Ground Penetrating Radar Equips Tunnel Shield Machines with "Smart Eyes"

A shield machine, fully named a tunnel boring machine (TBM), is specialized heavy machinery for tunnel excavation. Modern TBMs integrate optics, mechanics, electronics, hydraulics, sensors, and information technology. They perform key functions including soil excavation, spoil removal, tunnel lining assembly, and measurement-based guidance with correction capabilities. This complex equipment spans multiple disciplines—geology, civil engineering, mechanical engineering, mechanics, hydraulics, electrical systems, control systems, and surveying—and requires custom design and manufacturing tailored to specific geological conditions, demanding extremely high reliability. Tunnel boring machines are now widely used in subway, railway, highway, municipal, and hydroelectric power tunnel projects.

Challenges in Shield Tunnel Construction: Shields create annular gaps between the tunnel and surrounding ground, which are filled via backfill grouting. Inadequate or incomplete grouting, if undetected, can lead to poor tunnel quality and excessive surface settlement during construction, as well as tunnel instability and leakage during metro operations.

Real-Time Grouting Monitoring System for Tunnel Boring Machines – Giving TBMs Smart "Eyes": To address challenges in tunnel boring construction, Wuhan Shilong Technology Co., Ltd. has partnered with China Railway No. 10 Engineering Group and China Railway Beijing Engineering Bureau Group to develop a real-time grouting monitoring system. Utilizing ground-penetrating radar, this system provides TBMs with intelligent monitoring capabilities, enhancing both project safety and construction efficiency.

Real-time Monitoring System for Grouting Synchronization

Wuhan Shilong Technology Co., Ltd. innovatively integrates ground-penetrating radar (GPR) with shield tunneling machines. As the shield machine advances, GPR performs real-time scanning of the tunnel lining to assess its condition. Since water and concrete reflect electromagnetic waves differently, GPR enables accurate identification of the medium composition between segments and surrounding soil, as well as precise evaluation of grout filling behind the segments. During shield excavation, the synchronous grouting monitoring system delivers grout promptly into the annular gap formed between the shield tail and the segments. This ensures that newly detached segments gain immediate support from the surrounding soil via the grout, preventing soil collapse around the segments and controlling surface settlement. If leakage or voids are detected behind the lining, secondary grouting can be performed immediately, significantly enhancing construction safety and efficiency.

Currently, the system has been deployed on Jinan Rail Transit Line 6 by China Railway No. 10 Engineering Group and China Railway Beijing Engineering Group Co., Ltd. Overall feedback is positive, with work efficiency improved by over 50%. Group leadership has indicated that the system will be expanded to more tunnel shield construction projects in the future.