| The ultra deep foundation pit for the ship lock at the Madao Junction of the Pinglu Canal requires a maximum excavation depth of 57-62 m. The excavation involves diverse lithologies, including clay soils and clay gravel mixtures. The bedrock comprises mudstone, sandstone, siliceous rock, and limestone, exhibiting intense and uneven weathering, with well developed karst features in the limestone. Structurally, the area is complex with multiple folds and faults, leading to a fractured rock mass, densely developed joints and fissures, and consequently poor slope stability. Additionally, the hydrogeological conditions are extremely challenging. To address these complexities, a comprehensive investigation was conducted utilizing geological remote sensing and mapping, drilling, pumping tests, water pressure tests, the transient electromagnetic method, the surface wave method, borehole wave velocity tests, borehole televiewer logging, and laboratory tests. This approach successfully characterized the engineering geological and hydrogeological conditions within the pit area. Construction has verified that the exposed geological conditions align well with the investigation results, thereby mitigating the risks associated with the complex ground conditions. |