以某下穿库区铁路隧道为依托工程,对比分析有无渗流场作用和不同水深条件下,隧道结构应力变化规律以及围岩变形、塑性区和渗流场的变化特性,同时还考虑隧道加固圈厚度和渗透系数对围岩稳定性的影响。研究结果表明：地下水渗流场对围岩变形影响较大,不仅能引起大范围的库底沉降,而且能增大隧道拱顶和拱腰的位移,并且能够减小仰拱的隆起量以及加剧围岩塑性区的范围；隧道的开挖能够对地下水孔隙水压力的分布形成明显的扰动,并且在两拱脚处渗流速度最大,最大塑性区位于横向临时支撑处；注浆加固圈能够改善围岩的受力,隧道最优注浆圈厚度在5m,并且当渗透系数小于围岩渗透系数的1/50时注浆圈加固效果不再明显。%Based on a certain railway tunnel passing under a reservoir, a systematic study is conducted to identify the stability of the surrounding rocks of the tunnel which goes through the reservoir area, to compare and analyze the change law of the tunnel structure stress, the displacement and plastic zone of the surrounding rocks, the influence of the thickness of reinforcement ring and seepage coefficient on the stability of the surrounding rocks. The results indicate that the seepage field of the underground water has significant influence on the deformation of the surrounding rocks, it not only causes a large scale of settlement of the bottom of the reservoir but also increases the displacement of the vault and haunch; it reduces the uplift of the inverted arch and extends the range of surrounding rocks. The excavation of the tunnel obviously disturbs the distribution of pore water pressure of groundwater, the seepage velocity is fastest at the two arch foot and the most severe plastic zone is located at the lateral temporary support. The grouting reinforcement ring can improve the stress state of the surrounding rocks and the optimal thickness of the grouting reinforcement ring is 5 meters. The reinforcement effect is not obvious when the permeability coefficient of the grouting reinforcement ring is less than 1/50 of the surrounding rocks.
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