In the context of ongoing economic development and urban expansion, there is an urgent need to promote the resource utilization and recycling of construction waste. As a crushed material obtained from the screening of construction waste, recycled concrete aggregate has broad application prospects. This study focuses on four distinct particle size ranges of recycled concrete aggregate. By introducing the concept of aperture ratio, the shear characteristics of the interface between the recycled concrete aggregate and biaxial polypropylene geogrids are investigated through large-scale direct shear tests under three different vertical stresses and four different shear rates. The findings demonstrate that as the aperture ratio diminishes, the peak shear stress and residual shear stress at the shear interface increased, and the peak shear stress occurred at a later stage. Conversely, as the aperture ratio decreases, the peak apparent cohesion and residual apparent cohesion undergo a gradual increase, and the peak internal friction angle and residual internal friction angle also increase. The addition of geogrids effectively reduces the occurrence of shear dilation at the interface. By introducing the Kalhaway constitutive equation, the expression for shear stiffness is derived through linear and logarithmic fitting, and the shear stiffness corresponding to the stress state (σ_n, τ) is thereby obtained.

Prefabricated vertical drainage plate (PVD)-vacuum preloading method is effective in improving the dredged slurries. However, during the operating process, a dense area (soil column) with a gradually decreasing radius from top to bottom would be generated around the PVD, delaying the soil consolidation rate. Aimed at it, this paper assumed that the soil column radius attenuates linearly with depth, and based on the assumption of equal strain, and the Hansbo’s consolidation theory, the consolidation equation considering the change of soil column radius with depth is deduced. At the same time, by calculating the equation above, the influences of the permeability coefficient, the radius of the soil column and the variation of the radius of the soil column along the depth on the soil consolidation rate were explored, and compared with the existing laboratory test data. The result shows that the smaller the permeability coefficient of the soil column, the slower the dissipation of pore water pressure, and the slower the consolidation rate. As the soil column radius gradually increases, the soil consolidation rate gradually decreases. The smaller the residual coefficient after the attenuation of the soil column radius, the greater the attenuation degree of the soil column radius along the depth, the smaller the influence on the soil consolidation in the weak area, and the faster the soil consolidation rate. In the case of considering the soil column radius attenuation with depth, the presented results are in good agreement with the experimental findings.

To address the issue of decreased heat and vacuum negative pressure in soil, which leads to uneven reinforcement effect during vacuum thermal consolidation, the vacuum thermal consolidation combined with dynamic compaction method is applied for engineering waste slurry treatment, and the characteristics of soil compactness can be improved by dynamic compaction method. The influence of different tamping times on the reinforcement effect of soil was studied through four groups of model tests. Results show that when the settlement rate is 4 cm/(3 d), the tamping time is the best, the settlement of soil surface is 26.55%, 11.72% and 3.74% higher than that of other tests correspondingly, and the treatment effect of engineering waste slurry is the best, effectively solving the unsatisfactory reinforcement effect of deep soil under vacuum thermal consolidation and improve the uniformity of soil. Combined with the results of microstructure analysis, it can be found that due to the redistribution of pores between soil particles, the soil density is higher, and the shear strength of the cross plate increases accordingly under the appropriate tamping time. In addition, the drainage channels formed by the micro-cracks generated by the redistribution of internal pores can promote drainage and further improve the consolidation effect. Therefore, the shear strength of the cross plate and degree of consolidation of the soil can be enhanced under the appropriate tamping time.