Typical stone arch bridges in China and their introduction

The Zhaozhou Bridge is located in the southern part of Hebei Province, flowing through Zhao County. It was built in the Sui Dynasty (581-618 A.D.) during the Daye Period (605-618 A.D.), designed and constructed by the famous craftsman Li Chun, with a history of 1,400 years, and is the earliest and best-preserved ancient open-shouldered stone arch bridge in the world today. In 1961, Zhaozhou Bridge was listed by the State Council as one of the first batch of national key cultural relics protection units, and in 1991, the American Society of Civil Engineers selected Anji Bridge as the 12th "International Historic Civil Engineering Milestone", and constructed a bronze monument of "International Historic Civil Engineering Monument" on the east side of the north end of the bridge. and built a bronze monument of "International Historic Civil Engineering Monument" on the east side of the north end of the bridge. Zhaozhou Bridge, also known as Anji Bridge, is located on the Xiao River in Zhao County, Hebei Province, and is the earliest and best-preserved huge stone arch bridge in the world. It is known as "one of the four treasures of North China". It was built in Sui Daye (605-618 AD). The bridge is 64.40 meters long, with a span of 37.02 meters and a height of 7.23 meters, making it the largest span and the earliest single-hole open-shoulder stone arch bridge in the world today. Because the bridge has two small holes at each end of the shoulder, not solid, so it is called open-shoulder type, which is a creation in the history of the world's bridge building (no small arch is called full shoulder or solid shoulder type). There are a lot of bridges with many types and colorful.

Zhaozhou Bridge has been built 1400 years ago, experienced 10 floods, 8 wars and many earthquakes, especially the 7.6 magnitude earthquake in Xingtai in 1966, Xingtai is more than 40 kilometers away from here, and here there is also a four-point-something quake, Zhaozhou Bridge have not been destroyed, the famous bridge expert Mao Yisheng said, first of all, no matter what the internal structure of the bridge, just it can exist for more than 1,300 years on the description of everything. The 1963 floods flooded the bridge arches at the dragon's mouth, according to local elders said, standing on the bridge can feel the bridge shaking. According to records, Zhaozhou Bridge since its construction to date *** repair 9 times.

At the upper ends of the main arch coupon and added two small arches, one can save materials, the second is to reduce the weight of the bridge (reduce self-weight by 15%), and can increase the flow of the river under the bridge.

In May 1979, by the Chinese Academy of Sciences, such as the natural history group of four units composed of a joint investigation team, the foundation of the Zhaozhou Bridge investigation, the self-weight of 2,800 tons of Zhaozhou Bridge, and its foundation is just five layers of stone strips built into a high 1.55-meter abutment, built directly on the natural sandstone.

Such a shallow foundation is unbelievable, Mr. Liang Sicheng in 1933 when he visited the bridge, but also think that it is only waterproof flow of water and the use of the diamond wall, rather than bear all the load of the bridge coupon foundation. He wrote in the report:

"In order to measure the coupon foundation, we excavated in the north at the foot of the coupon, but in the present riverbed about 70-80 centimeters, that is, found to bear the coupon placed under the stone wall. Stone *** five layers, *** 1.58 meters high, each layer is slightly more than the upper - layer of the introduction, there is no solid foundation below, clearly just waterproof flow of water and the use of diamond wall, rather than bearing all the load of the bridge coupon foundation. Because 30-40 centimeters further down will see water, so unless a large-scale excavation, really can not reach the location of the foundation of the bridge according to our theories."

In order to protect the Zhaozhou Bridge, a new bridge was built 100 meters east of the bridge at the end of the last century, and its structure is still inherited from the Zhaozhou Bridge, except that the number of small arches on the main arch was increased to five on one side, and there are wheel prints and knee prints on the bridge.

Edit this section of the design innovation

(1) the use of rounded arch form, changed China's stone bridge is mostly semi-circular arch tradition. China's ancient stone bridge arch shape is mostly semi-circular, this form is more beautiful, complete, but there are two defects: First, inconvenient transportation, semi-circular bridge arch used for relatively small span of the bridge is more appropriate, while the large span of the bridge selection of semi-circular arches, it will make the top of the arch is very high, resulting in a high bridge with steep slopes, horses and pedestrians crossing the bridge is very inconvenient. Second, the construction is unfavorable, semicircular arch stone masonry with scaffolding will be very high, increasing the danger of construction. For this reason, Li Chun and craftsmen together creatively used the arc arch form, so that the height of the stone arch is greatly reduced. Zhaozhou Bridge, the main hole net span of 37.O2 meters, while the arch height of only 7.25 meters, the ratio of arch height and span of 1:5 or so, so that the realization of a low bridge and large span of the dual purpose of the bridge transition is smooth, vehicles and pedestrians are very convenient, but also has the advantages of materials province, construction convenience. Of course, the circular arch on both ends of the bridge foundation of the corresponding increase in thrust, the need for the bridge foundation of the construction of higher requirements.

(2) the use of my shoulder. This is Li Chun on the shoulder of the arch for major improvements to the previous bridge construction used in the solid shoulder arch to my shoulder arch, that is, in the arch at each end of the two small arches, near the foot of the arch of the small arch of the net span of 3.8 meters, the other arch of the net span of 2.8 meters. This big arch and small arch of my shoulder arch has excellent technical performance, first of all, can increase the flood capacity, reduce the flood season due to the increase in the amount of water produced by the impact of the flood on the bridge. Ancient Kasai River flood season, the water is large, the bridge's flood capacity is a test, four small arches can share part of the flood, it is calculated that four small arches can increase the water area of about 16%, greatly reducing the impact of floods on the bridge, improve the safety of the bridge. Secondly, my shoulder arch can save a lot of soil and stone materials than the solid shoulder arch, reduce the self-weight of the bridge body, according to the calculation, four small arches can save 26 cubic meters of stone, reduce their own weight of 700 tons, so as to reduce the bridge body on the abutment and the bridge foundation of the vertical pressure and the horizontal thrust, increase the stability of the bridge. Thirdly, it increases the beauty of modeling, the four small arches are balanced and symmetrical, the big arch and the small arch form a complete picture, which looks more light and beautiful, reflecting the complete unity of architecture and art. The fourth is in line with the theory of structural mechanics, my shoulder arch structure in bearing the bridge in a favorable situation, can reduce the deformation of the main arch ring, improve the carrying capacity and stability of the bridge.

(3) single hole. China's ancient traditional construction methods, generally longer bridges are often used in the form of multi-hole, so that the span of each hole is small, gentle slope, easy to build. But the porous bridge also has shortcomings, such as piers, not only is not conducive to boat navigation, but also impede the discharge of floodwaters; piers for a long time by the impact of water flow, erosion, easy to collapse over time. Therefore, Li Chun in the design of the bridge, took the form of a single hole long span, the center of the river does not set up piers, so that the stone arch span up to 37 meters long. This is an unprecedented innovation in the history of China's bridges.

Edit this section of the construction technology creativity

(1) the bridge site selection is more reasonable, so that the bridge foundation is stable and reliable.

Li Chun, based on his many years of rich practical experience, after rigorous and thorough investigation and comparison, chose to build the bridge on a relatively straight place on both sides of the Kose River, where the strata were alluvial deposits of the river, and the surface of the strata was a layer of coarse sand that had been washed away by the current for a long time, and the following was a layer of fine stone, coarse stone, fine sand and clay. According to modern calculations, the strata here can withstand a pressure of 4.5 to 6.6 kilograms per square centimeter, while the pressure of Zhaozhou Bridge on the ground is 5 - 6 kilograms per square centimeter, which is able to meet the requirements of the bridge. After selecting the site of the bridge, the foundations and abutments were built on it, and since the construction of the bridge up to now, the foundation of the bridge has only sunk 5 centimeters, which means that the stratum here is very suitable for the construction of the bridge.

(2) The Zhaozhou Bridge was built with a novel method of construction and easy to repair.

Li Chun on the ground, choose the nearby state county production of hard texture of green-gray sandstone as a bridge stone, in the stone arch masonry method, are used in the longitudinal (along the direction of the bridge) masonry method, that is, the entire bridge is composed of 28 independent of their own vouchers along the width of the direction of the parallel combination of the arch thickness of 1.O3 meters, each voucher independent of their own, individually, quite flexible, each voucher masonry completely together into an independent coupon, the voucher, the vouchers, the vouchers, the vouchers, the vouchers, the vouchers, the vouchers and the vouchers, the vouchers and the vouchers. After each coupon masonry completely together into an independent coupon, masonry after a coupon, move the weight of the "scaffolding", and then masonry another neighboring arch. This masonry method has many advantages, it can save the production of "scaffolding" used in the wood, easy to move; at the same time, but also conducive to the maintenance of the bridge, an arch coupon of stone damage, as long as embedded in the new stone, local repair on the line, but do not have to adjust the entire bridge.

(3) in maintaining the stability of the bridge has taken many rigorous measures.

In order to strengthen the lateral connection between the arches, so that the 28 arches form an organic whole, the connection is close and firm, Li Chun has taken a series of technical measures. l) Each arch is wide and narrow, slightly "closing" method, so that each arch is tilted inward, crowded against each other, to enhance its lateral connection to prevent the arch from tipping out;

(2)

The bridge has been built on the basis of a series of technical measures. Arch stone outward tipping; in the width of the bridge is also used a small amount of "closing points" approach, that is, from the ends of the bridge to the top of the bridge gradually contraction of the width, from the widest 9.6 meters contraction of 9 meters, in order to strengthen the stability of the bridge. 2) in the main coupon uniformly along the direction of the bridge width set up five iron rods, through the 28 vouchers, the ends of each rod has a Each tie rod has a semi-circular rod head exposed outside the stone to clamp the 28 arch coupons and enhance their lateral connection. In the four small arches also have an iron tie rod to play the same role. 3) In the outside of a few arches on the stone and the two ends of the small arches covered with a layer of arch protection stone to protect the arch stone; in the protection of the stone on both sides of the stone with hooks 6, hooked to the main arch stone to make a solid connection. 4) In order to make the neighboring arches close together, on both sides of the outer coupon between the neighboring arches are worn to play a role in connecting the "waist iron", the coupons between the "waist iron", the coupons between the "waist iron". ", the neighboring stones between the coupons are also in the arch back wearing a "waist iron", the arch stone chain. And the side of each piece of archstone are chiseled with fine diagonal lines to increase friction, strengthen the coupon lateral connection. These measures taken to make the whole bridge into a close whole, enhance the stability and reliability of the bridge.

(4) Zhaozhou Bridge is unique.

The abutment is the foundation of the whole bridge, and it must be able to withstand the huge horizontal thrust and vertical pressure caused by the decomposition of the axial force of the main arch ring (the main body of the bridge). Zhaozhou Bridge abutment has the following characteristics: l) low arch foot: arch foot in the riverbed under only half a meter or so; 2) shallow bridge foundation: the base of the bridge foundation in the foot of the arch of about 1.7 meters; 3) short abutment: from top to bottom, with gradual and slightly thickened stone strips built into a 5-meter-long, 6.7-meter-wide, 9.6-meter-high abutment. This is an economic and simple and practical bridge deck. In order to ensure the reliability of the bridge abutment, Li Chun has taken a number of corresponding measures to fix the foundation. In order to minimize the vertical displacement of the abutment (i.e., the subsidence caused by the vertical pressure of the main body of the bridge), Li Chun took the measure of driving many wooden piles into the side of the abutment to strengthen the foundation of the abutment; this method is often used in the construction of today's factories and bridges as well. In order to minimize the horizontal movement of the abutment (i.e., 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 abutment's back seat to counteract the effect of the horizontal thrust. In order to protect the bridge abutment and bridge foundation, Li Chun also set up a diamond wall along the river side, on the one hand, can prevent the erosion of water flow, on the other hand, the diamond wall and the bridge foundation and bridge abutment into a single unit, increasing the stability of the bridge abutment. By the above measures to ensure that the bridge has a strong abutment, improve the solidity of the bridge.

Edited Zhaozhou Bridge three best

(1) "coupon" is less than a semicircle. China's customary curved bridge holes, doorways and other buildings called "coupon". General stone bridge coupon, mostly semicircular. But Zhaozhou Bridge span is very large, from this end to that end has 37.04 meters. If the coupon is built into a semicircle, the bridge will be 18.52 meters high. So the carriages, horses and pedestrians across the bridge, it is like crossing a small mountain, very laborious. Zhaozhou Bridge coupon is less than a semicircle of a section of the arc, which reduces the height of the bridge, reducing the repair of the bridge stone and labor, but also make the bridge is very beautiful, very much like the rainbow in the sky.

(2) "hit" empty but not real. Coupon shoulders called "hit". General stone bridges are hit with stone masonry, but Zhaozhou Bridge hit not masonry, but in the coupon on each shoulder of one or two arcs of the small coupon. So the bridge body increased four small coupons, saving about 180 cubic meters of stone, so that the weight of the bridge reduced by about 500 tons. Moreover, when the Xiao River rises, part of the water can flow down from the small coupon, which can make the water flow smoothly and reduce the impact of the flood on the bridge, ensuring the safety of the bridge.

(3) hole masonry side-by-side. It uses twenty-eight small coupons juxtaposed into a 9.6-meter-wide large coupon. However, with the juxtaposition of masonry, the narrow coupons of the stone blocks are not interconnected, not as strong as the longitudinal type. In order to make up for this shortcoming, when building Zhaozhou Bridge, iron nails were added between the stones of each narrow coupon to make them connected as a whole. Constructed in parallel with the narrow coupon, even if the bad one, will not affect the whole situation, easy to repair, and in the repair of the bridge does not affect the traffic on the bridge.