Displacement and Deformation of the First Tunnel Lining During the Second Tunnel Construction

Abstract

A three-dimensional twin tunnels scale model was established utilizing the discrete element method (DEM) with PFC3D. This model aims to investigate the displacement (in horizontal and vertical directions) and deformation of the first tunnel lining in four different cases which the clear distance of twin tunnels are 5, 10, 15 and 20 m during the second tunnel construction process. The numerical results indicate that the clear distance between twin tunnels and the distance between the measurement points of the first tunnel and the excavation area of the second tunnel are two most critical factors that influence the displacement and deformation of the first tunnel lining. Meanwhile, the soil arching effect, gravity, water pressure and lateral pressure also have an impact on the behavior of the first tunnel. The maximum disturbance of horizontal and vertical displacements occurred in the time points of finishing of the second tunnel. However, the horizontal displacement of the first tunnel is much more sensitive to the vertical displacement. The first tunnel turns to the right and down in direction while having an anticlockwise rotation (φ) during the process of construction of the second tunnel. In addition, the displacement and deformation of the lining of the first tunnel are critical to monitor, and the necessary precautions should be taken to decrease the risk of craze. In conclusion, the influence of the second tunnel excavation on the first tunnel lining could be neglected when their distance is more than 15 m.

Research on the Resilience Evaluation of Urban Rail Transit Construction Organization Based on the Cloud Matter-Element Model: A Case Study of Nanchang West Station

“…The trust evaluation method based on the cloud model, such as Zhang, realizes the qualitative and quantitative transformation of trust and objectively reflects the randomness, fuzziness, and unpredictability of trust [42]. Zhang used the cloud model to calculate the degree of correlation of the risk in the reservoirinduced earthquake risk assessment system to the overall goal, which greatly avoided the error caused by personal subjective influence [43]. Wu et al used the cloud model to realize the transformation of experts classification of risk probability from qualitative to quantitative, which made the risk of surface subsidence in the subway shield construction stage clearer and more impressive [44].…”

A novel method to calculate pressure on the twin-tunnel in layered strata

“…However, the tunnel always buried in the complex soil layer. The existing methods are difficult to consider the effects from different soil layers [4] , [5] , [6] . To overcome the limitation of the existing methods, the proposed method is used to calculate the pressure of a twin-tunnel buried in layered strata.…”

Elastic-viscoplastic solution of a circular tunnel in Hoek-Brown rock mass

“…Jiang et al [10] divided the surrounding rock into the elastic region, the plastic region, and the plastic region, and obtained the stress and deformation solutions of each region. Wu et al [11] established a three-dimensional twin tunnels scale model utilizing the discrete element method (DEM) with PFC3D, and investigated the displacement (in horizontal and vertical directions) and deformation of the first tunnel lining in four different cases, in which the clear distance of twin tunnels is 5, 10, 15 and 20 m during the second tunnel construction process. These above solutions are instantaneous without considering the rheological factors.…”