厦门翔安海底隧道CRD法中各施工部对拱顶下沉的影响分析

文章以厦门翔安海底隧道陆域段软弱地层大断面浅埋隧道CRD法施工为工程背景,结合现场位移监控量测和实际施工情况,对不同开挖顺序下CRD法中各施工部对拱顶下沉的影响进行了分析研究。研究结果表明,翔安隧道CRD法拱顶下沉为台阶状上升曲线,最后趋于稳定;各分部开挖引起的拱顶下沉量具有一定的比例关系,可用于对最终拱顶下沉量的预报和控制指示;各分部仰拱及时闭合是控制最终下沉量的关键;采用CRD1、3部超前施工比CRD1、2部超前对控制拱顶下沉较为有利;施工中应重点监测和控制最早开挖的CRD1部拱顶下沉。

Analysis of arch crown subsidence caused by each heading excavation of Xiamen Xiang'an subsea tunnel constructed by CRD method

The land section of Xiamen Xiang'an subsea tunnel with small overburden,large cross-section and embedded in soft strata was constructed by Center-Cross-Diaphragm(CRD) method.A study of arch crown subsidence caused by each heading of CRD under different excavation sequences was carried out.Results indicated,arch crown subsidence vs.time graph took the shape of a uplifted zigzag with a final stable value,the subsidence caused by each heading excavation constituted a certain proportion of the final subsidence,which could be used as an indicator to forecast and control the final subsidence.To close the primary support of each heading as soon as possible is the key to control the final arch crown subsidence.Excavation sequence with headings CRD1 and CRD3 ahead is better to restrict the final subsidence than with headings CRD1 and CRD2 ahead.The supervision of arch crown subsidence should be focused on heading CRD1 which was excavated firstly.