There are numerous landslide sections along the railways of the Soviet Union that have been investigated to varying degrees. As one of the measures for landslide control, deep drainage has come into widespread use and, in many cases, constitutes an essential component of comprehensive slope-stabilization works. Deep drainage systems have already been implemented in major landslide areas such as Batraki, Oka, Ulyanovsk, Uvek, and Knyazev. Approximately 30 kilometers of drainage curtains have been constructed in these projects. A number of other large landslide sections still require dewatering, and deep drainage works are also planned for these sites. From a structural standpoint, the most widely used system is combined deep drainage, consisting of vertical wells or boreholes connected with drainage tunnels. The latter serve both water-conveyance and drainage functions. In a number of projects, tunnel construction personnel were confronted with serious support deformation problems. These deformations necessitated repeated replacement of tunnel supports long before the facilities were commissioned. Moreover, support deformation continued even after the tunnels entered service, and in some cases reached considerable magnitudes. For example, in one tunnel at Uvek Station, by the sixth year of operation, 50% of the installed reinforced-concrete frames had become deformed. Deformation on such a scale inevitably leads to a sharp increase in tunnel operation and maintenance costs. The tunnel support at Uvek was designed on the basis of rock pressure calculations determined according to the method of Professor M. M. Protodyakonov. This method has received the widest recognition and has proven effective in many practical applications. However, in the drainage tunnels at Uvek and Knyazev, the supports still experienced deformation despite the use of substantial safety factors in the calculations, because the actual rock pressure considerably exceeded the calculated values. Consequently, it became necessary to determine the extent, characteristics, and causes of support deformation. Determining the nature and magnitude of rock-pressure manifestations is an extremely difficult task, even after the rock strata have been exposed by excavation workings. Although Soviet scientists have recently made significant progress in clarifying the problem of rock pressure, these issues have not yet been conclusively resolved. Since the manifestation of rock pressure is directly related to deformation of the surrounding rock mass, our investigation must examine the behavior of the rock outside the excavation contour. In other words, it must reveal the response of the rock mass to changes in its conditions of occurrence and the resulting changes in its stress state. Clearly, such responses may be expressed in the destruction of rock continuity and changes in structure, resulting both from stress redistribution and from weathering processes acting during tunnel operation. Accordingly, the author was confronted with the task of resolving the following principal issues: a) determining the degree of disruption of rock continuity outside the excavation contour; b) determining the nature of changes in rock structure; c) establishing the depth to which such changes occur within the rock mass; d) revealing the development of fractures in the rock along the tunnel alignment; e) characterizing the moisture conditions of the rock outside the excavation contour; f) determining the physical and engineering properties of the rock in its various states; g) determining the influence of excavation methods, support systems, and lining backfill on rock deformation. The results obtained from the investigation of these issues may be used in the design and operation of underground excavation supports. At the same time, it should be noted that the conclusions presented in this work are applicable to specific mining and geological conditions. Certain individual findings may require modification when applied under different local conditions.