Acta Geodynamica et Geomaterialia

Title: ANALYSIS OF CYLINDRICAL TUNNELS UNDER COMBINED PRIMARY NEAR-FAULT SEISMIC EXCITATIONS AND SUBSEQUENT REVERSE FAULT RUPTURE
Authors: Gharizade Varnusfaderani Mahsa, Golshani Aliakbar and Maidian Sina
DOI: 10.13168/AGG.2016.0024
Journal: Acta Geodynamica et Geomaterialia, Vol. 14, No. 1 (185), Prague 2017
Full Text: PDF file (2.3 MB)
Keywords: Finite element method, Near-field ground motions, Fault slip, Tunnel lining deformation, Sectional forces in tunnel lining.
Abstract: An earthquake fault rupture generates two types of ground motion: permanent quasi-static dislocations and dynamic oscillations, characterized by strong pulses. This study investigates tunnel’s response to two different conditions using a 2D finite element program; the first one has a static dislocation corresponding to different earthquake magnitudes, while the second combines near-field seismic motions with three specific peak ground accelerations along with permanent dislocations. The impulsive ground motions affect the lining response further to other influential factors such as fault type and dip angle, making changes in sectional forces, displacement, and shear distortion of the lining. Moreover, pulse intensity, period, and frequency content are effective characteristics of impulsive motions that change in final response of the lining, subjected to subsequent static dislocations. Based on the second condition, at low PGAs, the pulse type is more effective to final response of the lining, due to forward and backward momentum specifications in impulsive motions. For earthquakes with high PGA and larger values in near-field parameters, both the pulse type and period are effective. The tunnel displacement increases at PGAs as large as 0.7 and 1g, unlike the low PGA as large as 0.35g, because of increasing soil stress and plastic strain, respectively.