下穿城市道路综合管廊施工超前支护管棚与小导管参数分析

在城市道路下方进行过路管廊施工可能会引起地层不均匀沉降，甚至过度沉降，影响正常交通，甚至会引发交通事故。文章为研究浅埋暗挖管廊工程对路面沉降的影响，以合肥宿松路快速化改造工程三标段综合管廊工程为背景，结合现场实测与数值模拟对超前支护中的管棚和小导管参数进行分析。结果表明：管棚的直径对控制地表沉降几乎无影响；管棚环向间距存在最佳值$0.4\mathrm{m}$ ；管棚与衬砌距离增大，管棚的支护效果降低；管棚支护可单独使用，小导管只能作为辅助超前支护方式。管棚与小导管的综合支护作用极有可能为两者分别支护作用的叠加；考虑实际施工中的其他不稳定因素，可确定最佳支护方案为：管棚直径 $69\sim 89\mathrm{mm}$ 、环向间距 $0.4\mathrm{m}$ 、与衬砌距离 $0.3\mathrm{m}$ ，小导管外插角 $45^{\circ}\sim 60^{\circ}$ 、环向间距 $0.3\sim 0.4\mathrm{m}$ 、长度 $2.5\sim 3.5\mathrm{m}$ 。

The construction of crossing gallery under the urban roads may cause uneven settlement or even excessive settlement, which will affect the normal traffic and even cause traffic accidents. In order to study the influence of shallow buried pipe gallery project on pavement settlement, based on the integrated pipe gallery project of the third section of the rapid transformation project of Susong Road in Hefei City, the parameters of pipe shed and small conduit in advanced support were analyzed by field measurement and numerical simulation. The results show that the diameter of pipe shed has little effect on the control of ground surface settlement. There is an optimal circumferential spacing of$0.4\mathrm{m}$ for pipe shed. As the distance between pipe shed and lining increases, the supporting effect of pipe shed decreases. The pipe shed support can be used alone, and small conduit can only be used as an auxiliary advanced support method. The comprehensive supporting effect of pipe shed and small conduit is likely to be superposition of their respective supporting effects. Considering other unstable factors in actual construction, the best supporting scheme is as follows: for pipe shed, the diameter is $69 - 89\mathrm{mm}$ , the circumferential spacing is $0.4\mathrm{m}$ , and the distance from the lining is $0.3\mathrm{m}$ ; for small conduit, the external intercalation angle is $45^{\circ} - 60^{\circ}$ , the circumferential spacing is $0.3 - 0.4\mathrm{m}$ , and the length is $2.5 - 3.5\mathrm{m}$ .