Measurement and numerical modelling of the process of tunnelling

In order to obtain a precise and reliable measurement database for the validation and qualification of simulation tools describing the deformations induced by tunnelling operations, two sites on the Lyon Metro D line extension have been intensively monitored. This paper presents the results of measurements from two experimental transverse tunnel sections of this line, A comparison with data from previous projects shows that the instability of the tunnel face and the annular void created by the passage of the shield constitute the principal sources of short-term settlement. Based on these measurements, a new procedure of numerical simulation in the plane strain conditions is proposed, taking into account various stages of construction. The comparison of the observed and simulated movements shows that the behaviour of soft ground is better simulated by displacement control than by stress control of the periphery of the excavation.