Experimental and Numerical Investigation of Infiltration-type Rainwater Drainage Systems : 실내 실험과 수치해석을 통한 침투형 배수시스템의 통합 연구

다국어 초록 (Multilingual Abstract)

Urbanization and the increasing occurrence of short-duration, high-intensity rainfall have exposed the limitations of Conventional Urban Drainage systems (CUDs), which rely primarily on surface conveyance and offer limited infiltration and temporary storage capacity. This study examines infiltration-type rainwater drainage systems (IRDs) to characterize their hydraulic and hydrologic behavior and to assess their performance in comparison with CUDs. The primary aim is to identify how IRDs influence runoff generation and attenuation, and to establish numerical modeling strategies suitable for their heterogeneous and anisotropic structure.
Rainfall experiments were conducted using full-scale IRDs and O-shape Channel system (OCs) physical model under identical initial and boundary conditions. The tests were performed after pre-saturating both systems to ensure consistent initial condition. The IRDs comprise a block layer made of permeable blocks and joints, and a sand layer composed of a granular sand medium. Measurements of outflow initiation, peak discharge behavior, and drainage patterns after rainfall cessation were used to analyze the infiltration, storage, and delayed-release characteristics of IRDs. The experimental observations show that IRDs delay runoff initiation, moderate surface discharge, and provide improved attenuation of hydrologic responses compared with CUDs.
A three-dimensional numerical model was adopted to reproduce these processes and to evaluate the flow mechanisms within the IRDs. Experimentally measured permeability and porosity obtained from constant-head tests primarily represent vertical hydraulic properties and did not yield sufficient correspondence with the rainfall experiments when directly applied to the numerical model.
This inconsistency arises from the heterogeneous and anisotropic block and sand layer structure, which cannot be fully represented at the grid scale. To resolve this issue, effective permeability (keff) and effective porosity (neff) were introduced to describe the averaged hydraulic behavior of IRDs. Incorporating these effective parameters allowed stable and computationally efficient simulations and improved the statistical agreement between numerical predictions and experimental observations. Sensitivity analysis confirmed that permeability and porosity exert substantial influence on the discharge behavior of IRDs, indicating that keff and neff should be employed when representing heterogeneous block layers in numerical simulations. The numerical model reproduced the overall trends observed in the physical experiments and demonstrated reliable predictive capability under varying conditions. These findings verify the hydrologic advantages of IRDs compared with CUDs and provide a basis for establishing design parameters that reflect realistic infiltration and drainage behavior. The outcomes of this study offer engineering guidance for the application, evaluation, and optimization of infiltration-based drainage systems in urban environments.

목차 (Table of Contents)

• Abstract i
• Table of Contents ii
• List of Tables iii
• List of Figures iv
• List of symbols ix
• List of Abbreviation xiii
• Chapter 1. Introduction 1
• 1.1. Background 3
• 1.2. Research scope 4
• 1.3. Research objective 7
• Chapter 2. Literature Review 9
• 2.1. Urban Runoff Behavior and Drainage System Design Principles 9
• 2.2. Concepts and Classifications of IRDs 12
• 2.3. Numerical and Physical approach 18
• 2.3.1. Numerical approach 18
• 2.3.2. Physical approach 31
• Chapter 3.Theoretical background 37
• 3.1. Conventional model 37
• 3.2. Coupled model 40
• 3.3. Effective permeability and porosity 47
• Chapter 4. Experimental and numerical study 51
• 4.1. Physical model 53
• 4.1.1. Experimental setup for material characteristics 53
• 4.1.2. Result of material characteristics 56
• 4.1.3. Experimental setup for rainfall simulation 63
• 4.1.4. Result of rainfall simulation 66
• 4.2.Numerical Analysis 76
• 4.2.1. Numerical setup 80
• 4.2.2. Numerical results of material characteristics 86
• 4.2.3. Rainfall numerical model 99
• 4.2.4. Integrated Analysis and parametric evalucation 107
• Chapter 5. Conclusion 114
• Reference 118
• 국문초록 128
• Acknowledements 131