To investigate the mechanical properties of polyvinyl-alcohol (PVA)-fiber-reinforced rubber concrete, 13 groups of PVA rubber/concrete specimens with PVA volume fractions of 0%, 0.5 vol%, 1.0 vol%, and 1.5 vol% and rubber particles with volume replacement sand ratios of 0%, 10%, 20%, and 30% were prepared, and the uniaxial compression full curve test was performed. The findings indicate that the bridging effect of PVA, as well as the synergistic effect of PVA and rubber particles, can improve the compressive properties of concrete, and the failure of the specimens demonstrates obvious ductile characteristics. Furthermore, PVA has a better impact on rubber concrete’s bearing capacity, crack propagation of the failure surface, and compressive strength in the latter stages. PVA-fiber-reinforced rubber concrete is thought to be a six-phase composite made up of the aggregate phase, mortar matrix, PVA fiber, rubber particles, aggregate–mortar interface, and rubber–mortar interface on the mesoscale. To simulate the entire process of concrete with varying PVA rubber/content from integrity to damage and cracking, a meso-numerical model of PVA rubber/concrete was constructed. The simulation results and test results are in good agreement, demonstrating the validity of the mesomodel and offering a theoretical foundation for the structural analysis and design of this type of concrete.

Foundation pit monitoring can only provide feedback regarding the deformation of the formation and envelope structure after construction, and it is difficult to predict the deformation law of a continuous underground wall in the later stage of underground grain silo support. Taking the deep foundation pit of a continuous underground wall of an underground grain silo as an example, this paper uses Abaqus software to simulate the force of the project, explores the calculation results of the planar elastic foundation beam considering the arch effect and the numerical simulation technology of the foundation pit’s support, and analyzes and compares the rationality of the model. The analysis of the deformation form of the continuous underground wall by both calculation methods is a parabolic combination. The maximum horizontal displacement of the continuous underground wall, according to the Abaqus software, is 6.23 mm, and the other calculation result is 4.7 mm; the maximum settlement on the surface is 11.34 mm, according to the Abaqus software, and the other maximum settlement is 8 mm. The simulation results show that the simulated value is basically consistent with the measured value, and the simulated value is slightly larger than the measured value because the interference conditions are idealized during simulation. The accuracy and rationality of the numerical simulation are verified, and the parameters, such as the thickness and burial depth of the continuous underground wall, can be changed to provide a reference for the support method of a deep foundation pit similar to a continuous underground wall.

The current study investigates the deformation and strength of Light-Weighted Soil (LWS) comprised of silt, Expanded Polystyrene (EPS) beads, cement, and water. The EPS bead sizes employed in this study are 4, 5, and 6mm in diameter with densities of 0.011, 0.009, and 0.006g/cm3 and cement concentrations of 10% and 15%. The effects of different EPS bead sizes and cement proportions on the mechanical properties (strength and deformation) of LWS are evaluated by Unconfined Compression Strength (UCS) tests. The findings show that the EPS bead sizes significantly impact the strength and deformations of the LWS. The smaller the EPS bead size, the higher the observed strength, but, on the other hand, bigger EPS bead sizes have lower strength and higher ductility. It was also revealed that the strength of LSW is entirely dependent on the cement concentration. High cement content in the LWS has more strength and brittleness, but it is more prone to deformation. The cost can be decreased by increasing the EPS bead size, and thus the prescription of mixed soil can be enhanced. The use of EPS beads with a diameter of 4-6mm is recommended in the construction process, especially in backfill for retaining walls. Each EPS bead size provides advantages in different context, depending on engineering applications and field conditions.

The expansion of China’s highways and railways, as well as the growing demand for them, has focused attention on the impact of traffic loads on foundation settling, uneven deformation, and ground cracking. These effects have garnered considerable research attention, with particular emphasis placed on integrating innovative materials into the soil matrix. This investigation involved loading experiments utilizing a combination of lightweight soil, expanded polystyrene (EPS), and cement. Consolidation tests assessed the extent of deformation and settlement, incorporating varying proportions of EPS and cement. The test results show that when subjected to confined conditions, the stress–strain relationship curve assumes a hyperbolic shape closely linked to the e-p curve. This shape effectively captures the unique structural characteristics exhibited by lightweight soils. As the size of the EPS particles and the applied stress increase, a corresponding rise in the strain of the specimens is observed. Simultaneously, as the strain magnitude increases, the elastic modulus experiences a decline. Additionally, it is noted that this trend further increases as the doping of the cement with EPS particles increases. When the EPS volume ratio and cement mix ratio remain constant across different specimens, there is a decrease in structural strength as the size of the EPS increases. In lightweight soil, settlement can occur rapidly, with approximately 95% of total consolidation deformation happening within a few minutes, which suggests that the settlement is instantaneous and primarily consolidation settlement. The structural strength of lightweight soil shows a negative correlation with the size of EPS, implying that larger EPS size may lead to a reduction in strength. Therefore, it is recommended to consistently use EPS beads with a diameter of 3–4 mm during construction.

Expanded polystyrene (EPS) foam concrete is attractive for lightweight building applications, yet its practical use is often limited by weak EPS–cement interfacial bonding, which promotes interfacial debonding and crack propagation and thereby compromises mechanical performance. Although nano-SiO₂ (NS) has been reported to improve EPS–cement compatibility, the interfacial strengthening mechanism is still not fully clarified across scales, especially the molecular-level interactions that govern the formation of a robust interfacial transition zone (ITZ). Herein, EPS particles were modified with NS and a multi-scale framework (macro tests, micro-characterization, and molecular dynamics (MD) simulations) was employed to establish a mechanistic linkage between interfacial chemistry/structure and macroscopic performance. The results show that an optimal NS dosage of 9% (by cement mass) increases the 28-day compressive strength and flexural strength of EPS concrete by up to 18.3% and 11.2%, respectively, compared with the unmodified system. SEM, XRD, and FTIR collectively indicate a denser interfacial microstructure, increased hydration-product accumulation near the EPS surface, refined interfacial porosity, and the occurrence of condensation-related reactions involving NS. MD simulations further reveal that NS facilitates the formation of molecular bridges between EPS and C–S–H through hydrogen bonding and ionic interactions, which enhances interfacial adhesion and contributes to improved ITZ thermal stability. This study provides a cross-scale mechanistic understanding for designing high-performance EPS foam concrete via targeted interfacial engineering. MD simulations further suggest that NS enhances interfacial bonding by increasing the occurrence of hydrogen-bond networks and ionic associations at the EPS/C–S–H interface, as evidenced by the intensified interaction-related distributions and peaks in the simulation outputs.