胶州湾隧道浅埋分岔段的设计及施工关键技术

在胶州湾隧道工程中，为满足城市交通规划和区域交通疏导要求，采取设置地下分流匝道的设计方案。双车道匝道隧道与3车道主隧道在地下小角度交汇，形成分岔隧道。由于该分岔隧道段埋深浅、地层条件差、地面环境复杂，给设计和施工带来了不小的难度。通过工程类比、数值模拟分析等方法确定小净距隧道段范围，对变净距并行隧道中夹岩分区段采取扩挖换填混凝土、对拉锚杆等措施；在特大断面隧道段通过预注浆加固地层、加强初期支护，采用台阶分块开挖方案；施工中采用微震爆破技术，较好地保护了围岩，最终成功实现了此浅埋分岔隧道的快速施工。通过现场监控量测数据反馈分析，所采取的支护参数、工程措施、施工方案合理，确保了工程的安全、顺利建成。

Key Technologies for Design and Construction of Shallow-covered Forked-section of Jiaozhou Bay Tunnel

A forked section is arranged in Jiaozhou Bay tunnel. Due to the shallow cover, poor geological conditions and complex ground surface environment of the forked section of the tunnel, there are great difficulties in the design and construction of the forked section. The range of the small spaced tunnel section is determined by means of engineering analogy and numerical simulation. Concrete filling and tie bolts are adopted to reinforce the rock pillar of the small spaced tunnel section. Pre grouting, primary support strengthening and bench excavating method are adopted for the large cross section tunnel section. Micro vibration blasting technology is adopted during the construction. In the end, rapid construction is achieved for the forked section. The monitoring results show that the support parameters, construction technologies and construction program adopted are rational and reliable.