本研究使用MTS動力三軸試驗系統，以半正弦波進行永久變形試驗，探討路基土壤材料在重覆載重作用之下，累積的永久變形行為；建立以不同含水量與不同應力水準的應力參數，與累積永久變形之最佳迴歸模式，以作為鋪面設計預測的參考依據。 永久變形試驗的結果顯示路基土壤材料在重覆載重作用下，累積永久變形量隨著載重次數的增加而逐漸增加。受測試體若達明顯穩定狀態，則試體受到反覆循環的軸差應力作用不會出現破壞的現象。高含水量、高應力水準下欲達試體的明顯穩定狀態，需要較多的重覆載重次數。達到明顯穩定狀態下的路基土壤受測試體，其回彈應變量與累積永久變形量，經由量化的統計迴歸方式分析後發現彼此間存在著明顯的相關性；此明顯的相關性將有助於設計研究人員以較少的施測次數（100次）試驗，來預測受測試體達明顯穩定狀態時所累積的永久變形。 此預測的模式將可大幅節省為求受測試體達明顯穩定狀態時所需的施測時間。預測的模式還可用於估計回彈模數值，以作為路基土壤鋪面厚度設計時參考之用。 This study investigates behavior of cumulative permanent strain of subgrade soil under repeated loading at various stress levels. Results of the permanent strain test shows that the accumulated permanent strain of subgrade soil under repeated loading continues to build up with increasing load repetitions. If the tested soil approaches apparent shakedown state, the tested soil does not appear failures after the deviator stress of repeated load cycles. Approaching apparent shakedown state of the tested soils under high water content and high stress level needs more repeated load repetitions. The relationship of the resilient modulus and permanent strain of tested subgrade soil, at apparent shakedown state, is established using statistic regression. The relationship helps designers in predicting accumulated permanent strain as the tested soils reach apparent shakedown state with less testing times. This prediction model will enormously save the testing time needed as reaching the expected apparent shakedown state of tested soils. This prediction model also can evaluate the values of resilient modulus as the reference of designing the thickness of pavements of subgrade soil.
