A recent study has uncovered the dynamic characteristics and vibration susceptibility of loess soils residing in Tongren County, Qinghai Province, shedding light on their behavior under varying conditions of water content and confining pressure. Researchers employed GDS dynamic triaxial tests to analyze these effects, finding notable reductions in the strength of Tongren loess as water content increased. The results are particularly concerning for the region, known for its complex geology and frequent landslide disasters.
The analysis reveals key insights about the intrinsic properties of loess, which is characterized by high porosity and weak interparticle bonding. This unique structure makes it especially prone to seismic activity and environmental changes. Tongren loess exhibited strong structural properties, conforming to the Hardin-Dinevich hyperbolic model, where the dynamic parameters are influenced by external factors such as moisture and pressure levels.
When subjected to rising water content, the study indicates substantial decreases—up to 83%—in dynamic cohesion, with the dynamic friction angle dropping to levels as low as 12 to 16 degrees. These findings suggest enhanced susceptibility to instability, illustrating the danger posed to slopes composed of Tongren loess, particularly during seismic events. Researchers noted, "Under the same conditions, the failure dynamic stress, maximum dynamic elastic modulus, and dynamic shear strength parameters of intact loess are greater than those of remolded loess," emphasizing the structural integrity of unaltered loess.
The need to understand the dynamic properties of loess is underscored by the geological complexity and seismic vulnerability of the region. Frequent seismic activity, coupled with rainfall, can trigger catastrophic landslides, highlighting the urgency of this research. Past events affirm the risk, as the region's susceptibility to liquefaction and subsidence remains high under dynamic loading conditions.
The tests employed allowed scientists to visualize how the interaction between water and loess affects its mechanical strength. The nonlinear stress-strain relationship observed during dynamic loading shows how loess responds to environmental pressures. It was determined, "The dynamic friction angle of Tongren loess is only 12° ~ 16°, making slopes composed of Tongren loess highly susceptible to instability," alerting civil engineers to potential risks when designing infrastructure.
This study not only provides data for assessing landslide risks but also lays groundwork for improved geotechnical engineering practices aimed at mitigating these landslides. By applying findings, engineers can develop models predicting landslide susceptibility under various rainfall patterns and construction activities. Implementing comprehensive drainage systems, considering seismic design principles, and employing appropriate land use planning can be highly beneficial to prevent future disasters.
Further research is recommended to evaluate the effectiveness of dynamic strength parameters and their applications to geotechnical stability assessments. Future investigations may also explore the long-term impacts of climate change on loess composition and structural integrity, seeking innovative engineering solutions to bolster loess slopes against natural calamities.