Effects of Rainwater Infiltration in Low Impact Development Facilities
on Adjacent Municipal Roads in Collapsible Loess
Abstract
The effective and reasonable construction of the low impact development
(LID) facilities in loess area depend on the functionality of typical
LID facilities and the safety of surrounding structures in areas. A
full-scale field test on rainwater concentrated infiltration of
bioretentions in a collapsible loess site was conducted in this study.
The water content and deformation law of the site were analyzed, and the
water movement law of the rainwater-concentrated infiltration at
bioretention facilities in the loess site was determined. The site
settlements were calculated as per the wetting deformation curve and
infiltration depths were calculated on an improved infiltration depth
model tailored to the loess area. The rainwater infiltration rules of
different bioretention structural forms are different in the collapsible
loess field. The diffusion rate of the retaining wall type in loess
decreases over time, while that on a sloping type does not. Within the
same infiltration time, the retaining wall has a stronger influence on
the site than the sloping type. When the water is concentrated in the
site, its influence on the subgrade settlement is small (generally less
than 1.5 mm) enough to satisfy the relevant engineering requirements. A
modified Green-Ampt model based on assumed loess saturated unsaturated
stratification can be used to predict the infiltration depth of facility
water at the site. The adverse effects of water infiltration related to
stagnant bioretentions can be mitigated by adjusting the initial water
content and saturated water content at the loess site.