Zhao Zhouqiao introduced?

Zhao Zhouqiao, also known as Anji Bridge, is located on the Weihe River in Zhao County, Hebei Province, across a river more than 37 meters wide. Because the bridge body is all made of stone, it is called "Dashiqiao" locally. Built in the Sui Dynasty from 595 to 605, it was designed and built by the famous craftsman Li Chun. It has a history of 1400 years. It is the second oldest single-hole open-shouldered stone arch bridge in the world (also a small commercial bridge) and the best preserved ancient bridge. Zhao Zhouqiao embodies the wisdom and crystallization of ancient working people, and creates a brand-new situation of bridge construction in China. It took Europe about 1397 (some data are about 700 years) to build a similar stone arch bridge.

196 1 was listed as the first batch of national key cultural relics protection units by the State Council, and won one of the top ten city cards in Shijiazhuang on 20 15. It is the first stone arch bridge in China. In the long years, it has experienced countless floods, wind and rain, snow erosion and eight earthquakes, but it is safe and sound, standing tall on the Qingshui River.

Building structure

This bridge is a hollow circular stone arch bridge, which is the earliest and best preserved giant stone arch bridge in China. Zhao Zhouqiao is the first open-shouldered stone arch bridge to be selected into the world record association Book of World Records, which is the best in the world. Zhao Zhouqiao, Cangzhou Iron Lion, Dingzhou Kaiyuan Temple Pagoda and Zhengding longxing temple Bodhisattva are called "Four Treasures of North China" by Hebei folks.

The bridge is 50.82 meters long, 37.02 meters across, 7.23 meters high and 9.6 meters wide at both ends. The design of the bridge completely conforms to scientific principles, and the construction technology is even more ingenious. Zhang said in the Tang dynasty that it was "made strangely, and people don't know why." The characteristics of this bridge are:

1. The whole bridge has only one big arch, 37.4 meters long, which was the longest stone arch bridge in the world at that time. Bridge opening is not an ordinary semicircle, but like a bow, so there is no steep slope on the road above the big arch, which is convenient for horses and chariots to get up and down.

Second, there are two small arches on the shoulders of the big arch. This is a very creative design, which not only saves stones and reduces the weight of the bridge, but also increases the water flow in bridge opening and reduces the impact of floods on the bridge when the river surges. At the same time, add an arch on the arch to make the bridge more beautiful.

Three, the big arch is composed of 28 arch rings, just like so many arches with the same shape are put together to make an arc bridge opening. Each arch ring can independently support its weight. If one arch ring is broken, the other arches will not be affected.

Fourth, the structure of the whole bridge is symmetrical, which is very harmonious with the surrounding scenery; The stone pillars and slabs on the bridge are also beautifully carved. Zhang Kun of the Tang Dynasty said that looking at the bridge from a distance is like "the clouds rise at the beginning of the month, and Changhong draws a stream". Zhao Zhouqiao's superb technical level and immortal artistic value fully show the wisdom and strength of our working people. Zhao Zhouqiao's design concept and exquisite workmanship are not only second to none among ancient bridges in China, but also according to the research on bridges in the world, open-shouldered arch bridges like this did not appear in Europe until the middle of19th century, which was later than China 1200 years ago.

basis

1979 in may, a joint investigation team composed of four units, including the natural history group of China academy of sciences, investigated the bridge foundation in Zhao Zhouqiao. The weight of Zhao Zhouqiao is 2,800 tons, and its foundation is only a abutment with a height of1.56m made of five layers of stones, which is directly built on natural sand and gravel.

Such a shallow bridge foundation is unbelievable. When Mr. Liang Sicheng inspected 1933, he thought that it was only a diamond wall to prevent water erosion, but not the foundation to bear the full load of the bridge ticket. He wrote in the report:

"In order to measure the coupon base, we dug at the foot of the coupon in the north, but about 70-8 1 cm below the riverbed, that is, we found a stone wall lying flat under the coupon. Stone * * * has five floors, and the height of * * * is1.58m. Each floor is slightly higher than the upper one, and there is no solid foundation below. Obviously, it is just a diamond wall used to prevent water erosion, not a foundation bearing the full load of bridge vouchers. Because water will be seen in another 30-40 cm, unless it is excavated on a large scale, it is really impossible to reach the bridge foundation position that we theoretically speculate. "

Its structure still follows Zhao Zhouqiao, but the number of small arches on the main arch is increased to five on one side, and there are wheel marks and knee marks on the bridge.

Mao Yisheng, a Chinese bridge scientist, also mentioned it in The Stone Arch Bridge in China.

Zhao Zhouqiao was founded in 605 AD, more than 65,438+0,400 years ago. It experienced 10 floods, 8 wars and many earthquakes, especially17.6 Xingtai earthquake on March 8, 966. Zhao Zhouqiao is only over 40 kilometers away from the epicenter and has not been damaged. Mao Yisheng, a famous bridge expert, said that no matter what the internal structure of the bridge is, only it can exist 65,438+. 1963 The flood flooded the arch of the bridge. According to the local old man, standing on the bridge can feel the bridge body shaking greatly. According to records, Zhao Zhouqiao has been restored nine times since its establishment.

(Remarks: During the restoration process, the bridge-building materials damaged in historical years were sorted out and collected, and most of them were stored in the museum of Zhao Zhouqiao Scenic Area. )

arched door

The arch in Zhao Zhouqiao is more suitable for bridges with smaller spans, while the semi-circular arch is used for bridges with larger spans, which will make the vault high and the bridge steep, making it inconvenient for pedestrians 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 7.23m, 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.

Shoulder opening

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, it can increase the flood discharge capacity and reduce the impact of flood on bridges due to the increase of water volume in flood season. The flood potential of Gujiao River in flood season is great, which is a test for the flood discharge capacity of the bridge. Four small arches can share part of the flood. According to the calculation, the four small arches increase the water area by about 16%, which greatly reduces the impact of flood on the bridge and improves the safety of the bridge.

Secondly, compared with the solid shoulder arch, the open shoulder arch can save a lot of earthwork materials and reduce the dead weight of the bridge. According to 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. Thirdly, the beautiful shape is added. The four small arches are balanced and symmetrical, and the big arch and the small arch form a complete picture, which is lighter and more beautiful, reflecting the complete unity of architecture and art. Fourthly, in line with the theory of structural mechanics, the open-shouldered arch structure makes the bridge in a favorable position when bearing load, which can reduce the deformation of the main arch ring and improve the bearing capacity and stability of the bridge.

haplopore

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.

Architecture

The site selection of Zhao Zhouqiao Bridge is reasonable, and the bridge foundation is stable and firm. According to his rich practical experience for many years, after careful investigation and comparison, Li Chun chose a relatively flat place on both sides of the Weihe River to build the bridge. The stratum here is alluvial by river water, 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 the bridge. After the bridge site is selected, the foundation and abutment are built on it. After the bridge was built 1400 years, the bridge foundation only sank 5 cm, indicating that the stratum here is very suitable for bridge construction.

Zhao Zhouqiao's masonry method 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 bridge building stone. 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; Arch thickness 1.03 m, each coupon is independent and operated separately, which is quite flexible. After each coupon is completely folded, it will be built into an independent coupon, and the supply of one coupon will be completed. Move the load-bearing scaffolding, and then build an adjacent arch. This masonry method has many advantages. It can not only save wood 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 ticket is damaged, it is only necessary to embed new stone and carry out local trimming, without adjusting the whole bridge.

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 piece adopts the method of widening the bottom and narrowing the top, so that each arch piece 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 width direction of the bridge, 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 lateral 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 the 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 closely stick together, waist irons are inserted between the adjacent arch stones on both sides of the outer vouchers, and waist irons are also inserted on the arch backs of the adjacent stones between vouchers, so that the arch stones are connected by chains. 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.

The flat arch is a flat arc arch, which not only increases the stability and bearing capacity of the bridge, but also facilitates the passage of people and animals on the bridge and saves stone. Li Chun also designed two small arches with shoulders at the two shoulders of the big stone arch, which enhanced the flood discharge capacity of the bridge and reduced its own weight.

Architectural value

The "voucher" is smaller than a semicircle.

China used to call the winding buildings such as bridge opening and doorway "coupons". Generally speaking, most of the tickets for Shiqiao are semicircular, but the Zhao Zhouqiao spans a lot, with 37.04 meters from one end to the other. If the ticket face is semicircular, the height of the bridge hole is 18.52 meters. In this way, crossing the bridge is like crossing a hill, which is very laborious. Zhao Zhouqiao's certificate is an arc smaller than a semicircle, which not only reduces the height of the bridge, but also reduces the stone and labor for repairing the bridge, and the bridge body is very beautiful, much like Changhong in the sky.

Two small arches were added at both ends of the main arch coupon. First, it can save materials. Second, reduce the dead weight of the bridge (reduce the dead weight 15%) and increase the discharge of river water under the bridge. Third, make the bridge more beautiful.

The "bump" is empty, but it is not real.

The two shoulders of the coupon are called "convex". Generally, the collision of stone bridges is made of stone, but the collision in Zhao Zhouqiao is not made of stone, but one or two arc-shaped coupons are built on each shoulder of coupons. In this way, four coupons were added to the bridge body, which saved about 180 cubic meters of stone and reduced the bridge weight by about 500 tons. Moreover, when the river rises, part of the water can flow downwards from the small ticket, which can not only make the water flow smooth, but also reduce the impact of flood on the bridge and ensure the safety of the bridge.

Parallel cave architecture

It uses 28 small tickets to form a large ticket of 9.6 meters in Zhang Kuan. But with side-by-side masonry, there is no connection between the narrow stones, which is not as strong as the column. In order to make up for this shortcoming, in the construction of Zhao Zhouqiao, nails were added between narrow stones to make them a whole. Even if a narrow ticket is broken, it will not affect the overall situation, and it is easy to repair, and it will not affect the traffic on the bridge when repairing the bridge.

win an honour

19614 March: the State Council and China were declared as the first batch of key cultural relics protection units in China, so they could not be opened to traffic.

199 1 year: The American Society of Civil Engineers selected it as the 12 "International Civil Engineering Historical Monument" in the world, and built the bronze medal monument of "International Civil Engineering Historical Monument" on the east side of the north end of the bridge.

1999: It was designated as a provincial patriotism education base.

Status: It is the best preserved and oldest single-hole stone bridge in the world.

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