Zhao Zhouqiao's open-shouldered arch is a great creation of working people in China. The open-shouldered stone arch bridge appeared in the west of14th century, more than 600 years later than China. Dr Joseph Needham, a famous British expert on the history of science and technology in China, once listed 26 scientific and technological achievements that spread from China to Europe and other regions from 1 century to 18th century, among which18 was an arch bridge. After the completion, Zhao Zhouqiao has become the north-south transportation hub of China, with the reputation of "a smooth road leads thousands of people to cross, and a courier drives all countries to connect". Under the bridge, people and cars come and go, which greatly facilitates transportation and people's lives and provides convenient conditions for people on both sides of the strait.
This bridge has been built 1300 years, during which it has experienced the influence of more than 8 earthquakes and the test of more than 8 wars. Bear the weight of countless people and livestock vehicles, endure the erosion of countless wind knives, frost swords, rain and snow, but the majestic posture still stands on the river.
After liberation, Zhao Zhouqiao was listed as a national key cultural relics protection unit, and the relevant departments carried out a thorough maintenance of this ancient bridge to maintain its glorious historical position. Zhao Zhouqiao has become a symbol of China people's wisdom and a place for patriotism and historicism education. The completion of Zhao Zhouqiao has an important influence in the history of Chinese bridges, and its bridge construction with long span, arc arch and open shoulders has opened up a new world. After the Sui Dynasty, many large arch bridges similar to those in Zhao Zhouqiao appeared, and now more than a dozen have been discovered, such as Puji Bridge in Yan County, Jingdezhen Bridge in Jincheng City, Yongtong Bridge and Jimei Bridge in Zhao County, Hebei Province. Zhao Zhouqiao has become a model of bridge construction in China.
However, outstanding technical achievements like Zhao Zhouqiao and outstanding bridge experts like Li Chun were ignored by feudal rulers in feudal society, and even left little trace in history books. We know nothing about this world-famous bridge except that it was designed and built by Li Chun, a craftsman of Sui Dynasty, which is a great pity. But even so, we still firmly believe that Li Chun, as a bridge expert, and Zhao Zhouqiao, as a historical bridge, will go down in the history of the motherland forever and be remembered by future generations.
Design Innovation Zhao Zhouqiao's design has the following innovations in the history of Chinese bridge technology:
The adoption of 1. circular arch has changed the tradition that most stone bridges in China are semicircular. The ancient stone bridges in China are mostly semicircular, beautiful and complete. But there are two disadvantages: First, the traffic is inconvenient. Semi-circular arch is more suitable for bridges with small spans, while semi-circular arch is used for bridges with long spans, which will make the vault very high and the bridge high and steep, making it very inconvenient for horses and chariots to cross the bridge. Second, the construction is unfavorable, and the scaffolding used for semi-circular arch stone masonry will be very high, which will increase the construction risk. To this end, Li Chun and craftsmen creatively adopted the form of circular arch, which greatly reduced the height of stone arch. The clear span of Zhao Zhouqiao main span is 37.02m, while the arch height is only 7.25m, and the ratio of arch height to span is about 1:5. In this way, the dual purposes of low bridge deck and long span are realized, and the bridge deck transition is smooth, which is convenient for vehicles and pedestrians. It also has the advantages of saving materials and convenient construction. Of course, the thrust of the circular arches at both ends on the bridge foundation also increases accordingly, which puts forward higher requirements for the construction of the bridge foundation.
2. Adopt a shoulder. This is a major improvement made by Li Chun on the arch shoulder. The solid shoulder arch used in bridge construction is changed into an open shoulder arch, that is, two small arches are set at both ends of the big arch, and the clear distance between the small arch near the foot of the big arch is 3.8 meters, and the clear distance between the other arch is 2.8 meters. This kind of open-shouldered arch with large arch and small arch has excellent technical performance. First of all, it can increase the flood discharge capacity and reduce the impact of flood on bridges caused by the increase of water volume in flood season. In ancient times, the grave with chaff was full of water, which was a test of the flood discharge capacity of the bridge. Four small arches can share part of the flood. According to the calculation, four small arches can increase the flow area by about 16%, greatly reduce the impact of flood on the bridge and improve the safety of the bridge. Secondly, compared with solid shoulder arch, open shoulder arch can save a lot of earthwork materials and reduce the dead weight of the bridge. According to the calculation, four small arches can save 26 cubic meters of stone and reduce the dead weight by 700 tons, thus reducing the vertical pressure and horizontal thrust of abutment and bridge foundation on the bridge body and increasing the stability of the bridge. Third, it adds a beautiful shape. The four small arches are balanced and symmetrical, and the large arch and the small arch form a complete picture, which is lighter and more beautiful, reflecting the complete unity of architecture and art. Fourthly, according to the theory of structural mechanics, the open-shouldered arch structure can make the bridge in a favorable state when bearing load, reduce the deformation of the main arch ring and improve the bearing capacity and stability of the bridge. 3. Single hole. In the traditional construction methods in ancient China, long bridges are usually in the form of multiple holes, so that each hole has a small span, a gentle slope and is easy to build. However, porous bridges also have disadvantages, such as many piers, which are not conducive to the navigation of ships and hinder flood discharge; The pier has been impacted and eroded by the current for a long time, and it is easy to collapse over time. Therefore, when designing this bridge, Li Chun adopted the form of single hole and large span, and no pier was erected in the middle of the river, which made the stone arch span as long as 37 meters. This is an unprecedented initiative in the history of Chinese bridges.
Zhao Zhouqiao is not only unique in design, but also creative.
1. The bridge site is selected reasonably to stabilize the bridge foundation. According to his rich practical experience for many years, after careful exploration and comparison, Li Chun chose a relatively flat place on both sides of the * * River to build the bridge. The stratum here is alluvial by rivers, and the surface of stratum is coarse sand layer washed by water, followed by fine stone, coarse stone, fine sand and clay layer. According to modern calculation, the stratum here can bear the pressure of 4.5 to 6.6 kilograms per square centimeter, while the ground pressure in Zhao Zhouqiao is 5 to 6 kilograms per square centimeter, which can meet the requirements of bridges. After the bridge site is selected, the foundation and abutment are built on it. So far, the bridge foundation has only sunk 5 cm, indicating that the stratum here is very suitable for bridge construction.
2. The masonry method in Zhao Zhouqiao is novel and convenient for construction and maintenance. Li Chun used local materials and selected hard blue-gray sandstone produced in nearby counties as the stone for building the bridge. In the stone arch laying method, the longitudinal (along the bridge direction) laying method is adopted, that is, the whole bridge is composed of 28 independent arch pieces side by side along the width direction, and the arch thickness is1.03m.. Each coupon is operated independently, and it is quite flexible. After each coupon is completely closed, it becomes an independent coupon. This masonry method has many advantages, it can not only save the wood used for "scaffolding", but also facilitate movement; At the same time, it is beneficial to the maintenance of the bridge. If the stone of the arch coupon is damaged, it is only necessary to embed new stone and repair it locally, without adjusting the whole bridge.
3. Many strict measures have been taken to keep the bridge stable. Li Chun adopted a series of technical measures to strengthen the horizontal connection between the arches, making the 28 arches form a tight and solid organic whole. 1) Each arch ticket adopts the method of "wide at the bottom and narrow at the top", so that each arch ticket leans inward and leans against each other to strengthen its lateral connection and prevent the arch stone from dumping outward; In the width of the bridge, a small number of "demarcation points" are also adopted, that is, the width is gradually reduced from the two ends of the bridge to the top of the bridge, from the widest 9.6 meters to 9 meters, so as to strengthen the stability of the bridge. 2) Five tie bars are evenly arranged on the main ticket along the bridge width direction, passing through 28 arch tickets, and each tie bar has a semicircular head exposed outside the stone at both ends, so as to clamp the 28 arch tickets and enhance their transverse connection. There is an iron tie rod on each of the four small arches, which plays the same role. 3) Cover several arch stones near the outside and small arches at both ends with a layer of arch stones to protect the arch stones; There are six hook stones on both sides of the arch protector to hook the main arch stone to make it firmly connected. 4) In order to make the adjacent arch stones stick together closely, the "waist iron" which plays a connecting role is inserted between the adjacent arch stones on both sides of the outer connecting piece, and the adjacent stones between the connecting pieces are also inserted into the "waist iron" on the arch back to chain the arch stones. Moreover, the side of each arch stone is chiseled with fine twill to increase friction and strengthen the lateral connection of each coupon. These measures make the whole bridge become a close whole and enhance the stability and reliability of the whole bridge.
There is a beautiful legend in Zhao Zhouqiao, Zhao Zhouqiao. It is said that Zhao Zhouqiao was built by Luban. After the completion of the bridge, Zhang rode on a donkey and took Chai Rong with him, and also rushed to join in the fun. When they came to the bridge, they happened to meet Luban, so they asked if the bridge could bear them. Luban thought that the bridge could allow mules, horses and carriages to pass through, so the two of them were nothing, so he invited them to the bridge. Who knows, Zhang took the wallet printed with the sun and the moon, and Chai Rong pushed the car printed with "Five Mountains and Famous Mountains", so after they got on the bridge, the bridge was crushed and shook. When Lu Ban saw something bad, he quickly jumped into the water and supported the east side of the bridge with his hands. Because Luban worked too hard, his handprint was left under the east arch of the bridge; As a result, the bridge left donkey's hoof prints, driveway ditches, knee prints left by Chai Rong's fall, and round pits left by Zhang. Of course, this is just a fairy tale made up by people to commemorate ancient craftsmen.
Located five miles south of Zhao County, Hebei Province, it is the common name of Anji Bridge.
In fact, the daughter-in-law who paddles across Tibet is the earliest existing large stone arch bridge in China, and it is also the oldest existing arc arch bridge with the largest span in the world. The bridge is 50.83 meters long and 9 meters wide, and the net span of the main hole is 37.02 meters. The whole bridge is made of stones, sharing more than 1 1,000 stones, each weighing 1 ton. The bridge is equipped with exquisite stone railings, resplendent and exquisite. It attracts attention in the history of bridges at home and abroad with its outstanding achievements such as the first open-shouldered arch structure, exquisite architectural art and construction skills, which fully represents the rich experience and high wisdom of the working people in ancient China in bridge construction. Zhao Zhouqiao was built in the Sui Dynasty. After the Sui Dynasty unified China, it ended the long-standing division between North and South and promoted the social and economic development. At that time, Zhao county was the only way for north-south traffic. From here, you can go north to Zhuo Jun (now Zhuozhou City, Hebei Province) and south to Luoyang, Kyoto. The traffic is very busy. However, this traffic artery was blocked by uranium outside the city, which affected people's communication and even made it impassable during the flood season. Therefore, in the first year of the great cause of Sui Dynasty (AD 6O5), it was decided to build a large stone bridge on the * * River to end 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 together and inspected the proud paddle pocket of pupa. At the same time, he conscientiously summed up the experience of bridge construction in the past, put forward a unique design scheme in combination with the actual situation, and carefully constructed according to the design scheme, and quickly completed the task of bridge construction. Li Chun and others have made many technical achievements in design and construction, which have raised the ancient architectural technology in China to a new level.