Shield tunneling database management for ground movement evaluation

Abstract

Tunneling in urban environments is very challenging and ground movements induced by tunneling are major concerns during excavation. Based on many case histories, one realizes that many factors such as geological conditions, shield operation, and tunnel geometry affect ground movements. Therefore, to understand the complicated behavior of ground-shield interaction, all geological data, instrumentation records, tunneling data, surveying records, and daily activity updates have to be systematically collected and managed. During the excavation of the Bangkok MRTA project, a 22 km twin-tunnel, observation and data collection were extensively conducted at the subway project while eight EPB shields were excavating the tunnel. In this context, a computerized database system was assembled using all information collected from the MRTA project which records on a ring-by-ring (1.2 m interval) basis. The database contains monitoring results that include all shield operational records, field instrumentation readings, and geological information. The database system consists of different hierarchic levels. The main database provides linkages to sub databases (e.g., second and third levels), and within main databases. Input data were associated with the lining ring number along the tunnel alignment. The main advantage of this computerized database is that it does not only serve as a data management tool, but can also be used for studying of the ground-shield interaction by providing: (1) records of operational parameters (i.e., face pressure, penetration rate, thrust force, grouting pressure, time and shield position) along the tunnel alignment; (2) instrumentation readings (i.e., surface settlements, sub-surface settlement, lateral deformation and pore pressure); (3) tunnel alignment coordinates; (4) instrumentation layouts; and (5) geological conditions. Hence, this computerized database is useful for the study of the EPB shield tunneling method and ground deformations. Moreover, the database was used as an evaluation system to identify which ground- and EPB-characteristic have the greatest influence on ground movements and to show correlations between parameters. Therefore, this developed database can help tunnel engineers and shield operators to evaluate ground deformations caused by the shields during the tunnel excavation. (A) Reprinted with permission from Elsevier. For the covering abstract see ITRD E124500.