在這張中國地圖上，如同血管一般遍布全國的不是公路，不是鐵路，而是一座又一座的橋梁，時(shí)至今日，在中國大地上已有各類公路橋梁超過 96 萬座，而在長達(dá) 40000km 的高鐵里程中，更有將近一半都是橋，他們跨越高山大川，連通城鎮(zhèn)村莊，讓中國成為了一座幅員遼闊的橋梁博物館，那么我們?yōu)槭裁匆ㄔO(shè)如此眾多的橋梁？這個問題當(dāng)我們換個視角便能找到答案。

On this map of China, what is like blood vessels all over the country is neither highway nor railway, but one bridge after another. Till now, there are over 960,000 highway bridges of all kinds in China. And of the 40,000 kilometers long high-speed railways, nearly half are bridges. They cross mountains and rivers and connect towns and villages, making China a vast "bridge museum". So, why should we build so many bridges? By changing our perspective, we will be able to find the answer to this question.

在你眼前這片土地上，西部的高原山地峽谷縱橫，東部的丘陵平原江河蜿蜒，原因的海線上又是島嶼散布海峽，海灣分隔兩岸，太多的天塹阻擋著人們的交通交流，甚至出路，人們該如何才能跨越這一切？在接下來的視頻里，你將會看到一部中國橋梁的跨越式，而首先我們必須從最經(jīng)典的一種橋開始說起。

On this land in front of you, horizontal valleys cut across plateaus and mountains in the west, while the meandering rivers flow through hills and plains in the east. On the sweeping coastline, islands are scattered, and the two sides are separated by straits and bays. With too many natural moats, obstructing the traffic, communication, and even people's way out. what can we do to get over it all? In the following video, you will see a spanning of a Chinese bridge, but first we must start with the most classic bridge.

## PART 1 架梁為橋

這是一種古老的橋形。2 墩架一梁，是為梁橋，而相鄰支座中心點(diǎn)的水平距離便是跨度，也正是它體現(xiàn)了一座橋梁的跨越能力。1937 年，中國人自行設(shè)計(jì)建造的第一座現(xiàn)代化大橋便是梁橋，盡管他在建成后僅僅 89 天就被射擊大橋的毛一生先生親自炸毀，但卻依然為 10 萬多人打開了逃離戰(zhàn)火的生命之路，這就是杭州錢塘江大橋。它的最大跨度約 66 米，相鄰 2 噸上共架一梁，稱為簡支梁橋，而如果將它的梁體加以延伸，形成多墩架一梁，便進(jìn)化為連續(xù)梁橋，由于梁體連續(xù)不間斷，前后可以相互約束，因此擁有更高的承載力，橋梁跨度也隨之提高，例如武漢長江大橋最大跨度達(dá) 128 米，在他的幫助下，中國人第一次跨越了長江天塹，可對于當(dāng)時(shí)的中國而言，這些鋼橋是如此先進(jìn)，如此昂貴，基本只能用于鐵路建設(shè)，好在一種新技術(shù)在國內(nèi)逐漸普及，它的原理十分巧妙，在混凝土中置入預(yù)先被拉伸的鋼筋，利用鋼筋的收縮欲望去平衡外力，量體便能承受比原先更大的荷載，從而支持更大的跨度，人稱預(yù)應(yīng)力混凝土技術(shù)。相比鋼鐵，混凝土顯然便宜多了，于是在預(yù)應(yīng)力技術(shù)的加持下，大量公路橋梁紛紛登上歷史舞臺，當(dāng)前跨度已達(dá)到 180 米。

This is an old type of bridge. With two piers and one beam, it becomes the "beam bridge". And the horizontal distance between the center points of adjacent supports is its "span". It is also the span that reflects the spanning capacity of a bridge. In1937, the first modern bridge designed and built by the Chinese was the beam bridge. Although it was blown up by Mr.Mao Yisheng who designed the bridge, only 89 days after completed, it still opened the way of life for more than 100,000 people to escape the war. This is the Qiantang River Bridge in Hangzhou, whose maximum span is about 66 meters. With one beam on two adjacent piers, it is called "simple-supported beam bridge". And it lits beam Iis extended to form "one beam on multiple piers", then it evolves into a "continuous beam bridge". Since the beam is continuous and uninterrupted and the front and rear can be mutually restrained, the load capacity is higher and the span of the bridge also increases. For example,the Yangtze River Bridge in Wuhan has a maximum span of 128 meters. With its help, Chinese people crossed the Yangtze River for the first time. But for China at that time, these steelbridges were so advanced and expensive that could basically only be used for railway construction. Fortunately, a new technology was gradually popularized in China which has very ingehious principles. By placing pre-stretched rebar into the concrete, and using the rebar's "shrinking desire to balance the external force, the beam can therefore bear a larger load than before and thus support larger spans. It is called "prestressed concrete technology". Compared with steel,concrete is obviously much cheaper. So.with the support of prestressing technology, a large number of highway bridges have entered the history stage, and the current span has reached 180 meters.

時(shí)至今日，梁橋的應(yīng)用已十分廣泛，更是形成標(biāo)準(zhǔn)組件，可以工廠制造，現(xiàn)場組裝，即便單跨跨度有限，但成百上千胯前后相連，便可以橫貫江河湖海，甚至已經(jīng) 165km 的長度，徹底取代路面，成為世界最長橋梁，不過想要繼續(xù)提升跨度，梁橋勢必要迎來一場進(jìn)化。

Till now, beam bridges have been widely used. Moreover, they form standard components which can be built in factory and assembled on site. Although the single span is limited, when hundreds or thousands of spans are connected back and forth, they can cross rivers, lakes and seas, and even completely replace the roadway with a length of nearly 165 kilometers, becoming the world's longest bridge. However, to continue to improve the span, beam bridge is bound to usher in an "evolution".

## PART 2 似梁非梁

這種橋具有和梁橋極其相似的外形，但它的量體和橋墩被固結(jié)成為一個整體，因此可以同甘共苦，共同抵抗量體的彎曲，這就意味著在橋墩的協(xié)助下，量體可以達(dá)到更大的跨度，或是選擇更加輕薄的橋面，這就是鋼構(gòu)橋。

This type of bridge has a very similar shape to the beam bridge. However, its beam and piers are cemented together as a whole, so they can "share weal and woe" to resist the beam bending together. It means that with the help of the piers the beam can achieve a larger span or choose a lighter and thinner deck. This is the "rigid frame bridge".

但美中不足的是，這種橋?qū)崦浝淇s十分敏感，如果橋墩過于倔強(qiáng)，量體便無法放飛自我導(dǎo)致變形無法釋放，為此工程師們?yōu)殇摌?gòu)橋設(shè)計(jì)了更高的橋墩，讓它變得柔軟靈活，以釋放量體的變形，尤其在高山峽谷地帶，這種高橋墩再合適不過，于是眾多高大挺拔的橋梁拔地而起，橋墩從橋面直插谷底，最高已突破 190 米，相當(dāng)于一座 60 多層的高樓。

But the downside behind this is that this kind of bridge is very sensitive to thermal expansion and contraction. If the piers are too "stubborn", the beam will not be able to "let go of itself", and eventually, the deformation can not be released. Therefore, engineers have designed higher piers for the rigid frame bridge to make it "soft and flexible" and to release the deformation of the beam. This kind of high pier is perfect especially in mountains and valleys. So, many tall and straight bridges rise up from the ground with piers plunging from the deck to the valley floor of which the tallest is up to 190 meters, equivalent to a 60-storey building.

不過，在平原之上，高聳入云的橋墩亦無用武之地，為了降低橋梁高度，同時(shí)保證橋墩的柔性，就需要給墩柱進(jìn)行瘦身，或采用特殊的橋墩形態(tài)，然而橋墩要薄，橋梁要穩(wěn)，成本還要低，三者互相制約，讓跨度超過 3 百米的鋼構(gòu)橋屈指可數(shù)，即便如此，2006 年建成的重慶石板坡大橋復(fù)線橋最大跨度達(dá)到 330 米，一舉成為世界上跨度最大的預(yù)應(yīng)力混凝土連續(xù)鋼構(gòu)橋。

Nevertheless, on the plain, the towering piers are no longer useful. In order to reduce the height of the bridge while ensure the flexibility of the piers, it is necessary to "slim down"the piers or adopt a special pier form. However, to make the piers thin, the beam stable, while the cost low is a restriction itself. It leads to numbered rigid frame bridges with a span of over 300 meters. Even so, the Double-line Bridge of Shibanpo Bridge in Chongging completed in 2006 whose maximum span reached 330 meters, becomes the prestressed concrete continuous rigid frame bridge with the largest span in the world.

不過梁橋也好，剛過橋也罷，倘若面對峭壁深谷或是橋下交通的需要，豎直的橋墩無處安放時(shí)，該怎么辦呢？

However, be it a beam bridge or a rigid frame bridge, when facing the circumstance of cliffs and deep valleys, or the need for traffic under the bridge, the vertical piers will have no place to be set. What can we do about it?

## PART 3 長虹臥波

此時(shí)人們需要的是一種一跨而過的橋形，比如拱橋。

At this time,people heed a kind of bridge that can span over the distance such as "arch bridge".

對于中國人來說，拱橋再熟悉不過了。

For Chinese people, the arch bridge is all too familiar.

被寫進(jìn)小學(xué)課本的趙州橋，1400 多年來，幾經(jīng)洪澇地震，其主體結(jié)構(gòu)卻依然完好。

The Zhaozhou Bridge, which was written into elementary school textbooks, still remains its intact main structure over 1400 years of floods and earthquakes.

這種拱結(jié)構(gòu)要求兩端不僅要向上托起橋身，還必須提供強(qiáng)大的水平推力，正是這樣的推力牢牢抵抗住汞的變形，從而提高了拱橋的跨越能力。

This "arch" structure requires that its two ends not only hold up the bridge but also provide a strong horizontal thrust. And it is this thrust that firmly resists the deformation of the "arch", thus increasing the spanning capacity of the arch bridge.

這是拱橋獨(dú)特的優(yōu)勢，卻也是挑戰(zhàn)。

This is the unique advantage of an arch bridge but also a challenge.

若遇上松軟脆弱的地基，兩端便無法提供如此有力的支撐。

If faced up with soft and fragile foundations, the two ends cannot offer such strong support.

人們只能盡量減輕橋梁自重來保持拱橋的穩(wěn)定。

People can only try to reduce the weight of the bridge to maintain the stability of the arch bridge.

例如由我國首創(chuàng)的桁架拱橋，纖細(xì)的混凝土拱架讓僑生更加輕盈，最大跨度達(dá)到 330 米。

For example, the truss arch bridge pioneered by China has a slim concrete skeleton which makes the bridge lighter, and its maximum span reaches 330 meters.

又或是在拱和梁的焦點(diǎn)間設(shè)置一細(xì)感，以細(xì)感的拉力代替制作的推理，成為細(xì)桿拱。

Or set up a"tie rod"in the intersection of the arch and the beam, to replace the push at both ends with the pull of the tie rod. This is the tied arch".

而隨著普通混凝土拱橋達(dá)到跨度極限，越來越多的新式拱橋開始涌現(xiàn)。

As ordinary concrete arch bridges reach their span limit, more and more new types of arch bridges are emerging.

比如將混凝土填充在鋼管中，為它增加一層保護(hù)殼，從而比普通混凝土更加堅(jiān)固牢靠。

Such as filling concrete into steel pipes to add a"protective shell"to it, making it stronger and more reliable than ordinary concrete.?

同時(shí)鋼管還能作為施工骨架，大大降低了拱橋的修建難度。

At the same time, the steel pipes can also be used as a construction skeleton, which greatly reduces the difficulty of building arch bridges.

更有甚者，以填充完畢的鋼管為骨架，在外層再次包裹混凝土，則演變?yōu)橐环N硬骨頭拱橋，人稱進(jìn)興骨架混凝土拱橋。

More than this, using the filled steel pipes as the skeleton, then wrapping the concrete again on the outer layer, it can evolve into a "hard bone arch bridge", namely the concrete arch bridge with stiff skeleton.

如今這種橋的跨度已突破 400 米。

Now the span of this kind of bridge has exceeded 400 meters.

而隨著我國鋼鐵產(chǎn)量躍居世界首位，橋梁建設(shè)逐漸走出了舍不得用鋼的時(shí)代。

With China's steel production jumping to the world's first, bridge construction has gradually stepped out of the era of "reluctance to use steel".

鋼拱橋也隨之崛起，它能與橫架鋼構(gòu)等結(jié)構(gòu)進(jìn)行組合，創(chuàng)造了一個又一個工程奇跡。

Steel arch bridges have also emerged. which can be combined with truss rigid structure and other structures, creating one engineering miracle after another.

時(shí)至今日，拱橋的跨度已達(dá)到 575 米，超過了一個躺島的中國尊。

Up to this day, the span of the arch bridge has reached 575 meters, more than a lying-down "China Zun".

而接下來登場的角色即將幫助我們突破 1000 米跨度大關(guān)。

And the next role on the scene will help us break the 1,000-meter span mark.

## PART 4 鋼鐵琴弦

這是今天的上海浦東。

This is today's Pudong, Shanghai.

早在 30 多年前，這里還沒有林立的高樓。

More than 30 years ago, there were no tall buildings here.

為了發(fā)展，人們迫切的需要一座跨江大橋。

In order to develop, people desperately needed a bridge across the river.

可是黃浦江兩岸相隔近 4 百米。

However, the two banks of the Huangpu River are nearly 400 meters apart.

而當(dāng)時(shí)的中國，還從未有橋梁達(dá)到如此跨度。

At that time in China, no bridge had ever reached such a span.

即便難度可想而知，同濟(jì)大學(xué)的李國豪校長和項(xiàng)海帆教授，依然力主自行建造這座黃浦江第一橋。

Even if the difficulty was conceivable, President Li Guohao and Professor Xiang Haifan of Tongji University still insisted on building the "first bridge over the Huangpu River"by ourselves.

項(xiàng)教授寫道，上海是我國的東大門，黃浦江大橋應(yīng)成為上海市的標(biāo)志，傳名于世，建造黃浦江大橋，不但是 1000 萬上海人民的夙愿，也是上海橋梁工程界的夢想，在學(xué)校我們也一直以此激勵橋梁專業(yè)的學(xué)生們。

Professor Xiang wrote, Shanghai is the eastern gate of China. The Huangpu River Bridge should become the symbol of Shanghai and be known to the world. The construction of the Huangpu River Bridge is not only the long-cherished?wish of 10 million Shanghai people, but also the dream of Shanghai's bridge engineering community. At school,we have always used this to inspire bridge majors.

最終，在 1991 年已不到國外方案一半的造價(jià)，上海南浦大橋正式通車，開啟了我國自主建設(shè)超大跨度橋梁的先河。

Finally,in 1991, with less than half of the cost of the foreign scheme, Shanghai Nanpu Bridge was officially opened to traffic, setting up a page for China's independent construction of super-span bridges.

這座大橋兩端佇立著兩座約 50 層樓高的高塔，梁、塔與橋面間以 180 根鋼索相連，如同一根根傾斜的鋼鐵琴弦，故名斜拉橋。

Both ends of the bridge stand two towers about 50 storeys high. The two towers are connected to the deck by 180 steel cables like tilted steel strings. Hence it is named"cable-stayed bridge".

但對于斜拉橋來說，這樣的跨度僅僅是小試牛刀。

But for cable-stayed bridges, such a span is only a"small test".

根根拉索向上提拉，竭力阻止兩體向下彎曲，如同有了一個隱形橋墩，極大地提高了橋梁的跨度潛力。

The cables are lifted upwards, trying to prevent the beam from bending downward as it has "invisible plers", which greatly increases the span potential of the bridge.

更重要的是，與生俱來的對稱形態(tài)，讓斜拉橋更容易實(shí)現(xiàn)自錨。

More importantly, the inherent symmetry of the form makes it easier for the cable-stayed bridge to "self-anchor".

穩(wěn)定的三角結(jié)構(gòu)，則具備更強(qiáng)的抗風(fēng)能力，這在無地可矛和風(fēng)力強(qiáng)大的海上得天獨(dú)厚，逐漸成為眾多跨海大橋的標(biāo)志。

The stable triangular structure has a stronger wind resistance which is unique in theanchorless" and windy sea, gradually becoming the symbol of many sea-crossing bridges.

加之工程材料和計(jì)算方法的革新，現(xiàn)代斜拉橋從誕生起，僅用了 50 多年，便完成了 1 千米的跨越。

Together with the innovation of engineering materials and calculation methods, since the birth of modern cable-stayed bridges, it took only more than 50 years to complete a 1,000-meter span.

然而角度傾斜的拉鎖將沿著兩體軸向產(chǎn)生水平的軸力。

However, the angularly inclined ties will generate horizontal "axial forces" along the axial direction of the beam.

隨著跨度延伸，拉鎖勢必增加，這種軸力也將逐漸累積，直到量體不堪重負(fù)。

As the span extends, the ties are bound to increase, and this axial force will also accumulate gradually until the beam is overloaded.

雪上加霜的是，當(dāng)拉索越來越長，越來越傾斜，巨大的自重令其彎曲下垂。

To make matters worse, as the ties get longer and more inclined, the huge self-weight makes them bend and sag.

再難以緊緊拉住龐大的量體，這便注定了斜拉橋的跨度極限。

It is no longer possible to tightly pull the huge beam, and predetermines the span limit of cable-stayed bridges.?

可謂是成也斜拉索拜也斜拉。

It can be said that "the success of the cable-stayed bridge is also the failure of the cable-stayed bridge."

因此若要向 2 千米跨度發(fā)起沖擊，只能指望最后一位選手了。

Therefore, to make a push for the span of 2,000 meters, we can only count on the last player.

## PART 5 跨度王者

在我國西南山區(qū)現(xiàn)代橋梁出現(xiàn)前，人們往往只能依靠原始的方式出行，比如索橋或吊橋。

In the mountainous region of southwest china, before the emergence of modern bridges, people often had to rely on primitive ways to travel, such as rope bridges or suspension bridges.

但他們的建造者和使用者一定想象不到這種橋會在今天達(dá)到 1700 百米的跨度成為橋梁界的王者。

But their builders and users must have never imagined that this kind of bridges can reach the span of 1,700 meters today and becomes the king of bridges.

這就是現(xiàn)代懸索橋。高聳的橋塔，彎曲的主纜，堅(jiān)實(shí)的錨碇，共同組成了他最基本的沉重體型。

This is the modern suspension bridge. Soaring bridge towers,curved main cables and solid anchorages constitute its most basic load-bearing system together.

和古老的索橋不同，現(xiàn)代懸索橋擁有格外堅(jiān)韌的主纜。

Unlike old rope bridges, modern suspension bridges have exceptionally tough main cables.

以位于江蘇的五峰山長江大橋?yàn)槔?，它的主纜以直徑 55mm 的高強(qiáng)鋼絲為基本材料，127 根為一數(shù)，352 數(shù)為一覽。

Take the Wufeng Mountain-Yangtze River Bridge in Jiangsu as an example: Its main cable is made of high-strength steel wire/witha diameter of 5.5 millimeter as the basic material, 127 wires in a bundle, 352 bundles to one cable.

雙纜并行承載的鋼梁重量超過 7 萬噸，相當(dāng)于 1000 架滿載的 c919 大飛機(jī)。

With double cables in parallel, the weight of the steel beam carries exceeds 70,000 tons, equivalent to 1,000 fully-loaded C919 aireraft.

相比如此巨大的量體，橋上往來的車流都顯得微不足道。

Compared with such a huge beam, the traffic on the bridge seems insignificant.

于是橋面不再像古老的索橋因外力上下波動。

So, the deck is no longer like the old rope bridge fluctuating up and down due to external force.

甚至足以同時(shí)通行四列高鐵列車，成為世界第一座高鐵懸索橋。

It even allows four high-speed trains to pass at the same time and becomes the world's first high-speed rail suspension bridge.

并且和斜拉橋不同，懸索橋的吊索垂直于墻面。

Moreover, unlike cable-stayed bridges, the slings of suspension bridges are perpendicular to the bridge deck.

因此無論跨度多長，都不會產(chǎn)生軸力擠壓量體。

Therefore, no matter how long the span is, no axial force is generated to squeeze the beam.

這也是為何眾多難以逾越的天塹都被懸索橋一一征服。

That's why many insurmountable dangers have been conquered one by one by suspension bridges.

而根據(jù)學(xué)者們的推算，懸索橋的跨度至少能達(dá)到 5000 米之多。

And according to scholars'calculations, the span of suspension bridges can reach at least 5,000 meters.

到這里，當(dāng)我們再回看這張地圖，也許會有不一樣的體會，我們或許很難想象，一代代建設(shè)者們是如何突破地形、地質(zhì)、水文、氣象、材料、結(jié)構(gòu)、通航、安全、壽命、造價(jià)、美學(xué)等種種條件的限制，即便在一窮二白的歲月里，也能創(chuàng)造出新的技術(shù)，實(shí)現(xiàn)一次又一次的跨越，但我們卻能清晰地看到，這近百萬座橋梁是如何見證著一個國家一路走來的歷程，那是錢塘江大橋落成時(shí)，這個民族最深重的苦難，是南京長江大橋落成時(shí)，這個國家自立更生的決心，也是上海南浦大橋落成時(shí)，那份拼命追趕世界的渴望，今天當(dāng)你走在中國任何一條公路或鐵路上，極大概率將和不止一座橋梁相遇，而無論你是否知道他的名字，他們都將無聲的佇立在這里，在大山之中，在江河之上，在海峽海灣之間，直至數(shù) 10 年，100 年甚至更加漫長的歲月，在這段歲月里，公路將通向天南，海北鐵路將去往四面八方，不計(jì)其數(shù)的人們將從這里走過，而這片土地上的每個角落也終將彼此相連。

Now, when we look back at this map again, we may feel different. We may find it hard to imagine how generations of builders have broken through terrain, geology, hydrology, meteorology, materials, structure, navigability, safety, longevity, costs, aesthetics and other constraints. Even in the years of poverty, they were able to create new technologies and realized new leaps again and again. Yet we can see it clearly that how these nearly one million bridges have witnessed the history of a country along the way. It is the deepest suffering of our nation in the completion of Qiantang River Bridge. It is the determination of our country to be self-reliant in the completion of Nanjing Yangtze River Bridge. It is also the desire to catch up with the world in the completion of Shanghai Nanpu Bridge. Today, when you walk on any highway or railway in China, there is a high probability that you will meet with more than one bridge. And whether you know their names or not, they will all stand silently here in the mountains, over the rivers, between the straits and bays, for decades, 100 years or more. Durihg these years, highways will go far and near, and so will the railways. Countless people are passing by. Finally, every corner of this land will be closely connected to each other.