Alluvial soils as subgrade material: Laboratory and statistical evaluation

摘要

In India, rural roads are constantly being constructed. To ensure proper design of rural roads, it is desirable to have an appropriate selection of design parameters. The California bearing ratio (CBR) method of pavement design is the most commonly used method employed for the foundation design of rural roads. In the CBR method, the CBR value of the subgrade soil is critical in deciding the overall thickness of the pavement. Additionally, for good drainage, a typical specification for the pavement foundation design requires the value of permeability coefficient of the subgrade material to be specified. Thus, permeability and CBR constitute two important parameters in the design and assessment of long-term performance of the pavement. In this study, laboratory investigation has been carried out on a number of soil samples procured from a roadwork project site. Preliminary tests, such as index tests and particle size distribution tests, useful for soil classification, were followed by light compaction, CBR and variable head permeability tests. Further, observations from the laboratory investigation are statistically analysed to study correlations among various parameters. Because the predominant soil type found in the study area is alluvial, this study also highlights the suitability of alluvial soils as pavement subgrade material.