内蒙古罕台川流域淤地坝土体渗透特性及微观机理研究OA

Addressing the lack of clarity regarding the micro-regulatory mechanisms governing soil permeability in silt-trapping dams,this study examines loess from four representative dams in the upper and lower reaches of the Hantai River basin.Employing variable-head permeability tests combined with quantitative-qualitative scanning electron microscopy(SEM)analysis,we elucidate the relationship between macroscopic permeability characteristics and microstructural features of the soil.Results indicate that all four dam soils exhibit low permeability characteristics,with permeability coefficients generally decreasing with decreasing moisture content.However,the downstream Housha Dam demonstrates a rebound in permeability despite lower moisture content due to its unique microstructure.From upstream to downstream,soil skeletal particles transitioned from coarse and loose to densely cemented;contact patterns shifted from point to surface-to-surface;and the pore system changed from interconnected macropores to closed micropores.The most downstream sand dam exhibited enhanced permeability due to reduced fractal dimension of pores resulting from particle homogenisation.The study confirms that soil permeability in sediment retention dams is dynamically regulated by the equilibrium between moisture content(enhancing permeability)and microstructural densification(inhibiting permeability).This research provides theoretical reference for impermeability design in sediment retention dams and the construction and maintenance of dam bodies on the Inner Mongolia Loess Plateau.