Abstract:

The influence of train caused vibration on surrounding free field and tunnel foundation pit excavation is analyzed by static load model and dynamic load model respectively based on software FLAC3D. Some conclusions are drawn as follows: 1) The results from static load model are smaller than those from dynamic load model. 2) The vertical components play one of the key roles in the train caused vibration load and its amplitude attenuates quickly along the horizontal direction; and the impact scope of vibration along horizontal direction is about 6 m. 3) The impact scope of vibration along vertical direction is about 20 m, and the relationship between settlement of foundation pit and depth presents quadratic curve. 4) The deformation of the foundation pit bottom during construction process presents inverted arch trend and its maximum value is about 5-8 mm. 5) The anchor cable supporting technology can evidently reduce lateral deflection of the foundation pit wall. The study shows that after adopting the retaining piles and anchor cable supporting system, the whole dynamic stability of the cutandcover tunnel is not significantly affected by train caused vibration load on existing railway.

Key words: train load, cutandcover tunnel, supporting structure, dynamic response, deformation law