Numerical prediction of the optimal shield tunneling strategy for tunnel construction in karst regions

Abstract

Shield tunneling in karst areas poses significant challenges, as vibration caused by the shield machine can disturb the stability of the karst caves, ultimately resulting in the collapse of a tunnel. In the present study, a numerical model involving an iteration process was developed based on the Mindlin solution scheme to identify the optimal shield tunneling speed for minimizing the disturbance to karst cave stability. The developed model was then implemented to investigate an underground tunnel constructed in a karst region with different shield tunneling strategies. By using the variation in the energy density of a karst cave as a performance index, the model predicts that when approaching the affected zone of a karst carve (e.g., approximately 5 m from the carve), the shield tunneling machine should be controlled within a certain speed (i.e., < 30 mm/min). Once the shield tunneling machine moves into the affected zone of the cave, the speed of the machine needs to be decelerated to 11 mm/min, and the speed of 30 mm/min can be restored when the shield machine moves out of the affected zone. This finding demonstrates that the developed model could potentially be used to identify the optimal shield tunneling speed to minimize the disturbance to karst cave stability and ensure the safety of tunnel construction in karst regions.

Research on Collapse Risk Assessment of Karst Tunnels Based on BN Self-Learning

“…Wang et al [20] analyzed the impact of semi-exposed karst caves of different sizes and at different positions on the stability of tunnel surrounding rock and the stress on the initial support structure through experimental methods. In the context of shield tunneling construction, scholars have used the FEM, field test, and model test to study the impact of karst caves of various sizes, spacings, and orientations on the stability of the surrounding rock during the excavation of shield tunnels [21][22][23]. Li et al [24] conducted a comprehensive geomechanical model test to examine the stability of the surrounding rock during the excavation of a shield tunnel and to uncover the causes of delayed water inrush in tunnels excavated near caves containing confined water.…”

Free roaming of 3D stratum models based on internal and external boundary identification

“…3D underground roaming provides a better understanding of underground regions. In geological and geotechnical engineering, underground construction is often more complex and dangerous than surface construction [1]. 3D underground roaming technology can be used to simulate and plan underground construction in a virtual environment, eliminating all possible problems in advance, thereby reducing construction risks, improving construction efficiency and reducing construction costs.…”

Mechanical Response Law and Parameter Influence Analysis of Karst Tunnel Dynamic Excavation

“…Zhang et al [26] proposed a ground stability evaluation and analysis system based on improved fuzzy comprehensive evaluation along the tunnel line in a karst area and a ground stability evaluation index system was established. Liu et al [27] developed a numerical model involving an iterative process. This model can determine the optimal shield tunneling excavation velocity needed to minimize the disturbance to the karst cave stability and ensure the safety of tunnel construction in karst areas.…”