COMPARATIVE STUDY OF GEODETICALLY AND PHOTOGRAM METRICALLY ESTABLISHED CONTROL FOR DUDHGANGA PROJECT

Abstract

Periodic Control Surveys are necessary for monitor-ing deformations in large engineering structures, in order to testify whether these structures are subject to local defor-mations as a function of time and whether these deformations are within the permissible limits for the safety of structures, If not remedial measures can be taken well in advance to save the structure as well as loss of human lives and property. The work pi'esented in this thesis relates to the photogrammetric monitoring of Dudhganga dam, presently under construction on Dudhganga river in Maharashtra State. The requirement of the project was to develop a suitable photo-gramme-trio system for monitoring the dam from the first stage of its construction. The establishment of photogranmetric system at site necessitated establishment of suitable camera stations, Geodetic stations and targets at suitable location to serve as control. The main object of this thesis was to carry out the precise geodetic control surveys to meet these requirements. The field work at project site was divided into two parts. The first dealt with the establishment of two geodetic stations well outside the influence zone, because of the un-favourable foundation problems, and 2 pairs of camera stations for photogranmetry and determination of the coordinates of these alongwith the target points. A Wild T3 theodolite and E.D.M. EOK 2000, were used for the geodetic survey work. The other part consisted of determining the coordinates of the same target points from the photogrammetric system. The photogrammetric system consisted of a Wild RC 5 (a) Camera, f = 210 mm, format size 18 x 18 cm. modified for use in terrestrial mode, with aerial film for photography and reduction of the data employing the analytical photo-grammetric approach. A comparis=on of the spatial coordinates of targets established geodetically and photogrammetrically has been made to find out the accuracy achievable by the present developed photogrammetric system. The accuracy obtained has been considered satisfactory within the constraints of the available instruments, and other facilities. The estab-lished geodetic station and camera stations shall be used frequently for future periodic monitoring throughout during the construction phases of the dam and thereafter.