Please use this identifier to cite or link to this item: http://hdl.handle.net/123456789/1041
Title: 3-D CONTROL BASELINE FOR DEFORMATION STUDIESAT THE IKPOBA DAM
Authors: EHIOROBO, O. JACOB
Keywords: Network
Angular and Linear measurement
Standard error
Issue Date: 2000
Publisher: journal of engineering sciences and application
Series/Report no.: Vol 1 (2);pp 68-87
Abstract: A network consisting of Braced quadrilateral and central figures with some overlapping diagonals was designed at the Ikpoba Dam site. From this network a braced quadrilateral was chosen as horizontal control baselines whilethe above quadrilateral together with an adjourning one were chosen as vertical control baseline. From prior estimates, standard error of angular and linear measurement was 1 and 2.5mm respectively. The number ofrounds for angular measurement was calculated to be 15 and fro linear measurements 8 in both directions. From the above results, the WILD T2 theodolite was chosen for angular measurements while the WILD DISTOMAT DI2000 was used for linear measurements. The zeiss Ni 002 level was used for leveling the two loops in both directions. A rigorous least square adjustment was thereafter carried out for both horizontal and vertical control baselines. The standard errors of angular and linear measurements after adjustments were ±0.”05 and 0.22mm respectively, while the standard error of the mean were ±0.”02 and 0.07mm respectively. The standard error for leveling in both directions was ±6mm while the standard error of mean was ±3mm. Using the x 2 (chi – square) distribution for our analysis, we found that at 95% confidence, interval 0.”01 ≤ σ ≤0”. 03 and for linear measurement 0.05mm ≤ σ ≤0.”13mm. From the above we can conclude with95% certainty that the quality of our work is very high. The result for leveling also shows that quality of results obtained corresponds to that given by 1 order leveling. Thus we can conclude that with good results and choice of suitable equipment and methods, we can get very good results even when we are constrained by Topography.
URI: http://hdl.handle.net/123456789/1041
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