环向盲管堵塞对隧道二衬背后水压力影响分析

Analysis of Influence of Circumferential Blind Pipe Blockage on Water Pressure Behind Secondary Lining of Tunnel

为研究环向盲管堵塞对隧道二衬背后水压力的影响规律,以西延铁路武家塬隧道为研究对象,采用FLAC3D进行不同水头高度下三维渗流数值模拟分析。结果表明:(1)无论盲管是否堵塞,隧道二次衬砌拱顶处的孔隙水压力最大,墙脚处的孔隙水压力最小。孔隙水压力沿着隧道纵向呈现周期性变化规律,在盲管处孔隙水压力最小,两盲管中间达到最大值。(2)隧道盲管堵塞后,堵塞处二次衬砌背后的孔隙水压力在短时间内将上升,然后逐渐下降至稳定,但高于盲管正常工作时的水压力。(3)随着水头高度增加,二衬背后水压力增加,盲管堵塞不改变水压力的分布规律。(4)盲管堵塞程度不同,二次衬砌背后水压力增加幅度不同,水压力从大到小依次为:双侧完全堵塞>双侧截面堵塞1/2>单侧完全堵塞>单侧截面堵塞1/2>无堵塞。研究成果可为山岭隧道运营期排水系统的维修养护提供参考。

To study the influence law of circumferential blind pipe blockage on the water pressure behind the secondary lining of tunnel,taking Wujiayuan Tunnel of Xi'an-Yan'an Railway as the study object,this paper uses FLAC3D for numerical simulation analysis of three-dimensional seepage under different waterhead heights.The results show that:(1)No matter whether the blind pipe is blocked or not,the pore water pressure at the arch crown of secondary lining of tunnel is at the maximum and that at the foot of wall is at the minimum.The pore water pressure presents a periodic change along the longitudinal direction of the tunnel,with the minimum at the blind pipe and the maximum in the middle between the two blind pipes.(2)After the tunnel blind pipe is blocked,the pore water pressure behind the secondary lining at the blocking place will rise in a short time and then gradually drop to be stable but higher than the water pressure when the blind pipe works normally.(3)With the increase of head height,the water pressure behind the secondary lining increases,and the blind pipe blockage does not change the distribution of water pressure.(4)The increase of water pressure behind the secondary lining varies with the degree of blind pipe blockage,and the order of water pressure from high to low is:bilateral complete blockage>1/2 bilateral section blockage>unilateral complete blockage>1/2 unilateral section blockage>no blockage.The study results can provide a reference for the maintenance of drainage system in mountain tunnels during operation.