隧道穿越千枚岩断层带大变形成因及处治技术研究

Study on Large Deformation Causes and Treatment Technology for a Tunnel Crossing Phyllite Fault Zone

以安岚高速公路多处穿越千枚岩断层破碎带的跷溪河隧道为工程背景,通过现场监测发现隧道穿越千枚岩断层带变形具有变形持续时间长、累计变形量大、变形速率高等特点,出现大变形的原因是千枚岩自身特性、断层构造作用、地下水、初始地应力场以及初期支护刚度不足、二衬施作不及时、施工工法不完全适应围岩特性等内外部因素共同作用造成的,施工中应加强现场监测并及时动态调整设计方案,处治方案应采用主动加固围岩、提高支护强度的综合处治技术。

Based on Qiaoxihe tunnel crossing phyllite fault fracture zone in An-lan expressway,it is found through field monitoring that the deformation of the tunnel passing through the phyllite fault zone has the characteristics of long deformation duration,large cumulative deformation and high deformation rate.The causes of large deformation are the combined action of internal and external factors such as the characteristics of phyllite,fault tectonism,groundwater,initial in-situ stress field and insufficient initial support stiffness,untimely construction of secondary lining and incomplete adaptation of construction method to the characteristics of surrounding rock.During the construction,the on-site monitoring shall be strengthened and the design scheme shall be dynamically adjusted in time.The treatment scheme shall adopt the comprehensive treatment technology of actively strengthening the surrounding rock and improving the support strength.