Deep settlement patterns for evaluating environmental impact of shield tunneling in soft ground

Abstract

Deep settlement caused by tunneling exhibit varied patterns of distribution along depth, depending on the construction disturbance, soil strata layers and properties around and above tunneling workface as well as surcharge or building gravity loads on the ground surface. Patterns of deep settlement distribution were formulated and analyzed by considering ground volume loss, dispersing of excess pore pressure, shrinkage of grouting slurry, surcharge and building gravity load above the tunnel, etc. Then, five typical patterns of deep settlement distribution were established by combining the respective effects of these factors and verified by an in-situ test on deep settlement distribution using multi position extensometers for monitoring effects of shield under passing a building. It is hoped that the achievements in the paper are helpful for prediction, monitoring and evaluation in the process of environment protection.