An Overview of Mechanical Tunneling Machines and Techniques for Soft Ground

This paper presents an overview of the tools and techniques used in soft-ground tunneling. The history of mechanized soft-ground tunneling is reviewed to describe the major advances leading to the development of the modern tunneling machine. Major subsystems of modern machine boring are then described in some detail, including excavation, support, and materials handling. The paper concludes with a summary of the current state-of-the-art of mechanical boring, followed by a look at near-term innovations and their impact on future machine boring.