Géologi rékayasa
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Géologi rekayasa nyaéta pamakéan elmu géologi keur nalungtik kajadian géologis sarta solusi téhnis kana bencana geologis sarta masalah géologi séjén nu pakait jeung kahirupan. Géologi rekayasa nalungtik kayaan dina waktu "perencanaan", analisa dampak lingkungan, rékayasa sipil desain, value engineering sarta salila konstruksi boh proyek pamaréntah jeung swasta sarta sanggeus konstruksi sarta fase forensic hiji proyek. Panalungtikan géologi rekayasa biasa dipigawe ku ahli geologi atawa ahli geologi teknik, profesional hasil pelatihan sarta nu boga kamampu dina rekonstruktsi jeung analisis bahaya geologi jeung kaayaan géologi. Sakabéh usaha di luhur keur "melindungi" masyarakat tur nu dipimilik sarta keur meupeuskeun masalah géologi.
Panalungtikan géologi rekayasa diperlukeun
- keur ngawangun paimahan, bisnis jeung industri;
- keur lingkungan jeung instalasi militer;
- keur kaperluan umum saperti sumber listrik, turbin angin, jalur transmisi listrik, tempat pangolahan limbah, tempat pangolahan cai, jaringan pipa (saluran cai, saluran cai kotor, outfall), torowongan, konstruksi dinu terjal, kanal, bendungan, reservoir, wangunan, jalan kareta, transit, jalan tol, jembatan, seismic retrofit, palabuhan udara jeung taman;
- keur tambang sarta eskavasi bahan galian, tanggul sesa ti tambang, reklamasi tambang sarta torowongan di tambang;
- keur program lahan baseuh tur ngahadean habitat;
- keur téhnik pantai, sand replenishment, bluff atawa kastabilan sea cliff, pelabuhan, pier sarta waterfront development;
- for offshore outfall, drilling platform and sub-sea pipeline, sub-séa cable; and
- for other types of facilities.
It is important to keep in mind that in engineering geology, there are only two important types of rock: those which can be moved by a bulldozer, and those which require dynamite.
Geologic Hazards
[édit | édit sumber]Typical geologic hazards evaluated by an engineering geologist include
- fault rupture on seismically active faults ;
- seismic and earthquake hazards (ground shaking, liquefaction, lurching,lateral spreading, tsunami and seiche events);
- landslide, mudflow, rock fall and avalanche hazards ;
- unstable slopes and slope stability;
- erosion;
- slaking and heave of géologic formations;
- ground subsidence (such as due to ground water withdrawal, sinkhole collapse, cave collapse, decomposition of organic soils, and tectonic movement);
- volcanic hazards (volcanic eruptions, hot springs, pyroclastic flows, debris flows, gas emissions, volcanic earthquakes);
- collapsible soils;
- shallow ground water/seepage; and
- other types of géologic constraints.
An engineering géologist or geophysicist may be called upon to evaluate the excavatability (i.e. rippability) of éarth (rock) materials to assess the need for pre-blasting during éarthwork construction, as well as associated impacts due to vibration during blasting on projects.
Methods and Reporting
[édit | édit sumber]The methods used by engineering geologists in their studies include
- géologic field mapping of géologic structures, géologic formations, soil units and hazards;
- the review of géologic literature, géologic maps, géotechnical reports, engineering plans, environmental reports, steréoscopic aerial photographs, remote sensing data, Global Positioning System (GPS) data, topographic maps and satellite imagery;
- the excavation, sampling and logging of éarth/rock materials in drilled borings, backhoe test pits and trenches, fault trenching, and bulldozer pits;
- geophysical surveys (such as seismic refraction traverses, resistivity surveys, ground penetrating radar (GPR) surveys, magnetometer surveys, electromagnetic surveys, high-resolution sub-bottom profiling, and other géophysical methods); and
- other methods.
The field work is typically culminated in analysis of the data and the preparation of an engineering géologic report, fault hazard or seismic hazard report, géophysical report, ground water resource report or hydrogeologic report. The engineering géologic report is often prepared in conjunction with a Rékayasa géotéhnik report by a géotechnical engineer. The report describes the objectives, methodology, references cited, tests performed, findings and recommendations. Engineering géologists provide géologic data on topograpic maps, aerial photographs, géologic maps, Geographic Information System (GIS) maps, or other map bases.