Rocks and minerals are fundamental introductions to the study of all natural history, leading to a greater appreciation of nature and earth engineering. Rock types are classified into three major groups: igneous, sedimentary and metamorphic, and then subdivided into several divisions.
Soil is that portion of the earth’s crust, which is fragmentary, rock dust or such that some individual particles of a dried sample may be readily separated by agitation in water; it includes boulders, cobbles, gravel, sand, silt, clay and organic matter. Soils are identified and classified according to their particle size and distribution for coarse grained soils, and their plasticity for fine grained soils, which are based on soil laboratory testing, and the Unified Soil Classification System.
The subsurface investigation is the first and most important step for all earthworks and structures. A drilling and sampling investigation should be carried out for all earthworks and structures, even modest ones, (i) before design is undertaken, or (ii) before the approval of a regulatory body is sought, and (iii) before construction tendering commences.
For the owner, designer, contractor or regulatory agency engaged in the planning, design, construction, operation or maintenance of civil works and mining projects, the properties of soil, rock, groundwater and contaminants, and their impact on earthworks, structures and humans is of primary importance. These earth engineering properties include structure, strength, deformation, permeability, surface water and groundwater interaction, geochemistry and seismicity.
The ever changing migration of atmospheric, surface and ground water is a complex interdependent system called collectively the hydrologic cycle. Although the hydrogeologist is concerned chiefly with groundwater, all aspects of the hydrologic cycle must be understood before an accurate characterization of the subsurface portion of the cycle can be achieved.
A geological site characterization is inadequate for quantitative design and construction purposes. A geological survey of the area indicates the type and pattern of subsurface strata to be expected. Topographic features may correlate to glacial deposits. A geologic survey of the project site identifies the types of overburden soil and bedrock strata which are likely to be encountered. The geoengineering consultant can carry out a study of the regional geology and the local geology in order to plan and execute a major site exploration program.
The universe is over 10 billion years old. Our solar system comprising the sun and nine planets including earth formed 4.6 billion years ago. The earth has a mass of 5976 million million million tonnes and an equatorial circumference of 40,075 kilometres. The earth’s crust is about 6 to 64 km thick under oceans and mountains, respectively. The crust floats on a semi molten mantle and a molten core. Oxygen is the most adundant element at 47 percent. Oceans cover 71 percent of the earth. Continental drift progresses slowly causing earthquakes, volcanoes and mountains. Rocks have mixtures of minerals. The three main rock groups are igneous, sedimentary and metamorphic. Weathering breaks rock into particles ranging in size from boulders, cobbles, gravel, sand, silt to clay. Climate significantly affects soils and vegetation.