Abstract: The challenges faced by boring machines tunneling in soft rocks are investigated based on numerous global engineering cases and theoretical studies, and targeted improvements and designs are proposed. These designs include soft rock and haftopen horseshoeshaped boring machines based on the design philosophy of advance stress release and horseshoeshaped boring machines with external advance support based on the design philosophy of timely support. Considering the excavation, support, and synchronous grouting characteristics of boring machines and construction experience in soft rock tunnels with large deformation, key techniques and construction schemes for horseshoeshaped boring machines are explored.  Moreover, technologies such as advance screw excavation equipment, external arch frame, and shield body diameter variation are applied to the design phase to fulfill the construction requirements. Finally, the development of soft rock tunnel construction equipment is examined, highlighting the need for multifunctional and multimodal boring machines suitable for various geologies. This search for new solutions for soft rock tunnels with large deformation aims to introduce a more efficient and effective way of constructing tunnels in challenging geological conditions.

Key words: soft rock tunnel with large deformation, horseshoeshaped boring machine, multifunction and multimode boring machine, advance screw excavation equipment, external arch frame, shield body diameter variation