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The Leaning Tower of Pisa
... Её опасный наклон был остановлен и уменьшен совсем недавно [3]. Итальянские инженеры сделали это путем управления грунтом и фиксации его [4]. ...
... Достоинством данного материала является соответствие его экспериментальным данным по собственным частотам башни. Первые два резонанса башни являются изгибными и находятся в диапазоне 0,95 -1.1 Гц [3,4]. Назначение башне модельной кладки дает в МКЭ-расчете собственные частоты, равные ~1,05 Гц. ...
... Концентратор 1c (σe=4,7 МПа) соответствует колонне нижней колоннады. Концентратор 2c (4,2466 МПа) связан с переходом от ствола к базису. Концентратор 3c (3,7224 МПа) возникает на стыке бази-са и фундаментного блока. ...
FEA of stress state for Pisa Tower is accomplished. Imaginary vertical orientation of the tower is simulated as well as its actual leaning position too. Moderate deformational incompatibility between “column drum” and “stem” load-bearing systems is revealed. Twofold overstressing of lower colonnade is found comparatively to the stem surface. Tower’s compressive stress concentrators are described. The inner helical passage into stem causes a periodical stress concentration about 1.5 – 2 times in the passage vicinity. Arch compression concentrator tied to stem – basis transition is revealed. Places for priority monitoring of marble masonry are pointed out.
Some methodic experience is gained due to lively and successful student participation in all phases of the Pisa Tower FEM simulation.
... On the other hand, the Garisenda Tower contends with the Pisa Tower the record of the most leaning medieval tower in Italy. After the stabilization measures carried out from the second half of 1993 to 2002, the Pisa Tower recovered part of its tilt, approximately 1800 arcsec, from its initial 5.5° of inclination, opening the competition between these two old 'madams' (Burland, 2004). ...
The Garisenda Tower and the Asinelli Tower, also widely known as the Two Towers, are the best preserved and famous medieval towers in the city of Bologna (Northern Italy). Standing one close to the other, right in the heart of the city centre, the Two Towers are delicate remains of the old towered city, which counted more than 75 towers in the 12th century.
The foundations of historic towers and the surrounding soil often hide major hazards for the long-term preservation of these heritage structures. The initial fundamental step to this aim is indeed a deep understanding of their original conception, foundations and subsoil. However, the idea that also such elements are an integral part of the overall structure, and thus subjected to the same conservation rules, is relatively new. The present paper outlines the investigation criteria applied to the soil-foundation systems of the Two Towers of Bologna and describes the authenticity of their characteristics, through the interpretation of new experimental data and the analysis of historical documents. A geotechnical perspective on this type of monuments turns out to be crucial in order to effectively understand the soil-structure interaction mechanisms, which govern their safety conditions over time. This study also aims to better understand the reasons why the Two Towers of Bologna, despite their numerous similarities, have reached completely different structural configurations.
The methodology described to investigate this case study, which required the integration of several aspects, can be usefully applied to any historic tower.
... The worldwide famous leaning tower of Pisa is another paradigmatic example of good geotechnical practice, as the preservation was successfully obtained by careful under-excavation (Burland et al., 2013), i.e. just carefully removing some soil in specific zones underneath the tower, without even touching it, thus keeping the solution in the uppermost part of the conventional integrity scheme of Figure 1. However, the tower of Pisa may be also seen as a misleading example, in the sense that the successful and fully respectful solution was obtained after almost one century of careful and detailed studies, investigations and monitoring, with no economic constraints, with the support of politics and public opinion, involving in the multidisciplinary study world leading experts. ...
... Especially in highly frequented places, a building problem and its reason may be interesting for the visitor, as their knowledge can satisfy his curiosity. One of the most famous places with a well-known building problem is the leaning tower of Pisa, which was founded on weak, highly compressible soils with high subsidence rates, and started leaning since its construction [9]. In this case, the tower's inclination, so to say the building problem, is the main touristic attraction, which is more valorised than the tower itself. ...
Architectonic heritage buildings attract millions of tourists for many reasons: their beauty, history, style, art, location, and so on. Presently, this list is being supplemented by the touristic exploration of the construction material, with particular emphasis on the natural stones. This material is the aim of urban geotourism because it can give precious information about its age, origin, paleo-environment, as well as its provenience, way of exploitation, transport, treatment and finally degradation by weathering, among others. Therefore, the study of the construction stones of heritage buildings constitutes a complement to the "classical" cultural items which are shown and presented during a visit. A particular segment in geotouristic activities may be the presentation of building problems to the visitors. There are many examples in this field, like moisture or cracks in the walls, unusual solutions in construction, disintegration of stones, and so on. These problems can have various causes: the capillary rise of groundwater in a wall, the lack of construction material, the heterogeneous composition of the substrate, the seismic activity, the weathering of material, to name but a few. For a visitor interested in science and technology, the knowledge of the problems, their origin and their solution (or, at least, the attempt of their solution) may be an unforgettable experience. The purpose of the work is to open a new point of view to architectonic heritage and its building problems, which can be used and explained in touristic activities. For this, mainly qualitative non-interventionist and participatory methodologies are applied. As a result, there will be the situation that the damage in one part leads to a profit in the other. This ambiguity may be resolved by considering that better knowledge about the state of the heritage building, which is made accessible to a larger public, will contribute to its preservation. So, the main conclusion is that geotourism applied to architectonic heritage and its problems is an important support to its maintenance because of the dissemination of the knowledge of what may happen with the construction material. Likewise, the knowledge acquired during a geotouristic visit may help to avoid similar problems in other buildings.
... Therefore, depending on the loading state and the in situ condition, in many cases, the deformation of clay may continue for a long time [3]. For example, in August 1173, the Leaning Tower of Pisa in Italy was constructed on a highly compressible clay deposit, and it displaced horizontally to the magnitude of 4.7 m in 1990, which is also increasing 1.5 mm/year [4]. A similar situation also may happen in any geotechnical structure founded on soft clay (see also Brand and Brenner [2]). ...
We develop a non-associated flow rule (NAFR) based elasto-viscoplastic (EVP) model for isotropic clays. For the model formulation, we introduce the critical state soil mechanics theory (CSSMT), the bounding surface theory and Perzyna's overstress theory. The NAFR based EVP model comprises three surfaces: the potential surface, the reference surface and the loading surface. Additionally, in the model formulation, assuming the potential surface and the reference surface are identical, we obtain the associated flow rule-based EVP model. Both EVP models require seven parameters and five of them are identical to the Modified Cam Clay model. The other two parameters are the surface shape parameter and the secondary compression index. Moreover, we introduce the shape parameter in the model formulation to control the surface shape and to account for the overconsolidation state of clay. Additionally, we incorporate the secondary compression index to introduce the viscosity of clay. Also, we validate the EVP model performances for the Shanghai clay,the San Francisco Bay Mud (SFBM) clay and the Kaolin clay. Furthermore, we use the EVP models to predict the long-term field monitoring measurement of the Nerang Broadbeach roadway embankment in Australia. From the comparison of model predictions, we find that the non-associated flow rule EVP model captures well a wide range of experimental results and field monitoring embankment data. Furthermore, we also observe that the natural clay exhibits the flow rule effect more compared to the reconstituted clay.
Italian experiences provide a long list of successful engineering solutions for the preservation of historic sites and, in particular, of tall structures like medieval and bell towers. Among them, Pisa Tower and Frari Bell Tower in Venice can demonstrate that innovative approaches and methodologies for the strengthening of historic foundations can be devised without any direct intervention on the structures and with the main aim of preserving their full integrity. Through purposely implemented and extensive real-time monitoring systems, it has been possible to minimize the impact of stabilization measures on the existing structures, including the historic foundations. The technologies used in the case studies described in this paper have proved to be especially gradual and flexible. Together with a number of other well described and successful examples of preservation activities currently available in the literature, such case studies will be hopefully used as a source of inspiration for future strengthening interventions aimed at preserving the integrity and the authenticity of historic foundations.
Asırlar boyunca doğal ve yapay etkenlere maruz kalan tarihi yapılarda bu etkilere bağlı olarak zamanla birçok hasar oluşmaktadır. Bu hasarlar; oluştuğu yere, biçimine ve yapının genel özelliğine göre değişmekte olup yapıların zarar görmesine, yıkılmasına ve yok olmasına yol açar. Özellikle koruma ve müdahale aşamasında bu hasar biçimleri doğru bir şekilde yorumlanması gerekmektedir. Bilinçsiz ve yanlış tadilat, onarım ve güçlendirme girişimleri, yapılarda ciddi sorunlara neden olabilmektedir. Bu yüzden bu çalışma kapsamında tarihi yapılarda uygulanan onarım ve iyileştirme metotları incelenmiş olup bu bağlamda dünyadan örnek tarihi yapılarda uygulanan onarım ve güçlendirme yöntemlerinde yapılan hatalar anlatılmıştır. Bu araştırmada, hasarlara müdahale ederken hasar nedenleri belirlenmesi gerektiği, birçok disiplinin bir arada çalışarak tercih edilen yapısal güçlendirme ve onarım uygulamalarının birçok analiz, deney ve testlerden geçmesi gerektiği gösterilmek istenmiştir.
Two examples of even, vertical lifting of building elements are presented. In the first example, after the raw state of the building was completed, the concept of land development around the building has changed. It involved in particular elevating the ground level by 0.8 m. As a consequence, the entrance to the building would be below the surrounding land. It was decided to lift the above-ground part of the building evenly by 0.80 m in order to avoid this. The lifting of the above-ground part of the building was designed and executed by detaching the building apart at the level of the floor and then lifting it evenly by 0.8 m. For this purpose, eighteen hydraulic jacks were used, installed in the bearing walls in the previously made openings. New technical cellars were additionally constructed as a result of the works. In the second case, the roof truss was raised in the residential building in use. The usable area of the attic was enlarged as a result of the works and the number of posts limiting the freedom of interior design was reduced. In both cases, a system of hydraulic jacks was used to move the structure vertically. With the presented procedure, no damage was caused to both, the building elements that were lifted and those unmoved. In addition, the even lifting of parts of the building allowed to avoid the troublesome dismantling and then restoration in a new location.
