مهراد موسوي رحيمي

Controlling the ground-borne vibrations affecting structures by changing the geometry of the foundation is an inexpensive and efficient method of reducing vibrations at the source. A review of the existing technical literature shows the lack of a comprehensive experimental study on the vertical vibrations caused by the railway under controlled conditions, which can be used to validate the numerical models. Also, verified numerical modeling has not been performed to eva‎luate the effect of geometry and embedment depth of foundation and load frequency on the magnitude of induced vibrations in the structures adjacent to the railway line. This deficiency has been resolved in the present study. In this research, using a small-scale laboratory method in 1-g conditions along with numerical simulation essential parameters in the vibration at the receiver location such as geometry and foundation depth, structure characteristics, loading frequency and speed, and distance from the excitation source has been investigated. The test measurements using point excitation show that the frequency of the local bending mode of the floors is the fundamental parameter in the vibration level of the structure adjacent to the track and the mat foundation is the most effective in reducing the vibration level in buildings, up to 50% compared to the single type; the reason for this is the reduction of stress concentration at the columns. Furthermore, the data obtained from the finite element simulation using the moving load demonstrate that increasing the train speed results in the amplification of the vibration amplitude in the soil and structure although, the ratio of vibration level on the floors to that on the soil has been decreased as the train speed has exceeded normal speeds; the structure has rigid-body-motion. At speeds of 80, 160, and 320km/hr, TR or vibration transfer ratios are 4.8, 3.22, and 2.74 respectively. Finally, The amplitude of the oscillations in soil has been diminished by moving away from the vibration source due to the increase of soil geometric damping in the exponential trend.

مدل‌سازي فيزيكي , شرايط 1-g , روش اجزاء محدود/نامحدود , ارتعاشات القايي قطار , هندسه پي , فركانس مود خمشي دال , حركت جسم صلب

Physical modeling , condition 1-g , Train-induced vibrations , Foundation geometry , Slab’s bending mode frequency , Rigid body motion , Infinite/finite element method

Mehrad Mousavi Rahimi

Jabbar Ali Zakeri