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Abstract: A novel method for dynamic risk assessment of oil spill accidents based on numerical simulation was presented in this paper. The dynamic risk assessment model was developed consisting of a comprehensive list of caused consequences like environmental damage, asset loss, health impact and social effect as well as emergency actions preventing these losses. Contributing events in the Mater Logic Diagram (MLD) of the dynamic risk assessment model were valued based on the simulated evolvement of oil contaminants under spill scenario on quasi-static fluid, which was obtained by coupling an oil spill model with hydrodynamic module in Jialing river of Three Gorges Reservoir in China after the impoundment of the reservoir to 175m water level in 2010. Calculated result of dynamic risk as grade IV indicated that the assessed oil spill was not as catastrophic as we thought because of the slow transport of oil fractions on water surface and absence of dispersed oil in water body due to the quasi-static fluid, very gentle wind and effective emergency actions, as well as by the reason that rare agriculture or industrial crops exist in spill adjacent area. [Copyright &y& Elsevier]

Abstract: High energy gas fracturing (HEGF) technique has been one of central stimulating measures to enhance oil recovery in low permeability reservoirs. But, in recently few years, some serious CO poisoning accidents took place in oilfields here in China. It is very important to reveal the dynamic mechanisms of carbon monoxide flow and diffusion to operating safety during high energy gas fracturing. In this paper, some dynamic mechanisms of carbon monoxide CO flowing inside a oil wellbore and diffusion on the top of the well during high energy gas fracturing were studied with fluid/gas hydrodynamics. The CO flow model within a wellbore and the diffusion model in air were established. The key factors affecting CO flow and diffusion such as wellbore pressure, gas–oil ratio, wind speed, leakage speed, air-permanence were inspected with mathematical simulation. It will be of significance to provide an important guidance for monitoring and preventing CO poisoning accidents during high energy gas fracturing. [Copyright &y& Elsevier]

Abstract: For the caving and sliding control of roadways with large cross-section, thick mudstone roof and abutment pressure influence, the cable truss system is proposed and its support mechanism is thoroughly analyzed in this paper. Furthermore, according to the geometric size and ground pressure conditions on field coal roadways Nos. 101, 102 and 103 in Xinyuan Coal Mine, three types of cable truss support systems are designed for obtaining the optimum cable truss support system. Then the corresponding parameters for each support design are determined by use of the numerical simulation method, and three kinds of support systems are put into practice. The field observation results show that roof should be effectively controlled by the normal cable truss structure consisting of two long cables and one connector, and both coal sides can be protected by the simplified cable truss structure composed of two short cables and one channel bar. Finally, the optimal support system is gotten which is much better than the other two support designs in rock deformation control effect and economic profits. [Copyright &y& Elsevier]

Abstract: With the rapid development in economics, subway systems have been constructed in many big cities of China. Computer evacuation models developed overseas are commonly applied in working out safety management scheme. However, input evacuation parameters are not compiled from surveying passenger behavior in China. In fact, very few studies were conducted on justifying such parameters. Staircases in subway stations, particularly those connecting the platform and the ticket hall, are identified as the ‘bottleneck’ during evacuation in the subway stations. The maximum upstairs speed and the average minimum width of staircase utilized per person are the two key parameters affecting the evacuation through the staircase. Effect of varying these two parameters will be studied in this paper by taking two subway stations in China as examples. Evacuation performance is predicted with the software buildingEXODUS. The default values in the software are used and adjusted through field survey. Effect of varying either or both of the two parameters is discussed. The possible causes on the differences and the factors to affect such effect are explored. It is found that changing both parameters simultaneously would reduce the overall evacuation time by 50%. The effect of varying the two parameters on the overall evacuation performance of the whole station depends also on the occupancy density in the station; and the travel distance from the outlet of the staircase between the platform and the ticket hall to the inlet of the staircase between the ticket hall and the ground surface. [Copyright &y& Elsevier]

Abstract: Crowding during the morning peak hours at a platform staircase in a subway station in China was studied in this paper. Passenger flow was surveyed with normal evacuation time recorded. The evacuation process was simulated with the software buildingEXODUS. Predicted results on the total evacuation time and maximum flow capacity of the selected staircase were compared with the field observations. Two parameters, the width of staircase utilized per person and the maximum upstairs walking speed used in the software were identified to be noticeably different from the field studies. Predictions agreed better with the observations after tuning these two parameters. It is concluded that the evacuation simulation software can be applied for safety design with appropriate tuning on the key parameters through field tests. [Copyright &y& Elsevier]