Principles of engineering geology modeling for hydraulic engineering consruction

Abstract

Construction of large hydraulic engineering installations and particularly high-head dams in folded mountain rock has placed fresh requirements on engineering geology. The calculation of dams on rock foundations, i.e., on elastic homogeneous and isotopic media with such heavy loadings on the foundation as represented by modern installations, results in big errors in evaluating stability and stress of the installations, in stability calculations for large rock slopes and the banks of reservoirs, in addition to several other important problems. Consequently, various types of models are being used increasingly in engineering geology for reproducing the different properties of the foundations. At a certain stage of accumulation of data, the investigator finds it necessary to generalize, in order to appreciate the nature of the relationships and interaction between the separate factors, the foundation and the engineering installation, etc. These interrelationships and interactions are represented in the form of circuit diagrams, in the natural physical or mathematical form, i.e., in the form of models providing a simplified representation of the object studied. In order to resolve engineering-geologic problems, models are set up which, depending on the form in which the data relating to the natural phenomenon or installation is expressed, may be to scale (graphical, natural, or of equivalent material), physical (hydrochemical, optical, etc.), or conceptual and mathematical (determinate, statistical).Engineering-geologic models must conform to the following requirements: simplicity of construction and sufficiently accurate representation over the whole range of measurements; a high degree of adequacy of the natural system or structure modeled; suitability for use in the design of planned installations and their foundations by existing methods of the mechanics of deformed media and hydromeehanies.The scale model is the most common and useful, the prototype of the object being subdivided into sections, reduced for ease of investigation and simple representation. Included are models of dam foundations, bridges, reservoir banks, etc.Physical models (electro-hydrodynamic, hydrochemieal, optical) simulate the geologic phenomena on the basis of generalization of their physical nature. This type of modeling is based on the principles of similarity, for example, between the laws of motion of water and an electric current.Conceptual models represent the conceptual image of some natural phenomenon, i.e., schematic models expressed in the form of various diagrams, mutual relationships, and variants. Such models express certain phenomena in the form of a hypothesis. An example of this type of model in soil mechanics is that of various types of rock. Conceptual models are qualitative and help largely in the study of complex geologic processes and bodies, and are a necessary stage in their study.Approaching the investigation of a given phenomenon by means of scale, physical, and conceptual models, data is obtained, allowing generaliz...