How can ancient buildings "renew their lives" after being "foot-soaked" by the flood?
Expert: Prescribe the right medicine for "extra injuries" and "internal injuries"
Our reporter Cui Shuang
The flooding this summer has made this year the most severely damaged cultural relics during the flood season in recent years. Similar to the 300-year-old Matouxi Wind and Rain Bridge in Zhangjiajie City, Hunan, the 400-year-old Lecheng Bridge in Jingde County, Anhui Province, and the 800-year-old Rainbow Bridge in Wuyuan County, Jiangxi Province, all have been affected by floods. News of the damage of the ancient bridge is endless. It's heartbreaking. Recently, there was news that 63 ancient buildings in Chongqing suffered floods.
my country's cultural relics are mostly wooden frame structures, and the main building materials are wood, bricks and tiles, etc., especially in some revolutionary sites, which are mostly ancestral halls and residential buildings. The building level is not high and they are easily damaged in natural geological disasters. How to protect and repair these "heirlooms" after flooding?
Different types of cultural relics have different violations
"Floods have caused serious damage to ancient buildings. This year, ancient bridges, ancient city walls, and ancient houses in some areas of our country were severely damaged due to the impact of heavy rains, and even collapsed or overturned, causing huge loss of cultural heritage value." Said Zhou Gan, a research librarian at the Museum.
"Our cultural relic types include wooden structures, ruins, grotto temples, murals and movable statues." Qi Ying, a lecturer at the School of Architecture and Urban Planning of Beijing University of Architecture and Architecture, told a reporter from Science and Technology Daily that different cultural relics are vulnerable to different types due to flooding. Damage: Humidity changes will cause damage to the material itself. In addition to stone, wood, mural painting, paint, etc. will be affected; mechanical impact will cause appearance damage, which is related to the location of cultural relics. The previous ones were impacted by flood peaks. All the bridges belong to this category; buoyancy will damage the original stressed structure of the structural system, and the ancient bridge collapsed because of this; material deformation will destroy the structural relationship, and microorganisms in the water will also cause long-term damage to the material. "Wooden structure is the first to be damaged. Its drying rate is related to its strength. After being exposed to moisture, the strength decreases, and the strength of the column foot and the overall beam will also decrease." Qi Ying said.
Try to use original components and traditional craftsmanship
“Ancient buildings need to be repaired and reinforced in time after floods.” Zhou Gan said, whether it is a masonry or timber load-bearing ancient building, scientific evaluation should be done before repair, and the evaluation includes: building damage Reasons, demonstration of reinforcement (repair) plan, and flood control capacity of the building after reinforcement, etc.
Zhou Gan said that for the repair and reinforcement of ancient buildings, it is recommended to focus on the following three factors: based on different damage reasons, take appropriate reinforcement plans; when carrying out repair and reinforcement of ancient buildings, try to ensure that the building components used belong to the original building body. In order to reflect the authenticity of the cultural relics themselves; when the ancient buildings are repaired and reinforced, the craftsmanship used should be traditional crafts to reflect the authenticity of the ancient building construction skills. Qi Ying said that the Rainbow Bridge, which was destroyed by the flood, was collapsed. It was necessary to rely on the original surveying and mapping information to collect raw materials as much as possible for reconstruction.
Regarding the restoration of water-damaged cultural relics, Qi Ying said that the restoration is directly related to the damage. The damage depends on whether it is "external injury" or "internal injury." "The former is the damage of the material itself, and the latter is the material combination relationship, which is the structure. And structural damage.” She further explained, “In case of'internal injury', we must first ventilate and dehumidify, and restore the original stable environment of the ancient building. Repair personnel must conduct strength testing of materials, and then take corresponding measures based on strength damage. In general, As long as the wood has not been soaked for a long time, the problem will not be too great, and the stone will be fine. If there is "extra injuries" such as de-tenoning, crooked flashing, and overturning of the wooden structure, it needs to be corrected or even dropped for major repairs."
"The core of avoiding water damage is the pre-planning, site selection and layout design. It is too late to discuss waterproofing when the building itself is damaged." Qi Ying emphasized, "Many of our traditional buildings pay attention to waterproofing in site selection, such as some underground mausoleums. There is a waterproof isolation layer, but it will be difficult to support this year's water conditions."
Flood control requires comprehensive planning and early warning
"This year's flood season, many ancient buildings in my country were damaged by floods, which sounded the alarm for the protection of cultural relics, and also put forward new issues for the protection of ancient buildings in flood protection." Zhou Qian said.
In his view, to avoid water damage, the first step is to make a comprehensive plan for flood protection and protection of ancient buildings. Taking into account the possible flood damage to ancient buildings of different types and regions such as houses, city walls, and bridges, preventive protection should be done in terms of the improvement of the drainage system and the reinforcement of the building itself.
"Secondly, we must do a good job in the early warning of flood prevention for ancient buildings." Zhou Gan said that scientific analysis should be carried out to demonstrate the possible maximum rainfall when the rainy season comes, analyze the possible forms of damage to ancient buildings caused by rain, and make preparations for different types of ancient buildings in advance. Scientific means of flood control. In addition, the regular maintenance of the drainage system of ancient buildings is also necessary to prevent problems before they happen. “The roof drainage, ground drainage, and underground (ditch, culvert) drainage of ancient buildings should be dredged and cleaned before the flood season. All rainwater outlets, repair damaged drainage facilities to ensure the normal operation of the drainage system." Zhou Qian said.