Abstract
Heaving soils are the most problematic worldwide. These soils develop swelling stress that produces uplift forces detrimental to the foundations. In engineering practice, swelling stress is not considered in general. Considering the swelling stress in foundation design enhances the service life of construction. The oedometer swelling test is the technique ordinarily used to assess the swelling stress. Nonetheless, the oedometer swelling test is cumbersome, time-consuming, making the test unattractive, and not cost-effective for the low-cost housing project. The objective of this research work is to propose a model to predict swelling stress as an alternative to oedometer testing. Geotechnical studies such as Atterberg limits, particle size distribution, free swell ratio, specific gravity, linear shrinkage, suction measurement, Proctor compaction test, and zero-swell test are performed to estimate the soil properties. Multivariate regression analysis is performed using NCSS.11 Program to develop the predictive model. The model is assessed base on the following: determining coefficient value, comparing predicted values with experimental values, comparing the proposed model with other existing models found in the literature. Besides, the Box-cox transformation function is used to improve the accuracy of the model. The developed model can be utilized to assess the swelling stress of compacted heaving soils, and it is much more accurate than other existing models.
Highlights
Introduction and BackgroundDefects on constructions caused by heaving soils were first reported in South Africa in 1950, especially in Goldfield Mine Free State
Model Equation (3) presented in Table 1 is developed without the soil suction using three independent variables as follows: Plasticity index, water content, and dry unit weight
WKS-C displays a higher amount of clay fraction estimated at 55.25%, whereas BLS-A displays a smaller amount of clay fraction estimated at 30.4%
Summary
Defects on constructions caused by heaving soils were first reported in South Africa in 1950, especially in Goldfield Mine Free State. Model Equation (3) presented in Table 1 is developed without the soil suction using three independent variables as follows: Plasticity index, water content, and dry unit weight. Reference [9] conducted a series of oedometer tests on heaving soils to determine the swelling stress developed within the soil specimens upon the initial moisture content, dry unit weight, and swell-shrink index. Reference [6] proposed a model Equation (7) to predict the swelling stress for heaving compacted soil for soil suction utilizing the soil-water characteristic curve (SWCC). Reference [11] investigated the swelling stress of heaving clay of Barranquilla, Colombia, and developed a semi-empirical model Equation (8) using the plasticity index (PI) and the water content (W). The swelling stress is (Ps) in kPa, and given in Equation (9)
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