富水粉细砂层隧道全断面水平旋喷超前预加固施工技术研究

Construction Technology of Advanced Reinforcement by Horizontal Rotary Shotcreting in Full Section of Tunnel in Water-rich Silt and Fine Sand Layer

桃树坪隧道穿越富水粉细砂层,开挖后砂层无自稳能力,突水涌砂及溜塌现象频繁,施工进度缓慢且施工风险极高。通过引进国外配套设备及施工技术,对富水粉细砂层隧道采用高强度的水平旋喷超前预加固、掌子面的玻纤锚杆约束加固、中下台阶的锁脚旋喷桩锚固、多种降水措施,可使软岩隧道采取大断面甚至全断面开挖;在开挖过程中增加了锁脚旋喷桩工艺,很好的解决了在软弱砂层下钢拱架没有着力点、沉降大等问题,使得高风险隧道转化为低风险隧道,并在成本控制方面达到了理想的预期效果。

Taoshuping Tunnel passes through water-rich silt and fine sand layer. Because the sand layer has no self-stabilization ability after excavation, accidents occur frequently and construction progress is slow. By introducing foreign matching equipment and construction technology, the full-section horizontal rotary jet grouting advanced reinforcement technology is adopted for the tunnel with rich water and fine sand layer. The problems of steel arch without focus and large settlement under soft sand layer are well solved. The high-risk tunnel is transformed into a low-risk tunnel, and the desired effect in cost control is achieved.