The behavior and properties of Tehran alluvial soils under cyclic loading of urban vibrations—a case study: Arash-Esfandiar tunnel

Abstract

Urban vibrations are increasing due to urban developments all over the world. These vibrations are daily applied to all surrounding structures, while their effects are not mainly considered in regular geotechnical analyses. This research will focus on how much urban vibrations cause displacement and strain in soil in a tunnel surrounding. In fact, using a case study data and combination of numerical analyses, empirical equations, and geodetic monitoring, the displacements and strains of soil caused by urban vibrations were calculated, compared, and evaluated. A traffic tunnel in Tehran (Arash-Esfandiar tunnel) was studied, in which a section was monitored by geodetic tools (simple instruments that are glued to the tunnel roof and their displacements measured using a theodolite). To complete the required data, microtremor recording equipment was employed to record real urban vibrations in the site. Then, using numerical modeling, the strains and displacements were obtained by applying the recorded vibrations to the model. The obtained strain values were employed to calculate the constant parameters of two existing empirical equations of Li and Selig and Chai and Miura. The obtained parameters conformed to the results of the previous studies and were all in the ranges given in those studies. Thus, the obtained parameters are proposed for the soil of Tehran for the first time. These parameters could be used for future studies on the effect of urban vibrations on Tehran soil. Furthermore, the calculated displacements were compared with the results of geodetic monitoring, which were in good agreement. The amounts of measured strains and calculated displacements show the importance of studies on the effects of urban vibrations.