Numerical Evaluation of Deflection and Swelling Pressure on Slab-On-Grade Foundation for Using Void Box in High Plasticity Soil

The purpose of this study is to evaluate the deflection and swelling pressure on Slab-on-grade foundation when using the void box in expansive soil. High plasticity expansive soil gained much concern among the engineers and scientist community due to its detrimental effect on foundation as well as the structure. Void space technology has been introduced for many years to leave some space for the foundation from the soil to minimize the effect. In order to effectively design this system, it is undoubtedly essential to predict the maximum deflection and swelling pressure underneath the void box. It is much difficult to obtain these required data from only field measurement. Therefore, a reliable model is often necessary to predict the swelling as well as pressure.

In this study, Geo-Studio was used as finite element analysis tool for the uncoupled analysis. A laboratory swelling test was performed to obtain the amount of heave for the selected soil in Texas. This experiment was simulated using the Geo-Studio program for the validation. This modeling approach was used in actual field scenarios.

From this study, it is found that, in case of a typical 16m length building with slab-on-grade foundation, water only penetrates nearly 2m after the possible maximum water influx for the yearly rainfall and prolonged flood. In case of using the extreme possible suction in Texas and considering higher hydraulic conductivity, water penetrates upto the active zone.