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Architects: ZHY design studio
- Area: 800 m²
- Year: 2022
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Lead Architect: Huaying Zhong
Text description provided by the architects. Karst landform is distributed in places like Guangxi, Guizhou and Chongqing. Guangxi is the place with the most widely distributed karst topography. KARST, refers to the geological process that water acts on soluble rocks mainly with chemical dissolution, supplemented by mechanical actions such as water erosion, subsurface erosion and collapse. Guilin landscape is a typical manifestation of karst terrain. Geographical landscapes like karst caves and sinkholes are formed by erosion. Dashiwei sinkholes in Leye County are the largest sinkhole group in the world, which is acclaimed as the "World’s Sinkhole Museum". The Yunhaitianzhou project is designed to experience such large-scale geographical wonders. The typical cases of viewing the large-scale geographical landscape of the canyon are as follows: The viewing platform of the Grand Canyon in Colorado, Arizona, the United States, and the suspended doughnut shape combines the soaring feeling of buildings with the tourism dynamic lines. Also, the buildings of the Shanxi Hanging Temple are integrated with the cliff wall, which is the representation of the Chinese landscape painting. The link between the cliff wall of Dashiwei sinkholes and the top of the mountain is covered with plants. So, tourists have to approach or exceed the cliff wall to experience the soaring feeling of the sinkholes. If the doughnut shape is adopted, huge support is needed at the rear to balance the front weight.
When the designer puzzled over the problem, he received a souvenir from a student for Teacher's Day. It’s a tumbler. This pole-styled tumbler shape inspired him immediately and made him reconsider the site selection of the viewing platform. The UAV terrain search and comparison result shows that it is 24 meters from the ridge fulcrum to the cliff wall. To view the cliff wall and experience the 613-meter sinkholes, people must go beyond this distance. Finally, it was decided to choose 34 meters as the design index of the overhang. The Yunhaitianzhou is composed of two winding curves, which respectively define the viewing platform that extends from the ridge to the cliff wall and constantly lowers at the same time, making people as close to the cliff wall as possible. The lower curve outlines the coffee shop inside and the height required by the structure. The V-shaped support limits the landing point of the whole building to a minimum scope. The transparent glass at the front of the platform makes people experience the feeling of a heartbeat at the 34-meter overhanging position. Going back to the coffee shop and overlooking the opposite direction of sinkholes, you can see the grand scenery with overlapping mountains. The transformation of the two experiences from a heartbeat quickening on the edge of the abyss to enjoying the open and peaceful mountain scenery makes people’s mood changes as ups and downs as the landscape.
It is only one of the challenges faced by the designer to decide on the 34-meter cantilever size. The deformation and amplitude control of the platform is to meet the needs of people’s psychological security, which brings greater difficulty to the design. The 400-meter-long crack at the top of the ridge is the main instability factor of the project. In addition to grouting treatment, the bearing of the building is designed to tilt inward, providing ridge encircling force with horizontal component force, and increasing the stability of the site. The design of building structure integration, combined with the structural design principle, makes the part with the largest deformation move back to the neck, and the deformation at the front end of the cantilever becomes smaller in this way. The use of a liquid damping box further controls the amplitude and vibration frequency, reduces the damage of vertical force on the mountain, and the dead weight of the building is reduced to the same weight as the rock excavated for the foundation. A space steel truss structure is adopted as the main structure of the viewing platform, and the front railings are taken as a part of the truss structure to make the front cantilever as thin as possible. The prestressed arch structure on the front cantilever is realized by increasing the column length, and the deflection under static load and partial live load is compensated as well, which also protects the glass from being deformed seriously. The arrangement of structural systems and components adapts to the distribution of forces, which perfectly corresponds to the architectural geometry at the same time.
For the parametric design of the curtain wall, the two main control curves of the main structure are not in the same plane. The torsional surface of the side facade glass curtain wall is resolved to the ruled surface, and the curtain wall frame layout reduces the blocking of sight on the landscape line. The continuous turning changes of components are described with a parametric design method, making it accurately positioned.
Taking into account the difficulty of water storage in karst terrain during the construction process, the local vegetation grows slowly and ecological conditions are poor, we build an 80-meter long and 10-meter wide viewing building in the limited site of the ridge. Three tower cranes lift the pre-assembled components to the top of the mountain by relay, and the construction is finally completed. The design of Yunhaitianzhou works out a solution from the perspective of design concept and technology for the dilemma between the protection and utilization of the natural landscape. The application of technology is not simply to achieve the digital index of cantilever size but to cope with the internal collision of design target technology and the fitness of the design concept, which will naturally produce the optimal solution of design, making more people experience the shocking feeling brought by sinkholes in karst terrain. The building cautiously responds to the fragile geological conditions in a high-profile manner, and behind the image with strong visual effect is the rational response after circumspect analysis. The 34-meter overhang between valleys is a bold attempt at the architectural structure. Looking at the whole sinkholes, the Yunhaitianzhou is just like a small boat among the mountains.
