Dynamic Interaction Research Of The Large Angle Oblique Metro Tunnels With Crack Under Vibration Loads Of Train

Xi’an,as an international city, has the increasing ground track traffic pressure, so the construction of subway is springing up in the big city.By now,there are two subways working in Xi’an,including metro line 1 and 2.The construction of mero line 3 will finished in 2015. And the metro line 4 is in the period of preparing. The geological problem of ground fissures and the movement of ground fissures will damage the tunnel and the metro rail.Subway construction and operation have brought the problem of the metro rail.Subwa construction and operation have brought the problem of the tunnel-stratum-ground fissure dynamic interaction and the subway vibration in ground fissure area.This paper is relying on the National Natural Science Foundation project“study on the interaction of the stratum–ground fissure –tunnel under the subway dynamic load”,based on the ground fissure belt of xi ’an subway project, design and carry out of the ground fissures and oblique horseshoe subway tunnel dynamic model test, in combination with numerical simulation, the ground fissures with oblique characteristics of the subway tunnel under train load are studied, mainly the understanding is as follows:(1)Subway travelling produces vibration propagation in all directions in the soil with different degree of attenuation, ground fissure has barrier the vibration.(2)The vibration of the ground fissures near the tunnel beneath the soil is larger than the upper soil layer; The response of subway tunnel arch at the bottom is more intense than of a hance and arch part.(3)As the ground fissure not activities,the earth pressure in the location of below the tunnel of train load is more larger; when the upper plate falling on the ground fissures, the earth additonal pressure in the upper tunnel present the larger in upper plate and the smaller in the lower plate.the opposite results exist in other stituation, which is located in the lower ground fissure additional earth pressure at the bottom of the largest near the tunnel;(4)Ground fissure is not activities, contact with the soil additional stress is larger at the bottom of the tunnel; Plate falling on the ground fissures, the footwall tunnel near ground fissures and plate tunnel on top of contact with the soil at the bottom of the additional stress is larger.(5) Sectional tunnel due to the influence of piecewise, strong vibration response than integral tunnel, the smaller the single length this kind of phenomenon is more obvious. Sectional tunnel compared to the vibration propagation along the tunnel longitudinal integral tunnel have greater attenuation effect.(6)The greater speed leads to the more instense vibration of tunnel and the layer. but the greater speed in the the degree of attenuation during the vibration propagation in stratum(7)Acorring on the activity of the ground fissure,the design is to be done in high-angle between the ground fissure and tunnel.