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:: Volume 8, Issue 1 (2-2017) ::
GEJ 2017, 8(1): 45-58 Back to browse issues page
Strain and Stress Modelling of 15th Khordad Dam
M. Falah Ahmadyzad, D. Zamzam
Abstract:   (2742 Views)

The main purpose on this research is to estimate Strain, Stress Ellipses and rotation parameters on the surface of 15th Khordad Dam. To reach this scope, first of all, a control Geodetic Network is preanalyzed to minimize the magnitude of semi major error ellipses on the control points, this network is predesigned out of the dam structure, for economic purposes this pre-analysis is done to save time as well as finance. To do this, the coordinates in which are utilized as the main coordinates of this control Network are driven indirectly from Manual GPS or from the old maps of this region. This geodetic control network is performed by first order design and second order design. The estimated data which is derived from the first and second order design is used to determine the type of surveying instruments and equipment to meet the primary determined precision, in face, the first order design tries to search a designed area or place to find the best and optimal place for the assumed coordinated, this would be achieved by maximizing the minimum degree of freedom, so different geometrical figures are computed to reach the above purpose in which the minimum degree of freedom is maximum, the second order design is to optimize the weight of geodetic observations, at this stage, the above geometrical figure driven from the first order design is fixed and the weight matrix is changed till the optimal precision for the semi major ellipses is achieved   then Geodetic observations in two different epochs on control geodetic networks is done and the adjusted coordinates of control networks by minimum constraint adjustment is calculated, this minimum constraint method is chosen because no one of those coordinates is assumed to be errorless data, for this reason, the above method is chosen to adjust and compute the data. In the next step, geodetic observations on the body of dam is done by applying the control networks coordinates in each epoch, the coordinated of the target points(on the body of dam) is calculated by Over Constraint method, this over constraint method here is used by applying the adjusted coordinates from the former stage, these points and coordinates already achieved the predetermined error ellipse so they can be applied as Control points with the pre assumed size for the absolute error ellipses . The displacement vectors are driven by the differentiation between two adjusted coordinated on the target points in two different epochs. By Delaunay triangulation the surface of dam is separated into multitude triangles, then by the estimated parameters of the displacement vectors in finite element method a displacement model is regressed on each triangle to estimate the parameters of strain ellipse, strain tensors for the center of each triangle is calculated by the finite element method. Magnitude of geometrical infinitesimal change, rotation and Azimuth of each geometrical change is calculated and then by the application of the Hook law the stress tensors are calculated on the center of each triangle. The graphical figures are calculated by GMT software to have visual view of all Strain changes.

Keywords: Stress, Infinitesimal Change, Displacement Vectors, Control Network
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Type of Study: Applicable | Subject: Geo&Hydro
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Falah Ahmadyzad M, Zamzam D. Strain and Stress Modelling of 15th Khordad Dam. GEJ. 2017; 8 (1) :45-58
URL: http://gej.issge.ir/article-1-194-en.html

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Volume 8, Issue 1 (2-2017) Back to browse issues page
نشریه علمی مهندسی نقشه برداری و اطلاعات مکانی Geospatial Engineering Journal