Record labor productivity of a tunnel drifter: 28.3 meters per month under permafrost conditions
Abstract Generated abstract
This article reports on the organization and performance of K. E. Shefer’s integrated tunneling brigade during rapid underground exploration work at the Karamken gold and silver deposit under permafrost conditions. It describes the brigade’s staffing, equipment, cyclic work schedule, drilling and blasting practice, ventilation, loading, and haulage arrangements, with technical and economic indicators for June to July 1972. The brigade drove 340 m of workings in 30 days and achieved a reported productivity of 28.3 m per tunneling worker per month. The authors argue that further gains were possible by reducing downtime, increasing compressed-air pressure, improving drilling and blasting methods, shortening ventilation time, and improving communications.
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RECORD LABOR PRODUCTIVITY OF A TUNNELING WORKER—28.3 METERS PER MONTH UNDER PERMAFROST CONDITIONS
V. G. Lukyanov, A. D. Gromov
(Presented by the scientific seminar of the Department of Geodesy, Mining, and Construction)
The integrated mine-tunneling brigade of K. E. Shefer is well known in the Ministry of Geology of the USSR and enjoys well-deserved authority. Holding a leading place among the high-speed brigades of the Sosnovka expedition, it increases from year to year the rate at which underground mine workings are driven. In 1964, Shefer’s brigade drove 193 m in a month; in 1969, 640.3 m; and in 1970, 1221.2 m of workings, with the productivity of a tunneling worker reaching 30.5 m per month, while the average productivity in the Ministry of Geology was 10–14 m per month. Therefore it was no accident that, when the need arose to complete, in the shortest possible time, the exploration of the Karamken gold-silver deposit of the Northeastern Territorial Geological Administration and to drive 31 thousand m of underground mine workings in 3 years, part of the brigade (headed by the brigade leader, the section chief, and the mechanic) was sent to this administration by order of the minister.
Twelve tunneling workers arrived at the work site. At the same time, 4 tunneling workers held blasting foreman certificates. The section chief, an electrician, and a mechanic arrived at the work site in advance. The work area, scope of work, and the required quantity of materials, equipment, and tools were specified. An underground traction power substation was installed; the required number of ties and rails was prepared; a dump was equipped; and a water tank was installed. The brigade was equipped with two PPN-1s rock-loading machines, fifteen UVO-0.8 mine cars, two electric locomotives (one 4.5-ARP, the other AK-2U), eight PR-30LU rock drills, and P-18 LK pneumatic supports.
Minor and preventive repairs of equipment and mechanisms during the work process were carried out by 2 electricians on the first shift, from 8 a.m. to 3 p.m. In case of emergency, a UAZ-452 vehicle was assigned to the brigade, on which explosives, emergency equipment, and electricians were delivered. The daily supply of explosives was stored in the working in a specially equipped place in accordance with the requirements of safety regulations. Compressed air was supplied through pipes 100 mm in diameter from a central compressor station equipped with four VP-20/8 compressors (3 in operation, 1 in reserve) and two VK-25 compressors (1 in operation, 1 in reserve).
Water was delivered to the face before drilling blast-holes in a barrel filled on the surface.
The brigade was assigned 2 adits, each with a design length of 300 and
600 m, of which crosscuts passed on both sides of the drift axis every 10 m, each 5 m long. Therefore, from 2 to 6 faces were in operation simultaneously. The crew was divided into 3 teams of 4 tunneling workers per team.
The work was carried out according to a cyclic schedule of 2–3 cycles per seven-hour shift.
Let us briefly consider the technology for performing the main operations of the tunneling cycle.
Drilling blastholes, charging, and blasting
Blastholes were drilled with PR-30LU rock drills with P-18LK pneumatic supports. Chisel bits reinforced with hard alloy, 40 mm in diameter, were used as the rock-breaking tip. The number of blastholes and their depth were determined by the cross section of the workings and the blastability of the rocks being driven.
For a working cross section of 5.8 m², the number of blastholes was taken as 19–21, with a depth of 1.8 m; for a cross section of 2.7 m², 14–16 blastholes with a depth of 1.8 m. The cut was a vertical wedge cut.
The face was drilled by two tunneling workers. Upon completion of drilling, the tunneling worker who did not have the “Unified Blaster’s Certificate” blew out the blastholes, moved the rock drills to a safe place, disconnected the hoses, and prepared the loading machine for loading the rock. The second tunneling worker, who had the “Unified Blaster’s Certificate,” delivered explosives to the face, charged the blastholes, and carried out the blast. For blasting operations, ammonite No. 6ZhV explosive, OShA firing cord, No. 8 detonator caps, and group-ignition cartridges were used.
Ventilation of the workings was carried out by a combined method using “Prokhodka-500-2M” fans. Exhaust fans were installed every 100–150 m along the working. The forcing “Prokhodka-500-2M” fan was located at a distance of 50–60 m from the face. Rubberized pipes 500 mm in diameter were used in the exhaust and forcing pipelines.
Loading and haulage of rock
To mechanize these labor-intensive cycle operations, a PPN-1s loading machine, UVO-0.8 side-dump cars, and 4.5-ARG and AK-2U electric locomotives were used. Car exchange was carried out in dead-end sidings. The average distance from the passing loop to the face did not exceed 30 m.
Haulage of loaded cars to the dead-end siding was carried out by the rock-loading machine; empty cars were supplied for loading manually. When cars were hauled by the 4.5-ARG electric locomotive, up to 10 cars were loaded and hauled to the surface at one time; when hauled by the AK-2U electric locomotive, up to 5 cars.
Usually two tunneling workers accompanied the loaded train to the surface.
Extension of the rail track was carried out by crew members as the face advanced by one rail section. In addition, the crew hung ventilation pipes and compressed-air pipes.
The crew achieved its best results in June–July, driving 340 m of mine workings in 30 calendar days and attaining record labor productivity for permafrost conditions—28.3 m/month per tunneling worker.
Technical and economic indicators of the brigade’s work
(June 10—July 10, 1972)
| Indicator | Value |
|---|---|
| Monthly advance, m | 340 |
| Productivity of one tunneling worker, m/month | 28.3 |
| Cross section of the working, m² | 2.7—5.8 |
| Average category of rocks penetrated according to the Unified Norms and Rates | 17.1 |
| Number of drill holes at the face | 14—21 |
| Depth of drill holes, m | 1.8 |
| Drill-hole utilization coefficient | 0.85—0.90 |
| Number of simultaneously operating rock drills at the face | 2 |
| Compressed-air pressure at the face | 4.5—5 |
| Number of working days per month | 30 |
| Number of work shifts per day | 3 |
| Number of cycles: in a shift | 2—3 |
| Number of cycles: per day | 6—8 |
| Duration of operations in the cycle, min: drilling | 70—80 |
| Duration of operations in the cycle, min: charging, blasting | 30—35 |
| Duration of operations in the cycle, min: ventilation | 30 |
| Duration of operations in the cycle, min: loading rock, haulage | 140—160 |
| Total cycle duration, min | 270—305 |
The productivity achieved by E. K. Shefer’s brigade is not the limit. The brigade had substantial reserves for achieving higher labor productivity. This becomes clear after analyzing the brigade’s daily productivity over the course of the month. Fluctuations in productivity by day are significant, ranging from 2 m per day for the brigade to 16.5 m. It follows from this that reducing unproductive expenditures to a minimum—those causing daily productivity to vary over wide limits—will make it possible to increase the rate of driving workings.
Other reserves for increasing the labor productivity of tunneling workers are:
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Increasing the compressed-air pressure at the face from 4.5 to 8 atm, making it possible to increase the mechanical drilling speed by a factor of 2—2.2 (according to foreign literature).
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Increasing the efficiency of drilling-and-blasting operations by:
a) using bits with a diameter of 36—38 mm;
b) using bulk explosives, which make it possible to mechanize the charging process and shorten the charging time;
c) using more rational types of cuts, making it possible to increase the drill-hole utilization coefficient to 0.9 and higher.
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Reducing ventilation time to 10—15 min.
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Providing the faces with reliable communication with the compressor station and the party base, which makes it possible to reduce downtime due to breakdowns, lack of materials, etc.
Elimination of the listed shortcomings will make it possible to raise the labor productivity of tunneling workers to 35—40 m per month.