Tunneling in highly permeable ground using a slurry shield machine can be challenging because it is difficult to form the so-called filter cake on the tunnel face to transport the support pressure. Consequently, destructive accidents might happen, such as face instability and water inrush. How to form an efficient filter cake in time is crucial during engineering practice, especially in ground with high permeability. Various theoretical and experimental analyses regarding the formation of filter cakes have been conducted. However, due to the complexity of this problem, which has to incorporate the mechanical and hydraulic behaviors of the fluid–solid mixture system, few numerical simulations are found in the literature. In this paper, with the aid of a newly developed numerical tool, a coupled CFD (computational fluid dynamics)–DEM (discrete element method) simulation is established to study the slurry infiltration and filter cake formation during slurry shield tunneling. The slurry infiltration process is simulated by modelling the scheme of the infiltration column test, in which sedimentation behaviors of slurry particles are captured and compared with experimental results. The results show that the sedimentation behaviors of the slurry particles and filter cake formation phenomenon are well captured by simulations and in accordance with the experiments, which indicates the robustness of the coupled CFD–DEM simulation used in present work.

This paper presents a smart solution for the utility tunnel, which allows hosting a wide range of water and energy utilities in an accessible underground space. It is well known that utility tunnels offer major advantages such as the possibility to inspect, maintain, and easily extend urban utilities without excavation, thereby eliminating disturbances related to urban excavation such as traffic jams, noise, pollution, and pavement degradation. However, despite these advantages, the effective development of this facility remains below expectations, because of serious challenges related to the security and governance of this “shared space”. The solution presented in this paper is based on discussions with experts and companies involved in the design, construction, and management of utility tunnels, as well as on the authors’ experiences in the design and implementation of smart solutions for urban utilities. The paper firstly presents the major challenges of utility tunnels and then discusses how theb smart technology could help in coping with these challenges. The paper presents the architecture of this solution, as well as the main layers of monitoring, information system data analysis, and system control. It also presents the methodology to be followed for the implementation of this smart solution. Finally, the paper discusses two major issues for utility tunnels: fire risk and risk assessment. The paper shows that the use of smart technology allows developing a comprehensive digital solution, which uses advanced monitoring system to collect real-time data about the tunnel environment and functioning. These data can be easily shared by authorized staffs. Analysis of these data allows improving the utility tunnel security and performances.

A new block-classification method for tunnel construction using a tunnel-boring machine (TBM) to capture the geometrical and mechanical transformation of rock blocks in the course of TBM excavation is proposed in this paper. The machine–block interaction is interpreted by dividing the joint blocks into blocks influenced by TBM excavation and blocks uninfluenced by TBM excavation. The influenced blocks are categorized further as contacting or noncontacting blocks according to whether they are in contact with the TBM. The contacting blocks include the front block, the corner block, and the rear block, based on the spatial location of blocks with respect to the cutterhead. Different types of blocks have distinct kinematic and mechanical characteristics. The sizes and shapes evolve, and the categories may be changed for rock blocks during excavation. The identification algorithms for influenced blocks and three types of contacting blocks are presented. Finally, a simple example considering a double-sh...