GEOLOGY IN ENGINEERING

Geology and its Relationship to Civil Engineering

Geology is the scientific study of the earth, especially its more or less accessible outer shell, or crust. It seeks to trace the history of the planet from time that it first became a separate entity down to the present day. In doing so it enlists the aid of other sciences, particularly astronomy, physics, chemistry, and biology, and without them geology would be little more than a description of rocks, mountains, rivers, valleys, etc. No natural feature is too small or too large to escape the attention of geology. It is interested in the origin of continents and ocean basins on the one hand, on the other hand it takes cognizance of the arrangement of atoms in the crystal line substances that form much of the earth’s crust.

Geology includes not only the study of materials and rocks but it is also concerned with ocean waves, flowing water, glaciers, and other agencies modifying the surface of the earth, as well as the study of the past development and distribution of living things. A subject so broad must necessarily be divided into numerous specialties and no less than twenty-five are currently recognized.

Geology in engineering treats problems such as:Minerals, Rocks, Geologic Structure, Subsurface Water, Rock Weathering and Soils, Erosion

and Deposition of Streams, Frost Action in Soils, Landslides and Related Phenomena, Volcanoes and Earthquakes, Historical geology, Soils Mechanics, Dams and Reservoirs, Tunnels, Highways and Airfields, Concrete Aggregates.

Explanatory Notes:Rock weathering – dezagregare in timp a rocilorTo relate – a lega

- a relatato be related to – a se inrudi cu

I. Exercises:Answer the following questions:

1. What is geology?2. What does it seek to trace?3. Do you know other sciences related to geology?4. What is geology interested in?5. What problems does geology treat?

II. Translate into Romanian with the help of a dictionary:A landslide is a perceptible downward sliding or falling of a mass of earth, rock or mixture of the two. The slope is usually steep and the movement rapid but exceptions may occur. Masses involved in landslides usually have fairly high water contents, but if much excess liquid is present the mass may assume the characteristics of a debris /grohotis/ avalanche, mudflow, or earth flow. Landslides may be divided into several classes according to the rate and character of the movement involved.

III. Use the following expressions in sentences of your own: more or less; to be interested in; on the one hand … on the other hand; not only … but also.

GEOPYSICAL EXPLORATION

Application of physical laws and measurements to the earth is known as geophysics: it includes diverse subjects as meteorology, oceanography, seismology, geodesy, and terrestrial magnetism.

Geophysical prospecting constitutes the practical side of the subject, and may be defined as “prospecting for mineral deposits and geologic structures by surface measurements of their physical quantities”.

Geological applications are forms of subsurface exploration, but they differ from core boring and other standard engineering exploratory methods in that the information obtained is always indirect and not subject to direct visual verification.

There are four geophysical methods of subsurface exploration:1. Electrical methods2. Gravity methods3. Magnetic methods4. Seismical methodsElectrical methods: The electrical conductivity and its reciprocal, the resisitivity of rocks or

soils are a function of the amount of dissolved electrolyte and the volume of interstitial water. The first is chiefly a function of the chemical composition, whereas the latter depends on the porosity. For example, sandstones are composed largely of insoluble minerals and thus tend to have relatively low concentrations of dissolved electrolytes in the interstices. As a result, their electrical conductivity tends to be low and their resistance high.

Engineering Applications: The chief civil engineering applications of the resistivity method are in estimating the depth of overburden at dam sites, estimation of the physical characteristics of the rocks underlying construction sites, location of construction materials and water bearing formations. When applied to underground water location, it is necessary to know in considerable detail the stratigraphic conditions in the area in question. When used for exploration of construction sites, the resistivity method does not do away with the necessary core boring, but it does serve to guide the location of borings and reduce the number of holes required.

Explanatory notes: core boring – luarea probelor prin foraresubject to – supus la…chief – principalchiefly – mai alesoverburden – supraincarcaredam sites – terenuri de digurito do away with – a elimina

EARTHQUAKES

As the name suggests, an earthquake is a shaking of the earth which may range from an imperceptible tremor to a catastrophically violent shock. Seismology, as the scientific study of earthquakes is called, is one of the youngest of the natural sciences, but despite its brief life span, great progress has been made in explaining the origin and mechanics of earthquakes. Although precise prediction of disturbances may never be realized, the knowledge mow available is sufficient to enable the civil engineer to estimate the danger in any given locality, and, if necessary, precautionary measures can be taken.

Structural safety and local stability of the ground . A study of past earthquakes indicates that damage is usually much greater on soft sands and other loose materials than on hard rock. For example in the San Francisco quake of 1906 it was found that damage was generally five to ten times greater on soft moist sands, loose sediments, and filled land over old swamps than on hard ground.

In addition to greater vibrations occurring in loose material that in hard rock, if a structure is placed on yielding materials, in the event of an earthquake, the inertia of the structure may cause it to settle into the foundation medium. In certain types of structures, serious damage may result from this cause. The process is very similar to vibrational methods of foundation stabilization in use by engineers. In Japanese earthquakes it has been found that rigid structures on loose materials far better than non rigid types.

Area of damage. It has been concluded from the record of past earthquakes that about 2000 to 2500 square miles is the maximum area of serious damage, even in severe shocks. Even the greatest earthquakes seldom cause damage over 25 miles from the epicenter. Like almost every other general statement, it would be easy to cite exceptions to this rule. The most conspicuous exception is the Assam, India earthquake of June 1897, in which damage of clasa X Rossi-Forrel extended on an average of 70 miles from the center of disturbance. This earthquake is, however, one of the most violent known.

Explanatory notes:Range – rindm sir, intindere, gama, domeniu, limiteRange of the voice – registru al vociiRange of colours – gama de culoriBeyond my range – in afara posibilitatilor meleWithin my range – cit pot eu sa cuprindTo range – a alinia, a orindui, His thoughts ranged over the past – gindurile ii rataceau in trecutLife span – durata de existentaSpan – deschidereLoose material – materiale necorozive, libereYielding materials – materiale care cedeazaFilled land –rambleu, umpluturaExercises

I. Ask six questions about the text and answer them.II. Translate into English:

Repartizarea cutremurelor: Studiind repartizarea (distribution) cutremurelor in timpul perioadei 1904-1940, se va observa ca regiunile seismice active ale pamintului se impart in patru zone bine conturate. (well-marked).

III. Fill in the blanks:Mr. Black is older … his wife. Mrs. Black is not … tall … her husband. This building is much

larger … our house. he is as old … his cousin. The Danube is not … long … the Nile.IV. Insert the right form of the adjectives and adverbs in brackets, add conjunctions

where necessary.Timisoara is a /small/ city Bucharest. He is the /young/ of the family. This is /good/ doing

nothing. All are pretty, but she is /beautiful/ of all. The Atlantic is /big/ the Pacific. The /long/ nights are in winter. The /soon/ this done, the /good/. The /big/ the buildings, the /many/ flats it will have.

V. Comment the following saying:An archeologist is the best husband a woman can have. The older she gets, the more he is

interested in her.