There is information about bridges in Xiangtan.
a bridge is an overhead man-made passage. It consists of upper structure and lower structure. The superstructure includes bridge body and bridge deck; The substructure includes pier, abutment and foundation. They hang high and lie low, with a variety of shapes, some of which are simple and elegant; Some cross the rocks and streams, and the mountains and rivers add luster; Some are located in downtown thoroughfares, and their shapes are ingenious; Some bridges are multi-purpose and ingenious. No matter the wind and rain, no matter the heat and winter, they always cross the river and fly to Tianjin for the vast number of pedestrians, horses and chariots in obscurity. The main purpose of building a bridge is to solve the traffic across water or valley, so that vehicles or pedestrians can walk on the bridge unimpeded. From its earliest or most important function, the bridge should refer to the road across the water. Therefore, Duan Yucai's annotation, which explains the word "Wen Jie Zi", reads: "The word" Liang Zi "uses wood to cross the water, which is also a bridge today." It shows that the original meaning of bridge refers to the passage with wood on the water, and then it extends to the form of "plank road" on cliffs and "flying pavilion" between pavilions and palaces. Modern bridges also play an important role in urban traffic. Starting from a flat bridge (overpass), connecting east, west, north and south, not only helps to alleviate traffic jams, but also becomes a beautiful scenery of modern cities.
Features of bridges
China is a bridge country with numerous mountains and rivers, and in ancient times, it was in the leading position in both bridge construction technology and bridge number. For thousands of years, bridges have long been an indispensable part of people's social life. However, due to China's vast territory, there are great differences in geography, climate, cultural customs and the development level of social productive forces from south to north and from east to west. Therefore, based on their own actual conditions and needs, after a long period of time, they have created a variety of bridge forms and gradually formed their own characteristics. Specifically, they have the following characteristics:
(1) Regional. China's vast land, the bridge between the north and the south and between the east and the west, influenced by its natural geography and humanistic society, has formed its own relatively independent style and characteristics according to local conditions. For example, the Central Plains in the north and the Yellow River Basin have relatively flat terrain and few rivers and waters, so people rely on mule-horse carts or hand-propelled carts to transport materials. Therefore, the bridges here are mostly Kuantan majestic stone arch bridge and Liang Shi bridge, so that ships can pass under the bridge; In the northwest and southwest regions, it is difficult to build piers because of the high mountains and steep valleys. Therefore, mountain materials such as rattan, bamboo cables and logs are often used to build rope suspension bridges or outrigger wooden beam bridges. The coastal areas of Lingnan, Fujian and Guangdong are rich in hard granite, so stone bridges abound. In Yunnan minority areas, because of the abundant bamboo, unique bamboo bridges can be seen everywhere. Judging from the style of the bridge, the bridge in the north is as rough and simple as the people in the north; Bridges in the south are as nimble and light as people in the south. Of course, this is also closely related to physical geography. For example, the rivers in the north have changed greatly due to the bullying of water flow and the impact of mountain torrents and ice, so the bridge must be thick and steady; However, the water potential of the southern river is relatively gentle and it is easy to navigate, so the bridge is relatively slender and beautiful.
(2) diversity. China is an ancient civilization, with vast territory and abundant resources, beautiful mountains and rivers, and great differences in geology and geomorphology between north and south, so the technical requirements for bridge construction are also high. Around the Han Dynasty, four basic bridge types of bridges: beam bridge, pontoon bridge, cable bridge and arch bridge, were all produced. According to their different building materials and structural forms, these four kinds of bridges have evolved respectively: wooden bridge, stone bridge, brick bridge, bamboo bridge, salt bridge, ice bridge, rattan bridge, iron bridge, reed bridge, stone pillar bridge, stone pier bridge, flood bridge, cantilever bridge, covered bridge, wind and rain bridge, bamboo bridge, stone bridge, retractable bridge, cable-stayed bridge and three bridges.
(3) versatility. In building bridges, craftsmen in ancient China paid great attention to maximizing the benefits of bridges. They could not only consider adapting to local conditions and proceeding from practicality, but also consider making bridges play a multi-functional role as much as possible. For example, most of the arch bridges in the south of the Yangtze River are flat at both ends and high in the middle, which not only produces the beauty of arc in modeling, but also facilitates boating. The corridor bridge, which is widely seen in southern China, fully reflects the multi-purpose characteristics of one bridge. In the south, it rains a lot and the sunshine is strong, so the bridge builder builds a gallery house on the bridge, which not only provides a place for passers-by to escape from the wind and rain, but also increases the self-weight of the bridge, so as to prevent the bridge from being washed away by floods and protect the wooden beams and iron cables from wind and rain corrosion. In particular, many of these covered bridges are also used as markets, accommodation and commercial activities because people used to rush. For example, Xiangzi Bridge in Chao 'an County, Guangdong Province, with a total length of more than 5 meters, is known as "one mile long bridge and one mile city", and there is a pontoon bridge that can be opened and closed in the bridge to facilitate navigation; Gallery houses are built on the bridge, and markets are made behind the building. During this period, shops are row upon row, from morning till dusk, bustling and lively, so that you can't smell the roaring tide and the wide river surface. Therefore, there is a joke among the people that "ask Xiangqiao when you arrive at Xiangqiao".
(4) public welfare. Since the bridge came into being, it has appeared as a sociality belonging to the people. Traditional buildings in China are generally private, and only bridges (except those in private gardens), whether built by officials or privately, are owned by the society. Therefore, for thousands of years, loving bridges and protecting roads has become a good fashion, while "repairing bridges and paving the way" is a charitable act that benefits the public and is highly respected by the public. Therefore, repairing or building a bridge has a broad mass character. Looking at historical records, there are probably four ways to build bridges in China: one is civil construction, that is, the bridge is built independently by one family and one surname; The second is to raise funds, report to the government for support and work together to build. This kind is the most common, such as the famous Zhao Zhouqiao and Quanzhou Luoyang Bridge, which were all built in this way. Third, officials advocate people's repair, which is advocated by local officials, pledged by gentry, and appointed officials or business gentry to preside over the completion. This is mostly a large bridge; Fourth, it was all funded by the government. Therefore, there are ancient bridges all over China, and even more bridges are built in the hinterland. Its quantity and wide distribution rank first in the world.
the emergence and development of bridges
before artificial bridges, many natural bridge forms were formed in nature due to the influence of crustal movement or other natural phenomena. For example, the Liang Shi Bridge in Tiantai Mountain in Zhejiang across the waterfall, the stone arch bridge (Xianren Bridge) in Guixi, Jiangxi, and the "single-plank bridge" formed by the natural fallen trunk by the river, or the natural "suspension bridge" formed by the intertwined vines on both sides, etc. Inspired by these Natural Bridge, human beings constantly imitate nature in the process of survival. At the beginning, it is probably to use a piece of wood to set up some wooden bridges on the river, or on the trenches around the clan settlement (the reason why the bridge was originally called "beam" may be because of this kind of beam passing by), or to cushion one stone pedal slightly out of the water with stones in a narrow and shallow stream to form a simple "jumping pier" Liang Shi Bridge (the original bridge is often imitated in the garden, called "Tingbu". These "single-plank bridges" and "jumping pier bridges" are the most primitive bridges of human architecture. Later, with the development of social productive forces, they gradually evolved from low-level to high-level, and then gradually produced various bridges across the air.
Bridges in China have roughly experienced four stages of development. The first stage is dominated by the Western Zhou Dynasty and the Spring and Autumn Period, including the previous historical era, which is the founding period of the ancient bridge. At this time, in addition to the original wooden bridge and Tingbu bridge, there are mainly two forms of bridges: beam bridge and pontoon bridge. At that time, due to the backward level of productivity, most of them could only be built in areas with flat terrain, narrow river body and gentle water flow, and bridges could only be wooden beam bridges, so the technical problems were easier to solve. On the other hand, pontoon bridges are often used in rivers with wide water surface and rapid water flow.
The second stage is dominated by Qin and Han dynasties, including the Warring States and the Three Kingdoms, which is the period of the creation and development of ancient bridges. Qin and Han Dynasties is a dazzling development stage in the architectural history of our country. At this time, not only the bricks of artificial building materials were invented, but also the arch coupon structure with the theme of masonry structure system was created, thus creating a prerequisite for the emergence of arch bridges later. The appearance of ironware in the Warring States period also promoted the multi-faceted utilization of stone materials in architecture, thus adding new components such as stone pillars, Liang Shi and stone bridge surface to the bridge based on the log girder bridge. Not only that, but its great significance lies in the fact that stone arch bridges came into being. The establishment of stone arch bridge has played an epoch-making role in the history of ancient bridge construction in China, not only in practicality, but also in economy and aesthetics. The great development of Liang Shi stone arch bridge not only reduces the maintenance cost and prolongs the service life of the bridge, but also improves the scientific level of structural theory and construction technology. Therefore, the use of building stones in Qin and Han Dynasties and the emergence of arch coupon technology are actually a major revolution in the history of bridge architecture. Therefore, according to some documents and archaeological data, about the Eastern Han Dynasty, the four basic bridge types, namely beam bridge, pontoon bridge, cable bridge and arch bridge, were all formed.
the third stage is a period dominated by the Tang and Song Dynasties, supplemented by the Jin, Southern and Northern Dynasties and the Sui and Five Dynasties, which is the heyday of the development of ancient bridges. Compared with the Qin and Han Dynasties, the national strength of Sui and Tang Dynasties was stronger, and the Tang and Song Dynasties achieved a long period of stability and unity. Industry and commerce, transportation and transportation, and the level of science and technology were very developed, and it was the most advanced country in the world at that time. After the Eastern Jin Dynasty, because a large number of Han nobles moved south, the economic center moved from the Yellow River basin to the Yangtze River basin, which made the economy of the southeast water network area develop greatly, and the economic and technological development in turn stimulated the great development of the bridge. Therefore, many bridges that attracted worldwide attention were created at this time, such as Zhao Zhouqiao, an open-shouldered stone arch bridge pioneered by Li Chun, a stonemason in Sui Dynasty, Hongqiao, a stoplog wooden arch bridge invented by abandoned soldiers in Northern Song Dynasty, Wan 'an Bridge in Quanzhou, which was founded by reciting, and Xiangzi Bridge in Chaozhou, Guangdong Province, which was a combination of Liang Shi Bridge and retractable pontoon bridge in Southern Song Dynasty. These bridges are well-known in the history of bridges in the world, especially in Zhao Zhouqiao. Similar bridges appeared in other countries in the world seven centuries later. Throughout the history of Chinese bridges, almost all major inventions and achievements, as well as bridges that can compete for the first place in the world, were created at this time.
The fourth stage is Yuan Dynasty, Ming Dynasty and Qing Dynasty, which is the saturated period of bridge development, and there are almost no major innovations and technological breakthroughs. At this time, the main achievement was to repair and transform some ancient bridges, and left many construction documents for bridge construction, which provided a lot of written materials for future generations. In addition, some arduous projects, such as Wannian Bridge in Nancheng, Jiangxi, and Panjiang Bridge in Guizhou, were completed. At the same time, many cable bridges have been built in Sichuan and Yunnan, and the construction technology of cable bridges has also been improved. By the end of the Qing Dynasty, in 1881, with the opening of the first railway in China, another technological revolution in the history of bridges in China was ushered in.