Abstract:
Rigid inclusions are often considered a ground improvement option that provides soil reinforcement and settlement mitigation. Most often, the improvement is modeled through the mechanical contribution of the rigid inclusion, and disregards the beneficial effect of the installation of the rigid inclusion on the mechanical properties of the soil. In other cases, the magnitude of improvement of soil properties is estimated based on mechanistic approaches. In the first case, ignoring the improvement in soil properties caused by installation of the rigid inclusions can lead to significant conservatism and unnecessary cost and schedule impacts on the project. In the latter, excessive optimism in the level of soil improvement can lead to por performance. This presentation will focus on the analysis of actual pre- and post-installation Cone Penetration Test (CPT) data that demonstrates the densification of soils with a significant granular component within a grid of rigid inclusions. The presentation will also discuss the range in densification effects and limitations for different soil types, including the effect that rigid inclusion installation has on soft sedimentary soils. It will also show the influence that the improved mechanical properties of the soil have on the evaluation of slope and foundation stability, and will discuss proper ways to pan and perform pre- and post-construction testing.