ENGINEERING GEOLOGY OVERVIEW

Jyotirmayee DashChitkara University

GEOLOGY : Derived from Greek Word “GE” meaning earth and “LOGOS” means Science

GEOLOGY : SCOPE & IMPORTANCE

GEOLOGY : Is scientific Study of Earth

GEOLOGY : Concerns with

•Study of Earth’s constitution

•Structure

•History of Development

GEOLOGICAL BRANCHES

ENGINEERING GEOLOGY

STEPS

GEOLOGICAL PROCESSES

•Economic geology

1-Mining geology

2-Petroleum geology

•Engineering geology

•Geochemistry

•Geomorphology

•Physical Geology

•Geotectonics

Branches of Geology

•Geophysics

•Hydrogeology

•Mineralogy

•Paleontology

•Petrology

•Stratigraphy

•Structural geology

•Crystallography

Branches of Geology

It Deals with Study of Mineral Deposits, their mode of formation, Occurrence and Distribution

Economic Geology

It Deals with Application of Geological Knowledge in the Field of Engineering.

Engineering Geology

It Deals with chemical constitution of Earth, the distribution and migration of various elements in the various parts of the Earth.

Geochemistry

It Deals with study of Land Forms

Geomorphology

It Deals with endogenous and exogenous agencies and the processes that bring about changes on the earth’s surface.

Physical Geology

It Deals with movements of the Earth’s crust and the deformations caused by them.

Geotectonics

It Deals with application of Physics which includes geodesy, seismology, meteorology, Oceanography and terrestrial magnetism.

Geophysics

It Deals with hydrological properties of Rocks and the occurrences of ground water, its movement and action.

Hydrogeology

It Deals with Minerals, their composition , characteristics mode of occurrences and their origin.

Mineralogy

It Deals with Fossils, Plants and Animals that are found in the rocks of past geological periods. They Indicate the climate , age and environment of deposition of the rock unit in which they are found.

Palaeontology

It Deals with Origin, structure, Texture and mineralogical composition of the different type of rocks.

Petrology

It Deals with Strata of sedimentary Rocks, their succession, thickness, age, variations and correlation.

Stratigraphy

It Deals with Configuration of Rocks in the Earth’s crust produced due to number of factors, generated both Exogenously and Endogenously

Structural Geology

It Deals with External Forms and Internal Atomic structure of the Crystalline minerals.

Crystallography

•Engineering geology is the application of geological data, techniques and principles to the study of rock and soil surficial materials, and ground water.

•This is essential for the proper location, planning, design, construction, operation and maintenance of engineering structures.

•Engineering geology complements environmental geology, or hydrogeology.

What is Engineering Geology?

Rock, soil, water, the interaction among these three constituents, as well as with engineering materials and structures.

What is Engineering Geology Study ?

•Geology provides a systematic knowledge of construction materials, its occurrence composition durability and other properties. Examples of such construction materials are building stones, road materials clays, limestones and laterites.

• The knowledge of the geological work of the natural agencies such as water, wind, ice and earthquake helps in planning and carrying out major civil engineering works , for example the knowledge of erosion, transportation and deposition helps greatly in solving the expensive problems of river control, coastal and harbour work and soil conservation.

Importance of Geology in Civil Engineering

•Ground water is the water which occurs in the subsurface rocks. The knowledge of its quantity and depth of occurrence is required in connection with water supply, irrigation, excavation and many other civil engineering works.

•The foundation problems of dams , bridges and buildings directly concerned with the geology of the area where they are to be built. In these works drilling is commonly undertaken to explore the ground conditions. Geology helps greatly in interpreting the drilling data.

Importance of Geology in Civil Engineering

•The stability of civil engineering structures is considerably increased if the geological features like faults, joints, bedding planes, folding , solution channels etc in the rock bed are properly located and suitably treated.

•Before starting a major engineering project, a detailed geological report which is accompanied by geological maps and sections is prepared. Such a report helps in planning and constructing a project.

Importance of Geology in Civil Engineering

The Engineering Geology was established in US after the St. Francis Dam near Los Angeles, CA failed on March 12, 1928. Engineering community realized the importance of Geology factor in civil engineering.

Before failure

•GEOLOGICAL PROCESSES.

Importance of Geology in Civil Engineering

.ROCK CYCLE

•WEATHERING

•COMPACTION

•LITHIFICATION

ROCK CYCLE

Diagenesis

Lithification

Recrystallization

Cementation

by silica or calcite

Compaction

Deposition

(Sediment is laid down)

Transportation

by

Water,ice, or wind

Weathering and Erosion of pre-existing rocks and minerals

Weathering, Sediment, and Sedimentary RocksWeathering, Sediment, and Sedimentary Rocks

•. 1.Weathering and ErosionWeathering and Erosion-from pre-existing rocks•2. TransportationTransportation- movement from one place to another (by wind, water, or ice)material is then deposited.•3. CompactionCompaction -- due to pressure; fine-grained sediments undergo more compaction than coarse sediments •4. CementationCementation -- precipitation of minerals around sediments (commonly quartz or calcite are precipitated) •5. RecrystallizationRecrystallization -- due to pressure, temperature changes •6. LithificationLithification -- squeezing out of fluid to make final solid rock

COMPACTION

LITHIFICATIONLITHIFICATION

Any rock fragment(size is > 4 mm=Pebble)

Fine-gravel/Granule(size <4mm)

Matrix: is the finer grains or material that surrounds the larger clasts. It consist of either clay, silt and sand.

Cement: dissolved substance that bounds the sediments.

1. Calcareous2. siliceous

SummarySummaryDifferent branches of geologyDifferent branches of geology

Importance of geology in civil engineeringImportance of geology in civil engineering

Some geological processesSome geological processes