含孤石软弱围岩隧道施工技术研究

以某含孤石Ⅵ级围岩单线铁路隧道为例,通过现场实测和数值计算对孤石对初期支护影响的基本规律进行了研究,并以此为基础提出针对此类地层的隧道施工方法。研究表明:软弱地层中距隧道较近的孤石会引起初期支护局部应力集中和围岩压力分布不均;就含孤石Ⅵ级围岩单线铁路隧道而言,半径超过0.5m、至隧道距离小于1.5m的拱顶、拱腰孤石会使与孤石临近部位的初期支护的弯矩、剪力明显增大;含孤石软弱围岩隧道宜选用交叉中隔壁等临时支撑较强的工法施工。

Research on the Construction Techniques for Tunnels in the Soft Surrounding Rock Stratum with Boulders

With a certain tunnel of the single-line railway in the Grade VI surrounding rock stratum with boulders as a practical example, the basic laws of the effects of boulders on the primary support are studied by site measurement and numerical calcula tions in the paper, upon the basis of which the construction methods for tunnels in this kind of stratum are put forward. The results of our research show that boulders in soft strata near the tunnel may cause the local stress concentration in the primary support and the uneven distribution of the pressure of the surrounding rock; as far as the Grade VI surrounding rock with boul- ders of the tunnel of the single-line railway is concerned, when the radius is greater than 0.5m, and the distance between the tunnel and boulders at the vault and the haunch is less than 1.5m, th~ boulders will make the moment and shear in the primary support in the nearby sections of the tunnel increase obviously; it is highly advisable that such tunnels in the soft surrounding rock stratum with boulders should be built by the method of crossing with bulkheads, in which case the temporary supports are usually strong.