飽和黏土單向度壓密潛變之實驗研究

中文摘要　　Ladd et al. (1977)綜合多位學者之單向度壓密試驗結果，得知不同厚度土壤對於應變-時間行為，主張可區分為假說A和假說B，此議題至今仍有爭議。本研究對單向度壓密試體以小階增量方式加載，以增加土樣壓密歷時，來驗證主要壓密完成壓縮量與壓密潛變歷時之關係。　　本研究使用石門淤泥、高嶺土、新塭黏土、石牌黏土、永安黏土和北投黏土土樣，以中型壓密儀製作14組均質試體，再以試體進行ACE單向度壓密試驗，並對試驗結果進行分析討論。　　研究結果顯示：(1)不論是低塑性黏土、高塑性黏土、或是高塑性粉土，增加壓密潛變時間所產生的主要壓密完成壓縮量並沒有因為時間最長就最多；(2) 不論是處於過壓密階段、跨越預壓密應力階段、或是正常壓密階段，將最終壓密應力主要壓密完成壓縮量正規化後，平均值接近1.0；(3) 大多試驗最終壓密應力主要壓密完成壓縮量正規化之值與1.0相近，或者比1.0略小，因此試驗結果顯示假說A比假說B較為符合。

關鍵字

黏土；壓密:潛變:時間

並列摘要

Ladd et al. (1977) summarized the results of one-dimensional consolidation test by several researchers and learned that the modeling of strain-time relationship of soils with different thicknesses are divided into hypothesis A and hypothesis B. There still exist controversial issues between them. In this study, one-dimensional consolidation tests with small loading increments are carried out so that the time to the end of primary consolidation under final load is increased considerably. In this way, the relationship between end of primary consolidation compression and time of consolidation may be examined. In this study, a 200 mm diameter oedometer is used for preparing reconstituted samples of Shimen silt, kaolin, Sinwen clay, Shipai clay, Yonyan clay, and Beitou clay. Each preparation produces four homogenous samples of the same specified preconsolidation pressure. This study conducts a large number of one-dimensional consolidation tests and obtains test results for analysis and discussion. The obtained test results show that: (1) whether the soil is low-plastic clay, high-plastic clay, or high-plastic silt, the end of primary compression is not directly proportional to the duration of drained creep; (2) the normalized end of primary compression under final load has an average value of 1.0, irrespective of the state of soil sample in overconsolidation, spanning the preconsolidation pressure, or normally consolidation; (3) majority values of normalized end of primary compression under final load are equal to 1 or slightly less than 1. Thus, it appears from the results of this study that hypothesis A is more reasonable than hypothesis B.