Civil Engineering Reference
In-Depth Information
V
m
V
m
IV
IV
1
1
2
3
4
5
6
2
III
III
II
II
I
3
4
5
6
7
160
8
m
0
20
40
60
80
100
120
140
1
2
3
4
5
6
7
8
9
10
Figure 3.8
Complex scheme of geological section (160 m wide) across a characteristic
depression (Lyutezh observation plot, northern part of Kyiv region) with lithostratigraphic
elements and zones of different hydrodynamic activity: (1) sod-meadow loamy sandy
soil; (2) sod-podzolic sandy soil; (3) fine-grained sands with seams of fractions: (4) fine
dusty; (5) coarse dusty; (6) clayey; (7, 8) ferruginous seams; (9) groundwater level in
winter (double-dotted dashed) and summer (dashed) periods; (10) annual average ground-
water level. Zones: I, central active; II, central passive; III, near-border active; IV, slope
passive; V, background.
The most common internal characteristics of the central parts of depressions
(Figure 3.8) are changes of the thickness of stratigraphic horizons, high hydro-
morphism, leaching of rocks, a high level of rock disturbance by ancient cryogen-
esis (mainly in the form of wedges and viens), and the formation of various
tumors and local geochemical barriers.
In the central part of the depressions in places of vertical cryogenic pseudo-
morphs (wedges, veins, cauldrons, involutions), the increased flow of water and
solutes (and sometimes of suspended fine fraction) is observed. At the bound-
aries of the lithological differences, the tumors are usually found in the form of
films, “beans,” “cranes,” tubes, peels, layers, lenses, etc., made mostly of iron ses-
quioxide nodules (in humid conditions), which often serve as a geochemical
barrier to dissolved and suspended phases.
For the structure of the transition zone (closer to the sides), a characteristic
is the smaller impact of hydromorphism, cryogenesis, and the chemical and phys-
icochemical transformations of rocks. In the sections there is a clear differentiation
of the stratigraphic and lithologic horizons, traces of paleocryogenesis presented
as small cracks, thin layering, and low-graded textures. In the near-slope zone, the
attenuation of geodynamic processes is seen: the small effect of hydromorphism
and faint traces of the geochemical and cryogenic transformation of rocks.
In rocks of central depressions, a lack of readily soluble minerals, degrada-
tion of the macroaggregate and macroporous structure, increasing density of
rocks (from the sides to the center), reduced permeability in undisturbed places,
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