Abstract: To investigate the mechanical behavior of karst tunnel support structures in dolomitic limestone formations, this study combines laboratory tests and numerical simulations based on the Lanhua Railway Tunnel project,analyzing the effects of permeability, porosity, and hydraulic head of karst water channels on tunnel structural stress.The results show that the dolomitic limestone formation in the study area is Grade IV? surrounding rock with uniaxial compressive strength of 26.3 MPa. The forces on both primary support and secondary lining structures increase with the permeability and porosity of water channels, showing faster initial growth rates that gradually slow down, while exhibiting linear growth with increasing water head height. Structural forces are most sensitive to water head height,followed by porosity, and least sensitive to permeability. Based on field conditions, a stability control technology of"advanced prediction + on-site treatment + post-construction monitoring" was proposed for tunnel karst sections,with application results demonstrating its effectiveness in ensuring construction safety of karst tunnels.