The need for comprehensive information on the characteristics and behavior of earth materials has been recognized for many years, perhaps for as long as significant construction has taken place in and on the surface of the earth. In recent years, however, the magnitude and complexity of engineered construction has greatly increased, resulting in a corresponding increase in the need for information on the engineering properties of soil and rock materials, Direct testing of soil and rock can be utilized to furnish necessary information. However, both field and laboratory testing can be extremely expensive, particularly where testing must include applications of stress to large masses of earth material, For this reason, significant technical and economic advantages can be realized through the development of indirect or short-cut methods for obtaining indications of the properties and characteristics of geologic materials.
Some years ago the value of topographic maps, aerial photographs, pedologic descriptions, and geological surveys in characterizing soil materials was realized. To make this information useful for engineering studies, a serious effort was initiated to obtain data on the engineering properties of various soil groups and associations established on the basis of geological and pedological surveys. The correlation of performance data with information on areal distribution and location furnished by geologic and pedologic works has proven extremely valuable in the planning and construction of facilities in and on soil.
In recent years, the size and importance of structures and facilities designed by engineers and architects has greatly increased. This has produced an increased interest in the rock materials underlying surficial soil layers. A clear need has arisen for a program to provide an engineering evaluation of rock materials for the purposes of location, design, construction, and maintenance of engineered facilities. However, a serious gap exists in the association of engineering characteristics with rock units identified on the basis of geological classifications, Therefore, there is a need for the development of a comprehensive evaluation program which permits utilization of existing data and which aids in the procurement of necessary information on engineering characteristics of rock
