Analysis of the Effect of the Micropile Umbrella on Ensuring Tunnel Stability and Settlements

Abstract

The primary objective of this research study was to accurately assess the beneficial impacts of the umbrella arch method (UAM) (as well knows as Forepoling Umbrella System (FUS) or micropile umbrella), on the stability and settlement of the future Poříčí tunnel, located in Czech Republic. In this study, through a comprehensive evaluation, initially, the information on the tunnelling procedure, the umbrella arch method deployment, and the various aspects of staged construction were gathered from Poříčí tunnel project, in consideration of actual field conditions. This information coupled with laboratory derived geotechnical properties of the existing rocks was in turn incorporated into a series of finite element simulation models using the Midas GTS NX software, to find the optimum parameters combination to minimize the internal tunnel deformation. Indeed, by incorporating the umbrella arch method in the tunnel, theoretically, a 42.17% reduction in vertical deformations at the tunnel crown were achieved.