Abstract: One of the main risks of shield construction in mixed ground is encountering local high-strength rock masses (like boulders and invading bedrock). It is hard for cutters to cut through these kinds of rock masses, and their presence creates limitations regarding the digging of traditional chamber openings or foundation pits. Controlled blasting with the help of ground holes overcomes the risk associated with these rock masses; it guarantees normal driving and ensures that the volume of broken soil is strictly controlled and meets the requirements of environmental, safety and professional health standards.