Title: Prevention methods development against aerosol terrorism for ventilation of Tbilisi subway Grant N 216968 Report - Presentation scientific results of the first period
Key personnel of the project Professor Omar Lanchava Dr Giorgi Nozadze Dr Nino Arudashvili Foreign consultants: Professor Nikolae Ilias Department of Mechanical Engineering, Industrial and Transport, University of Petrosani, Romania Professor Roland Moraru Vice-rector of University of Petrosani Department of Mining, Surveying and Civil Engineering
The essence of the problem: • the subway ventilation system have a potential hazard as there is possibility to spread a toxic substance underground by means of channels for performing an act of terrorism. • the problem is also the low effectiveness of ventilation systems during different emergencies including in the case of terrorism.
To achieve the objectives of the study it is necessary: - increase the efficiency of ventilation systems: - implement the optimal measures. In both cases, the efficiency and optimality of the measures to be taken are the main tasks of our research.
The poisoning dose of some toxic substances: CS - 0.005 mg/l Carbon monoxide (CO) - 0.0005 mg/l Zarine (GB) - 0.0005 mg/l Zoman (GD) - 0.0005 mg/l V-gas (VX) - 0.00001 mg/l
The Realistic of possibility aerosol terrorist attack: For poisoning 100 m3/s (360,000 m3/h) air is enough: 10 mg V-gas (VX) 50 mg CO, zarine or zoman 500 mg "CS"
Plan of first period that performed successfully: - differentiation of subway structures in according of ventilation systems. - performing of experimental and natural observations in Tbilisi subway tunnels. - adequate analysis of results.
Natural observations by micro barometers have shown that during of arrival of trains in the station takes place Increasing of pressure on the 48 Pa. During the train departure, on the contrary there is a reduction in pressure on the 30 Pa. This question will be clarified after purchase of the planned wireless monitoring system.
The natural observations task was also set by means of CFD methods for the conditions of Tbilisi Metro Basic data: Tunnel length - 1000m; Cross section - 16 m2, length of train 60 - 80 m; Train speed 10.0, 12.0, 15.0 m/s; Acceleration of the train – 1.0-1.2 m/s2, the train cross section 4.00, 5.00, 6.25 m2.
Principal scheme of numerical experiments with speed detectors and distance curves.
As a result of the simulation, was determined the variability of ventilation flow caused by the piston effect depending on the speed and cross section of the train and the geometry of the tunnel.
Numerical modeling results with the initial conditions (flow speed 6.0 m/s). Numerical modeling results with the initial conditions (flow speed 8.0 m/s).
Numerical modeling results with the initial conditions (flow speed 10.0 m/s). Numerical modeling results with the initial conditions (flow speed 12.0 m/s).
- - Average speed distribution in the moving inertial system. - the average speed of air flow in the gap between the train and the tunnel; - the average speed of air flow in front of the train; - the average speed of air flow in back of the train.
Calculations based on the principle of Galilean's relativity - the time of movement of the train at constant speed in the tunnel; - the average speed of the stream driven by the piston effect, m/s. Results
Besides that, there is in this job established that the geothermal field of a massif around underground structures located above the neutral layer is non-stationary because of the influence of solar radiation. Below the above marked layer, the formation of the geothermal field of the subsoil is due to the process of depths and is stationary. The definition of these fields is necessary for the performance of the thermal physical calculation of the ventilation and the specification of the air consumption of the underground facilities by the thermal factor.
Illustration of Determining the Natural Temperature of the Massif for Stationary Geothermal Field: The neutral layer repeats the Earth's relief form; t - The temperatures of massif around the tunnel and Neutral layer, ℃; 0.00, 5.00 - Tunneling levels of Floor and Ceiling.
Conclusions: The possibility of aerosol terrorist attack by ventilation channels is realistic, as for poisoning 100 m3/s (360,000 m3/h) air is enough: 10 mg V-gas (VX), 50 mg CO, zarine or zoman. 100 m3/s is the number of air that is moving by means of piston effect of one pair trains. For the conditions of the Tbilisi Metro, the average temperature of the neutral geothermal layer is 12.8 degree of Celsius, and its depth stratification is 30 m. In the tunnels of metro, the air volume is 2000-5000 m3 generated by the piston effect under the speed of the train 25-50 km/h.