Numerical modeling of tunnel interaction and normal faulting in sand Deposit

SummaryThe present paper studies on the propagation characteristics of fault rupture and the behavior of tunnel exposed to the fault displacements to increase the performance of earthquake-resistant structures. In this study, the effect of the presence or absence of the tunnel in the normal fault rupture propagation has been modeled by discrete element software. Also, in order to validate the numerical studies performed in this research, the results were compared with a series of centrifuge experiments results conducted at NCU centrifuge laboratory. The results indicate that the presence of the tunnel has changed the direction of the fault rupture, and also the shear zone in surface and subsurface of the soil layer has been widely spread. IntroductionThe main objective of the study is to provide understanding into shear zone and ground deformation taking place in sand with the presence of a tunnel in the faulting zone. The paper begins with an explanation on the construction of the soil model with DEM. The research continues with validation and comparison of DEM simulations with centrifuge results to gain a better understanding of this numerical modeling for replacing laboratory tests.Methodology and ApproachesThe discrete element method is a suitable numerical model for defining the mechanical behavior of spheres and integrated disks in which the particle-to-particle contact interaction is controlled and the particle motion is modeled particle by particle. In PFC modeling the composite material consists of a group of rigid grains that interact at their point of contact. The process of the modeling and the problem solving in PFC2D involved several steps that were accomplished by using appropriate Fish functions. Results and ConclusionsThe results indicate that the presence of the tunnel has changed the direction of the fault rupture, and also the shear zone in surface and subsurface of the soil layer have been widely spread with the presence of the tunnel. Comparison between numerical studies and centrifugal experiments shows that the interaction between faulting and tunnel depends on tunnel overhead pressure, tunnel stiffness, tunnel position relative to the fault center and soil mechanical parameters. It also shows the deviation of the faulting path, the surface displacements and the increase of the risk of normal faulting on the surface structures.