某钻爆法施工隧道围岩松动圈测试与分析

Testing and analysis of surrounding rock loose circle of certain tunnel construction by using drilling and blasting method

隧道采用钻爆法掘进,天然应力状态下岩体的平衡状态被打破,围岩应力将重新调整,在隧道周围形成松动圈。声波法技术成熟,测试仪器简便,现场操作简单。本文结合北京某公路隧道的工程实践,采用声波法对不同岩性、不同围岩级别的典型断面进行了松动圈测试。测试结果表明,围岩松动圈与岩体的强度、完整性密切相关,围岩的强度、完整性越差,松动圈就越厚,反之,则松动圈越薄。同一隧道断面,围岩松动圈厚度表现出拱顶大于两帮的分布规律。围岩松动圈的测试结果,可为隧道支护系统、变形原因分析及爆破设计优化等提供依据。

When the tunnel is excavated by drilling and blasting method,the equilibrium state of rock mass is broken under natural stress and the surrounding rock stress is readjusted,forming a loose circle around the tunnel.Acoustic wave method is characterized by mature technology,simple testing instruments and simple field operation.Based on the engineering practice of a highway tunnel in Beijing,a loose circle testing is carried out for typical sections with different lithology and surrounding rock levels by using acoustic wave method.The test results show that the strength and integrity of the surrounding rock are closely related to the loose circle.The worse the strength and integrity of the surrounding rock,the thicker the loose circle will be.Otherwise,the thinner the loose circle will be.In the same tunnel section,the loose circle thickness of surrounding rock shows the distribution law that the vault is larger than two sides.The testing results of the loose circle in the surrounding rock can provide the basis for the tunnel support system,deformation reason analysis and blasting design optimization.