Influence of Biologic Retention Zone Structure on Its Infiltration-Storage

To investigate the influence of structural parameters and combination mode of the biologic retention zone on its infiltration-storage effect, the evaluation index for determining the infiltration-storage effect of biologic retention zone was put forward, and the 16 groups orthogonal experiments under the different conditions of the biological retention zone structural layer parameters were carried out. The composition and content of the planting soil and packing layer, the position of the geotextile, the grain gradation of the sand layer, and the thickness of structure layer on infiltration-storage effect of the biological retention zone were studied quantitatively. The results show that the degree of effect which varies from large to small is the grain gradation of sand layer, the composition and content of packing layer, the structural thickness, the position of geotextile, the composition and content of planting soil. The optimal structure of the biological retention zone from top to bottom is: 20 cm thick planting soil, 35 cm thick filler layer (the volume fraction are 10% perlite, 5% vermiculite, 10% loam, and 75% sand), 10 cm thick sand (0−0.5 mm accounting for 15%, 0.5−0.7 mm accounting for 40%, 0.7−1.0 mm accounting for 30%, and 1.0−2.0 mm accounting for 15%), 20 cm thick gravel layer, and without the geotextile.