Analysis And Modeling Of Evacuation Process For Passenger Ships Considering Water Environment

As the most capable transportation vehicle for human beings,ships play an important role in the communication and development of the modern international society.When the water crisis occurs,the evacuation of the evacuation activities reasonably and efficiently means the greatest protection for the personal safety of the personnel on board.The simulation and prediction of the evacuation behavior of the ship personnel has far-reaching guiding significance for reducing the loss of water traffic accidents,guiding the escape operations on the ship,and optimizing the safety design of the ship cabin.Compared with the problem of evacuation of land-based buildings,the evacuation of people in the ship scene has its own particularity.The complexity and uniqueness of the ship cabin structure layout,the influence of the hull floating motion on the ship’s pedestrian movement ability,etc.,have caused great interference to the analysis and research of the evacuation of the ship’s crowd.In order to accurately describe and analyze the law of evacuation behavior of passenger ships in the water environment,this paper establishes a theoretical model based on the characteristics of pedestrians moving on the ship by the hull movement,and uses computer simulation technology as an experimental simulation method to conduct in-depth research on the evacuation activities of passengers on board.Based on the accurate description of evacuation scenes and pedestrian movements using multi-grid models,this paper proposes a new model that uses pedestrians to guide pedestrian movement.In this model,each of the next stand point of the evacuation process is determined based on the probability of each stand point in its action neighborhood.The calculation of the selection probability of each stand point in the neighborhood adopts the extended classical field model calculation method.And the static field coefficient,lattice resolution and update sequence are analyzed by the evacuation simulation experiment for two types of scenes of sparse crowd and dense crowd.The impact was studied.Compared with the traditional discrete model,the guidance of pedestrian movement in this method makes the pedestrian’s position and movement direction more selective at the next moment,which weakens the problem that the trajectory is serrated in the traditional model,making the simulation trajectory closer to reality.On the basis of the above,the relationship between the passenger density and the speed of the ship and the avoidance behavior are considered.The description of the description of the action neighborhood is further revised,and the experimental scenarios with different exit widths are used for simulation verification.The simulation results and the crowd evacuation matches the experiment data well.When on the water,the impact of hull movement on pedestrian speed is inconsistent in all directions.We change the shape of the action neighborhood to match the decay of pedestrians in all directions.Under the action of ship motion,an approximation estimation strategy is proposed for the determination of the shape of the action neighborhood.Firstly,through the analysis and derivation of the geometry theory,the downtilt direction and the downtilt angle of the ship’s heel and trim combination are calculated;then,the following direction of inclination is the guide,combined with the empirical formula of the world’s maritime research institutions on the pedestrian speed affected by the hull movement,calculate the moving speed of the pedestrian in the four directions of the down direction,the right direction,the left direction and the up direction;With the moving speed in four directions being the axis,the elliptic formula is used to approximate the attenuation speed of pedestrians in all directions.Through the above steps,the model of this paper approximates the action neighborhood of the descendant of ship motion as an elliptical shape extending downward.Through computer experiment simulation,the simulation results show that in the rectangular cabin,the downward sloping direction of the hull has a regular influence on the arch-shaped distribution characteristics of pedestrians at the exit.When the angle between the slewing direction and the exit direction is closer to 0°,the crowd arch is flatter,and when the angle between the hull down direction and the exit direction is closer to 180°,the crowd arch will be presented during the evacuation process.Apparent longitudinal stretching.Aiming at the crowd evacuation simulation in the ship scene,we propose a global evacuation simulation algorithm based on the previous research results.The algorithm is divided into two stages: scene preparation and evacuation simulation.In the scene preparation stage,based on the relative position of the safe area,based on the reasonable prediction of the crowd flow trend,the ship space is decomposed into blocks according to the "whole shipdeck-block",and the corresponding local static field is calculated.Further,in combination with the flow of the crowd,the execution order of the three levels of "deck sequence-block sequence-optimal sequence" in the simulation process is determined.In the simulated evacuation phase,the motion characteristics of pedestrians in the ship will be considered,and the pedestrian evacuation simulation in each block of the hull will be simulated in the set order.We use a passenger ship with two passenger decks,300 passengers and 8 crews as the simulation scenario.The proposed algorithm is in the case of the passenger ship in the horizontal,heel,trim and heel-trim.The situation is simulated by evacuation.The distribution of the types of people on board in the experiment refers to the relevant regulations of IMO.In the evacuation experiment of the hull heel,the pedestrian channel on the lateral downside side accumulates more flow than the floating side.When the heel angle is opposite,the distribution pattern of the overall evacuation group has a certain symmetry about the hull heading direction,and the overall evacuation completion time has little difference.In the evacuation experiment of the hull trim,the pedestrian has a greater moving speed in the pitch direction.When the evacuation target area is consistent with the pitch side direction,it has higher evacuation efficiency than the opposite,and the former has a shorter evacuation time than the latter.In the evacuation experiment in which both the pitch and the heel are considered,when the angle between the downward tilt direction and the target region is an acute angle,the overall evacuation time is shorter than the angle at which the angle is obtuse.In the evacuation simulation of the whole ship inclination,the evacuation time is relatively shorter when the hull down direction and the safety position are closer to 0° than the direction of most people in the hull.The flow pattern and evacuation time of the crowds simulated by the whole ship passengers are consistent with the actual evacuation experience observations.The paper comprehensively studies the basic model of pedestrian movement,the influence of hull tilt on evacuation activities,and the three parts of pedestrian evacuation simulation in complex passenger ship space,which provides a new theoretical tool for the analysis of evacuation activities on board.