地裂缝与斜交地铁隧道动力相互作用试验研究

DYNAMIC RESPONSE ANALYSIS OF THE OBLIQUE METRO TUNNELS IN GROUND FISSURES AREA

通过进行地裂缝与斜交地铁隧道的物理模型试验,研究地铁列车荷载作用下地裂缝与斜交马蹄形地铁隧道的动力相互作用特性。试验结果表明:地铁行驶产生的振动在土层中各个方向传播时会有不同程度的衰减,地裂缝对地铁振动具有阻隔作用;地裂缝附近隧道下方土层的振动要比上部土层强烈;地铁隧道的拱底部位相比拱腰和拱顶部位振动响应更强烈。地裂缝未活动时,隧道底部与土体的接触附加压力较大;地裂缝上盘下降时,位于地裂缝附近的下盘隧道底部和上盘隧道顶部与土体的接触附加压力较大。地裂缝未活动时,激振作用产生的隧道顶部和底部的附加应变均较小;地裂缝上盘下降后,位于上盘的隧道顶部和位于下盘的隧道底部产生负的附加应变,位于下盘的隧道顶部和位于上盘的隧道底部产生正的附加应变,且随上盘下降量的增大,附加应变逐渐变大。

A large scale model test was carried out to study the dynamic response of the oblique metro tunnel in ground fissures area under vibration loads of train. The test results show that subway produces vibration propagation in all directions in the soil with different degree of attenuation while moving,and ground fissures have barrier action on the vibration. The vibration of the ground fissures near the tunnel beneath the soil is larger than that of the upper soil layer,and the vibration response of the arch bottom of the subway tunnel is stronger than that of the hance and the vault. Before ground fissure movements,the additional contact stress is larger between the bottom of the tunnel and the soil; While the declining of the hanging wall of ground fissures,the additional contact stress between the bottom of the footwall tunnel and the top of the hanging wall tunnel near ground fissures and the soil become larger. Before ground fissure movements,the additional strain caused by vibration excitation at both the top and bottom of the tunnel are smaller. While the declining of the hanging wall of ground fissures, the negative additional strain occurs at the top of the hanging wall tunnel and the bottom of the footwall tunnel,while the positive additional strain occurs at the top of footwall tunnel and the bottom of halling wall tunnel. The additional strain becomes larger when the hanging wall declines.