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Stability of high slopes subject to landslides and rock chutes has always been an engineering problem. It has become particularly acute in recent years, with dams 200-300 m high being designed and built on mountain rivers in provinces of active neotectonics and seismicity. The great landslides of [1963][1964] in the valleys of the Vaiont (Italy), Visochitsa (Yugoslavia), Mochokh (Dagestan), and Zeravshan (Central Asia) rivers have convincingly demonstrated that such geologic phenomena are not peculiar solely to past epochs and catastrophic earthquakes,but constitute consequences of the geologic development of the upper part of the earth's crest.Despite the long-standing problem of stability for high slopes, no experimental study of the magnitude and distribution of stresses has been made for massifs of heterogeneous fractured rocks. At the same time, application of the various methods and model studies of stability is not justified on the basis of shear resistance data alone, without data on the magnitude and distribution of stresses within the rocks of the slopes. Serious errors have been made when hydrostatic stress distribution was used in determining the stress state within the sloping rock massif; these errors increased in the instance of high slopes in rocks of a complex geology.A lmowledge of stress state and its zonation in high-slope rocks is necessary not only in substantiated calculations and modelling, Many practical engineering and geomechanical problems call for a knowledge of stress distribution in the rock massif and of the zones of stress concentration and relaxation. As an example, scientifically substantiated selection of typical sites for field experiments in determining strength and deformation properties of rocks, their resilience, rock pressure, etc., particularly for hard and fractured rocks, is possible only with an understanding of their stress state. In that event, geomechanical experiments for relating the strength and deformation properties of the massif to its stress state, based on the data of stress distribution within the massif, are carried out prior to the complex and laborious field experiments.Stress state in the rock massif under natural conditions is set up by many natural factors; its magnitude and distribution vary greatly, depending on the geologic media of their operation. Human activity also affects the distribution of stresses, rearranging in many instances the natural stresses.The following are among the factors responsible for the manner in which stresses operate within the highslope rock massifs, particularly those situated in the folded and seismic provinces of complex geology: a) genetic and petrographic rock complexes, their composition, facies, and other inhomogeneities, texture, stratification, and position; b) tectonic deformations-faults, folds, crushing, and fracturing; c) primary fractures (lithogenetic and those produced by cooling, etc.) and the secondary ones (exogenous), superimposed on the primary ones, and tectonic; d) underground waters (including se...

The breach of reservoirs and lakes resulting in muddy floods of the Vaiont (Italy) or Issysk (near Alma Ata, 1968) type, cause the loss of human lifes and vast economic damages. The large landslides and earthslips listed in Table 1 were not produced by earthquakes, but represent a natural development of geologic phenomena likely to occur also in the future. Therefore, the problems ofestimatingthestabflity of high slopes having a complex geologic structure and development history and of the forecast of IandsIides and earthsiips on such slopes are extremely important.The main difficulty in elaborating on the problems related to the formation of mountainous slopes of complex geologic structure, and in evaluating their stability, is caused by the large number of interacting natural factors involved. The most important one, which is often ignored, is the geologic history of the high slope formation. Slope portions having different ages exhibit different degrees of stability, and the conditions of Iandslide and earthslip formation are also different. One of the most important theses of geologic engineering is that landslides and earthslips should be studied not separately, but in the framework of the entire slope and of all the factors generating them.For the construction of hydraulic structures it is important to estimate not only the dimensions of the geologic phenomena, but also the timing of thek occurrence. On the other hand, the practical significance of evaluating landslides of various volumes is not the same for the different structures and for the whole hydraulic complex, either during the construction period, or during the operation of the structures.The problem of geological phenomena classification is always controversial; nevertheless, even in the initial investigation stages it is necessary to classify the landslides and earthslips of the mountainous slopes, since otherwise their detailed investigation is difficult. Thus, a preliminary classification of mountain landslides and earthslips (based on examples obtained in the Naryn and Enisei valleys) in regions where the construction of dams is contemplated, can be done on the basis of the following data: a) the dimensions of the phenomenon,i.e., the volume of rocks contained in the landslide or earth slip; b) the relationship between the direction and gradient of the main tectonical fractures and fissure zones separating the unstable rocks from the bedrock formation and the direction and gradient of the slope; c) the chronology of the site where the landslide or earthslip originates in relation to the geomorphologicaI eIements of the slope, i.e., the portions of various age and gradient containing different zones of erosion, weathering, and natural stresses; d) the characteristics and strength indices of the material filIing the fractures, along which the landgide or eaxthslip blocks move; e) the time (conventional age) and approximate period of the initial occurrence; f) the basic factors determining the development of the landslide and earth slip.The vari...

One of the most important problems in engineering geology, geotectonics, seismology, and rock mechanics is that of the stress --strain state of geological bodies of various categories. It is complex and has not been developed far, although it is as important as the study of the mechanical properties of rocks. We cannot estimate their deformations without knowing their stresses. The natural stresses in the upper lithosphere, especially near the surface, form a system of partial stress fields which are highly variable in space and time; they are typified by an interrelation between the elements of the medium and the effective factors. For example, the density, deformability, strength, and permeability of a rock depend directly on the stresses, and changes in the mechanical properties affect the stress distribution.The development, distribution, and the magnitudes and changes of the stress components in the solid rock are important in the following theoretical and practical problems in geology, mining, and building. i) In assessing the engineering-geological conditions for the construction of underground structures and the working of mineral deposits (tunnels, hydroelectric stations, industrial systems, dumps, pits, and quarries), including prediction of rock pressure, shock bumps, falls of rock, blowouts, gas bursts, and water outbursts and quicksands.2) To estimate the long-term and short-term stability of high slopes and sides of deep quarries, especially those with complicated gelogical structure, and to predict landslides and caving.3) To form a scientific basis for predicting the movements of the rocks and the parameters of the subsidence craters at the surface above underground workings and old water and oil wells. 4) To investigate the changes in the seismic wave parameters (natural and those from large explosions) passing through rock masses in various states of stress and strain (deformation) with the aim of seismic microzonation. 5)In studies of problems in tectonophysics and the mechanisms of formation of folded and faulted structures and the analysis of present-day movements. 6) To predict changes in the seismicity of a region and movements of structural blocks of the rocks due to the construction of large reservoirs. 7) To put on a sound foundation the design and stability calculations of concrete dams and the reliability of pillars and supports in underground mining. 8) To give a sound basis for the methods of englneering-geologlcal tests and research into the strength and deformation properties of rocks at stress concentration sites.At present nearly everyone agrees that the natural stresses in the solid rock are due to the combined action of the following forces: i) gravitational (the weight of the rock); ii) tectonic (including astronomically and seismically generated forces); iii) hydrodynamic; iv) seothermal; v) crystallization. The relative indices of the individual stress fields are highly varied in particular cases. The gravitational and tectonic forces usually predominate. When we consider th...

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