Event date: on November 17, 2013, took place: a tunnel shield diving site maintenance

Event description

Project: the subway shield tunnel shield hyperbaric chamber silt cleaning, maintenance (shield 11 m in diameter),

Diving apparatus, KMB - 18 type

Relief plan: 60 m 35 min

Staffing: 2, diving supervision 1;

Party as requirements: divers into compression Chambers after pressure cabin pressure to 4.8 Mpa, into the bubble chamber and open the bubble tank with liquid level after the doors into the mud tank (within normal mud water, all there before divers into compression Chambers to level down to about 9 m water depth), under the muddy water tank to the bottom of the shield diameter will mud mud at the bottom of the tank with water cannons, nozzle pressure 350 Mpa, car washing with water cannon, stuck around 0.80 m long, no buffer) hit the mud circulation chamber (in the bubble chamber below), the iron in the mud and large stones clean water, repair damage shield (welding work) to run properly.

17 at 7:00 in the morning after the normal work, divers take tunnel shield transporters to job site, after tidying around 8:00, 3 divers enter pressure cabin pressure.

8:03 about pressure, divers sealed door opens the compression Chambers bubbles, the bubble chamber experiment diving helmet pneumatic circuit system and water cannons, then use pneumatic wrench open the bubble chamber and liquid level tank in the middle of the door seal into the liquid level tank.

Around 8:10 divers dressed into liquid level at the bottom of the tank began to turn the high-pressure spray after the completion of the liquid level inside the silt and sand into the mud circulation cabin cleaning, divers found in mud when the job is about 15 min cycle doors (0.70 m high and 1 m wide) side there is a big iron, covered by sediment precipitation is bad overall cleaning, then began to clean up the iron hardness larger sediment around, after the water cannons to hardness larger sediment hit a hole in the sand and mud, normal divers were swept around the nozzle sand, when visibility is zero, a diver could not judge point and the distance between the gravel, typically rely on feeling, nozzle head against to the sediment after wanted, as a result of nozzle in when not in use has also had a certain high pressure, at the start of a diver counterblows hoses to hit a hole, and make a suction around a gun, the diver gloves absorb gun in sediment and aperture place, at the time of mud hole in 3 cm in diameter, divers feel absorb gloves immediately after loosening the trigger, but water gun recoil due to high pressure to stop, the ends of divers his left index finger joints with a 3 cm long, 1 cm wide hole, they call diving supervision injured finger, and quickly out of the water, diving supervision and call the doctor and the project manager.

At about 8:30, 3 divers after closing the mud tank and tank sealing door return transition tank, close the transition between tank and tank began after decompression sealed door, diving doctor after sealing door window to observe the divers injury in disinfectant, gauze and some band-aid emergency trauma care supplies, according to the divers 60 m35min relief plan started to decompression, injured diver with the help of two other divers simple clean up the wound, sterilization, disinfection, and dressing wounds.

At about 10:30, transfer 3 divers from cabin decompression to 12 m water depth after transfer to dive decompression chamber.

Out of the capsule around deprives the diver safety supervision, and project manager on the spot, accompanied by rapid nearest hospital for treatment.

Doctor check after the wound of high pressure water conditions and treatment of injured after the simple introduction to the project manager, project manager decided to transfer, the doctor simply divers transfer after treatment with the wound.

Ticket is about divers began in a hospital for surgery, surgery time around 2 h, the doctor cleared by high pressure water to your fingers meat within the sediment as well as the high pressure water and soft tissue, although the bone is the damage of mucous membrane, but the divers finger nerves, blood vessels and soft tissue has different degree of damage.

Cause analysis,

1, low operation live underwater visibility;

2, high-pressure environment caused by nitrogen narcosis effect divers slow, response to poor judgment;

3, diver itself to the use of the high pressure water gun operation risk awareness;

4, professional equipment, the high pressure squirt gun is not the surface of the water does not have back cushion valve device.

Lesson and preventive measures

1, the depth of the water reaches a certain depth as possible using mixture or saturation diving;

2, using professional underwater air-pocket type water cannon;

3, raise awareness of the risks of homework divers use of water cannons.