Study On Ship Passenger Evacuation Model Considering Human Heterogeneity

Ensuring the personal safety of passengers is the primary goal and task to solve the safety problems in the process of the ship safety design.It is one of the important contents to guide each passenger in the dangerous area to the specific collection station quickly and safely.However,since most passengers in ship are heterogeneous groups where heterogeneities are related to gender,age,body size,mobility and decision-making behavior,etc.,the interaction among individuals in the evacuation crowd becomes greatly complex.And it is quite difficult to achieve the reasonable and efficient evacuation in emergency situation due to simultaneously the complex structure in the passenger ship,the large number of passengers,numerous personal heterogeneities,as well as the hull shaking or other complex factors in the ship.However,the visualized simulation of the ship passenger evacuation could be an effective solution to provide more intuitive evaluations and more reasonable suggestions for the decision makers.Thus,an evacuation model of heterogeneous pedestrian crowds was established in this paper for the passenger ship with rolling motion.And a series of simulation and detailed research on heterogeneous crowd evacuation process in passenger ship under static state and rolling state were carried out.In this paper,the social force model and the corresponding torque model were employed to describe the movement and rotation behavior of passengers.Additionally,the "visual area",the personal sensitivity to the space availability,the shortest path preference and the direction preference corresponding to the social "traffic norm" were introduced so that an optimization-based evacuation model for unidirectional flow has been established.Through the comparison of the results,the practicability and effectiveness of the proposed were tested.Simulation results showed that the pedestrian formation pattern after overtaking was strongly affected by the initial formation,including the initial positions and density of the slow pedestrians in the front.For example,in a dense heterogeneous pedestrian crowd,changes in the distribution location and density of slow pedestrians would lead to different crowd flow patterns in the corridor structure.Regarding the sparse pedestrian crowds,the results show that the egress time of the fast pedestrians was mainly influenced by the horizontal distance between the slow pedestrians in the front.In the corridor geometry without the bottleneck,the egress time of the fast pedestrians decreased first and then remains steady with the increasing horizontal distance.Meanwhile,in the cabin geometry the egress time of the fast pedestrians decreases first and then increases again with the increasing horizontal distance.That is,there was a crowd initialization distribution in the cabin structure that minimized the evacuation time of fast pedestrians.On the basis of the above ship evacuation model for unidirectional flow,an optimization-based ship evacuation model for heterogeneous pedestrian counter-flow was established considering the effect of counter-flow traffic,which could be used to reproduce simultaneously the "lane formation" self-organization phenomenon in the counter-flow,the overtaking behavior and the phase change of the pedestrian lanes observed in heterogeneous pedestrian crowd experiments.By comparing the simulation results with the experimental observation data as well as the results using other evacuation model,the rationality and accuracy of the model was tested.Simulation results showed,that within a moderate proportion of opposing pedestrians,lane formation can not only enhance the traffic efficiency of the bidirectional flow but also improve the mobility of fast pedestrians by providing more opportunities for the reallocation of the walking space shared by the occupants in the subsequent unidirectional pedestrian flow.Both the overtaking behavior of fast pedestrians in sparse heterogeneous crowds and,surprisingly,the personal preference for the right-hand traffic norm in a wide corridor might lead to a lower specific flow in a sparse heterogeneous pedestrian counter-flow.In addition,a strong personal preference for the right-hand traffic norm will always lead to the formation of two lanes in a heterogeneous pedestrian counter-flow,regardless of the corridor width,pedestrian density and other personal preferences.On the other hand,a preference for evading behavior may result in the formation of more lanes than a preference for going straight ahead does,up to the lane capacity of the corridor,under the condition of a weak personal preference for the right-hand traffic norm in the crowd.The evacuation mode of passengers and the key contents of evacuation research were analyzed according to the IMO's revised guidelines on evacuation analysis for new and existing passenger ships.In order to study the effect of ship model on evacuation,the rolling equation of passenger ship on sea surface in different wind conditions and the passenger speed reduction model under the rolling ship environment were both established.The influence of ship rolling angle,distribution position of passengers and the personnel heterogeneities on pedestrian walking speed in dynamic evacuation environment was studied.Results showed that,as the rolling Angle of passenger ship increased,the reduction of pedestrian speed increased gradually.At the same time,the farther the distribution of passenger was from the rolling axis of the passenger ship,the more obvious the reduction of pedestrian speed would be.On the other hand,the speed of healthy young men was less affected by the rolling motion of the passenger ship,and its speed attenuation degree was also small,while the vulnerable groups such as the elderly were more obviously affected by the rolling motion of the passenger ship,and the speed attenuation degree was larger.Based on the optimization-based ship evacuation model for heterogeneous pedestrian counter-flow and t the passenger speed reduction model under the rolling ship environment,a passenger ship evacuation model system for the heterogeneous crowd was established within the framework of FDS+Evac simulation platform.A three-dimensional crowd evacuation scene model was built based on a large ro-ro passenger ship.The simulation process of pedestrian evacuation was also developed.Through the evacuation simulation of the heterogeneous crowd on passenger ship,the influence of the structure of the ship,crowd density,individual heterogeneities,ship rolling,rescue personnel and other factors on the evacuation was studied.The results showed that a wider corridor can not only improve the passage efficiency of the crowd,but also avoid the crowd congestion in the cabin exit.The increase of the number of slow pedestrians in heterogeneous population leaded to more interactions among the crowd,which was likely to cause crowd congestion around bottleneck structures.As the rolling angle of passenger ship increased,the speed reduction degree of pedestrian gradually increased,leading to the gradually increased evacuation time.The elderly and other vulnerable groups were more sensitive to the rolling motion of passenger ships,so their speed reduction was more serious,greatly extending the evacuation time of the crowd.Simulation of heterogeneous crowd evacuation of passengers considering the flow of rescue personnel showed that "crowd shock" or crowd congestion may occur around the exit to the assembly station,and a crowd area of counter-flow and crossing flow were formed in the corridor connecting the safe exit and each cabin.In addition,the initial distribution and the number of rescuers had a significant impact on the evacuation process.Avoid confronting with the passenger crowd of at the narrow passageway or bottleneck exit as far as possible,so as not to form the crowd jamming and delay the time of passenger evacuation and rescue work.