Subsurface Layer Characterisation Research

Subsurface Layer Characterisation Research SUBSURFACE LAYER CHARACTERISATION FOR ENGINEERING PURPOSES USING VERTICAL ELECTRICAL SOUNDING IN BANANA ISLAND, LAGOS, NIGERIA OLADUNJOYE, H.T., 2OLALEYE, A.O. Dynamic Seven (7) vertical electrical sounding stations along two crosses were utilized to examine the profundity to able arrangement for establishment of building structures in Banana Island of Lagos. The investigation is intended to disentangle the nearness of issue soils that can be unfriendly to structures.  The sounding information utilized in this investigation was procured utilizing Schlumberger Electrode Configuration. The VES information were deciphered into a model bend utilizing forward displaying programming called Winglink. The translation boundaries (layer resistivities and thicknesses) for each VES point were gathered into three geo-electric areas to speak to the 2-D models of the subsurface layers in the investigation region. The last understanding outcomes (resistivities and profundities) displayed as geoelectrical segments and pseudosections were looked at inside the overviewed territory and corresponded with the borehole log-inferred profundities to decide a likely profundity for establishments of tall structure. The examination presumed that the geophysical examination is of extraordinary hugeness in incomplete bend coordinating understanding procedure gives the most reliably low rate deviation blunder edges among the three VES fundamental translation strategies. There is reliable increment top to bottom expectation mistake, with profundity, in all the understanding methods. Presentation Geophysical resistivity procedures depend on the reaction of the earth to the progression of electrical flow. In all techniques, an electrical flow is gone through the ground and the subsequent potential cathodes permit us to record the resultant likely distinction between the flow terminal is estimated. The clear resistivity is then an element of the deliberate impedance (proportion of potential to current) and the geometry of the cathode exhibit. Contingent on the overview geometry, the obvious resistivity information are plotted as 1-D soundings, 1-D profiles, or in 2-D cross-areas so as to search for peculiar districts. In the shallow subsurface, the nearness of water controls a significant part of the conductivity variety. Estimation of resistivity (opposite of conductivity) is, by and large, a proportion of water immersion and network of pore space. This is on the grounds that water has a low resistivity and electric ebb and flow will follow the easy way out. Expanding immersion, expanding saltiness of the underground water, expanding porosity of rock (water-filled voids) and expanding number of breaks (water-filled) all will in general diminishing estimated resistivity. Resistivity estimations are related with changing profundities relying upon the partition of the present and expected cathodes in the study, and can be deciphered regarding a lithologic and additionally geohydrologic model of the subsurface. The decision for Direct Current (DC) resistivity study in this task is because of its capacity to give a speedy succinct picture of lithological and groundwater attributes regarding its clear resistivity differentiate. In this work the electrical resistivity character gathered were model with Winresist and Winglink reversal programming. The layers boundaries (resistivities and thicknesses) acquired from information preparing were then transformed with Winglink to give two-dimensional pictures of the subsurface clear resistivity variety (Pseudosection). Be that as it may, information on the geography of the zone from obtained borehole log has assumed a crucial job in deciding the best fit model. MATERIALS AND METHOD OF STUDY The vertical electrical resistivity is utilized to decide the subsurface resistivity circulation and profundity of the sub-surface layers with the guide of electrical resistivity meter. In this investigation, Schlumberger exhibit of electrical resistivity technique was embraced in view of the minimal effort of the field activity, decreased coordinations labor and furthermore quicker. An aggregate of Six (6) vertical electrical sounding (VES) were estimated inside the zone. The resistivity estimation is taken by presenting little segment of power through two current cathodes (An and B) and estimating the resultant voltage drop between a couple of expected anodes (M and N). A straightforward determined estimation of evident resistivity is the boundary bearing the data for the qualities of the earth (Tonkov, 2008). From the establishment of electrical resistivity hypothesis is the ohms law (Grant and West, 1965; Dobrin and Sarvit, 1988):    â â â â â â â â (1) Where Ï  is the resistivity, R is the obstruction, L is the length of the directing chamber and An is the cross sectional region. For the strong earth, whose material is dominatingly comprised of silicates and essentially non channels, the nearness of water in the pore space of the dirt and in the stones breaks improves the conductivity of the earth when an electrical flow I is gone through it, along these lines making the stones a semi conductor.â Since the earth isn't care for a straight wire and it's anything but an anisotropic, at that point Equation 1 can be redone as:  â â â â â â â â â â â â â â â â â â â â (2) Where change in voltage and r is the range of current terminals side of the equator. Since the earth isn't homogeneous, Equation 2 is utilized to characterize a clear resistivity which is figured as the result of the geometric factor and the obstruction recorded in the electrical resistivity meter and resistivity the earth would have on the off chance that it were homogeneous (Grant and West, 1965;):  â â â  â â  â â â â â â â â â (3) Where, 2ï€r is then characterize as the geometric factor (G) fixed for a given anode design and is subject to the terminal game plan. The Schlumberger anode design was utilized for this investigation. The geometric factor is along these lines given as:  â â (4) Where AB is the separation between two current cathodes, MN is the separation between two likely anodes. Area AND GEOLOGY OF THE STUDY AREA The investigation zone is situated in the south-eastern piece of Lagos State between Latitudes 6â ° 25 to 6â ° 28 North of the Equator and Longitudes 3â ° 24 to 3â ° 30 East of the Greenwich Meridian (Fig.1.1). The examination region Lekki and its environ issituated inside the western Nigeria seaside rivers and tidal pond created by boundary sea shores related with sand testimony (Pugh, 1954). It frames some portion of the Lagos tidal pond framework known as the biggest of the four tidal pond framework in the bay of guinea coast (Adepelumi and Olorunfemi, 2000). Banana Island is a counterfeit island in Lagos State, Nigeria. It is situated in the Lagos Lagoon and connected toward the North-Eastern Ikoyi Island by a committed street strip which is connected to the current street arrange. The banana-molded Island is roughly 1,630,000 square meters in size (not exactly a square mile) and is isolated into 536 plots (of somewhere in the range of 1000 and 4000 square meters in size) principally orchestrated along circular drives, so intended to upgrade the generally private nature of Ikoyi. Banana Island is a counterfeit island recovered from segments of the Lagos Lagoon, topographic rise acquired at the site found the middle value of 4 meters above mean ocean level. The investigation territory is situated inside the beach front locale of Nigeria with an atmosphere of long wet season (April to October) and short dry season (November to March). Normal yearly precipitation is above 2000mm and fills in as a wellspring of groundwater revive. The territory is helpless to flooding after substantial precipitation during the wet season. Nigeria lies in a broad Pan-African versatile belt which isolates the West African and Congo Cratons. The belt is deciphered to have developed from the mainland crash between the West African craton and the Pan-African belt (Black et al., 1979; Caby et al., 1981). Geochronologically, the Precambrian rocks of Nigeria can be assembled into four significant classes (Liberian Orogeny 2800  ± 200 Ma, Eburnean Orogeny 2000  ± 200 Ma, Kibaran Orogeny 1100  ± 200 Ma and The Pan-African Orogeny 600  ± 150 Ma). These classes relate with the four orogenic occasions that have punctuated the Precambrian history of Africa (Odeyemi, 1979). Figure 2.1: Regional Geological Map of Nigeria (Modified after Ajibade et al., 1988) Beach front Nigeria contains two sedimentary bowls: The Benin-Dahomey bowl and the Niger Delta bowl isolated by the Okitipupa edge. The stones of the Benin bowl are predominantly sands and shales with some limestone which thicken towards the west and the coast just as down plunges to the coast. Late dregs are underlain by the Coastal Plains Sands which is then underlain by a thick dirt layer the Ilaro Formation and other more seasoned Formations (Jones and Hockey, 1964). The Coastal Plains Sands spring is a multi-spring framework comprising of three spring skylines isolated by silty or clayey layers (Longe et al., 1987). It is the principle spring in Lagos Metropolis that is abused through boreholes for residential and modern water flexibly. The sedimentary rocks of Lagos State are made out of five (5) sedimentary arrangements (Jones and Hockey, 1964) viz: Abeokuta Formation, Ewekoro Formation, Ilaro Formation, the Coastal Plains Sands and the alluvial stores. The waterfront fields sand otherwise called the Benin Formation extends over the Dahomey bowl into the Niger Delta Basin. The geographical developments of the investigation zone made out of dregs set down under fluviate, lascustrine and marine situations. These residue grade into each other and change broadly in sidelong degree and thickness (Adepelumi and Olorunfemi 2000). Longe et al., (1987) arranged the spring into three kinds. Quantitative translation of the bends included halfway bend coordinating utilizing two-layer Schlumberger ace bends and the aux

United States History Essays - Monopoly, Economic Liberalism

US History From 1790 to the 1870's, state and national governments interceded in the American economy for the most part to help private monetary interests and advance financial development. Somewhere in the range of 1890 and 1929, be that as it may, government mediation was structured essentially to check and control private financial action in the open intrigue. Survey the legitimacy of this announcement, talking about for every one of these periods in any event TWO significant zones of open financial strategy. The announcement is basically obvious, in the hour of 1790 to 1870's personal business was at its pinnacle, government and state did little to control or as a rule was supportive of huge business. Free enterprise was the basic strategy towards guidelines and professional interactions when all is said in done. Anyway structure 1890 and 1929 the mentalities changed, more individuals were worried about the prosperity or the individuals, worried about the regularly developing intensity of large organizations; government and state began to control them in the very manners that the past timeframe. I. 1790-1870 a. guideline 1. numerous organizations were allowed to do however they wanted I. Carnegie Steel ii. RR 2. imposing business models were built up I. multimillion dollar ventures were framed a. Standard Oil b. Carnegie Steel ii. minimal done to direct these large organizations a. not until Sherman Anti-trust Act was there an endeavor made to control restraining infrastructures 1. indeed, even that didn't have teeth 3. with the restraining infrastructures costs can be fixed, nothing was done to stop this until the late 1800's 4. free enterprise arrangements were supported at that point b. business by and large 1. directed in the manner the top 1% saw fit I. Andrew Carnegie ii. John D. Rockefeller iii. J.P. Morgan 2. huge business flourished while the entrepreneurs were left to the benevolence of the huge folks 3. economy depended on the couple of individuals that had all the cash I. this brought about numerous poor, barely any rich ii. once more government/state didn't do a thing till after the late 1800's 4. strikes and associations illicit at that point II. 1890 - 1929 a. guideline 1. Acts start to go on the defensive I. Sherman Anti-Trust Act ii. Interstate Commerce Act 2. Restraining infrastructures began to be separated I. Trust Busters a. Teddy Roosevelt b. Woodrow Wilson ii. guideline of business increasingly severe 3. Individuals begin to understand the shades of malice of a free enterprise economy I. nobody yet enormous business would benefit 4. old styles of thing are before long taken over by another reasoning I. all individuals are significant ii. economy which was principally coordinated towards the couple of riches was presently being coordinated towards the lion's share, not the minority b. business in General 1. associations lawful I. AFL 2. per capita salary rose from $450 to $567 3. indeed, even presidents see changed with the appointment of Roosevelt I. President was steward of the individuals ii. Hepburn Act a. directed RR b. moved to free enterprise 4. Degenerate business strategies transformed I. Unadulterated Food and Drug Act a. to control the deceitful strategies of the large organizations and to help the states of life. 5. notable individuals are progressively worried about the neediness of the nation I. presidents a. Taft b. Wilson ii. some rich iii. authors 6. approaches changed towards rich being terrifically imperative to an increasingly cognizant moralistic perspective on the individuals being significant All in all I accept that the financial strategies during 1790 to 1870 were in actuality set up to help private interests of the couple of well off in the U.S. in light of the ever common developing riches in people, for example, Rockefeller and Carnegie. Imposing business models and protections developed without restriction in this timespan. Things key to the people groups needs were dismissed, for example, associations and value guidelines Whereas in the 1890 to 1929 arrangements and perspectives were moved to an increasingly focal spotlight on the open interests and restraining infrastructures were beginning to be toppled by trust busters and laws and guidelines set against them, for example, the Sherman Anti-trust act and the Interstate Commerce Act which were first made successful with president Roosevelt.