富水粉细砂层隧道开挖坍塌的加固技术研究及效果分析

针对富水粉细砂层隧道开挖引发典型坍塌问题，采用现场勘查、理论分析、室内试验和数据监测等手段，对桃树坪隧道塌方处地表和双向开挖掌子面提出科学治理方案。通过注浆填充率、P-Q-t曲线及注浆效果分析。结果表明:由于坍塌处地层有一定的吸浆能力，虽注浆量逐渐减少，但其抗压逐渐增大，地层得到挤密性加固。注浆后砂层自稳能力明显增强，在稳定性增强的情况下，塌方后的支护体系比塌方前的支护体系增强很多。管棚的数量相对于原管棚设计根数有所减少，但是单根的强度比原设计的管棚单根强度有所增强，管棚施工间距超出设计间距10 cm，可通过超前密排小导管预注浆补强。

Research and Effect Analysis of Reinforcement Technology for Collapse during Tunnel Excavation in Water-rich Silty-fine Sand Layer

To solve the problem of collapse caused during tunnel excavation in water-rich silty-fine sand layer, a scientific treatment scheme is proposed for the collapsed surface and two-way excavation surface of Taoshuping Tunnel by field investigation, theoretical analysis, laboratory test and data monitoring. Grouting filling rate, P-Q-t curve and grouting effect are analyzed. The results shows that due to the grout absorption ability of the collapsed surface, although the grout amount decrease gradually, its compressive capacity is improved gradually, and the surface is reinforced by compaction. The grouted sand layer has higher self-stabilization ability, and with the stability improvement, compared with before collapse, the support system is better strengthened after collapse. The quantity of pipe shed is reduced compared with the designed pipe sheds, but single pipe shed has higher strength than original pipe shed, the space between pipe sheds is 10 cm more than design construction space, and preliminary grouting may be performed for reinforcement by advanced dense arrangement of small ducts.