为系统研究含软弱夹层水平层状泥岩中软弱夹层数量和位置对围岩稳定性的影响，依托关斗山单线铁路隧道，运用3DEC离散元软件构建多软弱夹层的隧道三维数值模型，获得隧道围岩位移和塑性区发展特征，对围岩稳定性进行分析。结果表明： 1）软弱夹层的数量对隧道围岩稳定性有显著影响，随着软弱夹层数量的增加，水平层状围岩位移量逐渐增大，塑性区面积逐渐扩展； 2）软弱夹层与隧道掌子面之间的相对位置关系对围岩稳定性至关重要，存在软弱夹层数量为2时围岩的总位移量与塑性区面积小于软弱夹层数量为1时的情况，此外，当软弱夹层存在于隧道的关键部位（如拱顶）时，其对结构稳定性的影响更为显著，可能导致隧道的稳定性大幅下降； 3）利用IBM SPSS软件对软弱夹层数量和位置分别进行单因素方差分析，计算得到2个因素的P值分别为0.037和0.019，因此，软弱夹层数量和位置对结构稳定性的影响在0.050水平上都显著，且软弱夹层数量的敏感性大于软弱夹层位置。
Presently, the study of influence of the quantity and location of weak interlayers on the stability of surrounding rock in horizontally-layered mudstone with weak interlayers remains insufficient. A case study is conducted on the Guandoushan single-track railway tunnel, and a three-dimensional numerical model of the tunnel with multiple weak interlayers is established using the three-dimensional distinct element code discrete element software. The displacement characteristics of the surrounding rock and the development of plastic zones are obtained, and the stability of the surrounding rock is analyzed. The results indicate the following: (1) The number of weak interlayers has a significant impact on the stability of tunnel surrounding rock. As the number of weak interlayers increases, the displacement of horizontally-layered surrounding rock gradually increases, and the area of plastic zones progressively expands. (2) The relative positional relationship between weak interlayers and the tunnel face is crucial for the stability of surrounding rock. When the number of weak interlayers is two (Case BC), the total displacement and plastic zone area of the surrounding rock are smaller than those in the case with one weak interlayer (Case A). Additionally, when weak gypsum layers are located in critical areas of the tunnel (e.g., the crown), their impact on structural stability becomes more pronounced, potentially leading to a significant decline in tunnel stability. (3) Variance analysis of the maximum total displacement of surrounding rock under different quantities and positions of weak gypsum layers is conducted using IBM SPSS software. The calculated P-values for the two factors are 0.037 and 0.019, respectively. Thus, both the quantity and location of weak gypsum layers have a statistically significant impact on structural stability at the 0.05 level, with the quantity of weak gypsum layers exhibiting greater parametric sensitivity than their location.
