CVE 311ENGINEERING GEOLOGY

ENGR S.O ODUNFADEPT. OF CIVIL ENGINEERING

UNIVERSITY OF AGRICULTURE, ABEOKUTA

Introduction

• Engineering geology is the application of geology in design, construction and performance of civil engineering works

Importance of engineering geology to in Civil engineering practices

• To recognise potential difficult ground conditions prior to detailed design and construction

• It helps to identify areas susceptible to failure due to geological hazards

• To establish design specifications• To have best selection of site for engineering

purposes• To have best selection of engineering materials

for construction

Geological Structures

• These are the modified structures formed from primary structures due to the influence of tectonic forces on it.

• It gives details about how inherent properties of rocks get modified , making them either suitable or unsuitable for civil engineering works. Emples are: Folds,Faults,Joints and

• Uncomformities•

• Not all rocks are suitable for the studies• The suitable rocks are: • Sand stones and shales – Sedimentary rock• Gneissses and schist ( to some extent) -

Metamorphic rock

Folds• They bend either upwards or down wards when a set of

horizontal layers are subjected to compressive forces• Parts of fold:• Limbs or flanks - side of a fold• Crest and trough – the curved portions of fold at the top

and bottom are called crest and trough respectively• Axial plane- Imaginary plane which divides the fold intotwo

equal or nearly equal halves’• Axis – Trace of intersection between the axialplane and the

crest or trough of the fold• Wave length – The distance between the successive crest

or trough

Classifications and types of folds• Based on diifferent principles the folds are

variously classified as • Symmmetrical and asymmetrical – symmetrical

character• Anticline and syncline – upward or downward

bend• Occurence of plunge – plunging and non-plunging• Uniformity of bend thickness – open and closed• Behaviour of the fold pattern with depth – similar

and parellel

Effects of Folds and their Engineering Importance

• Location of dams• Location of reserviours• Location of tunnels • Quarrying• Ground water occurence• Roads and railways

Faults

• These are fractures along relative i.e parallel displacement of adjacent blocks taken place.

• Parts of fault:• Fault plane The plane along which the

adjacent blocks relatively displaced• Footwall and hanging wall• Heave and thtow• Slip

Classification and Types of Faults

• Translational and rotational faults – based on type of displacement along fault plane

• Normal/Gravity and reverse/thrust, dextral faults – relative movement of the footwall and hanging wall

• Strike and dip faults – type of slip involved