Karst landforms are widely distributed all over the world. With the continuous improvement of infrastructure construction, tunnelling in mountainous karst areas is inevitable. Due to the complex hydrogeological conditions in karst areas, groundwater inflow during tunnelling is usually difficult to predict and can cause huge economic losses and casualties. Therefore, finding better ways to improve the prediction of tunnel water inflow is of great significance to ensure the safety of tunnelling. In this study, three commonly used modules (CHD, DRAIN and CFPM1) in MODFLOW are selected and compared to predict the water inflow of tunnels. We find that the CFPM1 module performs better in terms of considering both tunnel size and actual water inflow dynamics during tunnel excavation, which is a continuous process rather than an instantaneous process. Secondly, we build a hypothetical case and predict the tunnel water inflows using above three different modules. We find that the CHD module yields the largest initial and stable water inflow, followed by the DRAIN module, and the CFPM1 yields the least. Besides, as the most sensitive factor in the CFPM1 module, the influence of tunnel diameter on water inflow is discussed. Finally, taking the Shizishan Tunnel as an actual field example, we compare the simulation results of different modules with the measured tunnel inflow. In general, the prediction of the CFPM1 module is the closest to the measured value, and the prediction accuracy is the highest during the conventional tunnel construction process. However, when water-saturated karst features such as underground rivers, caves or faults are exposed during tunnelling, the water level may change instantaneously, which is more consistent with the principle of CHD module. In summary, this study provides theoretical and numerical support for the safe construction of relatively uniform rock mass tunnels in karst areas.

中文翻译：

---

预测相对均匀岩体中隧道开挖过程中涌水量的动态建模方法

喀斯特地貌在世界各地广泛分布。随着基础设施建设的不断完善，山区喀斯特地区的隧道掘进不可避免。由于岩溶地区水文地质条件复杂，隧道开挖过程中地下水涌入量通常难以预测，会造成巨大的经济损失和人员伤亡。因此，寻找更好的方法来改进隧道涌水预测对于保证隧道掘进安全具有重要意义。本研究选择MODFLOW中的三个常用模块（CHD、DRAIN和CFPM1）进行比较，以预测隧道涌水量。我们发现，CFPM1 模块在考虑隧道尺寸和隧道开挖过程中的实际进水动态方面表现更好，隧道开挖是一个连续过程而不是瞬时过程。其次，我们建立一个假设案例，并使用上述三个不同的模块来预测隧道涌水量。我们发现 CHD 模块产生最大的初始稳定水流入，其次是 DRAIN 模块，CFPM1 产生最少。此外，作为CFPM1模块中最敏感的因素，还讨论了隧道直径对进水量的影响。最后以狮子山隧道为例，将不同模块的模拟结果与实测隧道涌水量进行比较。总体而言，CFPM1模块的预测值与实测值最接近，在常规隧道施工过程中预测精度最高。然而，当隧道开挖过程中暴露出地下河、洞穴或断层等饱和水的岩溶地物时，水位可能会发生瞬时变化，这更符合CHD模块的原理。综上所述，本研究为岩溶地区相对均匀岩体隧道的安全施工提供了理论和数值支撑。