Analysis of the Dry Density–Moisture Content Relationship of Clay Soil Using a Gaussian Model: A Case Study in Pathum Thani, Thailand

Abstract

This study investigates the relationship between dry density and moisture content of clay soil using a mathematical modeling approach, with a focus on a case study in Pathum Thani Province, Thailand. The Modified Proctor Compaction Test was employed to obtain data under controlled laboratory conditions. Soil samples were collected from the field, oven-dried at 105°C, ground, and sieved to achieve uniform particle sizes. These samples were then compacted in standard molds in multiple layers to reduce voids and increase density. Statistical analysis, including Analysis of Variance (ANOVA), was conducted to examine trends and determine the optimum moisture content for compaction. Predictive models including Polynomial Regression, the Gaussian Model, and the Logistic Model were applied to estimate dry density based on varying moisture contents. The Gaussian Model demonstrated the highest predictive accuracy, supported by the lowest values of RMSE and MAE. It predicted a peak dry density of 1.505 g/cm³ at an optimum moisture content of 9 percent. The findings are consistent with previous research and suggest that the Gaussian Model is well suited for analyzing the compaction characteristics of clay soils. The results can be applied to geotechnical engineering design and construction planning in regions with similar soil profiles.