Evaluation of existing alluvial soil subgrade using dynamic cone penetrometer and index properties

The pavement structural failure of properly designed roads is major cause of concern for road authorities. The cost of rectification is huge and no one take the onus of failure. Most of the major roads are built with financial assistance of various development agencies thus the failure of roads defeats the primary aim of development of necessary road network that paves the way for further development activities. The performance evaluation of a flexible pavement is based upon its stability against the following failures
1. Pavement structure failure: Fatigue (Alligator) Cracking, Block Cracking, Edge Cracks, Reflection Cracking, Upheaval/Swell etc are considered as pavement structure failure and need lot of resources for rectification or reconstruction.
2. Surface failure: Pot Hole, Raveling/Weathering, Bleeding, Polished Aggregate Loss of Aggregate on Surface Treatments, Longitudinal/Transverse Streaking
3. Miscellaneous: local failure such as Utility Cuts/Patch Failure
The subgrade being the natural foundation, plays a crucial role in performance of road crust. In-situ subgrade strength can be estimated through a California Bearing Ratio(CBR) prediction model using Dynamic Cone Penetrometer (DCP), index properties of soil and laboratory CBR test procedure. The aim of the study is to find in-situ Million Standard Axel (MSA load carrying capacity without formation of ruts not more than 20 mm deep and development of not more than 3 mm wide cracks in 10% surface area. In this study, a stretch of 20 Km of 45 Km long State Highway No 11 section Ludhiana to Malerkotla is investigated. From the studies, it is found that expected performance of road can be evaluated based upon the perdition model. In this study, prediction model with three different soil groups, non-plastic soils having (PI=0), low plasticity index (PI 1 to 4) and soils with medium plasticity index (PI 5 to 7), is used. The effect of moisture on DCPI is used to evaluate the in-situ CBR at worst moisture conditions. To find the crust sufficiency equation based on Equivalent Single Wheel Load (ESWL) is used.