Geotechnical Studies at Gargash
The geotechnical studies at the construction site of the Iranian National Observatory at Gargash summit were carried out by drilling three borings.
The geomorphology studies of Gargash summit from engineering point of view, showed that there are traces of altered rocks in the layers beneath. It is possible that some parts of the rock below the foundation of the enclosure and the telescope pier does not have the required stability.
In such a case, the structure below the pier and the enclosure foundation must be fortified to prevent any even small sinking during the some tens of years of the telescope operation. For this purpose in a collaboration with the geologists and experts on rock mechanics who are involved in the design of the telescope pier and the enclosure foundation three borings were drilled.
The first boring was 30 m deep at the center of circle of the telescope pier and the enclosure. It turned out that although there are some traces of altered rocks in a depth between 10 m and 12m but this is not worrisome and the foreseen location is well suited for the installation of the telescope.
The second boring was at the border of the surrounding circle and below the observatory foundation, where the traces of altered rock can be viewed at the summit surface. The third boring was a little outside of the enclosure circle, towards the location of the support station.
The second and the third borings were each 20 m which was found to be sufficient regarding the rock quality due to geologists and the designers of the pier.
The conclusion of the results is that the selected location for the construction of the observatory, including the telescope pier and the surrounding enclosure is well suited. Some activities and arrangements which are required during the basework have been identified.
The Observers Residence
After the selection of Gargash at the geographical coordinates (N 330 40ʹ 26.6ʹʹ , E 510 19ʹ 7.4”) as the site for construction of the national observatory, the location of the telescope had to be chosen as well carefully. From the beginning the image quality of the telescope has had the absolute priority and this quality depends very much on the location of the 3.4 m telescope.
Thus for decision on the location of the telescope, apart from the flattening of the summit it was necessary to make a more detailed study of the airflow around the flattened area.
Utilizing data of topographic maps and the prevailing wind direction and taking into account the geographical features of the area, the best possible location for the installation of the observatory building and the telescope were determined. Parallel to these studies, the Iranian National Observatory made a public request for proposal and by relying on domestic expertise began the process of designing the three buildings of the enclosure, the support station and the observer’s residence. Among the essential questions at the design process was if the location of the observer’s residence, which is also the logistic station of the astronomers, employees and office space of the observatory can be placed at an elevation of 3200m close to the enclosure.
Although parts of the design work had advanced towards this direction, international consultancy showed that this elevation bears health risks for the employees and the residence was moved down the hill close to the city of Kamu. This move will also result in cost reductions during the construction and the maintenance.
The Observatory Road
The construction site of the national observatory lies out of the access of interstate roads.Taking into account the environmental conditions at altitudes above 3000 m, the special usage of the road under construction and attention to road construction directives are necessary conditions for the success of the project. The observatory road must be passable throughout the year, even and specially at the times of heavy snowfall. At the same time it must be capable of the transportation of specialized parts and optical instruments, which might be fragile and nonstandard regarding dimensions and weight, with the least of vibration and absolutely without shocks.
At the time being the design and construction of the final road, suitable for the transportation of equipment and parts and access of researches to the observatory site at the summit of Gargash is carried with a lot of effort. As a first phase a preliminary access road was temporarily built parallel to the final road in the year 2011.
Iranian National Observatory Road Map
Preparation of the site for installing equipment
The summit of Gargash is a harsh environment and the uneven ground was impossible to use for the installation of the telescope, the construction of the observatory building and the support station. Some studies were necessary to estimate the minimum amount of manipulation to allow for an optimal usage. Simulation studies and also measurements around the year showed that it was necessary to flatten the top 8 meters with respect to the highest point. This was done in the year 2012 the required area for the enclosure and the station were provided. The design studies also took into account the future requirements of the national observatory project.
Geology and Seismicity Studies of Garagsh
The observatory building like all other structures must be constructed on a foundation, which keeps it on a stable ground. Also the installation and the operation of the telescope requires a suitable ground free of vibration. The achievement of such a stable and suitable foundation requires a profound study of the layers of the ground beneath. Thus selecting the location, the procedure of the construction, and the specification of the basework for the observatory building is very important and obtaining geological data necessary at the site of the observatory is a necessity.
One should keep in mind that a location which seems ideal on the basis of astronomical and meteorological considerations might not be such agreeable according to geological aspects. It is also possible that the costs related to the preparation of the ground of the foundation of the observatory building and the telescope become rather high as they are proportional to the depth of the excavation until reaching an appropriate level and that the project management has no choice but to change the location. For a careful study of the layer structure beneath it is necessary to probe the ground at different positions and analyze samples of different layers. The aim of this undertaking is to identify the best possible location for the foundation of the telescope and the observatory building.
The number of the required samples might differ according to the judgment of the experts in the fields of soil mechanics and geology, but the out coming data must be rather precise. Ignoring such studies might result in unrecoverable damages to the undertaking. Data on the consistency, the sequence and the thickness of the layers are necessary parameters for the final selection of the construction site. This data can be extracted by making test drillings with specialized tools and taking cylindrical or tube-shaped core samples. In addition geological data on the active and inactive faults of the zone and seismological and seismicity data must be taken into account. The best location is where there is no sign of seismic activity and the structure of the layers is a parallel combination of soil and rock.
According to the fact that soil and rock mechanics investigations must be carried out at the same time together or even before meteorological and seeing measurements, INO obtained this important data by contracting Zarzamin Taban Co. in the year 2010.