滨海软土地区管廊路基变形特性分析

Analysis of Deformation Characteristics of Pipe Gallery Roadbed in Coastal Soft Soil Area

以福州滨海新城管廊路基工程为依托,运用FLAC3D有限差分软件,模拟软土地质条件下管廊路基施工阶段及工后运营期沉降特性。结果表明:基坑开挖阶段,基底最大隆起量为基坑开挖深度的0.14%,开挖对地表影响范围为4~5倍的开挖深度,基坑侧壁水平位移最大值为开挖深度的0.14%,大致在基坑开挖深度2/3处;基坑回填结束,管廊沉降逐渐增大并表现为均匀沉降;路基回填结束,管廊产生了0.25%的倾斜率。路基沉降受管廊影响,出现不对称沉降,左右两侧最大差异沉降率分别为1.33%,1.00%。管廊位置处沉降出现突变,两侧沉降值最大相差22mm;工后20年时,管廊沉降值及横向位移值变化不大,倾斜率变为0.42%,路基沉降变为竣工时4倍,左右两侧最大差异沉降率分别为0.38%,1.00%,管廊存在处路基顶面出现S型沉降曲线,且该现象越来越明显。

Based on the engineering of pipe gallery roadbed in Fuzhou Binhai New City,FLAC3D finite difference software was used to simulate the settlement characteristics of pipe gallery subgrade in the construction stage and post-construction operation period under soft soil geological conditions.The results show that in the stage of foundation pit excavation,the maximum uplift of the foundation is 0.14%of the excavation depth,and the influence range of excavation on the surface is 4~5 times of the excavation depth.The maximum displacement of horizontal displacement of the side wall of the foundation is 0.14%of the excavation depth,which is about 2/3 of the excavation depth.After the backfilling of the foundation pit,the settlement of the pipe gallery gradually increases and shows uniform settlement.After the subgrade backfilling,0.25%inclination rate is generated for the pipe gallery.The settlement of the subgrade is affected by the pipe gallery,and there is asymmetric settlement.The maximum differential settlement rate on the left and right sides is 1.33%and 1.00%respectively.There is a sudden change in settlement at the position of pipe gallery,and the maximum difference of settlement value on both sides is 22 mm.After 20 years of construction,the settlement value and lateral displacement value of the pipe gallery change little,and the inclination rate becomes 0.42%,the settlement of the subgrade becomes 4 times of that in the completion,and the maximum difference of the left and right sides of the settlement rate is 0.38%and 1.00%respectively.The S-shaped settlement curve appears on the top surface of the subgrade where the pipe gallery exists,and this phenomenon is becoming more and more obvious.