以落錐貫入試驗推求土壤之塑性限度

Use of the Fall Cone Test to Estimate the Plastic Limit of Soils

馮道偉(Tao-Wei Feng)

《中原學報》 26卷3期 (1998/08) Pp. 27-32

https://doi.org/10.6358/JCYU.199808.0027

摘要

細顆粒土壤因含水量不同而呈現不同的狀態，分隔半固體狀態與塑性體狀態的含水量稱之為塑性限度。塑性限度是大地工程地盤調查中經常需要測定的土壤性質之一，但傳統的塑性限度試驗方法常因人為因素影響過高而受質疑。本文提出一個改良的測定塑性限度的試驗方法，利用落錐貫入土壤試樣中，由貫入深度可推估塑性限度之值。文中比較以該試驗方法及傳統的試驗方法測得之塑性限度，結果顯示兩種試驗測得的塑性限度僅有少許差異，由於落錐試驗受人為因素影響的程度較傳統試驗為低，建議以之替代傳統試驗。

關鍵字

塑性限度 ； 落錐 ； 不排水剪力強度 ； 細顆粒土壤

並列摘要

Plastic limit is the water content dividing plastic state and semi-solid state of a saturated fine-grained soil. The traditional method for determining the plastic limit has frequently been questioned for involving influences from personal judgments. This paper presents an improved method for determination of plastic limit. A fall cone is used with a newly developed specimen ring to measure depth of penetration of the cone at water content near the plastic limit. Non-linear relationships between depth of penetration (log) and water content were obtained and used to evaluate values of the plastic limits of 6 soils used in this study. Results of tests and analyses show that plastic limit of soils can be determined using the improved method. As compared to the traditional method, the advantages of the improved method include both less effect from personal judgments on test results and higher quality of specimens.

並列關鍵字

Plastic Limit ； Fall Cone ； Undrained Shear Strength ； Fine-grained Soil.