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a clay-sand alternation was placed in the vessel, thrust-faults appeared
besides the diapir and cryptodiapir forms (Gretener, 1969).
Crawell, Page and Tabor, Rettger, Berry and Price, Gretener (1969)
believe that many depositional structures and faults in California formed
due to local increase in pore pressure in clays according to this mecha-
nism. Similar observations were recorded in small and large mines after
the removal of ground. There was recorded the load alleviation of ground
at the base that caused a significant heaving, bulging of the construction pit
bottom with the maximum at the center of the pit (Gretener, 1969).
Noteworthy in this respect are the observations conducted by the
Hydroenergoproject Institute of the power station in the process of con-
struction. The construction pit had the size of 42 by 61 m and the depth
30-35 m. It experienced unloading after the removal of ground and heaved
in the pit center by more than 10 cm. The important phenomenon was
the heaving of compact and apparently totally compacted Cambrian clay
(although only by 1.6 to 1.9 cm) (Ulitkin, 1955). The foundation ground
load alleviation and the heaving of construction pit bottoms indicate the
elastic behavior of high-humidity compressed ground. This property is
especially significant in the clay rocks with AHPP. The elastic deformation
in the ground at the foundation of a construction pit makes the bottom
surface convex like a low-angle anticline (Figure 5.2).
H, m
20
1
10
2
3
9
Rise of the pit bottom
4
-10
5
-20
6
Figure 5.2 Uplift of construction pit bottom for hydrotechnical facilities (After
A.I.Ulitin): 1. Vegetation layer, 2. Dolomites and dolomitic limestones, 3. Oolitic
sandstone, 4. Fucoid sandstone, 5.  5. Thinly alternating fine-grained sands and clays,
6.  Compact Cambrian clay.
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