软土地层大断面矩形顶管施工引起切口前方地表隆起分析

Analysis on Ground Surface Heaving ahead of Cutting Face Caused by Largesection Rectangular Pipe Jacking in Soft Soil Layer

  • 摘要: 文章以宁波地铁某车站出入口大断面矩形顶管工程为依托,对顶管推进过程中切口前方地面所产生的较大隆起进行研究。通过结合现场顶进的施工情况,对顶管整个顶进过程地表变形的监测数据进行分析。并采用PLAXIS有限元软件模拟不同顶推力和无土体加固情况下的顶管推进施工,与监测数据进行对比分析。结果表明:地表产生较大隆起是因为顶推力过大,当顶推力大时地表主要发生隆起,反之,地表主要发生沉降;在紧邻结构的顶管出入口处使用旋喷桩加固,效果并不理想,并造成了刚开始顶进地表即隆起的现象。在软土地层中顶管顶进挤压时地表隆起迅速,而顶推面过后的地表沉降缓慢,施工中要格外注意。

     

    Abstract: The large ground surface heaving in front of the cutting face during the pipe jacking is studied on the ba? sis of a large-section rectangular jacking pipe works at the entrance/exit of a subway station in Ningbo. The monitored data of ground surface deformation in the whole pipe jacking process are analyzed in combination with the jacking situation on the site. Moreover, PLAXIS finite element software is used to simulate pipe jacking under different jacking forces and without soil reinforcement, and the simulated results are compared and analyzed with the monitored data. The analysis results show that the large ground surface heaving can be generated due to excessive jacking force, and vice versa; the jet grouting piles used for reinforcing the entrances/exits area adjacent to the structure have no desirable effect, and it could cause the ground surface heaving at the beginning of jacking. The ground surface heaves rapidly when the pipe jacking and extruding in the soft soil layer, but subsides slowly after the jacking face passing. So, special attention should be paid during the construction.

     

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