Core Viewpoint - The successful completion of the TBM breakthrough for the Chongqing Rail Transit Line 7 Phase I project marks a significant milestone in the construction of a vital north-south transportation artery in western Chongqing, enhancing connectivity among various urban clusters [1][2]. Group 1: Project Overview - The Chongqing Rail Transit Line 7 Phase I project spans approximately 28 kilometers with 18 stations, connecting key areas such as Xiyong, Hangu, and Jinfeng [1]. - The recently completed section measures 2,340.669 meters, with the TBM segment accounting for 1,727.363 meters, navigating through complex geological conditions including high-strength sandstone and mudstone [1]. Group 2: Technical Innovations - The project team implemented innovative technologies to address the challenges of tunneling through long-distance, high-strength rock layers, utilizing a proprietary wear-resistant coating with a shear strength exceeding 350 MPa, significantly enhancing tool durability [2]. - The team achieved a remarkable feat of continuous tunneling through hard rock without the need for opening storage or changing tools, ensuring a smooth construction process [2]. Group 3: Safety Measures - To mitigate the risk of segment uplift in hard rock layers, the project team meticulously controlled tunneling parameters and optimized grouting processes, resulting in high-quality tunnel lining with no significant misalignment or damage [2]. - A specially developed track surface treatment device was created to enhance traction on steep gradients, effectively addressing safety concerns during transportation within the tunnel [2].

Core Points - The "Electric Pioneer" TBM (Tunnel Boring Machine) has commenced operation, marking the start of the shield tunneling phase for the Chongqing Rail Transit Line 7 Phase I project, which spans approximately 28 kilometers and includes 18 stations [1][2] - The project aims to enhance the north-south transportation capacity in Chongqing, connecting various urban clusters and facilitating transfers with existing and under-construction rail lines [2] Group 1: Project Overview - The Chongqing Rail Transit Line 7 Phase I will connect key areas such as Xiyong, Hangu, and Jinfeng, with a total length of about 28 kilometers and 18 stations [1] - The tunneling section includes a 3.3-meter shallow cover segment and a challenging 1,332-meter segment with a 38‰ gradient, requiring significant engineering solutions [1] Group 2: Technical Specifications - The "Electric Pioneer" TBM has a working length of 85 meters, a diameter of 6.84 meters, and weighs approximately 500 tons, with a main drive power of 945 kW and a maximum thrust of 4,344 tons [2] - The TBM is designed to achieve an average daily advance rate of 9 to 12 meters while performing excavation, support, and ventilation tasks [2] Group 3: Engineering Innovations - The construction team has implemented 3D simulation technology for advanced planning and developed an intelligent control system for real-time data analysis to ensure efficient tunneling [1] - A special wear-resistant layer with a shear strength exceeding 350 MPa has been added to the TBM's cutting tools to enhance durability against hard rock formations [1]