Abstract:

The hardening soilsmall (HSS) model has significant advantages in simulating and predicting the deformation of surrounding strata induced by shield construction in a soft soil layer. However, several calculation parameters are in the model, which cannot accurately ensure the simulation results when crossing underneath multiple buildings. Based on the field measured stratum and building deformation data, a threedimensional numerical model of shield tunnelsurrounding building group integration realtime feedback is developed. Next, through the numerical model of the test section where the shield does not cross underneath buildings and the measured values of ground settlement, a set of HSS model correction parameters suited for local soil layers is obtained by inversion. Finally, based on the HSS model, the parameters of the building foundation, soil model, and shield model are modified according to the measured values of building points, surface settlement, and the adjustment of technical parameters of shield advancing. The engineering applicability is validated in the Suzhou metro line S1 shield section project, and the results show the following: (1) For the tunneling of a circular shield with a diameter of 6 m, the principal subsidence deformation of the surface of the soft soil layer and adjacent buildings is affected by the tunnel face along the range of the excavation direction of 50 rings and the opposite excavation direction of 35 rings. (2) Due to the construction methods such as early grouting reinforcement, the measured settlement of the building foundation is generally smaller than the calculated value and the deformation of the adjacent surface. (3) The main risk lies in the first excavated left tunnel, and the deformation of the later excavated right tunnel is minor in terms of mechanical mechanism and related to the primary and secondary release of ground stress. The simulated and measured settlement of the first excavated right line tunnel is 0.5 ~ 0.7 times that of the left line tunnel.

Key words: hardening soilsmall model, shield tunnel; numerical simulation, ground subsidence, building subsidence