| 摘要: | 近來台灣經濟逐漸發展，相對公共建設需求大幅度提升，在公共建設興建中，臨時道路成為不可或缺的角色，因為讓工程的大型機具容易地進出工地，但必須在軟弱可壓縮的土壤路基上鋪設臨時道路，加上台灣處於亞熱帶濕暖多雨型氣候，在本島各處會出現豪雨，可能使原本承載力低的軟弱土壤達到飽和，承載力再降低，在施工期間或之後，容易道路產生承載力破壞，而有過大的沉陷，衍生出工安意外事故造成人民生命財產損失與社會成本增加。為了加強軟弱土壤的承載力，可使用地工合成材料(如地工格網或地工織物等)，並藉由地工合成材應用於道路加勁之力學機制改善軟弱土壤承載力不足的特性。本研究透過加州承載比試驗(California Bearing Ratio)，模擬現實臨時道路中路基層的狀況，以中央大學紅土當作路基層土壤，再以不同含水量作為試驗變因來觀察，探討在無鋪面的狀況下，其承載力的變化。由初步試驗結果看來(1)在無浸泡水狀況，夯實含水量增加，試體之CBR 值會降低，相反地，在浸泡水狀況，夯實含水量增加，試體之CBR值會上升，表示夯實含水量多寡都會影響到承載比，只是兩者趨勢不同，且發現試體膨脹量對於浸泡水後的承載比有密切的關係，(2)浸泡水與鋪設位置不同情況下，地工織物加勁效果在改良式夯實曲線的乾側、O.M.C 側與濕側有不同趨勢，並以整體來看，加勁效果順序為濕側大於乾側大於O.M.C 側。;Recently, Taiwan′s economy gradually has developed, in opposite to the demand of infrastructure greatly enhance. In the infrastructure, Temporary road becomes indispensable role, because let large equipment of engineering to easily access the site. However, temporary road must be laid on the soft and compressible of soil subgrade. Because Taiwan is a subtropica and warm and rainy climate, throughout the island will have heavy rain, it may make the original soft soil with the low bearing capacity to reach saturation, the bearing capacity further reduce. During construction or after, the roads easily produce bearing-capacity failure, and there is a large settlement, derivative to safety
accident causes the loss of lives and property and the increment of social costs.
In order to strengthen the bearing capacity of weak soil, geosynthetics can be used (such as geogrids or geotextiles ) and by goesynthetics used in the mechanical mechanism of stiffened road to improve the insufficient bearing capacity characteristics of soft soil. In this study uses the California Bearing Ratio test, simulate the subgrade condition of reality tmporary road, use Central University laterite soil as a subgrade soil. And then use the different moisture content as the test factor is observed, to investigate the changes of bearing capacity in the unpavement.
The following summaries from preliminary test result are
addressed:(1) In the unsoaked condition, compaction moisture content increases, the CBR value of the specimen reduces. Conversely, compaction II moisture content increases, the CBR value of the specimen rises, indicate the amount of compaction moisture content will affect the bearing ratio,
and the swelling amount of specimen after immersion in water are closely related to the bearing ratio; (2) In soak and different laying position condition, stiffening effects of geotextiles in the dry side, the O.M.C side and the wet side of the modified compaction curve have different trends.
In conclusion, the stiffening effects on the wet side of the optimum moisture content are greater than on the dry side of the optimum moisture content. And the stiffening effects on the dry side of the optimum moisture content are greater than on the optimum moisture content side. |
