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湖北宜巴高速公路峡口隧道最大埋深1480m,围岩多为粉砂质泥岩、泥质灰岩、页岩等,强度低,节理、裂隙十分发育,属典型深埋软岩隧道,开挖过程中极易产生大变形、塌方等灾害。结合峡口隧道工程施工,开展了隧洞变形、接触应力、结构应力等项目的现场监测工作,监测结果表明,峡口隧道具有围岩变形大、变形速率快等特点,围岩变形与结构受力具有明显的时间、空间效应,并与开挖方法、衬砌跟进时机密切相关。根据现场监测结果,提出了围岩幂函数型流变力学模型,并对流变力学参数进行有限元方法数值反演。提出了峡口隧道的合理支护方式,应用反演得到的围岩流变力学模型,开展隧洞开挖与运营的有限元数值仿真,分析围岩变形与隧洞支护结构受力情况,并对隧洞长期稳定性进行评估,结果表明所采用所提出的支护方式的可行的。
The maximum buried depth of Xiakoukou Yibao Expressway in Hubei is 1480m. Most of the surrounding rock is silty mudstone, argillaceous limestone and shale. The strength of the surrounding rock is very low. The joints and fissures are well developed. It is a typical deep-buried soft-rock tunnel excavation During the process, large deformations, landslides and other disasters are easily caused. Combined with the construction of Xiakoukou tunnel, on-site monitoring of tunnel deformation, contact stress and structural stress are carried out. The monitoring results show that Xiakoukou tunnel has the characteristics of large deformation and fast deformation of surrounding rock, deformation and stress of surrounding rock It has obvious time and space effects and is closely related to the timing of excavation and lining follow-up. According to the field monitoring results, a rheological mechanical model of rock mass power function is put forward, and the numerical inversion of rheological mechanical parameters is carried out by finite element method. The reasonable support method of Xiakou tunnel is proposed. The rheological mechanics model of surrounding rock is obtained by inversion. The finite element numerical simulation of tunnel excavation and operation is carried out. The deformation of surrounding rock and the force of tunnel supporting structure are analyzed. The long-term stability of the tunnel is evaluated and the results show that the proposed support method is feasible.