Geology - Earth Science. Its emergence and development.
Since ancient times people began to study the Earth's structure, composition and properties make it of rocks and processes, continuously changing the Earth's surface. By the end of the XVIII century. He accumulated a considerable stock of information about the Earth that could take shape independent science, called "geology" (tenure), and in the XIX century. - "Geology" (Earth Science).
Intensive development of the geology has led to the accumulation of a large amount of factual material, resulting in separate sections of the geological sciences have become separated into independent scientific disciplines. Having mineralogy (the study of the composition, origin and properties of natural compounds - minerals that form the earth's crust), petrography (the study of minerals, aggregates -Horn rocks, their composition, structure, origin and circumstances of occurrence), dynamic geology that studies the processes that are changing the face of the Earth , stratigraphy (the study of the layers of the earth's crust), tectonics, which studies the structure of the crust in historical sequence, historical geology, which studies the history of the earth's crust from the beginning of its development to date, hydrogeology (the study of groundwater), geology and other sciences.
Start using geological observations and research in the construction of civil engineering relates to the XVIII century. According to NN Maslov, the first work in this area should be considered as "Memorial note on the production of the factory", compiled by Gregory Makhotina. This "Note" contains valuable information for the justification of dams and plant facilities.
The need to conduct geological surveys and studies for the construction pointed out by MV Lomonosov, who in his work "On the Layers of the Earth", wrote: "... the builder listens to the hardness of the earth in the ditches for foundations».
It is interesting to note that the first geological surveys for construction were the builders themselves. Russian railway engineer Mikhail Volkov in the works, "A note on the study of the earth soil, produced in the building art" (1835) and "On the base of the stone buildings" (1840) resulted in geological studies for the construction and classification of soils was thought out as the reason facilities.
English surveyor and builder of roads and canals W. Smith (1769-1839) not only made observations for direct use in the construction, but, summarizing the findings, discovered the possibility of comparing the sedimentary rocks at the prisoners in their fossilized remains of animals and plants. Thus began the paleontological method in the study of the sequence of layers of sedimentary strata.
By studying the rocks as the soil bases of buildings and structures, civil engineers first tried to determine the magnitude of the resistance of soil allocated to them pas unloading. Very fruitful was the study of Russian engineers GB Pauker and VI Kurdyumova, laid the foundation of the theory of strength and stability of the soil as the plants grounds. In the future, this work became the foundation on which there was a new science - soil mechanics.
As a discipline of physics and mathematics cycle of soil mechanics sets mathematically expressed in patterns of interaction between structures and soils grounds only to the extent that the processes taking place at the same time in the soil, are mechanical. In fact, in rocks having more than mechanical and chemical, electrical, and even in some cases the biological processes.
The problem of engineering geology is wider - it is designed to identify all the conditions in which the interaction occurs under construction and structures aligned with their environment on the whole space covered by this interaction. For example, the construction of even a small dam can cause a rise in the groundwater level over a large area, and therefore, cause a change in the conditions of existence of the buildings in which the foundations and basement floors were originally above the groundwater level.
Modern engineering geology as a science has three main tasks:
Since the construction practice rocks called soils, the initial section of engineering geology, allowing the first of these tasks, given the name of Soil Science. The section examines and allowing the second task, called dynamic engineering geology or engineering geodynamics. The third section is called the regional engineering geology.
FP Savary-sky in the 30-ies of XX century on the basis of numerous geotechnical studies Russian and Ukrainian engineers and geologists. He created the first major work in this area, which he called "Engineering geology". In the future, engineering geology was developed in the works of Soviet scientists NV Kolomna, IV Popov, VA Priklonskii, EM Sergeeva and others.
Engineering geology is closely connected with the doctrine of groundwater - hydrogeology. The development of hydrogeology began somewhat earlier geology and in parallel with it. Hydrogeology Development contributed VS Ilyin, GN Kamensky, AK Lange, AF Lebedev, AN Semnhatov and others.
In modern conditions civil engineers usually do not conduct geotechnical studies - for this there are specialized geotechnical organization; however, in the design and implementation of the construction, they need to know, understand and take into account the geotechnical and hydro-geological conditions of the construction site. They should be able to deliver the correct and timely task in front geologist geotechnical studies; Civil engineers must be able to make the right decision on carrying out engineering and construction activities required in the particular circumstances of the construction site.
In 1889, the American scientist Clark for the first time to determine the average chemical composition of the Earth's crust on the basis of chemical analyzes of all known in his time rock (6000 analyzes). Since then, many scientists were engaged refinements average data of the chemical composition of the Earth's crust. Species analysis shows that the crust of almost 50% oxygen atoms, and the first three elements (D, CI and Al) constitute over 80% of its weight. Play a role of iron, calcium, sodium, potassium, magnesium and titanium.
Pure chemical elements found in the earth's crust are extremely rare, they usually form chemical compounds more or less constant composition. These homogeneous in composition and structure of the natural chemical (mainly inorganic) compounds resulting from various processes occurring inside the Earth's crust and on its surface, called minerals. Various mineral assemblages, combined origin (genesis), create rocks that compose the crust.
The processes of change in the composition and structure of the crust, and the formation and destruction of rocks, called geological processes. Their studies the dynamic geology.
At the time of geological processes can occur in different terms: some are completed quickly, such as volcanic eruptions, earthquakes, rock falls, etc. (As a rule, such processes occur sporadically, irregularly), while others are carried out constantly, continuously, but very slowly - tens and hundreds of thousands of years and more. For example, a waterfall washes away the rock that drops of water, but the rate of erosion is very slow. This powerful waterfall like Niagara, develops mechanical force to 147-108 watts, and blurs your doorstep at a rate of 30 mm per year. The accumulation of loess in northern China occurs at a rate of about 1 mm per year.Literature: Peshkovski LM, TM Pereskokova "Engineering geology:. Textbook for university students of the Higher School, 1982.."