Abstract: The breaking of high-strength reinforced concrete segments in main tunnel construction presents challenges such as large disturbance, low efficiency, and high energy consumption. To address these limitations, a circumferential-cutting type cutterhead designed for connection tunnel boring machines is introduced. First, the shortcomings of traditional connection tunnel construction methods are analyzed, and an innovative method that breaks reinforced concrete segments through local cutting ring grooves using a circumferential-cutting type cutterhead is proposed. Second, a tunnel boring machine with a circumferential-cutting cutterhead is developed based on this concept, along with a full-scale test platform for in-plant testing. These experiments specifically assess performance differences between circumferential and full-section cutting methods. Finally, the developed equipment is applied to the connection tunnel of the  Suzhou rail transit line S1 to verify its field practicability. The results reveal the following: (1) By cutting only a single ring groove, disturbance to the reinforced concrete segments and surrounding strata of the main tunnel is extremely low, thereby ensuring construction safety. (2) The required torque and thrust are significantly lower than those of the full-section cutterhead, resulting in higher working speed and lower energy consumption. (3) The equipment successfully facilitates the rapid removal of the reinforced concrete segment at the receiving end within a short construction period, verifying its advanced design and engineering applicability.

Key words: connection tunnel, tunnel boring machine, circumferential-cutting type cutterhead, cutting ring