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The Astyanax species complex has two morphs: a blind, depigmented morph which inhabits caves in México and an eyed, pigmented surface-dwelling morph. The eyed morph can also be found in a few caves, sometimes hybridizing with the cave morph. This species complex has arguably become the most prominent model system among cave organisms for the study of evolutionary development and genomics. Before this study, 32 caves were known to be inhabited by the cave morph, 30 of them within the El Abra region. The purpose of this study was to conduct new surveys of the area and to assess some unconfirmed reports of caves presumably inhabited by troglomorphic fish. We describe two new localities, Sótano del Toro #2 and Sótano de La Calera. These two caves comprise a single hydrologic system together with the previously described cave of Sótano del Toro. The system is inhabited by a mixed population of troglomorphic, epigeomorphic, and presumably hybrid fish. Furthermore, Astyanax cavefish and the mysid shrimp Spelaeomysis quinterensis show a phylogeographic convergence that supports the notion that the central Sierra de El Abra is a biogeographical region that has influenced the evolutionary history of its aquatic community across species. The presumptive location of the boundaries of this biogeographical region are identified.

Nnumerical simulation of the process of injection of mortar into the thickness of the sandy base during the work on lifting and leveling the structure by the method of compensatory injection is carried out. An author's program has been developed that implements the finite element method (FEM) in a spatial formulation, taking into account the elastic-plastic nature of soil deformation, in which a special element in the form of a spheroid has been developed to describe the expanding area at the location of the injector, which changes its volume during the injection of mortar. During the verification of the program, the results of mathematical modeling were compared with the data of a physical experiment conducted by PhD Luca Masini from the University of La Sapienza (Rome, Italy). Numerical modeling of the stress-strain state of the base of the structure during repair work is considered by the example of lifting the foundation plate of the Zagorskaya PSPP-2. A number of tasks are being solved related to minimizing the number of injection columns, their location, the pitch of the cuffs, the selection of portions of the injected solution, taking into account the requirements for uniform lifting of the foundation plate in order to avoid additional cracking.