通车荷载下不同覆土厚度的地铁隧道开挖对管线安全性的影响

EFFECT OF SUBWAY TUNNEL EXCAVATION WITH DIFFERENT COVERING THICKNESSES ON PIPELINE SECURITY UNDER TRAFFIC LOAD

地铁隧道的开挖将对临近的地下管线造成较大的影响。当管线附近同时存在新隧道开挖和通车中的地铁时,管线将同时受二者的影响。采用三维有限元方法分析在临近的地铁通车荷载作用下,不同覆土厚度的地铁隧道因开挖造成的地表沉降值和沉降槽曲线。利用沉降值和沉降槽曲线推算出保证管线安全性的控制参数。并得出新建隧道的覆土厚度对参数的影响,再将计算值与实测值进行比较。研究结果表明:(1)通车荷载的考虑和新建隧道的不同覆土厚度对参数的影响较大。(2)随着覆土厚度的增大,地表最大斜率和Smax/i有所增长,增长趋势随覆土厚度增大而减缓。(3)随着覆土厚度的增大,地表最大沉降值和地表损失系数呈现线性增大趋势。(4)随着覆土厚度的增大,沉降槽拐点曲率呈现线性降低趋势。(5)通过计算值与工程实测值的对比可知,有限元模拟结果与实测结果吻合,所推公式求得的参数与实测值求得的参数相吻合。

The subway excavation has great influence on underground pipeline. The pipeline would be influenced by both excavating subway-tunnel and operating subway when they are near the pipeline. Three-dimensional finite element analysis models are established to calculate the surface settlement and settlement tough. The models are established with different covering thicknesses and with the influence of an operating subway. Parameters for ensuring security of underground pipeline are obtained by surface settlement and settlement tough , and relationships between covering thickness and the parameters are discussed. Then calculation values of surface settlement,settlement trough and parameters are compared with test values. It shows that:(1) The influence of operating subway and covering thickness can not be neglected. (2) Maximum surface slope and Smax/i grow,when soil the covering thickness increases. The trend of growth becomes slow,with the increase of coveing thickness. (3) Both the maximum settlement and surface loss coefficient express a linear growth when the covering thickness rises. (4) However,the curvature of settlement trough decreases with the enhancement of covering thickness. (5) The values from calculation are similar with that from test,and the parameters from calculation are similar with that from test too.