列车荷载下新地铁隧道开挖对周边管线的影响

Study on Influence of Subway Tunnel Excavation on the Pipeline under the Existing Subway Vibrating Load

利用FLAC3D有限元模拟软件,模拟在既有地铁荷载下进行北京直径线开挖。结合实测结果,研究了隧道周边管线的位移、应力及地表沉降。结合相关管线安全性评价标准,对地下管线的安全性进行分析预测。结果表明,管线水平及倾斜变形均在标准控制范围内。利用地表沉降预测管线安全性时,发现地表沉降最大值、地表最大斜率、地表损失系数及地层移动坡角值均小于控制值。但管线的部分区域最大主拉应力集中于1.6～1.72 MPa范围内,略大于混凝土抗拉强度1.43 MPa。为了保证管线的正常使用,需对管线周围土体进行加固。

The excavation of new subway line is simulated using FLAC-3D software with consideration of vibrating load from the existing subway. The surface settlements at each excavation step and the settlement curve are studied as well as the displacement and maximum principal stress of pipeline next to the excavating tunnel. In addition, the numerical results are contrasted with the construction values. And the safety of pipeline is judged based on the pipeline security evaluation criteria. The results show that the horizontal and inclination deformation of pipeline is un- der control. And the surface settlements, maximum slop of surface, surface loss coefficient and the ratio of maximum surface settlement and settling tank width coefficient did not exceed the criteria values. However, the maximum principal stress of pipeline in some parts was in range of 1.6 - 1.72 MPa, which slightly exceeded the concrete tensile strength 1.43 MPa. In order to ensure the safety of pipeline, the soil reinforcing near the pipeline is needed.