潜盾隧道急转弯(R=20m)困难问题之克服

Overcoming the Difficult Problems of Shield Tunneling in Extreme Turn(R=20m) Section

近年来,随着都市地下结构物的密集化,为减少与现存地面或地下结构物间之干扰等因素,潜盾隧道急转弯段的施工案例有日渐增加之趋势。在进行急转弯段施工时,必须事先充分掌握急转弯段的地质条件,并研究该范围之推进方法、环片规格、超挖量与辅助工法等,采取妥善的因应对策,才能确保急转弯段的施工安全。文中工程案例依据其急转弯段(R=20m)之地质条件,选择适当潜盾机型及其支持系统,拟妥完整机内灌浆计划,藉由制作泥及浆材之调整以因应急转弯段之施工需求,并介绍了多项应用于本工程之辅助工法,包括:1.特殊黏土灌浆;2.背填灌浆;3.微型固定袋。因未由地面施作任何的辅助地盘改良工作,完全不会在地面造成任何的交通不便或环境影响。

In recent years, underground structures become more crowded in urban area, for reducing the interference with existing ground or underground structures, the construction cases of shield tunneling in extreme turn sections have an increasing tendency day by day. Before tunnehng in the extreme turn section, it is necessary to study the geological condition, the proper advancing method, the specification of the segments, the over cut quantity, and the auxiliary ground treatment method previously. Adopting proper countermeasure can guarantee the construction safety of the extreme turn section. The present case of this article chooses a suitable shield machine and proper support system according to the geological condition of the extreme turn section （ R = 20m）. Proposing a well developed grouting project from inside the shield, and by adjusting the stabilizer and the grout material, meets the demand of the construction of the extreme turn section. Some auxiliary countermeasures applied in this project are introduced, including special clay grouting, back fill grouting, and miniature fixed bags. Without executing any auxiliary ground treatment method, the surface is free from traffic inconvenience and environment pollution.