Permanent Deformation of Subgrade Soils Phase 2: Repeated Load Testing of Four211 Soils

摘要

This reports the second phase of a three-phase project to study the permanent211u001edeformation behavior of subgrade soils. Four Arkansas soils were tested in this 211u001ephase to develop data that can be used in Phase III. Phase III will examine the 211u001eeffect of factors such as deviator stress, moisture content, first cycle freeze-211u001ethaw, density, load history, and soils type in subgrade permanent deformation. 211u001eAll the repeated load tests were conducted using the test protocol established 211u001eduring the first phase of this study. The test protocol consists of repeated load 211u001etriaxial testing. The confining pressure of repeated load testing was set to a 211u001efixed value of 21 kPa (3 psi). Load frequency was 1 Hz with a duration of 0.1 211u001esecond followed by a rest period of 0.9 second. Deviator stresses were varied to 211u001edetermine their effect on the deformation accumulation. Moisture contents were 211u001eset to three levels to simulate the service range of highway subgrades in 211u001eArkansas. The moisture contents were 105%, 110%, and 120% of the soil's optimum 211u001emoisture content. Some specimens were subjected to one cycle of freeze-thaw to 211u001egain data on the effect of this parameter.