Based on the underground loess tunnel between Gongxingdun Station and Jiaojiawan Station on the metro line 1 in Lanzhou, two kinds of models of layered finite element numerical model were established by using MIDAS GTS software, where the mold modification method was adopted with the consideration of the two typical immersion types, i.e. from ground surface to bottom (surface water infiltration) and from bottom to ground surface (underground water level rising). The influence of two types of immersion on the tunnel deformation was simulated and analyzed. The results indicated that the different immersions did not change the final settlements. The settlement velocity of the immersion from bottom to ground surface (underground water level rising) were lager than the other type, i.e. the immersion type from ground surface to bottom (surface water infiltration), and might occur more suddenly. The collapse in deep loess was more unsafe and more adverse to the monitoring, early warning and prevention of metro tunnel settlement.%以兰州地铁1号线拱星墩~焦家湾区间暗挖黄土隧道工程为背景,利用MIDAS-GTS软件,采用密模修正法,针对自上而下浸水(地表积水入渗)型、自下而上浸水(地下水位抬升)型2种模型分别建立有限元数值模型,模拟隧道2种浸水方式对隧道变形的影响.研究结果表明:浸水方式的不同并没有改变地面最终沉降量.2种浸水方式地表沉降均发生突变,"自下而上"的浸水方式地表沉降发展速率更快,深层黄土的湿陷更具危险性、更不利于地铁隧道的沉降监测预警及防控.
展开▼
