The Influence of Back Pressure and Consolidation Stress on the Coefficient of Permeability of Compacted Soils

• Published in: Transactions of The Japanese Society of Irrigation, Drainage and Reclamation Engineering Vol. 1984; no. 113; pp. 51 - 56,a2
• Main Author: TORIYAMA, Koushi
• Format: Journal Article
• Language: English; Japanese
• Published: The Japanese Society of Irrigation, Drainage and Rural Engineering 1984
• ISSN: 0387-2335; 1884-7234
• DOI: 10.11408/jsidre1965.1984.113_51

The influence of back pressure and consolidation stress on the coefficient of permeability of compacted soils are investigated with laboratory works using compacted decomposed granite soil and Fujinomori clay. The permeability tests are conducted using triaxial cells, and back pressure or consolidation stress is applied up to 6.0 kg/cm2. From these experiments, the following results are obtained: (1) For compacted decomposed granite soil in which moisture content is in the range of 1.0 to 4.0% of wet of optimum moiture content wopt, the coefficient of permeability k increases more than twentyfold by increasing back pressure ub but for the soil in the other range of moisture content, k increases only about twice by increasing ub, and as a result, the large change of k in the vicinity of wopt disappears. (2) For the compacted Fujinomori clay, the coefficient of permeability is about 1.0×10-7-4.0×10-7cm/s and it does not change with the variation of compacted moisture content and increase of back pressure. (3) The coefficient of permeability decreases from 1/2 down to 1/5 by increasing consolidation stress from 1.0 to 6.0 kg/cm2. From these results, it is concluded that the influence of back pressure must be taken into consideration while selecting the impermeable material of fill dam.