Integrated modelling of the clogging processes of plastic grid permeable pavement

Abstract

Because of rapid urban expansion increasing the area of impervious land surfaces and climate change, flood risks and extreme precipitation events are projected to become severe challenges in the future. Sustainable Urban Drainage Systems (SUDS) are designed to increase urban surface permeability and reduce stormwater runoff. As a commonly used SUDS technique, plastic grid permeable (PGP) pavement effectively reduces urban surface runoff. However, clogging is a severe problem that reduces the operational performance and lifespan of PGP. Further research is needed on the clogging process, but it is challenging to conduct field experiments to predict permeable pavement's long- term performance for engineers and researchers. This study aims to evaluate the suspended particle clogging process and mechanisms of PGP using a modelling approach. A 1-D model was developed with COMSOL Multiphysics to understand the clogging process, based on the spatially and temporally mathematical expression. The new integrated hydraulic and clogging model for the PGP system consists of three parts: 1) Hydraulic model, 2) Rainfall-infiltration boundary (RIB) condition and 3) Clogging model, which named as the PGP-HRC model. The PGP-HRC model focuses on the interaction, feedbacks, and parameter changes between the three parts. The hydraulic model and RIB provide water flow driven force for the clogging model. Over time, clogging reduces the media porosity and further changes the soil properties, affecting the hydraulic model and RIB. By testing the model input parameters with different rainfall intensity, initial soil water content, suspended particle concentration, particle size and duration, the clogging time, depth and mechanisms of the PGP system can be understood. PGP-HRC model enables detailed study of hydraulic and clogging processes within porous media, and can be adapted for a range of applications. For the mitigation of surface water flooding, it provides a platform to test the design and maintenance of PGP, which will help for climate adaptation strategy and extreme precipitation in the urban area.