View of Assessment of structural problems in Mardin Castle

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Advanced Engineering Days aed.mersin.edu.tr

Assessment of structural problems in Mardin Castle

1Mardin Artuklu University, Department of Architecture and Urban Planning, Türkiye, lalekaratas@artuklu.edu.tr

2Mersin University, Faculty of Engineering, Department of Geological Engineering, Türkiye, aydinalptekin@mersin.edu.tr

3Mersin University, Faculty of Engineering, Department of Geomatics Engineering, Türkiye, myakar@mersin.edu.tr

4Munzur University, Department of Architecture, Türkiye, muratdal@munzur.edu.tr

Cite this study: Karataş, L., Alptekin, A., Yakar, M., & Dal, M. (2023). Assessment of structural problems in Mardin Castle. Advanced Engineering Days, 6, 9-13

Keywords Abstract

Mardin Castle Structural damages Stone material Restoration

The hill on which Mardin Castle is built consists of cliffs in the form of a cliff. Large-scale displacements and separations in the rocky formation cause serious structural and static problems on the huge structure, and smaller-scale erosion and deterioration in the castle structure. In the castle structure, which is a symbol for the region; In its current form, it needs maintenance, repair and protection interventions. Our study aims to determine the structural problems of Mardin Castle in response to this need. Observational detection and photographing documentation methods were used in the study. As a result of the study, the biggest structural problems in the castle; It has been determined that there are deteriorations in the form of cracks, separations and losses in the natural rock that forms a carrier for the fortification walls. Losses in natural rock leads to the collapse of parts of the main walls; cracking, splitting and splits caused joint openings, lattice load balance changes and partial lattice losses. Our study is valuable in terms of revealing the structural problems that carry risks at the point of ensuring the sustainability of the building and offering intervention proposals to prevent new problems.

Introduction

The hill on which Mardin Castle is built consists of cliffs in the form of a cliff. The plain on the top of the hill naturally forms a castle. Existing remains of the castle include the fortification and bastion walls, starting from the western edge and extending along the southern edge, and ending with a polygonal structure in the east. Both the city walls and bastions and the remains of the buildings in the castle have undergone changes with the deteriorations that occurred over time due to debris and earth filling, repairs and other interventions; It has reached the present day by losing its architectural integrity to a large extent. Problems in the natural rock on which the main walls sit, precipitation, water absorption-salt outflows from the ground and physical stresses due to plant growth, joint mortar/filler discharges (losses) in the wall and other carrier elements, unit material and mesh section losses in the mesh, joint in the mesh These are the problems that threaten the building elements and materials such as openings, plant (tree roots and stems) development, openings in the top cover and increased moisture as a result of soil filling. Structural problems in the castle include deteriorations that weaken the weave and thus accelerate the process that threatens the weave and its material. These problems, which accelerate the destruction, also show themselves as an important factor in material deterioration. The building in its current form needs maintenance, repair and protection interventions [1]. This study aims to determine the structural problems of Mardin Castle in response to this need.

Material and Method

In order to determine the structural problems of the castle, the structure was examined on site. The problems observed in the structure were photographed and documented. The data obtained from the field has been

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classified under various sub-headings and an ontological approach has been adopted in the representation of structural problems.

Results

Ground Damages

The castle is perched on a high rocky hill with steep slopes. The fortification walls sit on the natural limestone rock, which is partially processed and used as a foundation. This natural rock on which the fortification walls are located is subject to a great deal of erosion (mechanical) due to environmental effects, natural causes and the soil filling accumulated in the castle (with mechanical effects such as water, moisture and salt outflows, frost and tectonic movements and/or softening of the clayey texture within the stone by water absorption).

abrasion=erosion and chemical dissolution=corrosion); In addition to mechanical stress (water and frost, water and salt outflow) effects, large and small blocks, mono-blocks have been separated into pieces. With the erosion and separation of the natural rocks (growing cracks and crevices, formation of deep crevices, fragmentation, ruptures and losses) reaching an advanced level, the movements and losses in the carrier foundation also affected the fortification walls resting on the rock. part of it has survived to the present day. Joint enlargement-opening, deterioration in the masonry, masonry stone losses, edge and corner fractures have occurred in most of the existing walls that have survived to the present day (Figure 1).

Figure 1. Erosion of the natural rocks on which the walls sit [2]

Structural Crack

It is the situation where the masonry unit stones are separated from their joints in a horizontal, vertical or diagonal manner and emerge as a structural problem throughout the building. These cracks and splits show themselves in the form of splits between the masonry stones on the body walls and cracks / crevices in the weave.

Under this title, cases where cracks, crevices and separations are continuous along a part of the masonry are examined. These cracks and disintegration also cause breakage and fragmentation in unit stone elements (Figure 2).

Figure 2. Structural crack [2]

Joint mortar losses in the mesh

In the upper sections of the wall, the gap between the mesh material, the water inlets to the mesh, the salt outflows from the repair mortars and the vegetative growth are the sources of deterioration. Precipitation, which is one of the important sources of deterioration, and salt outflow caused by humidity and frost events cause

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crumbling and fragmentation in the weaker mortar materials as well as in the stone materials with the mechanical pressures they create. It can be observed that the deterioration starts with crumbling from the surface of the mortar that provides the connection, and in the areas of advanced deterioration, it also causes the joint filling consisting of small rubble stones in the rubble mesh to spill, gradually leading to losses up to the shedding of all the joint material. It is understood that the deterioration also caused the masonry unit material stones and lattice sections on the walls to fall due to the ongoing problems. Openings on the walls, precipitation and plant growth, joint openings and losses caused by problems in the rocks on which the wall sits are other factors that have a chain effect on the occurrence of such problems. The source of the deterioration is mostly due to the changes in the load balance (balance transferred from top to bottom in load bearing) due to ruptures/separations in the natural rock bearing the wall, new load pressures in the lattice and unit material losses. Joint openings in the mesh pose a static protection risk for the wall where the problem is seen, as well as a source for new deteriorations that will increase in the material and mesh in the formation zone (Figure 3).

Figure 3. Joint mortar discharges/losses in the lattice [2]

Losses in knitting unit material and knitting sections

These are the dissolutions and dispersions that are observed between one or more of the unit stone elements, where the weathering and cracks in the masonry texture do not follow a linear line and are not continuous. In such damages, a few unit elements constituting the lattice were locally weathered and the masonry stones were dissolved and dispersed. In the occurrence of damage; The changes in the load balance, the displacement and static problems in the rock formation on which the structure is located, and the effects of unit element losses in the masonry can be counted as triggering the discharge of the bonding joints and mortars between the unit elements.

(Figure 4).

Figure 4. Losses in knit unit material and knit sections [2]

Dissolution / Dispersion in Tissue

These are the dissolutions and dispersions that are observed mostly between one or more of the unit stone elements, where the weathering and cracks in the masonry texture do not follow a linear line and are not continuous. In such damages, a few unit elements constituting the lattice were locally weathered and the masonry stones were dissolved and dispersed. In the occurrence of damage; The changes in the load balance, displacement and static problems in the rock formation on which the structure is located, and the effects of unit element losses

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in the masonry can be counted as triggering the discharge of the joint and mortar between the unit elements (Figure 5).

Figure 5. Example Photo of Dissolution / Dispersion Problem in Tissue [2]

Damages caused by landfill

The earth fill, which covers the ruins of buildings with different functions, which accumulates in the intermediate part between the inner and outer walls within the fortification translation in the castle, and is even partially seen in the castle, can dissolve in the water accumulated by the rains. It is a source of deterioration that dissolves salt and causes it to reach building materials and building elements, and to damage it with frost events and salt outflows. It is known that soil filling facilitates the access of water to the building materials, and the movement of water brings with it problems such as salt formation, thus crumbling, cracks and losses in the mortar and stone materials, and the change of the load balance. The earth fill, which covers the building remains under the ground and accumulates around the fortification walls, ensures the continuous contact of the building parts with the ground water (moisture) and threatens the durability of the building materials with the formation of salt and frost (Figure 6).

Figure 6. Soil, Debris, etc. in the Masonry. Architectural Gaps Closed with Fillers [2]

Discussion

The biggest risk for the castle walls and the structures in the upper part of the castle is the erosion and displacement problems of the rocky structure on which the castle structure is built. Pieces that broke off and fell from the rocky structure in the past have emerged as an important threat to the settlements on the southern slope of the Castle. The natural rock formation forms the natural basis of both the city walls and the structures on the Kale. Therefore, it has been determined that if the problems in this rocky formation cannot be solved, the problems of the castle wall structure and the structures above it cannot be solved. In addition, it is seen that castles in many cities have been damaged or even demolished as a result of earthquake-induced events in our country recently [3].

In this context, in future studies, seismic risk and loss estimation studies of the castle are important for the process of deciding on the hazard calculation [4-12]. In addition, storing all these historical and seismic data on HBIM platforms in order to ensure a sustainable preservation of the historical building will be of great benefit in ensuring the conservation management of the building. In many studies in the literature, it is emphasized as a necessity to transfer the data of historical buildings to the HBIM environment [13-18]. At the point of preserving our local history, such civil initiatives made by scientists in academia as well as state institutions are of great importance [19].

13 Conclusion

One of the biggest problems in the castle is the deterioration seen in the form of cracks, separations and losses in the natural rock that forms a carrier for the fortification walls. Losses in natural rock leads to the collapse of parts of the main walls; cracking, splitting and splits caused joint openings, lattice load balance changes and partial lattice losses. There are problems, it is necessary to intervene in the natural rock in order to take precautions and prevent new problems. It is possible to examine the necessary interventions in natural rock sections with cracking, splitting and separation under the following headings.

• Natural rock sections/areas deemed appropriate to remain in place should be determined by static calculations and measurements made by subject experts.

• As was done in the construction of the castle, the problematic natural timber section should be strengthened with support structures. However, solutions should be produced by considering the strength, adequacy and compatibility of the systems such as walls and buttresses with the original.

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