A soil identification method for potential road construction problem sites on the Olympic Peninsula, Washington

Koler, T.E. 1995. A soil identification method for potential road construction problem sites on the Olympic Peninsula, Washington Environmental and Engineering Geoscience. 1(2):129-137 (Summer 1995). https://doi.org/10.2113/gseegeosci.I.2.129

Keywords: soil identification; Washington State; soil strength

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Abstract: Several logging road subgrades and cut slopes failed under wet conditions in the 1980's on the Olympic Peninsula in Washington. Although standard laboratory soil test results did not indicate this would occur, field tests showed possible soil failure. A majority of these soils were coarse-grained with significant amounts of fines (silt and clay). Field soil identification methods indicated that these soils had a moisture content above the plastic limit; the laboratory test results were mostly non-plastic. During construction, the soils performed like plastic soils with low strength values, although in the laboratory the soils had suitable strength values for normal road construction methods. An hypothesis that standard laboratory tests for soil strength values do not detect organic and/or clay minerals that lead to failure under wet road construction conditions on the Olympic Peninsula was proven correct. A combined field and laboratory testing procedure was developed for identifying these soils.

Moscow FSL publication no. 1995j