Predicting the consolidation settlement using the Compression Index and Coefficient of Consolidation based on sieve #40 and #200 in Pakistan

Abstract

This study aims to develop empirical correlations for the compression index (Cc) and the coefficient of consolidation (Cv) with the liquid limit (LL) for soils from various locations in Pakistan. This research addresses the gap by offering a simpler, cost-effective method to estimate Cc and Cv based on LL, thereby reducing the need for extensive laboratory testing. Soil samples were collected from 100 different sites and subjected to comprehensive laboratory testing, including sieve analysis, hydrometer analysis, specific gravity determination, Atterberg limits, and consolidation tests using an Oedometer apparatus. A critical comparison was made between the liquid limits obtained from soils passing through sieve #40 and sieve #200, highlighting the impact of fine sand inclusion on LL values. Initially, 40 correlations were developed by exploring various soil index properties; however, only 4 correlations were retained due to the minimal impact of other parameters compared to the liquid limit on the compression index and coefficient of consolidation. Priliminary attempts to correlate Cc and Cv with multiple soil parameters through a multilinear regression model indicated high p-values, prompting a focus on LL as the sole predictor. The simplified model demonstrated statistical significance, with low p-values affirming the robustness of the correlations. To validate these findings, additional soil samples from 50 locations were analyzed, and the resultant percentage error for both Cc and Cv was found to be less than 1%, ensuring the reliability of the developed correlations. By comparing the results with past research, it was observed that previous models often overestimated or underestimated Cc and Cv values. This research offers more accurate and region specific correlations, enhancing the understanding of soil compressibility characteristics in Pakistan