Behavior of a Foundation Built on Geogrid-Reinforced Sand in the Presence of Twin Subsurface Voids

Underground voids can affect the stability of a foundation and increase structural settlement, especially when they are located directly beneath the foundation. They can arise from a range of sources, including natural formations and buried infrastructure. If these voids interact with the foundation, they can lower its bearing capacity, making them hazardous and costly to remedy. The behavior of soil having a single void has been the subject of past research, but few studies have examined the behavior of soil with twin voids. The current study used physical modeling to examine the effect of the use of geogrids on the behavior of a sandy bed with twin voids. The variables examined included soil density, void embedment ratio, void distance ratio and the number and vertical spacing of the geogrid layers. The use of scaled reinforcements sets this study apart from comparable investigations. Particle image velocimetry was used to examine the development of the failure wedge and the strain rate produced at the surface. The outcomes indicated that both an increase in soil density and the number of geogrid layers greatly increased the soil load-bearing capacity. The bearing capacity of dense soil reinforced with two layers of geogrid increased by 51.8% compared to dense soil without reinforcement. The shear strain rate at the critical slip surfaces beneath a foundation built on dense soil decreased strongly with the use of two geogrid layers.