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Written by Li Chenyang, Reporter for "Chinese Science News", and Intern Reporter Wang Zhaoyu
Stretching from Xining, Qinghai Province in the east to Lhasa, Tibet in the west, the Qinghai-Tibet Railway, spanning 1956 kilometers in total, resembles a radiant dragon basking in the sunlight. It traverses grasslands, crosses snow-capped mountains, cuts through deserts, and navigates past magnificent western landscapes, winding its way up to the Kunlun Mountain Pass at an altitude of 4767 meters and the Tanggula Station at an altitude of 5068 meters.
This railway, the highest-altitude railway in the world, has been bestowed with the most romantic of names - the "Sky Road".
Even for a lofty "Sky Road" reaching into the clouds, staying grounded is essential. However, at least 550 kilometers of the land beneath the Qinghai-Tibet Railway tracks lies within permafrost zones.
Permafrost refers to soil containing ice that remains at or below zero degrees Celsius. Building roads on such terrain is fraught with challenges, primarily due to the repeated freezing and thawing of the permafrost with temperature fluctuations, leading to deformation and damage to the roadbed.
The principle, easily understood even by elementary school students, has perplexed the world's finest engineering experts for over a century. From Siberia in Russia to Alaska in the United States, and then to the Greater Khingan Mountains in China, bumpy and uneven roads and railways bear witness to the arduous struggle between humanity and the natural environment.
The boundless millennium-old permafrost of the Qinghai-Tibet Plateau made constructing a railway seem like an "almost impossible task" until scientists from the Chinese Academy of Sciences proposed their bold idea.
For half a century, from conception to realization, the journey unfolded.
The Qinghai-Tibet Railway: Overcoming Challenges with Scientific Endeavor
The images in this article are provided by the Northwest Institute of Research.
"It's time to make the decisive move to kickstart the construction of the Qinghai-Tibet Railway. This is a major decision we should make as we step into the new century." On November 10, 2000, senior leaders of the Communist Party of China made this directive on a report regarding the Qinghai-Tibet Railway, signaling the imminent commencement of the project for the third time.
Over the past half-century, the Qinghai-Tibet Railway project has encountered twists and turns. In 1984, the relatively favorable conditions of the Qinghai-Tibet Railway's Xining to Golmud section were officially put into operation. However, due to insufficient economic strength and unresolved technical issues such as plateau and permafrost, the Golmud to Lhasa section of the Qinghai-Tibet Railway was shelved for more than 20 years since the second suspension of construction in 1978.
"The success or failure of the Qinghai-Tibet Railway lies in its roadbed, and the key to the success or failure of the roadbed lies in the permafrost." This statement, like a mantra, echoed once again in the ears of every scientific worker.
This time, would it be feasible?
Not long after assuming the position of the first director of the Cold and Arid Regions Environmental and Engineering Research Institute of the Chinese Academy of Sciences (hereinafter referred to as the Cold and Arid Institute), Academician Cheng Guodong received a call from the leadership of the Chinese Academy of Sciences.
"The leadership attaches great importance to this matter and asked me to quickly write a report to demonstrate whether the permafrost problem can be solved and how to solve it," he recalled.
Before this, Chinese scientists had been grappling with the permafrost of the Qinghai-Tibet Plateau for over 40 years. As early as the 1950s, a group of young people was sent abroad to study in the Soviet Union, including the first generation of permafrost experts in China. When the Qinghai-Tibet Railway project was first planned, Zhou Youwu, Tong Bolian, and others who studied at the Permafrost Research Office of Moscow University returned to China and joined the permafrost research team, commencing systematic research on the permafrost of the Qinghai-Tibet Plateau.
At the outset of their research, they were astonished to find that permafrost, this so-called "special soil" occupying only a small portion of textbooks, turned out to be the biggest obstacle to construction on the plateau!
It was a time of burning passion. Shi Yafeng, who investigated water resources in the Qilian Mountains, Zhu Zhenda, who fought desertification along the Baolan Railway, and Zhou Youwu, who researched permafrost in areas related to the Qinghai-Tibet Railway, all realized through numerous perilous scientific expeditions that the sparsely populated western China was a treasure trove full of scientific mysteries. They unanimously submitted reports to the Chinese Academy of Sciences, applying to establish a specialized institution in Lanzhou, Gansu Province, to explore the unique natural geographical problems of the western region. The Chinese Academy of Sciences strongly supported this initiative and soon granted approval.
In the following years, based on the original research teams, the Chinese Academy of Sciences established the Glaciology and Permafrost Research Laboratory and the Desert Research Laboratory of the Institute of Geography successively. In 1965, the two research laboratories merged to establish the Lanzhou Institute of Glaciology, Cryopedology, and Desert Research, the predecessor of the Cold and Arid Institute, which was integrated as the main body of the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences in 2016. Accompanying this was a group of scientists who harbored dreams of the Qinghai-Tibet Plateau, gathering in Lanzhou, dedicating their lives to China's permafrost cause.
Also in 1965, Cheng Guodong's fate took a turn. He bid farewell to his hometown of Shanghai and came to the Permafrost Research Laboratory of the Lanzhou Institute of Glaciology, Cryopedology, and Desert Research, and was then dispatched to conduct surveys on the Qinghai-Tibet Plateau, forging an inseparable bond with this vast land covered with permafrost.
"From the beginning, all our research has been closely linked to the Qinghai-Tibet Railway," Cheng Guodong said.
Over the past 40 years, despite the Qinghai-Tibet Railway project being shelved twice, scientific workers' research on permafrost has never ceased. Chinese Academy of Sciences and other research units have been steadfast in this field, accumulating rich basic research results. In particular, the "Cheng's Hypothesis" proposed by Cheng Guodong in 1983 — the development of a thick layer of segregated ice near the upper limit of permafrost, which occurs year after year, resulting in a thick layer of underground ice near the upper limit of permafrost — has been acclaimed by international peers as the "theory of relativity" in permafrost science, providing important theoretical basis for solving technical problems in permafrost engineering.
In the late 1980s and early 1990s, relying on the Lanzhou Institute of Glaciology, Cryopedology, and Desert Research, the Chinese Academy of Sciences actively established the State Key Laboratory of Frozen Soil Engineering, built a world-advanced permafrost research platform, gathered an important team of talents, and accumulated valuable research results.
Training soldiers for a thousand days, using them for a moment. When the country decided to launch the Qinghai-Tibet Railway project for the third time, the perseverance, preparation, and layout during those long years finally burst forth with tremendous force.
At the moment when the task was received, although Cheng Guodong felt a bit nervous emotionally, he had long been prepared. They had already thought about how to solve the permafrost and roadbed problems faced by the construction of the Qinghai-Tibet Railway for a long time.
Emulating nature, turning passivity into initiative.
Academician Cheng Guodong (second from the right) leads the team in conducting experiments on frozen soil. On October 2, 2001, the Chinese Academy of Sciences held a major project defense meeting. "Active Cooling Subgrade Technology" was the highlight of Cheng Guodong's presentation at this meeting. The essence of this technology lies in being "active". Before this, people had been "passive" for too long in the face of frozen soil. The traditional methods used domestically and abroad mainly involved raising road embankments or laying insulation materials, much like how old ladies used to cover ice cream with a blanket in order to prevent it from melting. However, this method only delayed the thawing of frozen soil and couldn't solve the problem fundamentally.
Cheng Guodong's approach was straightforward: instead of using a "blanket", why not use a "refrigerator" to achieve long-term, stable, and sustainable cooling of the subgrade? But how do you tailor-make "mini refrigerators" for miles of roadbed? This is where Cheng Guodong's years of foundational theoretical research in the field of frozen soil came into play.
China is the world's third-largest country with frozen soil, with permafrost areas accounting for one-fifth of the country's land area. Contrary to what many people might think, permafrost is not only found in remote and extremely cold areas, but also in places with relatively high average temperatures such as Hebei and Shanxi. Under special environmental conditions, permafrost can also form in these areas.
Cheng Guodong's team observed an interesting phenomenon in some small hills in rural Hebei: the temperature difference between the surface and the soil layer less than 1 meter deep could exceed 30 degrees Celsius. During the peak of summer, locals would go to these places to cool off, digging into the soil to bury watermelons, which would quickly turn into refreshing ice-cold watermelons.
After research, the team discovered that the secret of frozen soil in Hebei lies in the layer of gravel hidden beneath the soil. The air convection between the gravel forms a "thermal semiconductor" effect, which blocks surface heat in summer and releases heat from underground in winter, acting as a true natural "refrigerator".
The ingenious design of nature excited Cheng Guodong greatly: if the North China Plain, with its scorching summers, could have unfrozen permafrost, then there must be a way to preserve permafrost on the Qinghai-Tibet Plateau as well!
Cheng Guodong's idea of "active cooling subgrade" was recognized by the Chinese Academy of Sciences. The Chinese Academy of Sciences established a major project and allocated 23 million CNY in basic research funds to support their work. The Ministry of Railways also posed a challenge, allowing them to implement various measures first on a 14-kilometer section of railway mainline.
This 14-kilometer embankment was intentionally located in the most adverse natural conditions. The Qinghai-Tibet Railway initially started construction on three test sections—the Qingshui River section, the Tuotuo River section, and the Beiluhe River section, with the latter having the most stringent conditions. The permafrost layer here has the highest ice content, and the soil temperature is relatively high, often close to zero degrees Celsius. Any slight negligence in construction could lead to the thawing of permafrost.
Would the solutions devised by scientists in the laboratory be feasible in the face of the unforgiving forces of nature? At this moment, nobody knew the answer.
Researching while doing, adapting dynamically to ever-changing circumstances.
Academician Lai Yuanming (middle) at the trial site along the Qinghai-Tibet Railway. Previously, the best frozen soil engineering in the world was the Trans-Siberian Railway. One hundred years after its construction, the disease rate has reached 30%. In various other roads and railways around the world, the disease rate is often even higher. The Qinghai-Tibet Railway is a project of the century, and it must maintain an extremely low disease rate in the global warming environment to ensure the long-term stable passage of trains at a speed of 100 kilometers per hour. To achieve this goal, there is no previous experience to draw on, and both researchers and engineers have to feel their way across the river.
To expedite the application of scientific research results, the project team has created a new working mechanism - the dynamic design concept. After scientists propose a solution, the leading unit of the project organizes top experts nationwide for discussion. Once the proposal is approved, it is disseminated to design institutes in the form of publications to initiate subsequent design work. After construction begins, scientists track and monitor in real-time to continuously improve the design. It is this model that has created the miracle of the speed of technology transfer, allowing the "almost impossible" project to take root and extend rapidly across the Qinghai-Tibet Plateau. "We've encountered a group of practical people!" Looking back on this history, Ma Wei, a researcher at the Northwest Institute, couldn't help but sigh.
However, accidents still occur. In 2003, a climate change assessment report from relevant national departments caused concern. The report indicated that the Qinghai-Tibet Plateau is expected to warm by 2.2 to 2.6 degrees Celsius in the next 50 years. With such a temperature increase, the original high-temperature permafrost embankment construction plan would not effectively protect high-temperature, high-ice-content permafrost. After discussions, researchers unhesitatingly overturned all the existing plans and switched from embankments to dry bridges. "This is a revolution in the entire Qinghai-Tibet Railway construction plan," said Wu Qingbai, a researcher at the Northwest Institute and director of the National Key Laboratory of Frozen Soil Engineering.
However, on other sections, embankments of at least two to three hundred kilometers have been constructed, and the relevant design schemes cannot cope with such significant temperature changes. Some believe that these embankments must be abandoned, and new routes must be selected, which would undoubtedly result in tremendous waste.
Cheng Guodong believed that national funds should not be wasted in this manner. He brought in a talented young person from the institute to discuss how to solve this problem - he was the later-elected academician of the Chinese Academy of Sciences in 2011, Researcher Lai Yuanming. With no precedent, Lai Yuanming and his student Yu Wenbing conducted numerous experiments and proved that block stones with a particle size of 22 centimeters have the best cooling effect. They then conducted multiple wind tunnel experiments and proposed the groundbreaking "U-shaped embankment" scheme, which significantly enhanced the cooling effect of the embankment. "With this change, the two to three hundred kilometers of embankments already constructed can be utilized. If we had abandoned them and selected new routes at that time, the investment of over 30 billion CNY might have been wasted," Lai Yuanming said with relief. In Ma Wei's view, everything about the Qinghai-Tibet Railway work is "dynamic." This "dynamic" is still ongoing today. The "Qinghai-Tibet Railway Permafrost Engineering Long-term Observation System," established at the beginning of the construction of the Golmud section of the Qinghai-Tibet Railway, has been closely monitoring the "temperature" changes of permafrost along the railway line.
Looking at the entire Qinghai-Tibet Railway, it seems like a moving museum of roadbed cooling technology: sunshade embankments, sunshade board embankments, block stone embankments, U-shaped block stone embankments, ventilation pipe embankments, thermal rod embankments... Various upgraded and updated "refrigerators" showcase the innovative achievements of researchers at various stages.
Ma Wei is installing relevant experimental instruments in the field.
Wu Qingbai is drilling permafrost core samples by the roadside.
The spirit of the yak, advancing in adversity.
Every member of this team has their own thrilling "Highland Survival Diary". In the early stages of the project, scientists stationed at the northern bank of the river had only two single tents to live in. At night, the howling wind outside seemed to whisper in their ears, making them worry that they and their tents would be blown away by the strong wind at any moment. Later, the project management department specially delivered two cotton tents, improving everyone's living conditions. Later on, these researchers took matters into their own hands and built houses on the plateau. But building houses in such an environment was not easy. They remembered the publicity online about Chinese scientists building lightweight and warm prefabricated houses in Antarctica, so they contacted the same manufacturer to provide building materials. When the manufacturer heard the whole story, they immediately said, "Even if we lose money, we must do it. We also want to contribute to the Qinghai-Tibet Railway." And so, little by little, the Northwest Institute of Research on Permafrost in the North Bank of Qinghai Plateau established the National Field Scientific Observation Research Station for Permafrost Engineering Safety, becoming a "ark" for scientists stationed in the depths of Hoh Xil.
北麓河站
Life on the plateau turns even the simplest tasks into daunting challenges. Take eating, for instance – when venturing outside, your sausages, eggs, and canned goods are frozen solid, requiring you to thaw them slowly on the hood of your car using its engine heat. And even when you manage to thaw them, the combination of basic food and the dulled taste buds from altitude sickness makes everything taste like wax.
Sleeping is no easier – the occasional inns along the way offer rudimentary conditions, some lacking even a fireplace, leaving you to endure the night cocooned in filthy blankets. The oxygen-deprived air induces splitting headaches and restless nights, leading to a joke popular on the plateau: "Did you sleep well last night?" "Absolutely, I must've slept over 30 times."
Even shaving becomes a grand affair due to its rarity. Cheng Guodong, once a handsome young man from Shanghai, earned the nickname "Cheng Big Beard" upon arriving on the plateau. He waits for the perfect weather day, basking in the warm sunlight before daring to wet his beard and carefully shave it off.
Before the completion of the Kunlun Mountain Tunnel on the Qinghai-Tibet Railway, Lai Yuanming ventured inside to place temperature and stress-testing devices to further study the distribution of frozen soil. In the high-altitude region at 4500 meters, amidst explosives and toxic gases, Lai Yuanming recalls feeling nauseous to the point of vomiting profusely. Since then, he has suffered from recurring headaches, only finding relief through rinsing with warm or hot water.
"The 'frozen soil people' are known for their endurance, often sleeping under the stars with the earth as their bed. Working outdoors, we all got sunburnt and shed a layer of skin," Lai Yuanming chuckles, extending his hand, marked with white spots bestowed by the sun as his "medals."
There's a story often recounted, always evoking sympathy: during the crucial phase of constructing the Qinghai-Tibet Railway, the first station master of Beiluhe Station, Liu Yongzhi, spent nine months a year conducting experiments and monitoring the plateau. Upon descending for a medical examination, his blood was so thick from prolonged oxygen deprivation that it couldn't be drawn.
People often refer to hardworking individuals as "old yellow cattle," but here, the preferred term is "yak spirit." Scientists from various backgrounds at the Chinese Academy of Sciences become highlanders in Northwest China, forged physically and mentally robust, unwavering in their determination.
Building Dreams on the Plateau, Conquering Limits to Achieve Excellence
On July 1, 2006, the Qinghai-Tibet Railway officially opened. On that day, researchers from the Cold and Arid Regions Environmental and Engineering Research Institute, along with over 60 foreign experts, boarded the train bound for Lhasa. The train attendant explained to passengers, "The Qinghai-Tibet Railway, stretching from Golmud in the north to Lhasa in the south, covers a total length of 1118 kilometers, with 960 kilometers at an altitude exceeding 4000 meters. Constructing a railway in permafrost regions at such high altitudes is extremely rare in the history of world railways. Researchers from the Chinese Academy of Sciences' Cold and Arid Regions Environmental and Engineering Research Institute tackled the longstanding problem of permafrost in railway construction by using active cooling methods..."
Hearing this, Lai Yuanming couldn't help but tear up. He turned to look out the window, where distant mountains rose and snow-capped peaks soared. The Qinghai-Tibet Railway has created a world-class miracle. Jerry Brown, chairman of the International Permafrost Association, praised it as representing the latest advances in permafrost engineering, a field where other countries can learn from China's achievements. Nature magazine extensively covered the Qinghai-Tibet Railway, highlighting its environmentally friendly approach to solving the global challenge of constructing roads in permafrost regions under conditions of climate change, marking a significant milestone. Domestically, it has been hailed as "one of the most difficult railway engineering projects in history" and "one of the most spectacular railways in the world." In 2005, the construction and research team of the Qinghai-Tibet Railway permafrost embankment received the Outstanding Science and Technology Achievement Award from the Chinese Academy of Sciences. In 2008, the Qinghai-Tibet Railway project won the National Science and Technology Progress Special Award, with the Permafrost and Cold Region Engineering Research Innovation Team being one of the main units. In 2017, this team once again won the National Science and Technology Progress Innovation Team Award.
On the vast land of China, there are countless roads. But if there's one road that connects the most beautiful dreams of China from time to space, from legend to reality, it must be the Qinghai-Tibet Railway. "The Yellow River comes from the west, deciding the Kunlun, roaring for thousands of miles and touching the dragon's gate," Li Bai exclaimed in poetry about the majestic and perilous terrain here. "As long as the Kunlun Mountains exist, the railway will never reach Lhasa," asserted an American traveler in the 20th century. Generals of the Han Dynasty's expeditions, Tang Dynasty princesses in marriage alliances, all sighed deeply along the seemingly endless journey shrouded in death; during the Republic of China era, Mr. Sun Yat-sen outlined in "National Building Strategies" a railway network connecting Lhasa with Kunming, Chengdu, and Lanzhou... In 1973, Chairman Mao Zedong said to King Birendra of Nepal during a meeting, "If the Qinghai-Tibet Railway is not built, I can't sleep." For many years, the Qinghai-Tibet Railway has been the long-cherished wish of the Party and state leaders and the fervent expectation of the people of Tibet and the entire nation. The completion and opening of the Qinghai-Tibet Railway completely eliminated the time and space barriers between Tibet and the mainland, greatly promoting ethnic unity, regional development, and economic and cultural prosperity.
The spirit of the Qinghai-Tibet Railway, "challenging limits and daring to excel," shines in every participant of the project. Among this stellar team, the generations of "permafrost people" from the Chinese Academy of Sciences have written an immortal chapter with their wisdom and sweat.
The spirit lives on, passed down through the generations. Until today, researchers from the Northwest Institute continue to work tirelessly on the Qinghai-Tibet Plateau, monitoring the frozen soil, environmental changes, and railway operations along the line. When discussing the future, Zhang Mingyi, vice president of the Northwest Institute, speaks without grandeur. Taking over the baton from the older generation of scientists, he firmly says, "We will inherit and carry forward the innovative spirit, practical spirit, and dedication spirit of the older generation of scientists, and will always guard the Qinghai-Tibet Railway, making every effort to ensure its safe operation."
Zhang Mingyi is conducting field tests on frozen soil roadbeds.
China Science News: March 4, 2024, Special Issue, Page 4.
