Aiming at the problem of serious soil cracking during electro-osmosis stage in the treatment of dredged slurry by vacuum pre-loading in combination with electro-osmosis method, this study proposes a new vacuum pre-loading method in combination with electro-osmosis and with dynamic compaction to overcome these drawbacks. Meanwhile, different current ratios are used to characterise the different activation times of the dynamic compaction to achieve the optimal activation time. Five laboratory tests were performed on dredged slurry in self-made plexiglass model bucket, and the electric current, drainage of soil, soil surface settlement and vane shear strength, etc. in the reinforcement of dredged were monitored. The test results show that the combined action of the vacuum pre-loading, electro-osmosis, and dynamic compaction process enhances the circuit current, improves the efficiency of the electro-osmotic drainage, and thus promotes the drainage of the soil and ultimately yields a better reinforcement effect. Meanwhile, the dynamic compaction process effectively reduces the energy consumption in the process of vacuum pre-loading combined with electro-osmosis. In addition, the optimal effect owing to the dredged slurry can be evoked when the dynamic compaction is activated in the middle stage of the electro-osmosis process.

To investigate the interface shear characteristics between various geosynthetics and recycled concrete aggregate (RCA), 30 large‐scale monotonic direct shear tests were conducted. The main work was to analyse the effect of a biaxial polypropylene geogrid, a glass fiber geogrid, a warp‐knitted polyester geogrid, a woven geotextile, and geonet on the interface shear properties of RCA. The test results show that adding a biaxial polypropylene geogrid or a geonet to RCA can improve its interface shear strength. The inclusion of glass fiber geogrids, warp‐knitted polyester geogrids, and woven geotextiles decrease the interface shear strength of RCA. The reinforcing RCA with geosynthetics can effectively suppress its shear dilation, and the change in internal friction angle is consistent with the change law of the material interface enhancement coefficient. Finally, the aperture size of a geogrid has a significant effect on the mechanical properties of the geogrid‐RCA interface. The interface shear strength increases first and then decreases with an increase in the ratio between aperture size and median particle diameter. It is concluded that there is an optimal range of aperture ratio between a geogrid and RCA.

To address the issue of uneven shear strength distribution in dredged sediment during electroosmosis treatment, a grouting system was employed to inject CaCl₂ into the anode region and Na₂SiO₃ solution into the central region. An experimental study was conducted to examine the effect of injection timing on the electrochemical treatment of dredged sediment. Five experimental groups, each with different Na₂SiO₃ injection timings, were established. The impact of injection timing on the macroscopic electrochemical reinforcement was assessed based on current, drainage volume, settlement, moisture content, and shear strength. Additionally, the ion concentration of effluent from the cathode was measured, and scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) were employed to analyze ion migration and pore characteristics. The results indicated that when CaCl₂ was injected into the anode at the start of the experiment and Na₂SiO₃ was injected into the central region after the current had decayed by 70% from its peak, the drainage volume reached its maximum. Under these conditions, the average shear strength increased from nearly 0 kPa to 48.2 kPa, yielding the optimal reinforcement effect. The strength in both the central and cathode regions also improved, and the strength distribution between the anode and cathode became more uniform, with the strength ratio decreasing from 1.91 to 1.65, thereby enhancing the overall soil strength distribution. The Na⁺ concentration in the cathode effluent was highest, suggesting that Na⁺ migration played a predominant role in electroosmotic drainage. Furthermore, the electrochemical reactions generated cementitious materials that effectively filled the soil pores. SEM imaging and MIP pore size analysis revealed a reduction in porosity and an increase in soil compaction.