O. D. ALIMOV, I. G. BASOV, B. L. STEPANOV

EXPERIENCE IN THE USE OF EARTH-CUTTING MACHINES FOR DRAINING BOGS

Look at the map of our country and note what enormous areas are occupied by bogged lands. Nearly two thirds of all the bogs in the world are located on the territory of the Soviet Union [1]. The Far North and Western Siberia are the most heavily bogged.

In the West Siberian Lowland, the Ob–Irtysh watershed in the area of the left tributaries of the Ob River (Parabel, Vasyugan, Bolshoi Yugan, and others) is especially heavily bogged. Here, on the flat terrain, as a result of precipitation and groundwater, and also because of limited evaporation, boggy tracts reach enormous dimensions. In many districts only narrow strips along rivers, where the excess waters drain into them, are not bogged; all the interfluvial spaces, however, are occupied by bog systems extending for hundreds of kilometers [1].

Tomsk Oblast lies almost entirely in the southeastern part of the West Siberian Lowland. In terms of the size of its territory (314.3 thousand sq. km), it is larger than Italy (310 thousand sq. km); within the oblast’s borders three countries such as Bulgaria, Czechoslovakia, and Hungary could be accommodated at the same time. But, unfortunately, up to 31% of the oblast’s area is occupied by bogged lands [2]. The bogs of Tomsk Oblast occupy an area equal to the territory of the People’s Republic of Bulgaria. Impassable mires hinder the development and study of mineral resources hidden in the earth’s depths. Enormous reserves of iron ore that have already been explored cannot yet be developed, since they lie beneath bog mires. The development of explored oil and gas fields will also be made difficult.

Forest is the principal wealth of Tomsk Oblast, but a significant part of the forest tracts is situated on bogged soils. The forests there are stunted, and their exploitation is difficult. In this connection, the drainage of bogs is of especially great importance for Tomsk Oblast.

In our country, large-scale work is being carried out to drain bogs. Various mechanisms have been created for performing these works, but the digging of drainage canals in bogs, owing to the specific character of bog soils, is still associated with great difficulties. Therefore, further research is needed into methods of draining bogs and into the mechanisms required for this purpose.

The work was carried out with the participation of laboratory assistants E. I. Lisovskii, G. F. Van’shin, and V. G. Yudin.

Under the direction of Professor N. I. Pyavchenko of the Krasnoyarsk Institute of Forest and Timber of the Siberian Branch of the USSR Academy of Sciences, a method was developed for cutting drainage ditches in bogs by blasting. The essence of this method is that along the route of the future ditch a slot is cut, into which an elongated charge of explosive (EE) is placed. The explosive cartridges are tied to wooden slats and lowered into the slot. After this, the slot is filled in and the charge is detonated. Depending on the requirements imposed, by varying the size of the charge it is possible to obtain ditches of different depth and width.

With the aid of blasting, an enormous amount of work can be performed in very short periods of time, but the production of preparatory work for placing explosives in boggy soils is very labor-intensive. Existing machines cannot pass over the bog in summer and cut the slots. To carry out these operations manually (digging the slots, placing the explosive in them, etc.), when at every minute one may sink into the quagmire and clouds of mosquitoes and midges swarm overhead, is very difficult and at times even impossible.

Having acquainted themselves with Professor N. I. Pyavchenko’s method, the authors proposed carrying out the work of digging the drainage ditches by blasting in winter, using bar-type machines for cutting frozen ground to cut the slots; such machines have now become widely used in construction work during the winter period.

In 1961–1963, at the Department of Mining Machines and Mine Transport of the Tomsk Polytechnic Institute, several types of such machines were developed on the basis of domestic tractors and trench excavators. In operation, these earth-cutting machines cut slots in frozen ground 14 cm wide to a depth of up to 1.8 m, which is quite sufficient for placing explosive charges in bogs.

The first experiment in digging ditches for draining bogs in winter was carried out by the Department of Mining Machines and Mine Transport of the Tomsk Polytechnic Institute jointly with the technical department of the Tomles combine and the educational-experimental farm of the Tomsk Forestry Technical School in March 1963 in the Timiryazevsky forestry enterprise of Tomsk Oblast. This forestry enterprise was carrying out work on draining bogs in the area of Lake Peschanoe (near the city of Tomsk). To drain one of them, the level of which was 2.5 m above the level of the lake, it was necessary to cut a drainage ditch 400 m long. This could achieve not only the drainage of the bog territory for subsequent forest planting, but also raise the water level in the lake, which in recent years had been drying up.

In summer the bog was impassable both for crawler tractors and for other transport vehicles.

The winter of 1962–1963 was snowy, and the bog intended for drainage was covered with a thick snow cover; its peat layer had only slight freezing. Under such conditions, the use of earth-cutting machines was dangerous.

The available earth-cutting installations are intended for work on hard frozen soils, and to provide considerable tractive effort they have great weight. During the experiments it was proposed to use the “Moroz” earth-cutting installation for cutting slots. It is mounted on the crawler chassis of an ETU-353 excavator and has a weight of 10 tons. The great weight of the installation and the associated danger of its movement over the bog made it necessary to carry out preparatory measures. It was decided to clear the route of the future ditch of snow and allow the soil to freeze.

In several passes, a TDT-60 skidding tractor with a wedge attached at the rear cut a route for the future ditch through the snow cover of the bog, pushing the snow to the sides. The cleared section froze through for several days. After this, experiments began on cutting the frozen peat with the “Moroz” earth-cutting unit (Fig. 1), which consisted of a crawler chassis with a 54 hp engine mounted on it, a gearbox, and a cutting-unit reducer from a KMP-type coal-cutting machine with a bar as the working member. The bar is an endless chain, moving in a guide frame and consisting of cams and plates. Teeth reinforced with hard-alloy plates are inserted into the cams. The speed of movement of the chain can be varied within the range of 0.35–5.2 m/s. The bar can be driven into the soil and its position changed during the cutting process by the machine operator using a hydraulic system.

Fig. 1. General view of the “Moroz” earth-cutting unit while cutting slots in a bog.

When working dense frozen soil, the bar was, as a rule, set at an angle of 90° to the horizontal. In this case the soil thrown out of the slot by the working run of the cutting chain (by the teeth and cams) falls off it before reaching the drive sprocket and is not carried by the idle run back into the slot. The slot thus remains clean.

At the beginning of the experiments on cutting peat in the bog, difficulties arose in obtaining a clean cut slot. The depth of freezing of the peat in the bog was no more than 0.5 m. When the bar of the earth-cutting machine was positioned at an angle of 90° to the soil surface, the crushed semi-liquid peat brought to the surface by the teeth and cams of the bar was again carried along by the idle run of the chain and filled the slot being cut. This deficiency was eliminated by setting the bar at an angle of 60° to the soil surface. In this case, the crushed peat mass carried out of the slot by the working run of the cutting chain was thrown off by centrifugal force at the drive sprocket and fell in front of and alongside the ...

with the cutter bar and was not carried by the idle branch back into the slot. In order that the semi-liquid mass would not slide into the slot after the passage of the cutter bar, it was removed to the side with shovels. Thus, the slot was clean (Fig. 2). In the future, machines for cutting bog soils should be provided with a wedge or screw mechanism for moving the mass brought out of the slot to the side.

Fig. 2. Slot in a peat bog, cut by the “Moroz” installation.

The productivity of the “Moroz” machine, with the cutting chain moving at 1.25 m/sec and with a slot depth of 1.2 m, was 3 m/min of finished slot; at a chain speed of 2.4 m/sec, the slot-cutting speed reached 20 m/min. The average productivity of the machine was 300 m/hour.

In addition to the “Moroz” installation, a lighter and more maneuverable earth-cutting installation, BETN (Fig. 3), created on the basis of the ETN-124 trench excavator, was tested for cutting slots in the bog. This installation, which had the pneumatic-wheeled chassis of the “Belarus” tractor, moved freely along the prepared route, cutting a slot to a depth of up to 1000 mm. The hourly productivity of the installation reached 250 m.

After the passage of the cutter bar, the slot was gradually filled with bog water, but it did not silt up, since the upper layer of the peat bog was frozen.

The blasting workers who performed these operations had not previously carried out similar work in bogs. Therefore, at first they conducted several trial explosions on small sections, and subsequently blasted

Fig. 3. The BETN earth-cutting unit cuts a slit in a bog.

Fig. 4. Preparation for placing a ribbon charge of explosive in a slit in the peat bog.

sections 50 m long. The cartridges with explosive (ammonite) were tied to wooden slats (Fig. 4). The slats were lowered into the slit and pressed down from above with wooden wedges. The slit was partly filled with pulverized peat. For the most part, however, water served to tamp the slit. The consumption of ammonite was 2 kg per 1 m of the future ditch.

During the explosions, the peat together with ice was lifted upward and thrown to the sides; part of the blasted soil fell back into its former place (Fig. 5). In addition,

Fig. 5. Explosion in a bog.

moreover, after the explosion the ditch was partly filled with a mass of peat that had separated from its walls. In this connection the surface level of the blasted section was only 0.5–0.8 m lower than that of the unblasted section, and the ditch was poorly defined. On the following day the ditch was already more clearly defined, since during the night the destroyed peat deposit had settled, and the emerging bog water gradually filled the ditch (Fig. 6).

As an experiment, on the second day of work another method was used for immersing the charge in the slit. The cartridges with explosive were tied together with the detonating cord into bundles at one-meter intervals (Fig. 7). After the bundles had been prepared along the entire section intended for blasting, they were lowered into the slit and covered from above with pulverized peat.

Fig. 7. Preparation of brushwood charges for the explosive.

Fig. 6. View of a canal in a bog one day after the explosion.

peat. The result of the explosion in this case was similar to that produced earlier.

Apparently, for work on bog soils, a directed explosion will be more effective, when two explosions are carried out along the line of the ditch. During the explosion, the first, main charge throws the entire mass of earth upward, while the second, detonated with a slight delay after the first, casts the soil to the side away from the ditch.

The experiments carried out showed that the blasting method can be used for digging drainage ditches in hard soils and on bogs in winter. In this case, it is most expedient to place the explosives in slots successfully made by self-propelled bar machines for cutting frozen ground.

In order to improve this method, research and experimental design work should be carried out in the directions of finding the most expedient methods of placing and detonating explosives, the most effective working members of machines for preparing ditches for the placement of explosives, and of creating light, maneuverable, highly cross-country earth-cutting machines.

For digging ditches on bogs in winter, it is advisable to test single-bucket and multi-bucket excavators working in combination with bar-type earth-cutting machines. In these cases, depending on the required width of the ditch, the bar machine can cut two or three slots, and then the excavators, with their working members, can remove the soil enclosed between the slots. According to this scheme, in Tomsk in the winter of 1962–1963 work was already being carried out in digging trenches in hard soils, and this work yielded positive results. In addition, on the basis of light multi-bucket excavators and bar-type earth-cutting machines, in our opinion, machines of the multi-bucket type should be created whose working members would make it possible, in winter, to cut drainage ditches in boggy soils 800–1200 mm deep and 300–600 mm wide.

References

1. V. V. Romanov. Bogs and Their Properties. Gidrometeoizdat, Leningrad, 1953.
2. B. G. Iogansen. The Nature of Tomsk Oblast. Tomsk, 1959.