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- Title
Studying the Hydraulic Heterogeneity of Cambrian Clays at the Substantiation of Final Isolation of Toxic Wastes.
- Authors
Vilkina, M. V.; Nikulenkov, A. M.; Rumynin, V. G.
- Abstract
The hydraulic heterogeneity of Cambrian clays is examined in the context of the problem of final isolation of wastes at Krasnyi Bor burial ground. The properties of clays were studied in a laboratory using undisturbed samples taken from pit walls and borehole core samples. In addition, the permeability heterogeneity of clays was studied in situ by packer interval pumping with the use of Lugeon method. Visual studies of outcrops in LSR quarry has shown that the clay massif has a block structure. The blocks are separated by a system of orthogonal subhorizontal and subvertical fractures. The size of blocks increases with depth from a few centimeters to several tens of meters at a depth of 20 m. However, no open fractures have been found during geotechnical studies of core samples taken from numerous wells. Laboratory studies showed that the average hydraulic conductivity of Cambrian clay along the bedding is 8.8 × 10–7 m/day, and that аcross the bedding is 9.0 × 10–8 m/day. The value of conductivity anisotropy is stable for all samples and averages 9.5. Selective pumping tests in the well showed that, under natural conditions, the block system is consolidated, i.e., the clay massif works as an impermeable aquiclude. Injection into isolated intervals with a gage pressure above 4 times the lithostatic value causes opening of the fracture system. The hydraulic conductivity of the rock with open fractures can reach 0.5 m/day. However, at a decrease in the gage pressure, the fractures close and the clay massif again becomes a flow barrier. Thus, depending on the external conditions, Cambrian clays can serve as either an impermeable barrier or a permeable medium.
- Publication
Water Resources, 2022, Vol 49, pS47
- ISSN
0097-8078
- Publication type
Article
- DOI
10.1134/S0097807822080127