The first phase of a three-phase research investigation of cut slope design criteria for southeastern Washington loess has been completed. A literature review of engineering properties of loess from other locales and design criteria applied by various state transportation departments was conducted. Also, a preliminary field investigation was made to collect representative soil samples and record failure mechanisms. Past research has revealed that proper drainage control in combination with water content and gradational characteristics are the primary factors influencing cut slope performance in loessial soils. Analysis of 40 soil samples collected during the field study demonstrate a close similarity between southeastern Washington loess and deposits from the central United States. Although physical properties are similar, differing climates produce a disparity in failure mechanisms between midwestern and southeastern Washington loessial deposits.
Washington State Transportation Center (TRAC)
Aggregate gradation, Design, Drainage, Embankments, Erosion, Failure, Guidelines, Literature reviews, Loess, Moisture content, Soils, Slope stability.