黄土地区引水隧洞施工围岩变形特征分析

Analysis on Deformation Characteristics of Surrounding Rock in Diversion Tunnel Construction in Loess Area

为研究引水隧洞施工期间的变形特征,依托某黄土地区引水隧洞工程为例,综合采用现场实测数据分析和数值模拟开展隧洞的变形特征研究。结果表明:(1)隧洞拱顶位移变化速率和累计沉降值最大,且出口右线的沉降速率比左线的更大。与出口相比,进口处的地面沉降值明显较小,其中进口处地面的最大沉降值为35 mm,出口处地面最大沉降为70 mm;(2)建立数值有限元模型进行计算表明,数值模拟结果与实际监测规律基本一致,其中实测隧道开挖结束的拱顶最大沉降为60 mm,而数值模拟结果为78 mm,两者相对误差在20%以内;随着隧洞的开挖,隧道应力发生重分布,衬砌两侧发生应力集中,最大值为6.0 MPa,顶部围岩应力达到2 MPa。

In order to study the deformation characteristics of the diversion tunnel during construction,based on the diversion tunnel project in a loess area as an example,the deformation characteristics of the tunnel were studied by comprehensively using field measurement data analysis and numerical simulation.The results show that:(1)The displacement change rate and cumulative settlement value of the tunnel vault are the largest,and the settlement rate of the right line of the exit is greater than that of the left line.Compared with the exit,the ground subsidence at the entrance is significantly smaller,the maximum ground subsidence at the entrance is 35 mm,and the maximum ground subsidence at the exit is 70 mm;(2)The numerical finite element model is established and the results show that the numerical simulation results are basically consistent with the actual monitoring data.The maximum settlement of the arch at the end of tunnel excavation is 60 mm,while the numerical simulation results is 78 mm,and the relative error between the two was less than 20%.With the excavation of the tunnel,stress redistribution occurs and stress concentration occurs on both sides of the lining,with the maximum value of 6.0 MPa and the stress of the top surrounding rock reaching 2 MPa.