STABILITY OF HEADINGS AND PLANE FACES OF UNDERGROUND OPENINGS IN SOFT CLAY STABILISED BY CEMENT TREATMENT

Abstract

Face stability is typically quantified using a stability number. However, there is as yet a stability number that can quantify specifically an opening with an improved soil layer and an improved soil face. The failure mode of such openings has also not been studied. In order to allow engineers to easily adopt designs for such tunnel, a proper design framework (including failure mode and stability chart) is needed. In addition, spatial variability of cement treated soil exists due to site workmanship leading to negative impact on stability. Therefore, a preliminary random finite element study was also carried out. This study has shown that it is possible to design for underground openings with an improved soil layer and an improved soil face. Furthermore, the data gathered can inform engineers on how to come up with efficient designs for such openings with improved soil surrounds and improved soil faces.