CVE 311 ENGINEERING GEOLOGY ENGR S.O ODUNFA DEPT. 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