川西高原隧道软岩大变形施工处治措施研究

Study on Treatment Measures for Large Deformation of Soft Rock in Western Sichuan Plateau Tunnel Construction

得荣一号隧道位于我国川西高原甘孜藏族自治州得荣县境内,隧址区穿越泥盆系强风化云母片岩,受构造断裂带影响,岩体裂隙发育、软弱易变形。经查勘及补勘,分析大变形及施工段落软岩变形监测数据后,采取的处治措施为:(1)对大变形侵限严重段采取拆换拱措施,软岩塌方涌泥段进行洞内大管棚及超前加固处治;(2)充分预判地质情况并结合既有施工段变形监测数据,取其中20 m作为试验段,调整原设计支护参数及预留变形量;(3)加强施工控制及锁脚布置,短进尺、早封闭,及时反馈试验段变形监测数据并再次调整设计。施工后期未出现变形侵限等问题,从而降低工程施工风险。

Derong Tunnel 1 is located in Derong County,Ganzi Tibetan Autonomous Prefecture in the Western Sichuan Plateau.The tunnel site passes through Devonian strongly weathered schist,affected by structural fault zone,rock mass fracture development,weak and easy to deform.After supplementary survey,and theoretical analysis of large deformation and monitoring of soft rock deformation data in construction section,taking the following treatment measures:①Arch removal and replacement measures for the section with large deformation and serious invasion,advance reinforcement treatment of landslide mud gushing section through large pipe shed in tunnel.②Fully predict the geological conditions and combine the deformation monitoring data of the existing construction section,taking 20 m as the test section,adjust the original design support parameters and reserved deformation.③Strengthen construction control and strong foot lock,short footage,early closure,adjust the design again through feedback data of the actual deformation monitoring of test section.In the later stage of construction,there is no deformation or invasion,which reduces the construction risk.