relevant micro-concepts of common nigerian civil engineering

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2.4 Hydraulic works: include harbours, canals, barrages, spillways, flood control, sea defence,civil works associated with hydro-electric power, pumping stations, irrigation, aqueducts,pipelines, water supply and treatment, main drainage and sewage treatment. Even though thecentral theme in hydraulic works is the beneficial harnessing of the properties of water formankind, nonetheless many of the associated structures required are very huge engineeringedifices of soil, rock, concrete and steel. Jetties, Terminals and deep water ports are verycomplex hydraulic structures to construct: the Rotterdam, as example, is the world’s largest port(by length of quay or berth in the port). There are also canals and Inland Navigations, thenotable ones being St. Lawrence Seaway, Europe canal, Grand Canal, Amazon, Mississippi,Suez, Panama, etc. In Nigeria, dredging has been undertaken for inland navigation on the Niger,Imo and Cross Rivers. Flood control and sea defences are great schemes for protection againstriver floods and tidal waves. Their main material is sand/soil and rock boulders as well as sheetpiles of steel or gravity walls of masonry. Pipelines can be of asbestos-cement, galvanized ironand plastic: recently, some Nigerians have been writing on bamboo soil pipes.3.0 MICROCONCEPTS OF SOIL AS FOUNDATION AND CONSTRUCTIONMATERIALFrom the account of structures presented above, it is clear at this stage that one of the versatilecivil engineering materials is the soil. Later on, when I shall be listing an account of my personalcontributions in research and practice, it would then be observed that Nigerian soils exist inmany varieties exhibiting different properties and characteristics, some attractive and otherproblematic. Basically, in summary, soils are applied in practice as:i) Foundations of buildings and all forms of structures.ii) Construction material for road base, sub base and sub grade courses in roadways.iii) Construction material for the foundations of paved areas, parking spaces, airporttarmacs etc.iv) Construction material for earth dams, cutoff walls, central core of rock fill dams andcertain seepage and erosion control structures.v) Construction material for earth fills beneath the floors of structures.vi) Construction material for backfills behind retaining wall structures.8
vii)viii)Construction material in caisson foundations and land reclamation schemes as well asdredging and other works.Construction material for buildings of mud, compressed earth and burned bricks/firedclay.In all theoretical and practical applications of soil, the fundamental considerations and principlesare aimed at assessing the strength (shear) and consolidation/compressibility characteristics ofthe material. It is interesting to have known that when the twin world trade centre towers of 110storeys (411.5 metres) collapsed following the terrorist attacks of September 11, 2001, thesubstructure supported by the soil was quoted to be undamaged. Indeed the soil has atremendous capacity to take impacts from crushes of explosives, plane crashes, shuttle machinesand, of course, the world’s structures of all sizes and heights. The soil takes the loads imposedby these situations quite comfortably: frequently it does so with very prominent and noticeabledeformations and settlements depending on the material plasticity. Because the strength andconsolidation characteristics of the soils are so influential, I have found it convenient to classifythe theorems and principles associated to these properties (i.e. shear and settlement) as macroconcepts.However, there are certain micro-concepts related to the behaviour and response of thesoils to loading conditions that affect their strengths tremendously but which we frequentlyeasily overlook. One of these micro-concepts deals with the influence of water within the voidspaces of the soils. The concept is easily explained by the piston and spring analogy.A load (stress), σ is applied on the piston. The loads taken by the spring and water are σ / and u,respectively. At the beginning, as long as the weep hole is closed, σ = 0 and σ = u; i.e. the wholeload is taken up by the water. When the weep hole is opened gradually, stress is transferred fromthe water to the spring so that σ / > 0 so that at any finite time, t, σ = σ / + u and at t = ∞, u = 0 andσ = σ / .9
Page 1 and 2: RELEVANT MICRO-CONCEPTS OF COMMON N
Page 3 and 4: aggregates, sand, admixtures, fabri
Page 5 and 6: portion of gravity masonry construc
Page 7: eference is usually made to them, n
Page 11 and 12: settlements were quoted in London a
Page 13 and 14: too much on the wet side of optimum
Page 15 and 16: the cement, replaces the absorbed w
Page 17 and 18: 5.2 Hydration of Cement: When water
Page 19 and 20: TYPICAL PROPORTIONS (%) OF MAJOR CO
Page 21 and 22: v) Temperature for curing also affe
Page 23 and 24: Research on Nigerian timber has bee
Page 25 and 26: the health of the common man and ce
Page 27 and 28: the specification by as much as 0.8
Page 29 and 30: MEAN CUBE STRENGTHS FOR VARYING TEM
Page 31 and 32: eported on earlier in Chapter 8. Fo
Page 33 and 34: 3. Balogun, L. A. (1991) “Effect
Page 35 and 36: 33. Ola, S. A. (1978). “The geolo
Page 37: pioneer young consultant engineers

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