Engineering-Geological Classification of Bogs in the Alexandrovskoye Ob Region
Abstract Generated abstract
This paper addresses the engineering-geological significance of widespread bog formation in the Alexandrovskoye Ob region, where waterlogging strongly affects conditions for civil, pipeline, and road construction. Using engineering-geological survey materials, aerial observations, and aerial photographic interpretation, the authors propose a classification based on microlandscape character, feeding conditions, waterlogging, peat decomposition, bog-water level, peat thickness, and associated construction implications. Two main bog types are distinguished: slightly to moderately waterlogged bogs and strongly watered bogs with frequent open water surfaces, with their distribution varying between the left and right banks of the Ob River. The study also notes spatial relations between bog flow, natural drainage, and tectonic structures, contributing a regional framework for evaluating construction conditions in boggy terrain.
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ENGINEERING-GEOLOGICAL CLASSIFICATION OF BOGS IN THE ALEXANDROVSKOYE OB REGION
E. S. Tsotsur, T. Ya. Emelyanova
(Presented by the scientific seminar of the Department of Hydrogeology and Engineering Geology)
One of the principal factors determining the engineering-geological conditions for the development of the Alexandrovskoye Ob region is physical-geological processes and, in particular, bog formation. Bogs in the study area are widespread and occupy 75–80% of the territory on the right bank of the Ob River and up to 20% in its left-bank part.
Bog formation is caused by many factors: the exceptional flatness of the surface, poor drainage, the shallow occurrence of the first aquifer near the surface, the predominance of precipitation over evaporation, and neotectonic movements. The most widespread on the interfluves and river terraces are raised sphagnum bogs with a ridge–hollow–lake complex. In addition, on floodplains and terraces, considerable areas are occupied by lowland and transitional bogs. The areas of distribution and the character of bogs largely determine construction conditions in the region. This, as well as the uneven areal development of different types of bog landscapes, the differing character of waterlogging, the forms and sizes of bogs, their depths, and the types of peat, makes it necessary to compile an engineering-geological classification of bogs.
The engineering-geological classification of the bogs of the region has been compiled on the basis of available materials from engineering-geological surveys, aerial visual observations, and aerial photographic survey data, using the experience of existing classifications. In the existing construction and engineering-geological classifications of bogs (Orduyants, 1946; Dertsakyan, 1965; Borodavkin, 1968; Sergeev, 1970), bog types are distinguished according to different criteria in accordance with the requirements of one or another type of construction.
The assessment of bog types in the proposed classification is given in relation to civil, pipeline, and road construction. The basis for distinguishing bog types is the character of the microlandscapes, feeding conditions, and the degree of peat decomposition, established in the course of the survey. The engineering-geological and construction assessment of bogs is given by analogy, taking into account existing classifications. Two types of bogs have been distinguished (Table 1).
Type I. Bogs with slight and moderate waterlogging, with a bog-water level of 0.2–0.5 m. The width of the bogs is from 0.2 to 3 km. The thickness of peat is from 1 to 7.8 m.
Table 2
Results of determination of the penetrability of formations in boreholes 260, 261, 262, and 264 of the Pervomaiskoye oil field
| Borehole no. | Filter length per one hole, cm | Thickness of formation per one hole, cm | Borehole radius, cm | Filter radius, cm | Greatest penetration of the non-Newtonian oil, cm | Geometrical characteristics: external-zone line, 1/cm | Geometrical characteristics: drying-zone line, 1/cm | Orifice diameter, mm | Inflow in boreholes under steady conditions, cm³/sec | Selection of liquid in a given regime, thousand cm³ | Selection of liquid by the end of work under the given regime, thousand cm³ | Radius of influence of the borehole, cm | Geom. characteristic: linear flow zone, 1/cm | Sum of geometrical characteristics, 1/cm | Effective penetrability under the given regime, md |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 260 | 6,111 | 16,667 | 9,55 | 21 | 1900 | 1,0732 | 0,5761 | 3 | 358,13 | 44480 | 44480 | 4651 | 0,0537 | 1,7030 | 10,35 |
| 260 | 6,111 | 16,667 | 9,55 | 21 | 1900 | 1,0732 | 0,5761 | 5 | 516,69 | 45571 | 90051 | 5547 | 0,0643 | 1,7136 | 10,67 |
| 260 | 6,111 | 16,667 | 9,55 | 21 | 1900 | 1,0732 | 0,5761 | 8 | 781,87 | 88663 | 178714 | 6402 | 0,0792 | 1,7222 | 10,98 |
| 260 | 6,111 | 16,667 | 9,55 | 21 | 1900 | 1,0732 | 0,5761 | 4 | 459,28 | 33895 | 212609 | 8994 | 0,0933 | 1,7426 | 11,04 |
| 260 | 6,111 | 16,667 | 9,55 | 21 | 1900 | 1,0732 | 0,5761 | 5 | 522,16 | 37595 | 250204 | 9169 | 0,0944 | 1,7437 | 11,10 |
| 260 | 6,111 | 16,667 | 9,55 | 21 | 1900 | 1,0732 | 0,5761 | avg. | 10,83 | ||||||
| 261 | 9,444 | 9,444 | 11,87 | 23,4 | — | 1,0891 | — | 4 | 273,64 | 52160 | 52160 | 5482 | 0,5778 | 1,6669 | 4,87 |
| 261 | 9,444 | 9,444 | 11,87 | 23,4 | — | 1,0891 | — | 6 | 328,06 | 21258 | 73418 | 5794 | 0,5836 | 1,6727 | 4,68 |
| 261 | 9,444 | 9,444 | 11,87 | 23,4 | — | 1,0891 | — | 6 | 341,73 | 17223 | 90641 | 6408 | 0,5943 | 1,6834 | 4,92 |
| 261 | 9,444 | 9,444 | 11,87 | 23,4 | — | 1,0891 | — | avg. | 4,82 | ||||||
| 262 | 6,000 | 11,20 | 9,46 | 21 | 1300 | 1,0732 | 0,5859 | 4 | 419,64 | 15106 | 15106 | 2930 | 0,0725 | 1,7316 | 9,95 |
| 262 | 6,000 | 11,20 | 9,46 | 21 | 1300 | 1,0732 | 0,5859 | 6 | 587,77 | 16928 | 32034 | 3623 | 0,0915 | 1,7506 | 10,34 |
| 262 | 6,000 | 11,20 | 9,46 | 21 | 1300 | 1,0732 | 0,5859 | 8 | 826,97 | 74425 | 106460 | 5611 | 0,1306 | 1,7897 | 11,11 |
| 262 | 6,000 | 11,20 | 9,46 | 21 | 1300 | 1,0732 | 0,5859 | 6 | 604,17 | 13051 | 119511 | 6827 | 0,1481 | 1,8072 | 10,97 |
| 262 | 6,000 | 11,20 | 9,46 | 21 | 1300 | 1,0732 | 0,5859 | avg. | 10,59 | ||||||
| 264 | 5,208 | 9,722 | 8,82 | 20,3 | 1300 | 1,0679 | 0,6814 | 6 | 820,14 | 67907 | 67907 | 5164 | 0,1419 | 1,8912 | 14,59 |
| 264 | 5,208 | 9,722 | 8,82 | 20,3 | 1300 | 1,0679 | 0,6814 | 4 | 656,17 | 30960 | 98867 | 6945 | 0,1724 | 1,9217 | 15,08 |
| 264 | 5,208 | 9,722 | 8,82 | 20,3 | 1300 | 1,0679 | 0,6814 | 8 | 1022,87 | 108257 | 206870 | 6845 | 0,1709 | 1,9202 | 15,08 |
| 264 | 5,208 | 9,722 | 8,82 | 20,3 | 1300 | 1,0679 | 0,6814 | 6 | 902,15 | 32477 | 239347 | 8802 | 0,1967 | 1,9460 | 14,12 |
| 264 | 5,208 | 9,722 | 8,82 | 20,3 | 1300 | 1,0679 | 0,6814 | 4 | 539,93 | 44018 | 280166 | 11535 | 0,2245 | 1,9738 | 12,79 |
| 264 | 5,208 | 9,722 | 8,82 | 20,3 | 1300 | 1,0679 | 0,6814 | avg. | 13,87 |
Type II. Strongly watered bogs, with a bog-water level of 0.0–0.5 m, with widespread open water surfaces. The width of the bogs is up to 5 km. Peat thickness is 1.0–6.0 m.
Bogs of Types I and II are distributed unevenly across the territory. On the left bank, Type I bogs predominate. Only in the south of the region, in the Ob–Vasyugan interfluve, are bogs of both Types I and II widely distributed. On the right bank and in the valley of the Ob River, Types I and II bogs are distributed unevenly, but in comparison with the left bank, Type II bogs predominate.
In ground surveys and in the interpretation of aerial photographs, the flow of bogs is clearly visible, especially in the right-bank part and in the southern part of the left bank, in areas where negative tectonic structures are distributed. In the north of the left bank of the Ob River, in the zone of development of positive structures, the flow of bogs is absent in places, which indicates a process of natural drainage.
REFERENCES
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P. P. Borodavkin. Pipelines under Complex Conditions. Moscow, Nedra, 1968.
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A. K. Dertsakyan, B. D. Makurov. Crossings of Trunk Pipelines through Bogs. Moscow, Nedra, 1965.
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K. S. Ordunts. Construction of Railway Embankments on Bogs. Moscow, Transzheldorizdat, 1946.
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L. I. Sergeev. Engineering-Geological Characteristics of Peat Massifs of the Central Part of Western Siberia and Methods for Their Study. Abstract of Candidate’s Dissertation. Moscow, 1970.