地表條形載重對擋土牆造成之側向土壓力

Abstract

本論文探討回填土伴隨地表條形載重對作用於擋土牆主動土壓力之影響。本研究利用國立交通大學模型擋土牆設備探討平移模式牆位移所造成土壓力之變化。試驗採用36%相對密度之渥太華砂為回填材料，其單位重為15.6 ，內摩擦角為31.3 。根據實驗結果，獲得以下各項結論。 1. 以空中霣降法所製作之鬆砂土體，其靜止土壓力係數 與Jaky建議的公式互相吻合。 2. Coulomb理論 能準確預測在水平移動牆模式下的水平主動土壓力係數 。 3. 當地表載重作用於背填土上方(假設牆不動)，實驗量測之側向土壓力 分佈介於DM-7.2所建議的 與1.6 之間。其側向土壓力增量係數 隨載重增加而遞增，並隨載重外移而遞減。 4. 牆發生額外移動量時，實驗的側向主動合力增量 與semiempirical rules相吻合，Steenfelt & Hansen理論計算明顯高估載重作用下與牆移動時的側向土壓力 5. 側向合力增量 的合力作用位置隨牆移動量而遞減，直到 約達到常數1/3。

This paper presents experimental data of earth pressure, which backfill carries a surcharge acting against a vertical rigid wall, which moved away from a mass of dry sand. Ottawa sand is prepared at relative densities of 36% with air-pluviation method. The instrumented retaining-wall at National Chiao Tung University was used to investigate the variation of lateral earth pressure due to strip surcharge induced by the translational wall movement. For all tests, the soil unit weight is 15.6 , and the angle of internal friction of the soil is 31.3 . Based on this study, the following conclusions can be drawn. 1. For soil placed with the air-pluviation method, the coefficient of earth pressures at-rest as comparing with the well-known Jaky solution, values have been well suitable by the Jaky formula in the loose sand. 2. Coulomb theory provides a good evaluation of active thrust as a result of the translational wall movement. 3. As the surcharge is located on the backfill (assuming no wall movement), the distribution of experimental lateral pressure increment could be reasonably described with and 1.6 suggest by the Navy Design Manuel DM-7.2. The increases with increasing and decreases with increasing parameter . 4. For further wall movement, the experimental lateral active force increment is agreed with semiempirical rules. Steenfelt and Hansen’s theory definitely overestimate the lateral earth pressure due to the surcharge and further wall movement. 5. The location of decreases with increasing wall movement until reaches a constant value of about .