We continue the “Keyhole” section. In it, an MS correspondent spends one day with a builder, “spying” on his work. This time the hero of the column was the explosivesman of the ninth section of SMU-6 Nikolai Zemskov. He showed why blasting is a real art.
Zemskov's morning begins with preparation. First, he checks the equipment - the explosive machine and the henku (explosive chain resistance meter KHN 2570 P - editor's note), and prepares the slingshot with the explosive wire. Then, with the mining foreman, he orders explosives from the explosive warehouse.
A specialized permanent underground warehouse is designed to store a certain amount of explosive materials, which are issued strictly according to documents. Zemskov works with ammonite. Having received it in the required volume, the specialist goes to the site.
Ammonite is a powdery industrial explosive. This is what metro builders use in BVR. The advantages of ammonite are low sensitivity to mechanical stress, high chemical resistance and relative safety in production, storage and handling.
At the Rzhevskaya station of the Big Circle Line under construction, drilling and blasting operations (D&B) began in December last year. At that time, only a vertical shaft more than 70 meters deep was ready. By the end of January, most of the mining yard had already been completed: 39 horseshoe-shaped half rings had been installed, with eight remaining to be installed.
Next, the blasters will work on the approach adits to the station and only then on the station tunnels. Drilling and blasting is the most optimal solution for the rapid penetration of hard rocks that builders encountered during the construction of Rzhevskaya.
Zemskov arrives at the site and goes down into the mine to inspect the drilled face: check the depth and direction of the holes, the reliability and fencing of the scaffolding. Then he blows a long whistle, signaling the start of work. Everyone leaves the site of the explosion and goes to a safe area. Only employees familiar with special instructions remain.
– The shift engineer sets up posts. The guards make sure that no one approaches the face. They sign the vouchers,” explains Zemskov. “From now on, the responsibility falls on them.
Then the electrician on duty goes down to the face and checks it for stray currents. The worker looks for where they come from and eliminates them. To do this, turn off the power supply, leaving only emergency lighting with a voltage of no more than 24 volts. When everything meets the standards, the mining foreman gives Zemskov the command to load.
The blaster “throws” the ammonite along the holes that the miners had drilled in advance. He pushes each charge with a hammer - “wades” it. Then he installs and checks the explosive circuit with a meter. If it turns out to be broken, the specialist restores it. As soon as everything is set up, Zemskov and his assistants finally rise to the surface.
At the top, having connected the machine to the mine station, the metro builder gives two more long signals. He sets up the device and presses the button: an echo and a barely perceptible tremor sweeps across the site. The explosion is completed.
Now the face is “blowed through”: the ventilation is turned on to exhaust. Only after 18 minutes according to the estimated time, the shift engineer and the blaster go down. They use a special device to check the concentration of harmful gases in the air. If the permissible value is exceeded, ventilation continues.
The face is also checked for “failures” - charges that did not fire. They are eliminated by explosion. This is followed by another ventilation. Three loud whistles signal the end of the BVR. Now the miners will get to work and extract the waste rock.
Zemskov says that he came to Mosmetrostroy in 1976, after returning from the army. He started at SMU-2 as an insulator. Then he studied at a technical school to become a bomber. At the Chekhovskaya station I received my first experience in a new position. In his entire 43-year career, there are no injuries or accidents to his memory.
– You can’t joke with BVR, everything here must be taken seriously. Blasting requires calm, caution and concentration. A detonator should be like an artist: charge and detonate so beautifully, so that nothing unnecessary is damaged. This is a whole art.