回填土傾角對靜止土壓之影響

Abstract

回填土傾角對靜止土壓之影響研究生：蔡毅中 指導教授：方 永壽 博士國立交 通大學土木工程研究所摘要 本研究探討回填 土傾角的改變，剛性擋土牆所受靜止 土壓力之影響。本研究利用國立交 通大學模型擋土牆設備進行試驗。所用回填土材料為疏 鬆之氣乾渥太華 砂 (ASTM C-109)。本研究建議使用土楔平衡法(Wedge Equilibrium)來估 擋土牆後水平背填土的靜止土壓力。依據試驗結果，可獲以下幾點結論： 1. 水平背填 土所造成的靜止土壓力接近線性分佈，並與以土楔平衡法 的預 估值相當一致。合力 作用點位於距牆底0.34~0.36H處。 2. 回填土傾角為正時，測得之土壓力分佈與彈性解 相當一致，然而當 回填土 傾角為負時，測得之土壓力明顯高於彈性解。 3. 靜止 土壓力係數隨著回填土傾斜角增加而升高。當回填土傾角為正 時， 測得之土壓合力 ，與彈性解相當一致。 4. 特別當有伸張應力時，分 離顆粒的土體應用於彈性疊加應力 上，可能會導 致錯誤。 Earth Pressure At-Rest with Sloping BackfillStudent: Yi-Chung Tsai Advisor: Dr. Yung-Show FangInstitute of Civil EngineeringNational Chiao Tung UniversityABSTRACTThis paper investigates the earth pressure at-rest against a non- yielding wall with sloping backfill. A unique model retaining wall syste m at the National Chiao Tung University is used for this study. Air-dry Ottawa silica sand (ASTM C-109) is used as backfill for the experiments. A Wedge equ ilibrium method is proposed to estimate the earth pressure at-rest against a n on- yielding wall with horizontal backfill. Based on the test results, the foll owing conclusions can be drawn.1. The distribution of the earth pressure at-re st against the wall with horizontal backfill is nearly linear, and in fairly g ood agreement with the solution calculated with the wedge equilibrium method. The point of application of total thrust is located about 0.34 to 0.36H above the wall base.2. The measured pressure distributions against the wall are in f airly good agreement with elastic solutions for positive backfill inclinations . However the pressure measured are significantly greater than the elastic sol utions for negative i angles.3. At-rest earth pressure coefficient {embed Equa tion.2 |} increases with increasing slope angle {embed Equation.2 |}of the bac kfill. The experimental {embed Equation.2 |} values are in good agreement with elastic solutions for positive backfill inclinations. The elastic solution te nds to underestimate the coefficient {embed Equation.2 |} for backfills with n egative sloping angles.4. The application of superposition of stresses may be misleading on a mass with discrete particles, especially when tensile stress i s involve.