马湾隧道浅埋偏压段初期支护变形原因分析及参数优化

Deformation Cause Analysis and Parameter Optimization of Primary Support of Shallow-buried Unsymmetrically-pressured Section of Mawan Tunnel

为解决伏牛山地区浅埋偏压隧道开挖支护后初期支护大变形问题,从初期支护变形原因、主要的技术措施以及施工组织措施等方面进行研究,采用物探、钻探、试验段、监控量测、数值模拟等方法对初期支护变形原因进行深入分析,并与现场开挖揭示情况比对,得出原设计初期支护参数偏小是造成隧道初期支护开裂的主要原因。根据变形分析结论,在施工现场支护技术上,采用加大初期支护钢架型号、增加系统锚杆及初期支护背后注浆固结等支护措施;在施工组织措施上,遵循短台阶、短进尺、快封闭、仰拱衬砌适时跟进的原则组织施工。采用以上浅埋偏压隧道施工方法,能有效地控制初期支护变形,确保隧道施工安全。

The primary support deformation of unsymmetrically-pressured tunnels in Funiushan area is serious. As aresult, study is carried out on deformation causes, main countermeasures and construction organization. The deformationof the primary support is analyzed in terms of geophysical prospecting, drilling, test, monitoring and numericalsimulation; the analytical results are compared to actual conditions; and the original design of primary supportparameters is regarded as the main causes of primary support cracks. Thus countermeasures, i. e. improvement of steelframe, adding systematic anchor bolts and grouting behind primary support, are adopted based on existing primarysupport technology; construction organization methods, i. e. short bench, short advance, rapid ring closure and timelyinverted arch lining, are used. The primary support deformation has been successfully controlled and the constructionsafety of the tunnel has been guaranteed by adopting above-mentioned technologies.