Numerical Simulation of Interactions between the Shield-Supported Tunnel Construction Process and the Response of Soft Water-Saturated Soils

Abstract

During the design and construction of shield-driven tunnels, a reliable analysis of the construction process is required for the prognosis of the process-induced surface settlements, changes in soil stresses, and changes in groundwater conditions, as well as for the determination of the loads acting on the tunnel tube and on the tunnel-boring machine. In this context, numerical simulation methods like the finite-element method allow for a realistic description of the construction process and its impact on the surrounding underground. The investigated problem is governed by the interactions between the tunneling process and the surrounding underground and its constituents—soil grains, groundwater, and pore air. The tunnel-construction process interacts with the surrounding underground via the heading face support, by frictional contact between shield skin and soil, and because of grouting of the annular gap. Considering these interactions, a holistic simulation model is presented for the process-oriented simulation of shield-supported tunnel advance and its interactions with fully saturated, partially saturated, or nonsaturated soft soil. Its applicability is demonstrated by selected simulations of real-scale examples. Parametric studies are performed to investigate the influence of soil conditions and of process parameters on the time-variant settlements and groundwater conditions, showing its capabilities with respect to the simulation of the soil-process interactions in front, above, and behind the tunnel-boring machine.