How happened to the 12-death explosion caused by the tunnel gas accident? How to prevent?

According to the SAWS website news, about 50 minutes, the territory Dafang County, Bijie City, Guizhou Province, the fast train into your gas explosion occurred in the construction seven rock tunnel 14:05 February.

It ended at 4:45 on May 3 Xu, the accident caused a total of 12 people were killed and 12 injured. At present, the emergency rescue work is over, and the aftercare and investigation processing work is in progress.

The State Administration of Work Safety issued warning notices to the nation and asked all localities to deeply learn lessons from accidents, strengthen construction and construction safety management, carry out in-depth investigation and management of hidden dangers, and vigorously implement various safety precautions and measures to prevent similar accidents from occurring.

How did the tunnel gas explosion happen? There have been similar accidents before this:

At 13:24 on February 2015 Ri 36 minutes by China Hydropower Construction Group Co., Ltd. 35 If the construction bureau (in water 15 Bureau) construction of towns and five Luodai Longquanyi District Luo Road Tunnel, a gas explosion accident It caused 7 deaths, 19 injuries, and direct economic losses of 16.2 million yuan.

December 22, 2005 14 40 points, Dujiangyan to Wenchuan highway Dong Mountain Tunnel particularly significant gas explosion occurred, resulting in 44 deaths, 11 people were injured, the direct economic loss of 20.35 million yuan. This was the biggest accident that occurred in the tunnel under construction since the founding of the People's Republic of China.

Let us look for the source of the accident from the above two accidents.

01 2015 : Gas explosion accident of tunnel 1 under construction

Around at 13:10 on February 24, Sun Zhongliang, Chang Jin-liang, Wu Zhongxiu, any move to create four people climb the fence into the right hole isolation Tunnel, Sun Zhongliang, four people entered the tunnel about 20 minutes, a gas explosion occurred inside the tunnel.

After the accident, the traces caused by the shock wave at the scene and the on-site inspection were analyzed. The detonation point was located at about 582 to 588 meters in the right tunnel of the tunnel . Chang Jinliang’s explosion caused the accumulation of sparks during the inspection of the vehicle, resulting in detonation and detonation. The gas layer accumulating at the top of the tunnel quickly spreads to the face of the right and left holes (through a communication channel at 600 meters ), causing gas explosions between the initial and second linings of the right and left holes respectively, causing walking Sun Zhongliang, about 670 meters from the entrance to the cave , and Wu Zhongxiu, who are located in the car about 250 meters from the entrance to the cave , died.

The blast wave generated by the blast blew outwards at an angle of 30 degrees along the entrance , and destroyed the houses, facilities, and equipment within a radius of 200 meters . This caused Xue Lijun, who was resting in the material room, and Lin Chenggao, a pedestrian on the road outside the tunnel, to die on the spot. Wu Hexiu, Deng Caifeng, and 20 people who were resting and entertaining in the sheds and Changlong Brickyard were injured.

After the accident, Wei Cailing, Gao Renxiang and others climbed out from the collapsed board room and immediately called emergency telephone numbers “ 119 ” and “ 120, ” and medical institutions in cities and districts promptly treated the injured.

Around at 21:35 on February 25, Wu and repair wounded died.

The accident investigation report pointed out the cause of the tragedy:

1. The direct cause.

Downtime during May 1 Tunnel Road, Luo Spring Festival holiday stop the wind, the accumulation of a large number of tunnels Nevas, and achieve explosive limit; February 24, the construction unit 4 Slag driver in violation of safety rules, crossing the fence into unventilated tunnel During the maintenance of the vehicle, sparks detonated the gas in the tunnel and caused an accident.

2. Indirect reasons.

( 1 ) Responsibility for the main part of the safety production of Luqiao Company of the 15th Bureau of Reclaimed Water is not fulfilled. First, the safety awareness of project safety managers is weak. The person in charge of the project department did not fully understand the degree of gas hazards, implemented the relevant provisions of the "Technical Specifications for Construction of Highway Tunnels" and was not in place. During the Spring Festival holiday, the work stopped and stopped, resulting in a large accumulation of gas in the tunnel. Second, safety management was not in place. The work arrangement before the Spring Festival was suspended was unreasonable, and the system of leading and leading was not implemented; the third was that education and training were not in place and safety education and written technical disclosures were not given to guards; Fourth , the construction of Wuluo Road No. 1 tunnel was handed over to Shaanxi Zhongtong for violations . Tunnel company implementation.

( 2 ) The main responsibility for safe production of Shaanxi Zhongtong Tunnel Company is not fulfilled. In the construction of the project, there is no person responsible for safety production inspection and certification as the person in charge of the construction site; during the suspension of the Spring Festival, effective measures to forbid personnel from entering the stop-and-go wind-high gas tunnel are not established and implemented, and no high gas tunnel is set outside the tunnel entrance. The effective warning signs; the education and training of the operators is not in place, and safety education and written technical disclosure have not been provided to the personnel on duty.

( 3 ) The supervision responsibility of Yatong Highway Supervision Office is not in place. The supervision of the construction site was weak. The construction unit did not set effective warning signs for high gas tunnels outside the entrance to the tunnel, did not formulate and implement effective measures to prohibit personnel from entering the stoppage and stoppage of high gas tunnel operations, education and training were not in place, and the person in charge of the construction site. No safety production inspection certificate and other issues are oversight.

( 4 ) The safety management responsibility of the project management company of Chengluodong extension line was not implemented. Supervise the construction unit to strengthen the on-site safety management, timely investigate and rectify the hidden dangers of various types of safety accidents, formulate and implement effective measures for the safety operations of high gas tunnels, and ask the staff of Shaanxi Zhongtong Tunnel Company who have no safety production assessment certificate to be responsible for the construction site. Oversight.

( 5 ) The safety supervision responsibility of the Transport Bureau of Longquanyi District was not implemented. The safety supervision of Wuluo Road project was not in place. Before the Spring Festival, the on-site safety inspection of the Wuluo Road project was not conducted carefully or deeply. The construction unit was not urged to set an effective warning sign for the high gas tunnel outside the entrance of the tunnel, and the establishment and implementation of unauthorized entry of personnel was prohibited. Stoppage of work and effective measures to stop high wind tunnel operations.

02 2005 : Gas explosion accident at Dongjiashan tunnel

According to reports at the time, back in 2005, March 6, Dong mountain tunnel hole left in the excavation of gas deflagration occurred, but fortunately the fire was promptly extinguished, causing no major damage. After the left-hole accident, many workers also reported the accidents in the tunnel to their superiors several times. Many migrant workers have reported that when they hammered a stone with a hammer, they caused a deflagration of gas in the cave. Both the hair and the beard had been scorched. After reflecting it to the construction unit, they did not cause enough attention to the responsible person.

Some migrant workers said that before the accident, the gas concentration in the tunnel was too high. After they went down, they often felt headaches and chest tightness. After reflecting on the leaders of the construction units, they did not take care of them or let them work as usual. A migrant worker from Zunyi, Guizhou, reported that at about 5 a.m. on the 22nd , he smelled a pungent smell of wood that was a bit rotten, and he felt a headache. He then reported to the contractor that the gas concentration might be too high. High, required to stop construction, ventilation out of the tunnel. The contractor did not agree to stop work, but allowed him to go through the air. These facts all indicate the severity of high gas in the area and the historical situation near the tunnel. However, many accidents did not cause the construction unit to be vigilant!

The investigation team found that the tunnel construction site is in the coal-bearing formation and the gas emission volume increases. When the arches were connected to the ribs and welded on the face, minor local combustion occurred several times. In the second lining pouring operation, the gas concentration in the waterproof panel is relatively high. The relevant units have insufficient understanding of the hazards of tunnel gas in this region, and relatively lag behind in predicting and judging technical means of gas in the tunnel. Failure to correctly define and advance forecast of the gas tunnel grade has led to the construction and supervision of the tunnel in accordance with the low-gas tunnel. Hidden danger is the main reason for this accident.

The accident investigation report pointed out the cause of the tragedy:

The direct cause of the accident:

Due to the landslide at the face of the face and the abnormal gas emission, the concentration of gas near the template trolley reached the explosion limit, and a short-circuit caused by short-circuiting of the three-pole plug suspended near the distribution box of the template trolley caused a gas explosion.

The main cause of the accident:

First, the construction company has one railway and four companies, and illegally subcontracts labor services to unqualified production teams. The safety management in the construction is confusing; the ventilation is poorly managed, and the gas concentration of the vault on the right-hand face is often exceeded; some of the tile inspectors are not certified, and the inspection quality and frequency do not meet the regulations.

The second is that the Supervisory Institute, Iron Technology Institute (Beijing) Engineering Consulting Co., Ltd. has not performed its duties correctly, and key positions personnel have no card posts.

Third, the project legal person Sichuan Duwen Road Co., Ltd. failed to correct the problems of illegal subcontracting and chaotic management of construction units, and failed to take effective measures against hidden gas hazards during construction.

Fourth, the Sichuan Provincial Communications Department’s Highway Planning, Survey, Design and Research Institute, the design agency, lacks awareness of the abnormal gas emission involving construction safety, and the preventive measures are not in place.

Gas tunnel construction safety prevention measures

1 Do a good job of forecasting tunnel gas ahead

In order to ensure the safety of gas tunnel construction, comprehensive geological prediction of the tunnel should be carried out based on the characteristics of geological structure and gas spillage. In order to ensure the accuracy of geological forecasting and accurate prediction of surrounding rock structure and gas enrichment ahead of the tunnel face, it is necessary to verify each other by various advanced detection methods to ensure accuracy. Then according to the results of geological forecasting, a corresponding method of gas control shall be worked out to ensure the construction safety of the tunnel.

2 Strengthen the inspection work of gas

According to the previous gas tunnel explosion accident case, it can be seen that the main reason for the explosion of the gas tunnel is that during the construction of the tunnel, there are missing information, missing reports, and missing processing of gas information. Therefore, in order to ensure the safety of gas tunnel construction, gas monitoring must be conducted in a timely and accurate manner during the construction of the tunnel. The detection of gas concentration is a key part of the gas tunnel construction. To ensure the safety of the tunnel construction, it is necessary to monitor the gas concentration in the tunnel and the operation status of the fan in real time to ensure the safety in the tunnel.

3 Ensure a reliable ventilation system

Strengthening the ventilation management within the tunnel to ensure uninterrupted ventilation during the construction of the gas tunnel is the fundamental measure to solve the problem that the gas concentration in the tunnel does not exceed the standard, and it is also the main means for diluting gas and smoke and dust. Ventilation must be carried out according to the design and specification requirements. In accordance with the gas control requirements, the tunnel ventilation must be equipped with a standby fan and backup power supply. At the same time, it must ensure that the standby power supply or standby fan ensures automatic switching between 24h continuous ventilation. In the event of a power outage, another power source can be started within 10 minutes to ensure ventilation. In addition, the fan should also be equipped with a dedicated transformer, dedicated lines and special switches.

4 Explosion-proof modification of construction equipment

In order to prevent gas explosions and other disasters in gas tunnels, the electrical equipment and operating machinery in the high gas and gas outburst work areas must be explosion-proof. During the construction of the gas tunnel, suitable explosion-proof treatment shall be adopted for the working machinery. It must be required that the electrical equipment entering the speed adjustment must be an explosion-proof type equipment permitted by the coal mine, and the gas tunnel must use explosion-proof electromechanical equipment. Therefore, before tunnel construction, general-purpose electromechanical equipment should be transformed into explosion-proof electromechanical equipment.

5 Establish a sound management system

The perfect safety management system is the basic guarantee for safe production. Therefore, before the construction of a gas tunnel, it is necessary to establish a sound safety management system, such as the electric welding system of the tunnel, the tunnel ventilation system, the gas inspection system, and the gas tunnel inspection and registration system. Before construction workers enter the tunnel, they must be inspected by the staff on duty at the entrance. It is forbidden to carry tobacco, ignition articles or wear chemical fiber clothes into the tunnel. It is forbidden to use incandescent lamps and electric furnaces that are prone to sparks. Do not engage in electricity, gas welding and so on. Exhaust vehicles adopt diesel vehicles or install exhaust emission purifiers to prevent the sources of danger caused by tail gas emissions.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.