The method for hlgh-pressure grouting the rock surrounding an underground excavation has recently come into increasingly widespread use in hydraulic construction as a means of increasing its bearing capacity. St is assumed that under certain conditions, high injection pressure may lead to the development of prestress not only in the lining itself, but also in the rock mass surrounding it. In a number of cases, this apparently makes it possible to dispense with the massive concrete and reinforced-concrete linings of underground excavations and construct in their place thin smoothinglinings with deep high-pressure rock grouting.Pressurized tunnels have been constructed abroad with the use of this effect, e.g., in the Roselend-Bati tunnel in France, the Festinnyoung tunnel in England, the Capivari-Cachoeira tunnel in Brazil, the Wainberg and Reizach tunnels in the Federal Eepublic of Germany, etc. [1, 2]. Major complex studies of problems associated with the efficiency of high-pressure grouting were conducted in Yugoslavia during construction of the Rama hydroelectric plant [3, 4]. Grouting of the rock surrounding an excavation with the installation of only a thin smoothing jacket was first employed in the USSE during construction of the diversion tunnel for the Inguri plant.No special studies of the process of rock prestress by grouting or its effectiveness were conducted in test passageways during construction of the ~ngurl and Charvak hydroelectric plants~ the only indicator of quality improvement in the rock mass revealed in the investigations was a significant reduction in seepage and an increase in the elastic-resistance fac-There are many examples of study of the prestress condition of concrete linings formed by the pressure injection of grout both in our country and abroad. Examples of the measurement of the prestress state developed directly in the rock mass itself by grouting are lacking, however| i.e., in describing the qualitative possibility of creating a prestress condition in the rock surrounding a tunnel by the injection method, not one of the authors cites quantitative indicators for this condition. Prestressing of the rock forming the unsealed opening around the tunnel lining by the injection of grout under a pressure of 1 MPa into cracks was investigated by the V. V. Kulbyshev Moscow Order of Red Labor Banner Civil Engineering ~nsti-tute. The investigations were conducted on a large-scale three-dimensional model of a tunnel excavation with a lining in a fissured rock mass of average toughness (Fig. i).The model of the structure had an outside diameter of 136 cm and a length of 80 cm and represented a tunnel excavation with a thin nonrelnforced lining with an inside diameter of 50 cm, a thickness of 3 cm, and a fissured rock mass surrounding the lining to a depth of 0.8 the diameter.Since the model makes it possible to examine the effect of grouting at a considerable distance from the lining, a grouting depth of 0.8 of the tunnel diameter, which is the maximum depth recommended for this purpose~ wa...

The majority of rocks through which hydraulic tunnels are driven are not isotropic and their elastic properties vary with direction. This is due either to the inhomogeneous nature of fissuring of the rock mass in various directions or to its bed structure, with different dips of the beds. The plastic characteristics of the mass in the direction of stratification and in the direction perpendicular to the beds may differ several times over.On account of the anisotropy of the rocks, a circular tunnel excavation is subjected to nonuniform deformations around its circumference, under the action of nonuniform internal pressure, resulting in additional bending stresses in the lining. Even in homogeneous isotropic rocks because of the shallow location irregular deformations of the excavation contour remit from the uniform internal pressure.A theoretical solution has been formulated by S. G. Gutman [1] for a circular tunnel excavation in a homogeneous isotropic elastic medium (E = const), which can be used for determining the deformation both of the excavation contour and of the free surface. S. G. Gutman has also provided a solution for a particular case of anisotropy, for an orthotropic medium under conditions where its elastic characteristics are governed by the relationship =2G(l+ ~, the adoption of which provides a strict solution to the problem, on the basis of experiments on an isotropie model [2]. There is no analogous solution for the general case of anisotropy, and it is probably very difficult to obtain one.Experimental investigations have been carried out in the laboratory of the V. V. Kuibyshev Moscow Civil Engineering Institute, Faculty of Hydraulic Engineering Works, for investigating tunnel excavation and lining of a tunnel at a shallow depth, employing models in an orthotropic medium with horizontal bedding of the rocks. This paper examines the results of the investigations.The experiments were carried out on models of coarse-grained material with a gypsum binder, since it is relatively simple to set up models of an anisotropic rock mass using gypsum stone. Prior to setting up the model, work was carried out for determining the physical-mechanical properties of the model material for the purpose of selecting the mortar composition. For this purpose, use was made of the recommendations by G. M. Koganov, drawn up by him at the above-mentioned laboratory.Gypsum with a water-gypsum ratio 1:1 was taken as the basic material. Tests on prismatic specimens 7 X 7 X 21 cm yielded mean values, from 15 specimens, of Young's modulus E=23.8 X 103 kg/cm z, Poisson's ratio 0.19-0.20, and critical compressive strength 24.5 kg/cm z. As the result of the investigations, a procedure was formulated for preparing the mortar, by which the scatter of the properties of the specimens did not exceed 20-25%, which can be considered as satisfactory for this type of investigation. The investigations were carried out on a frame rig (Fig. 1) made up from No. 14 100 x 100-cm channel iron.The orthotropic model of the rock mass was set up ...

In studying interrelated problems in various branches of science and engineering, as well as economic activity. the "system" concept, "systems approach." and "systems analysis" are widely used.Systems approach and systems analysis are methods of constructing complex economic-organizational and engineering systems under conditions where the associations that permit solution of economic problems, which cannot be described in full by mathematical relationships, are uncertain. They are. however, subject to analytical analysis, which makes it possible to substantiate reliably the solutions adopted by managers. A characteristic feature of the systems approach consists in the fact that it can be applied to units that are partly nonmaterial and e~tremely heterogeneous. For example, a systems analysis of the operation of an establishment may include people, machines, buildings, stock deliveries, production output, and even personnel initiative, resulting in an optimal relationship between these elements in the interest of established business.

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