Geology/scope of engineering geology
Sir , what are the applications of engineering geology in civil engineering projects ? I have heard that it helps in site investigations etc but how it actually works , kindly tell me and please elaborate.
Engineering geology bridges several disciplines.
The area of Engineering geology covers aspects of civil engineering, but focuses more on earth materials and processes.
For instance, a civil engineer might know a lot about the engineering properties of soils, clays and gravels, but does generally not know much about the processes by which the materials were formed or deposited.
He might know that soil X is prone to creep when saturated with water, but might not be able to identify the landforms in the field that would be prone to soil creep, or even know that by excavating in a particular location, he might actually cause soil creep to activate when it was at equilibrium.
The engineering geologist might also be versed in mining geology and engineering.
Some find work focusing on geological hazard areas, where they are qualified to fill the role of civil engineer and have the geological expertise to make informed and educated decisions on how to deal with geohazards without making them worse. I such cases a civil engineer might just deal with the effects of the hazards. Say if you were dealing with the creeping slope as mentioned above, the civil engineer might just address the problem by building a retaining wall and call it solved. The engineerin geologist might recommend putting in drains to mitigate the underlying water saturation problem and thereby stablizing the slope by reducing the water in the soil, and retaining the original slope. The same could be done by shallow water wells. Erosion problems are often great examples of how the two professionals approach problems differently. The GeoEngineer realizes that in a majority of the cases mother nature cannot be stopped and that lots of money is just wasted by trying temporary engineering fixes. It would be cheaper in the long run to change locations, move a house, condemn property or the plans, than to implement an engineering fix that will have to be repeated ever few years as mother nature continues her processes that cannot be stopped.
By examining the underlying geology before beginning engineering projects, money can be saved and problems avoided by recognizing the sometimes inappropriate nature of the underlying geology and geological materials for the planned project application.
A large appartment complex was build in Canada on thixotrophic materials. The project was completed, and a small earth tremor liquified the underlying materials and the new complex slid off a hillside into the St. Lawrence River. In Rio de Janero appartments and other buildings were build at the foot of stabalized land slides along the narrow beaches along parts of the bay. The soil from the slides had stabalized at very steep slopes. Construction necessitated excavation of the toe of the slides rendering them unstable and reactivated them. The next rainy season water saturation of the slide materials resulted in landslides that destroyed the newly constructed buildings causing millions $$ in lost building costs and deaths. So thorough assessment of the geological implications and risks are necessary.
Another example is fill material going into marshlands or for reclaimation of near shore waters. In seismically stable areas this is fine, but in seismically active areas prone to earthquakes it is disasterous. The Marina District of San Francisco is an example. The water saturated fill material shakes like a bowl of gellitin when there is an earthquake magnifying the destructive lateral shockwaves many times resulting in greater damage than in more stable areas nearby.