Abstract
The utilization of tail void grout as a stabilizing and sealing agent in mechanized tunneling procedures is of paramount significance, given the geological and engineering conditions inherent to tunneling projects. Prior to its application within a tunnel, a detailed evaluation of the fresh-state characteristics of the grout, as well as the time-dependent evolution of its hydro-mechanical properties, becomes imperative. This review paper aims to provide a comprehensive introduction to the various types of tail void grouting materials used in mechanized tunneling. The potential for behavior enhancement of the grout through the utilization of different additives, considering diverse mixing ratios in varying ground conditions, is discussed. Moreover, an in-depth analysis of the fresh- and hardened-state properties of different grout types, along with the cross-effects induced by additives in the grout mixture, is presented and reviewed. The paper also delves into the testing methodologies and property investigations employed to assess different grout types using experimental approaches. Additionally, a detailed overview of the numerical simulation of mechanized tunneling is provided, with a particular emphasis on the role of grout. Finally, the coupled hydro-mechanical effects of typical grout additives are explored, and the applicability of various grouting material according to the ground conditions is presented and discussed.