Slogan of Zhaozhou Bridge

Li Chun is a famous bridge craftsman in my country's Sui Dynasty. He built the world-famous Zhaozhou Bridge, created a new situation in my country's bridge construction, and made great contributions to the development of my country's bridge technology.

Li Chun was an ordinary craftsman in the Sui Dynasty. Due to the lack of records in historical books, his life, place of origin and dates of birth and death are no longer known. We can only know that it is based on the "inscription" written by Zhang Jiazhen for Zhaozhou Bridge in the Tang Dynasty: "Zhaojun's first river stone bridge is the trace of Sui craftsman Li Chun. It was made strangely and people don't know why." Li Chun built this famous stone bridge.

There is also a beautiful legend about Zhaozhou Bridge. It is said that Zhaozhou Bridge was built by Lu Ban. After the bridge was completed, Zhang Guolao, one of the Eight Immortals, rode his donkey backwards and took Chai Rong with him. I also happily went to join in the fun. When they came to the bridge, they happened to meet Lu Ban, so they asked if the bridge could withstand them. Lu Ban thought to himself: This bridge can be crossed by mules, horses and carts, so two people are nothing, so he invited them to get on the bridge. Unexpectedly, Zhang Guolao was carrying a bag containing the sun and moon, and Chai Rong was pushing a cart carrying the "Five Famous Mountains", so after they got on the bridge, the bridge was shaken by the pressure. When Lu Ban saw something was wrong, he hurriedly jumped into the water and held on to the east side of the bridge with his hands. Because Lu Ban exerted too much force, his handprints were left under the east arch of the bridge; the bridge also had imprints of donkey hoofs, lane ditches, a knee mark left by Chai Rong when he fell, and Zhang Guo's fallen bamboo hat. The circular crater made while on the bridge. Of course, this is just a myth made up by people to commemorate the skilled craftsmen in ancient times.

Zhaozhou Bridge is the common name of Anji Bridge. It is located on the ** River five miles south of Zhao County, Hebei Province, spanning the north and south banks of the ** River. It is the earliest existing large-scale stone arch bridge in my country. It is the oldest existing open-shoulder arc arch bridge with the longest span in the world. The bridge has a total length of 50.83 meters, a width of 9 meters, and a clear span of the main hole of 37.02 meters. The entire bridge is built entirely of stones, with more than 1,000 stones used. Each stone weighs 1 ton. The bridge is equipped with exquisite stone railings, which are majestic, smart and exquisite. With its original shoulder-arch structural form, exquisite architectural art and construction skills and other outstanding achievements, it is eye-catching in the history of bridges at home and abroad. It fully represents the rich experience and high wisdom of ancient my country's working people in bridge construction.

Zhaozhou Bridge was built in the Sui Dynasty. After the Sui Dynasty unified China, it ended the long-term division and war between the north and the south, and promoted social and economic development. At that time, Zhao County was the only way for north-south transportation. From here, one could reach the important town of Zhuojun (today's Zhuozhou City, Hebei Province) in the north and Luoyang, the capital of Kyoto, in the south. The traffic was very busy. However, this traffic artery was blocked by the Yangtze River outside the city, which affected people's movement and was even impassable during the flood season. Therefore, in the first year of Daye of the Sui Dynasty (AD 605), it was decided to build a large-scale bridge on the Yangtze River. The stone bridge ended the long-term traffic inconvenience. Li Chun was appointed to be responsible for the design and construction of the bridge. Li Chun led other craftsmen to come here and conducted on-the-spot inspections of the ** River and the geology on both sides. At the same time, he carefully summarized the experience of previous bridge construction and put forward a unique design plan based on the actual situation. According to the design plan, he carefully and meticulously construction, and the task of building the bridge was quickly completed. Li Chun and others created many technical achievements in design and construction, raising ancient Chinese construction technology to a whole new level.

The design of Zhaozhou Bridge has the following innovations in the history of bridge technology in my country:

(1) The use of arc arch form has changed the tradition that most large stone bridges in my country are semicircular arches. Most of the arches of ancient stone bridges in my country are semicircular. This form is more beautiful and complete, but it also has two shortcomings: First, transportation is inconvenient. Semicircular bridge arches are more suitable for bridges with relatively small spans, while The use of semicircular arches for long-span bridges will make the vaults very high, making the bridge high and steep, making it very inconvenient for vehicles, horses and pedestrians to cross the bridge. Second, the construction is unfavorable. The scaffolding used for the semicircular arch stone masonry will be very high, which increases the risk of construction. To this end, Li Chun and the craftsmen creatively adopted the arc arch form, which greatly reduced the height of the stone arch. The clear span of the main hole of Zhaozhou Bridge is 37.02 meters, while the arch height is only 7.25 meters. The ratio of arch height to span is about 1:5, thus achieving the dual purpose of low bridge deck and long span, and the bridge deck transition It is stable and very convenient for vehicles and pedestrians. It also has the advantages of saving materials and convenient construction. Of course, the thrust of the arc-shaped arch on the bridge foundations at both ends increases accordingly, which requires higher requirements for the construction of the bridge foundation.

(2) Use open shoulders.

This is a major improvement Li Chun made to the spandrels. He changed the solid shoulder arches used in previous bridge construction to open shoulder arches, that is, two small arches are set up at both ends of the big arch, and the small arch near the big arch foot has a clear span. is 3.8 meters, and the clear span of the other arch is 2.8 meters. This kind of shoulder arch with a large arch and a small arch has excellent technical performance. First of all, it can increase the flood discharge capacity and reduce the impact of floods on the bridge due to the increase in water volume during flood seasons. During the flood season in ancient times, the water potential of the ** River was relatively large, which was a test for the flood discharge capacity of the bridge. Four small arches can share part of the torrent. It is calculated that the four small arches can increase the water-crossing area by about 16%, which greatly reduces the impact of floods on the bridge. influence and improve the safety of the bridge. Secondly, compared with solid shoulder arches, the open shoulder arch can save a lot of earth and stone materials and reduce the self-weight of the bridge body. It is calculated that the four small arches can save 26 cubic meters of stone and reduce its own weight by 700 tons, thus reducing the impact of the bridge body on the abutment and foundation. Vertical pressure and horizontal thrust increase the stability of the bridge. Thirdly, it increases the beauty of the shape. The four small arches are balanced and symmetrical. The large arch and the small arch form a complete picture, which looks more light and beautiful, reflecting the complete unity of architecture and art. Fourth, in line with the theory of structural mechanics, the shoulder-arch structure puts the bridge in a favorable condition when carrying load, can reduce the deformation of the main arch ring, and improve the bearing capacity and stability of the bridge.

(3) Single hole. Traditional construction methods in ancient my country generally use porous forms for longer bridges, so that the span of each hole is small and the slope is gentle, making it easier to build. However, porous bridges also have disadvantages. For example, there are many bridge piers, which is not conducive to boat navigation and hinders the release of floods. The bridge piers are subject to long-term impact and erosion by water flow, and are prone to collapse over time. Therefore, when Li Chun designed the bridge, he adopted the form of a single-hole long span without piers in the center of the river, making the stone arch span as long as 37 meters. This is an unprecedented initiative in the history of bridges in our country.

Zhaozhou Bridge not only has a unique design, but also has excellent construction technology and a lot of creativity.

(1) The bridge site selection is reasonable to make the bridge foundation stable and reliable. Based on his many years of rich practical experience, Li Chun chose a relatively straight place on both sides of the ** River to build the bridge after strict and thorough investigation and comparison. The stratum here is formed by alluvial river water, and the surface of the stratum has been washed by water for a long time. Coarse sand layer, followed by fine stone, coarse stone, fine sand and clay layers. According to modern calculations, the ground here can withstand 4.5 to 6.6 kilograms of pressure per square centimeter, while the pressure of the Zhaozhou Bridge on the ground is 5-6 kilograms per square centimeter, which can meet the requirements of the bridge. After the bridge site was selected, the foundation and abutment were built on it. Since the bridge was built, the bridge foundation has only sunk 5 centimeters, indicating that the stratum here is very suitable for bridge construction.

(2) The Zhaozhou Bridge has a novel construction method and is easy to construct and repair. Li Chun used local materials and selected hard blue-gray sandstone produced in nearby counties as the bridge construction stone. In terms of the stone arch laying method, he adopted the longitudinal (in the direction of the bridge) laying method, that is, the entire bridge is made of 28 independent arches are combined side by side along the width direction. The thickness of the arches is 1.03 meters. Each arch is independent and can be operated separately. It is quite flexible. After each arch is completely closed, it becomes an independent puzzle. After completing one Provide coupons, move the weight-bearing "scaffolding", and then build another adjacent arch. This masonry method has many advantages. It can not only save the wood used to make the "scaffolding" and make it easy to move; it is also beneficial to the maintenance of the bridge. If the stones of an arch are damaged, just embed new stones and perform partial repairs. Rather than having to adjust the entire bridge.

(3) Many strict measures have been taken to maintain the stability of the bridge. In order to strengthen the horizontal connection between each arch and make the 28 arches form an organic whole with tight and firm connections, Li Chun took a series of technical measures. l) Each arch adopts the method of being wider at the bottom and narrower at the top, with a slight "pointing" method, so that each arch is tilted inward and crowded against each other to strengthen its lateral connection to prevent the arch stones from toppling outward; in the width of the bridge A small amount of "tightening" method was also adopted, which is to gradually shrink the width from both ends of the bridge to the top of the bridge, from the maximum width of 9.6 meters to 9 meters, to enhance the stability of the bridge. 2) Five iron tie rods are set up on the main bridge evenly along the width of the bridge, passing through the 28 arch bridges. There are semicircular rod heads exposed at both ends of each tie rod outside the stone to clamp the 28 arch bridges and strengthen them. Horizontal connections. There is also an iron tie rod on each of the four small arches that plays the same role. 3) A layer of arch protection stones is covered on the outer arch stones and the small arches at both ends to protect the arch stones; there are 6 hook stones on both sides of the arch protection stones to hook the main arch stone. The connection is strong.

4) In order to make the adjacent arch stones fit tightly together, "waist iron" is worn between the adjacent arch stones on both sides of the outer arch, and the adjacent stones between each arch are also connected. There is a "waist iron" pierced on the back of the arch to link the arch stones. Moreover, the sides of each arch stone are chiselled with fine diagonal lines to increase friction and strengthen the lateral connection between the coupons. The adoption of these measures makes the entire bridge a tight whole and enhances the stability and reliability of the entire bridge.

(4) The abutment of Zhaozhou Bridge is unique. The abutment is the foundation of the entire bridge and must be able to withstand the huge horizontal thrust and vertical pressure caused by the decomposition of the axial force of the bridge's main arch ring (the main body of the bridge body). The abutment of Zhaozhou Bridge has the following characteristics: 1) low arch foot: the arch foot is only about half a meter below the river bed; 2) shallow bridge base: the bottom surface of the bridge base is about 1.7 meters below the arch foot; 3) short abutment : From top to bottom, gradually thickened stone strips are used to build a bridge abutment that is 5 meters long, 6.7 meters wide and 9.6 meters high. This is an economical, simple and practical bridge abutment. In order to ensure the reliability of the bridge abutment, Li Chun took many corresponding measures to consolidate the foundation. In order to reduce the vertical displacement of the bridge abutment (that is, the sinking caused by the vertical pressure of the main body of the bridge), Li Chun took the measure of driving many wooden piles beside the abutment to strengthen the foundation of the bridge abutment; this method is used in It is also often used in the construction of factories and bridges today. In order to reduce the horizontal movement of the abutment (that is, the backward movement of the abutment caused by the horizontal thrust of the main body of the bridge), Li Chun adopted the method of extending the back seat of the abutment to offset the effect of horizontal thrust. In order to protect the bridge abutment and bridge foundation, Li Chun also set up a diamond wall on one side of the river. On the one hand, it can prevent the erosion of the water flow. On the other hand, the diamond wall is integrated with the bridge abutment and bridge abutment, increasing the bridge's The stability of the platform. The above measures ensure that the bridge has a solid abutment and improve the solidity of the bridge.

The open-shoulder arc arch form of Zhaozhou Bridge is a great creation of the working people of our country. The open-shoulder arc stone arch bridge only appeared in the West in the 14th century, which is more than 600 years later than our country. In his masterpiece "History of Science and Technology in China", Dr. Joseph Needham, a famous British expert on the history of Chinese science and technology, listed 26 scientific and technological achievements that were spread from my country to Europe and other regions from the 1st century to the 18th century. The 18th of them is Curved arch bridge. After the completion of the Zhaozhou Bridge, it became the hub of transportation between the north and the south of China. It has the reputation of "a smooth road with thousands of people passing through it, and a post messenger traveling across all nations." Boats sail under the bridge, and people, horses, and vehicles pass over the bridge, which greatly facilitates transportation and people's lives, and provides convenient conditions for people to travel on both sides of the Yangtze River.

It has been more than 1300 years since this bridge was built. During this period, it has experienced the impact of more than 8 earthquakes, the test of more than 8 wars; it has withstood the heavy pressure of countless people and livestock vehicles, and suffered countless It has been eroded by wind, frost, ice, snow and rain, but its majesty has not diminished, and it still stands tall on the Yangtze River.

After liberation, Zhaozhou Bridge was listed as a national key cultural relic protection unit. Relevant departments conducted thorough repairs on this ancient bridge to maintain its glorious historical status. Zhaozhou Bridge has become a symbol of the wisdom and wisdom of the Chinese people and a place for patriotism and history education. The completion of the Zhaozhou Bridge had an important impact on the history of bridges in my country. Its long span, arc arch, and large shoulders created a new world for future bridge construction. After the Sui Dynasty, many large-scale arch bridges similar to those in Zhaozhou appeared, and more than a dozen have been discovered, such as Puji Bridge in Nao County, Shanxi, Jingde Bridge in Jincheng, Yongtong Bridge in Zhao County, Hebei, Jimei Qiao et al. Jizhou Bridge has become a model of bridge construction in my country.

However, outstanding technical achievements like Zhaozhou Bridge and outstanding bridge experts like Li Chun were not taken seriously by feudal rulers in feudal society, and they even did not leave many traces in history books. , except that we know that Sui Dynasty craftsman Li Chun designed and built this world-famous bridge, we know nothing else about it, which must be said to be a big regret. But even so, we still firmly believe that Li Chun, as a generation of bridge experts, and Zhaozhou Bridge as a historical bridge will always be recorded in the history of the motherland and will be remembered by future generations.