Preflex Wale을 적용한 흙막이 벽체의 거동 특성에 관한 연구 = A Study on the behavioral characteristics of earth retaining walls using Preflex Wale

다국어 초록 (Multilingual Abstract)

This study aims to provide fundamental data for evaluating the applicability of Preflex Wales by analyzing their behavioral characteristics and assessing their structural safety under various hypothetical ground conditions and commonly used steel sections. Structural performance was evaluated using both numerical analysis and field testing, including a full-scale test employing a Preflex Wale fabricated with the frequently used H-section steel (H350×350×12×19, SS400). Within the allowable tensile stress range of the applied steel materials, the maximum central displacement limits of the Preflex Wale were analyzed. For a wale length of 10 m, allowable displacements were determined to be up to 10 cm for 200×200 sections, 6 cm for 300×300, and 5 cm for both 350×350 and 400×300 sections. Corresponding allowable end moments were calculated as 348.4 kN·m, 494.0 kN·m, 812.4 kN·m, and 1,342.7 kN·m, respectively. The maximum end forces were estimated at 69.7 kN for 200×200, 162.5 kN for both 300×300 and 350×350, and 268.5 kN for 400×300 sections. Through stepwise loading analyses of the curved beam behavior, it was found that while the bending stress ratio remained generally stable even with increased displacement, shear performance was comparatively weaker. The results indicate that shear reinforcement is necessary in segments where shear forces exceed allowable limits. Comparative evaluations of effective span lengths under loading revealed that the Preflex Wale (δmax = 5 cm) exhibited significantly higher resistance than normal wales. Depending on span length, load-carrying capacity improved by approximately 369%∼80% for 200×200, 280%∼64% for 300×300, 215%∼61% for 350×350, and 236%∼65% for 400×300 sections. However, when the design span exceeds 15 meters, the increase in load resistance becomes marginal. This reduction is attributed to the rapid decline in allowable bending stress caused by increased buckling length. Based on the application of Preflex Wale to virtual cross-sectional models, the allowable bending stress ratio demonstrated an average safety improvement of 3.53 times compared to normal methods when applied to excavation depths ranging from 5 m to 20 m. In addition, the allowable shear stress ratio was found to increase by a factor of 1.23. From the beginning of excavation to the completion of pier concrete placement, field tests were conducted to measure earth pressure behind the wale, flange strain, and displacement. Results confirmed that Preflex Wales demonstrate more effective resistance to active earth pressure than normal wales.

목차 (Table of Contents)

• Ⅰ. 서론 1
• 1. 연구배경 및 목적 1
• 2. 연구의 동향 2
• 3. 연구방법 및 내용 3
• Ⅱ. 흙막이 공법의 이론적 고찰 5
• 1. 흙막이 공법의 일반사항 6
• 2. 흙막이 벽체의 거동 및 해석 13
• 3. 흙막이 벽체의 해석방법 28
• 4. 흙막이 부재의 해석방법 39
• Ⅲ. Preflex Wale의 구조해석 44
• 1. Preflex Wale의 일반사항 45
• 2. Preflex Wale의 구조안전성 검토 49
• Ⅳ. Preflex Wale의 적용성 및 경제성 검토 94
• 1. 굴착깊이에 따른 적용성 검토 95
• 2. 지반조건에 따른 적용성 검토 101
• 3. 지하수위조건에 따른 적용성 검토 106
• 4. 상재하중에 따른 적용성 검토 111
• 5. 기존공법과의 경제성 검토 116
• 6. Preflex Wale의 현장 적용 시험 결과 121
• Ⅴ. 분석 및 고찰 131
• 1. Preflex Wale의 구조안전성 분석 132
• 2. Preflex Wale의 적용성 분석 139
• Ⅵ. 결론 146