well as the composite foundations bearing capacity of prefabricated O-QGS solidified soil pile and cement high-pressure rotary jet grouting pile used for strengthening soft foundations, were analyzed. The feasibility of prefabricated O-QGS solidified soil pile used for strengthening soft foundations was verified in practice. The present study shows that the UCS of O-QGS solidified soil is 7.25 MPa at 28 days, and the water stability coefficient of O-QGS solidified soil is larger than 0.8. Compared with the method of cement highpressure rotary jet grouting pile to reinforce soft foundation, the bearing capacity of prefabricated O-QGS solidified soil pile to reinforce soft foundation is higher, and the cost can be saved by 22.4 %.

An integrated model that considers multiphysics is necessary to accurately analyze the time-dependent response of hydraulic structures on soft foundations. This study develops an integrated superstructure-foundation-backfills model and investigates the time-dependent displacement and stress of a lock head project on a soft foundation during the construction period. Finite element analyses are conducted, incorporating a transient thermal creep model for concrete and an elasto-plastic consolidation model for the soil. The modified Cam-clay model is employed to describe the elasto-plastic behavior of the soil. Subsequently, global sensitivity analyses are conducted to determine the relative importance of the model parameters on the system's response, using Garson's and partial derivative algorithms based on the backpropagation (BP) neural network. The results indicate that the integrated system exhibits pronounced time-dependent displacement and stress, with dangerous values appearing during specific periods. These values are easily neglected, highlighting the importance of integrated time-dependent analysis. Construction activities, particularly the backfilling process, could cause a sudden change in stress and significantly impact the stress redistribution of the superstructure. Additionally, the mechanical properties of concrete have a significant impact on the stress on the superstructure, while the mechanical properties of the soil control the settlement of the integrated system.