Gensheng Zhao

In implementing ship channels in mountainous rivers with complex topography, navigation safety has become paramount for facilitating efficient tunnel operations. The security of large vessels in tunnels has recently been the focus of a considerable amount of research in the inevitable trend of vessel upsizing. This study analyzes the characteristics of unpowered coasting distance for ten-thousand-ton bulk carriers through ship simulations. The study discovered a positive correlation between coasting length and variables including tunnel width, water depth, and sectional coefficient. Moreover, it explores the maneuvering characteristics throughout the tunnel traversal process. It proposes a vessel-following model based on car-following theory and defines different types of following distances to determine the transportation capacity of the tunnel. The research findings greatly enhance tunnel navigable safety and optimize ship tunnel operations.

The simulation of Concrete Gravitational Dam burst floods is an important research content in the field of disaster prevention and mitigation in water conservancy projects. Due to the extreme rainfall, earthquake, structure failure and etc., the concrete gravitational dam usually breaks in a short time period. The dam break flood will give an extreme risk to the downstream communities. Taking the flood simulation of the Kaliwa Dam in the Philippines as an example, based on the downstream channel of the dam body and the measured terrain on both sides, a numerical simulation model of one-dimensional and two-dimensional coupled flood evolution is constructed, and the numerical simulation of the flood evolution process of the dam collapse is carried out, counts the inundation range, water depth, flow velocity, flood arrival time and other disaster causing factors in the downstream inundation area, and draws the flood hazard map of both banks downstream. The simulation results show that the KALIWA burst accident occurred, the total inundation area downstream is over 38 km² in the downstream of the Kaliwa Dam. The dam break flood peak takes 1.5 h to reach the downstream estuary, which is the shortest time. The General Nakar City and Infanta City are inundated completely with the depth of 1.0 m to 2.0 m. The terrain near the upper reaches of the lower estuary is open and flat, the downstream area will be affected seriously by the flood. It is proposed to build a flood warning system to give the people downstream of Kaliwa Dam. The results of the research will provide a scientific basis for dam-break flood risk analysis, disaster assessment.

Shiplifts are one of the main types of navigation structures in canals and high dams in natural rivers.

The Baihutan hydro-junction of Changshanjiang River is located in the straight section of S-shaped channel, and the upstream approach channel is located in the concave bank of the bendy section of river. Navigable flow conditions in the entrance area of upstream and the bend connection area are complicated and disordered under the influence of circumfluence. Ships are prone to drift due to the high-speed transverse flow, which makes it difficult to meet the requirements of safe navigation. In the present study, the navigable flow conditions were evaluated by building a 1:80 hydraulic model and the remote-control ship model test were carried out. Besides, flow conditions in the entrance area, the approach channel and the bend connection area were investigated, and optimization and improvement measures were also proposed. Researches indicated that, affected by the water flow at the top of the bend and the narrowed river channel, the transverse and longitudinal flow velocity in the entrance area and the bend connection area were faster. Adjusting the layout of channel to reduce the angle between the mainstream and the axis of the channel, and expanding the cross-sectional area of the approach channel could effectively improve the navigable flow conditions and ensure the navigation safety. The results of this study can provide references for similar rivers.