Use of the stiffness method to evaluate the improvement of the bearing capacity of soil reinforced by microgrids

Abstract

The search for soil strength and stiffness improvement is essential in geotechnical engineering. Geosynthetic reinforcement has been considered an effective solution, as it increases the stability of geotechnical works and reduces settlement. These materials are used in works that require greater stiffness, as well as shear and tensile strength, such as foundations and retaining walls. Among geosynthetics, microgrids are used to promote the separation and reinforcement of soils. However, because it is a recently developed geosynthetic on the market, little is known about its properties in soil reinforcement structures, especially when compared with other geosynthetics with the same function, highlighting the need for more research. This research aimed to evaluate the improvement in the bearing capacity of soils reinforced with microgrids. As the results of the pressure x settlement curves did not characterise a typical physical failure behaviour, the failure was conventionally defined based on the Décourt stiffness method. Through the analysis of pressure x settlement curves, the behaviour of natural soils was compared with (i) compacted samples and (ii) compacted samples reinforced with three layers of microgrids. This demonstrated the increase in soil bearing capacity and stiffness through these improvement techniques, which was even more significant when microgrids were inserted in the compacted soil sample. The inclusion of microgrids as a reinforcing element is an effective alternative for stabilising foundations. The stiffness curves showed a tendency to stabilise without reaching zero stiffness, which, according to the Décourt method, confirms the absence of physical failure.