The impact of landslide-generated impulse waves on dams releases substantial hydrodynamic pressures, posing severe threats to dam safety. In this study, physical similarity model experiments and numerical simulations are conducted to investigate the interaction between the impulse wave and dam. Based on the physical experiments, the variation of hydrodynamic pressures with runup heights of impulse waves, the variation at different horizontal directions and water depths is examined. The distributions of maximum hydrodynamic pressures, including positive hydrodynamic pressure (PHDP) and negative hydrodynamic pressure (NHDP), are studied. The influence of the runup height of impulse waves on the dam is analyzed. Using the discrete element method and smoothed particle hydrodynamics method, the influence of dam face inclination on hydrodynamic pressures is explored. The results show that the variation of hydrodynamic pressures is related to the impulse waves running up and the position of the dam surface. Below the positions where maximum hydrodynamic pressures occur, both PHDP and NHDP exhibit characteristics of initially decreasing rapidly, followed by a slower decrease. Furthermore, both PHDP and NHDP on the dam flanks are larger than those near the horizontal center of the dam. The runup height of the impulse wave has a positive influence on the maximum value of the hydrodynamic pressures, while the distribution characteristics remain almost unchanged. Based on the experimental results, empirical formulas for hydrodynamic pressures are established in both vertical and horizontal directions. Additionally, with decreasing dam face inclinations, the runup height of impulse waves, maximum PHDP, and rate of decrease in PHDP with water depth gradually increase. It is recommended to reinforce the dam surface in areas where hydrodynamic pressures are high, especially near the normal water level and on both flanks of the dam. This study contributes to enhancing the understanding of hydrodynamic pressures on dams under complex topographic conditions.

High-elevation landslides impacting water bodies may trigger secondary disasters of landslide-generated impulse waves (LGIWs), which can cause substantial losses. This study employs a coupled discrete element method (DEM) and smoothed particle hydrodynamics (SPH) method to estimate the potential LGIWs hazard induced by the Meilishi (MLS) high-elevation landslide in the Gushui Reservoir. The DEM is used to simulate the landslide failure and sliding processes, while the SPH method is used to capture the water motion. To quantify the interaction between the DEM and SPH simulations, the dynamic boundary condition approach is utilized herein. The results show that the landslide mass exhibits significant deformation and disintegration characteristics during the sliding process. The volume release rate and the volume release ratio at different elevations show similar variation characteristics; however, the sliding velocity and kinetic energy release rate at lower elevations are significantly higher than those at higher elevations. The landslide forms an accumulation body approximately 1013.5 m long in the river channel without causing river blockage. The amplitude of the leading wave is much higher than that of the subsequent waves. There is no obvious wave reflection in the collapse area due to the convex shape of the opposite bank. The maximum water level (MWL) on the right side of the dam is higher than on the left side. The numerical model is then validated using large-scale prototype-specific physical model experiments, and the results indicate a high degree of consistency between the two models. Subsequently, the validated model is used to analyze the influence of entry velocity on the LGIWs hazard. Under the most dangerous condition, the landslide impacts the water with an entry velocity of 81.8 m/s, and the MWL is 2285.92 m on the dam face, showing a low possibility of overtopping. This study provides beneficial insight for accurately understanding the LGIWs hazard induced by MLS landslide and serves as a valuable reference for disaster prevention and mitigation.

Purpose: The purpose of this study is to investigate the effects of spatial variability and parameter correlation on the structural responses and reliability of moderately buried tunnels during excavation. The study aims to clarify how cross-correlated random fields (CRF) and stratigraphic anisotropy influence tunnel failure mechanisms and to provide quantitative insights for reliability-based tunnel design. Design/methodology/approach: A stochastic numerical framework was developed based on Copula theory to generate CRF for the cohesion and internal friction angle of surrounding rocks. The random fields were incorporated into a two-dimensional numerical model, and 65,100 Monte Carlo simulations were performed to evaluate tunnel responses under various stratigraphic dip angles and Kendall correlation coefficients. The probability of tunnel failure was quantified using two indicators: crown settlement and the proportion of the plastic zone. Findings: The results show that parameter correlation strongly affects tunnel reliability. As the Kendall correlation coefficient increases from negative to positive, the dominant failure mode shifts from crown-settlement-controlled to plastic-zone-dominated behaviour. The smaller of the horizontal and vertical scales of fluctuation (SOF) governs the lower bound of tunnel failure probability. Although the stratigraphic dip has limited influence on settlement, it significantly affects plastic zone development, revealing the anisotropic nature of spatial variability in rock masses. Originality/value: This study provides a quantitative framework for integrating parameter correlation and spatial variability into tunnel reliability analysis. The findings enhance the understanding of anisotropic effects in red-bed rock masses and offer practical guidance for the design and risk assessment of tunnels in heterogeneous geological environments.