高速公路路堤下暗挖隧洞施工引起的路基沉降实例分析

Analysis of Roadbed Settlements Caused by the Excavation of a Tunnel Under-passing Expressway Embankment

在高速公路路堤下进行暗挖隧洞施工将不可避免地对围岩产生扰动,从而引起地层位移和路基沉降,过大的路基沉降将影响高速公路的正常运营,因此分析和控制路基沉降是高速公路路堤下隧洞设计与施工的难点和重点。以黔东火电厂排洪及供水隧洞为实例,采用FLAC3D软件分析了隧洞施工对高速公路路基沉降的影响特点。计算结果表明,加强超前支护是控制地层位移和路基沉降的有效手段,采用大管棚及超前小导管注浆技术能有效控制路基沉降并保证高速公路正常运营。在隧洞施工过程中对路基沉降进行了详细监测,监测结果表明隧洞开挖对高速公路路基有一定扰动,但对高速公路正常运营基本无影响。

Excavation of a tunnel under-passing expressway embankment will cause ground displacement and embankment settlement which would affect the normal operation of the expressway. The flood-discharge and water-supply tunnel of Qiandong Thermal Power Plant was taken as an example in this paper, the characteristics of expressway embankment settlements caused by tunnel construction were analyzed by using FLACD3D software. Results showed that strengthening by advance support was an effective approach to control the ground displacements and embankment settlements. Pipe-roofing pre-support technology and the advance small pipe grouting technology could effectively control the embankment settlements and ensure the normal operation of the expressway. Embankment settlements were monitored closely during the tunnel construction and the measurement results showed that tunnel excavation caused a certain disturbance to the expressway embankment which did not affect its normal operation.