邻近地裂缝地铁隧道地震响应分析

西安地铁3号线有3个区间隧道近距离平行通过地裂缝。采用数值模拟方法分析地震荷载作用下地铁隧道场地的动力响应。分析结果表明,地震荷载作用下竖向土压力增量在地裂缝上下盘处差异明显,地裂缝上盘竖向土压力增量明显大于下盘;在施加地震荷载后地铁隧道拱顶处的竖向土压力迅速上升,震级越大竖向土压力越大;隧道内力中轴力最大值在右拱脚处,左拱脚次之;剪力最大值在右拱腰处,左拱腰次之;正弯矩和负弯矩的最大值接近,均在右拱腰处,左拱肩和右拱脚处弯矩偏小,其余弯矩值在30～60 k N·m。

Analysis on Earthquake Response of Metro Tunnel Induced by Nearby Ground Fissure

There are three interval tunnels in Xi'an metro line 3 parallelled to the ground fissure in short distance.The dynamic response of metro tunnel site under earthquake load was analyzed by using numerical simulation method.The analysis results show that the vertical soil pressure increment under earthquake load is obviously different between the hanging wall and the footwall of the ground fissure,and the vertical soil pressure increment on the hanging wall of the ground fissure is obviously larger than that on the footwall.The vertical soil pressure at the vault of metro tunnel rises rapidly after the earthquake load is applied,and the greater the magnitude,the greater the vertical soil pressure.The maximum axial force of the tunnel is at the right arch foot,followed by the left arch foot.The maximum shear force is at the right arch waist,followed by the left arch waist.The maximum values of positive and negative bending moments are close to each other,both at the right arch waist.The bending moments at the left shoulder and right foot of the arch are relatively small,while the rest are between 30 kN·m and 60 kN·m.