回填土傾角對被動土壓之影響

Abstract

實際工程中，頗多於斜坡上建造擋土牆之案例。故邊坡上作用於擋土牆後 之土壓力變化情形值得注意。本論文探討一座以傾斜渥太華砂回填之剛性 牆，因牆的被動位移所引致之土壓力變化情形。為研究此問題，本論文利 用國立交通大學模型擋土牆設備進行試驗。經分析試驗結果後，得到下列 各項結論: 1.實驗所量得之土壓力，隨牆被動位移量的增加而增大，終於 達成一最大值後即不再增加。庫倫被動土壓力理論與實驗得到之被動土壓 力係數符合良好。在牆移動期間，土壓力之分佈基本上仍呈線性分佈，且 不論背填土傾角為何，被動土壓合力作用點都大約保持在距牆底 0.33H - 0.41H 之位置。 2.隨著回填土傾斜角之增加，被動土壓力係數呈急劇 的增加。達到被動狀況所需之牆移動量也隨 i 角之增加而加大。 3.試驗 結果顯示，回填土表面所觀察到之破裂線與對數螺旋法所估算之結果頗為 符合。 This paper aims to study the development of the earth pressure due to passive movement of a rigid wall with a sloping backfill. A unique model retaining wall system was constructed at the National Chiao Tung University to investigate the problem. Based on the experimental data, the earth pressures measured, at different depths, with various sloping backfills, increase with increasing passive wall movenent before reaching a maximum value. The experimental passive earth pressure coefficient Ｋp,h is in good agreement with Coulomb's solution. With increasing passive wall movement, the earth pressure remains almost a linear distribution. No matter what value the sloping angle i is, the point of application of the total thrust would act at 0.33H - 0.41H above wall base. With the increasing sloping angle (from -i to +i), the passive earth pressure coefficient Ｋp,h increases rapidly, and the wall movement required to reach the passive state also increases. The experimental results show that, the location of surface crack observed is in good agreement with the value estimated by the log--spiral method.