A survey and assessment of the technical condition of basement and semi-basement structures in public buildings aged 60 to 130 years were conducted to evaluate their suitability for use as basic shelters. Based on the survey results, the most adverse impacts were identified, including changes in groundwater levels, improper building operation, and the characteristic damages to underground structural elements. Structural solutions were proposed to eliminate the consequences of these damages. The reviewed cases indicate that the vertical and horizontal waterproofing systems used during construction cannot perform their function throughout the building's entire life cycle. When designing new buildings, waterproof materials should be used for the enclosing structures of underground premises. While this may have a higher initial cost than membrane or coating waterproofing, considering life-cycle costs, it can provide a positive economic effect and improve the quality and comfort of the indoor environment.

The technology of loess solidification plays a crucial role in addressing issues such as soil erosion, with the key material in this process being the loess stabilizer. To tackle the high energy consumption problem associated with traditional loess stabilizers primarily composed of Portland cement, this study employed a more ecological sustainable alternative by incorporating solid waste coal gangue and magnesium oxysulfate (MOS) cement as a binding agent for consolidating loess. The alterations in bulk density, porosity, mineral structure, and microstructure of the consolidated soil with different MOS content were systematically investigated and validated. The pore size of MOS-solidified loess decreased significantly to a range of 0.04-3.60 mu m compared to 0.80-3.88 mu m for pure loess. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and thermogravimetric (TG/DTG) analysis revealed that the addition of MOS binder generated hydrated magnesium silicate (M-SH), Mg(OH)2, and a small amount of 5Mg(OH)2 & sdot;MgSO4 & sdot;7H2O phase which filled the gaps between soil particles and bonded them together effectively. When the proportion of MOS binder added reached 11 %, the compressive strength of stabilized loess after curing for 28 days increased up to 9.4 MPa. After immersion in water for 24 h, the strength only decreased by 5.3%, with a softening coefficient of 94.7%. The test results consistently indicate that the enhancement in mechanical properties can be attributed to the binding effect facilitated by MOS. The ecological composite binder based on coal gangue and MOS demonstrates great potential in the field of soil stabilization.

The structural damage caused by salt weathering in loess soil is a crucial factor leading to soil erosion and geological disasters in the Loess Plateau region of China. However, the impact of salt weathering on the structural damage and strength degradation of soil under unidirectional dehumidification conditions remains unclear. To gain a comprehensive understanding of the structural damage process and strength characteristics of soil under salt weathering, this study focuses on Q(2) loess (silt loam, a loose aeolian deposit) in Fugu County, Shaanxi Province. Multiscale observations tests and direct shear tests were conducted on samples with varying sodium sulfate contents. The research findings indicate that at the macroscopic scale, The 3.0 % salt content sample experienced the most severe salt weathering, exhibiting characteristics of powdering and disintegration. Moreover, it exhibited the highest expansion displacement, reaching 22 mm. In addition, all samples go through three stages during the entire salt weathering process, namely budding, growth, and stable stages. At the mesoscopic scale, the displacements and expansions caused by salt crystallization growth on soil particles and pores were captured in real-time. Furthermore, the crystallization behavior of sodium sulfate differs on the surface and near-surface of samples as water content decreases, resulting in four distinct layering structures. At a microscopic scale, salt weathering leads to the formation of aggregates and the generation of numerous expansion pores within samples. Not only that, the shear behavior of samples transitioned from strain-softening to strain-hardening after salt weathering, with the peak strength significantly weakened compared to the residual strength. Additionally, before a salt content of 1.5 %, the cohesion of samples experiences the greatest decline, gradually slowing down thereafter, ultimately decreasing by 16 kPa. However, the decrease in the friction angle is less significant, with only a decrease of 4.8 degrees. In summary, an increase in sodium sulfate content exacerbates the occurrence of salt crystallization-induced expansion and soil drying-induced coagulation phenomena in saline soils, resulting in severe damage to soil structure and strength. This study will provide valuable insights for soil and water conservation as well as disaster prevention in the Loess Plateau region, serving as a crucial reference for future research and engineering practices in the region.

The Loess Plateau is highly susceptible to gully headward erosion, highlighting the urgent need for soil stabilization. In this study, a series of physical and mechanical properties, water physical properties and microstructure tests were carried out to explore the loess improvement for potential control of headward erosion in loess gullies. Experimental results reveal that the addition of the Consolid System to loess soil leads to an increase in the plastic limit and liquid limit of the soil, while the soil retains its characteristics as a type of low plasticity soil. The dry density of the stabilized loess soil decreases, while the unconfined compressive strength increases. Regarding the water-physical properties, the swelling and shrinkage properties of modified loess soil were significantly improved while the permeability coefficient slightly decrease. Furthermore, the surface energy decreased, resulting in increased water repellency, while the pore volume remains relatively unchanged. A recommended minimum mixing ratio of the Consolid System is 1.5% to resist water erosion. In conclusion, the implementation of the Consolid System not only enhances the strength of loess soil and its water repellency, but also preserves the advantageous water drainage characteristics inherent to loess soil. Consequently, loess soil stabilized by the Consolid System holds promising potential for applications in areas covered with loess soil.