Key Shield Construction Technologies in Middle Route Yellow River-Crossing Project of South-to-North Water Transfer Project

There are many difficult technical problems in the construction of the Yellow River-Crossing Shield Project in the middle route project of the South-to-North Water Transfer Project,due to complicated geological conditions,large buried depth,high groundwater pressure,long tunnel line and large tunnel diameter. In the construction practice,some technologies are developed,to ensure the successful project construction. They include mud configuration technology,excavation surface stabilizing technology,wall-back grouting technology (beyond the current standard practice),shield construction seepage control technology under high groundwater pressure,shield access section ground consolidation technology,hyperbaric operation technology under large buried depth and high groundwater pressure,shield construction attitude control technology,precise long distance shaft connection survey technology,long distance mud transportation technology,high gradient driving technology. Various technical indexes in the Yellow river-crossing shield project are satisfactory,and these technologies would provide some guidance for similar projects in the future.