On the morning of January 8, the CPC Central Committee and the State Council grandly held the National Science and Technology Award Conference in Beijing. The "Key Technologies for the Jinping II Ultra-deep Buried Extra-large Water Diversion Tunnel Power Project," jointly completed by the East China Investigation and Design Institute of Power Construction Corporation of China (PowerChina) as the lead research and development unit and Yalong River Hydropower Development Co., Ltd. and other units, won the second prize of the 2017 National Science and Technology Progress Award. As a successful example of technical breakthroughs, this achievement was written into the "13th Five-Year Plan for Power Development" and has played a leading and demonstrative role in China's deep underground engineering construction. In the future, PowerChina people will continue to follow the direction indicated by the 19th National Congress of the Communist Party of China, fully apply these achievements to the new journey of building a beautiful China in the new era, and continue to make new and greater contributions to the country's economic and social development and the people's better life.
　　Dream of the Great River Bend
　　The Jinping II Hydropower Station utilizes the natural drop of the Yalong River's great bend, cutting the bend and straightening it to excavate tunnels for water diversion and power generation. With a total installed capacity of 4,800 MW, it is the hydropower station with the highest water head utilization, largest power generation, and best benefits among the cascade stations on the Yalong River. It is a landmark project for implementing the "West-East Power Transmission" and "Sichuan Power Transmission" strategies. Among them, 4 water diversion tunnels, 2 auxiliary tunnels, and 1 construction drainage tunnel form a group of 7 parallel large deep-buried tunnels, with a total length of 120 kilometers. It features deep burial, long tunnel lines, large tunnel diameters, high in-situ stress levels, complex karst hydrogeological conditions, and difficult construction layout. It is currently the largest and most comprehensive hydropower tunnel group project in the world, both built and under construction.
　　The planning, survey, and design of the Yalong River Jinping Great Bend began in the 1960s. The idea of cutting the bend and straightening it, excavating tunnels through Jinping Mountain for water diversion and power generation, is wonderfully fascinating, but the difficulties and obstacles encountered have also caused those who conceived it to work tirelessly and lose sleep.
　　The late academician of both the Chinese Academy of Sciences and the Chinese Academy of Engineering, and hydropower "doyen" Pan Jiazheng, once said: The Jinping II water diversion tunnel will surely be feasible, but many difficulties will be encountered; harmful gases are not scary, the most terrifying are rockbursts and sudden water inrushes.
　　How to solve high in-situ stress strong rockbursts and high-pressure large-flow sudden water inrushes is the key bottleneck restricting the construction of the project.
　　The World's Largest Karst Hydrological Tracer Test
　　In the 1990s, in order to obtain geological information along the tunnel line, the East China Investigation and Design Institute proposed excavating two 5-kilometer-long geological exploration adits parallel to the water diversion tunnel line to further ascertain the engineering geological and hydrogeological conditions of the Jinping Hydropower Station. This was unprecedented in China's hydropower survey history. However, when the No. 1 exploration adit was excavated to 3,948 meters, a huge water spray occurred, and the exploration test adit, which lasted 1,312 days, was forced to "suspend excavation."
　　Subsequently, in order to ascertain the groundwater recharge, runoff, and enrichment conditions, technicians from the East China Investigation and Design Institute started with the hydrogeological field analysis revealed by the excavation of the long exploration adit and the groundwater sealing, and conducted the world's largest karst hydrological tracer test with leading analysis methods around the 150-kilometer great river bend.
　　Investigators repeatedly crossed the 4,488-meter-high Jinping Mountain, traversed the mountains and rivers on both sides of the Yalong River, surveyed an area of more than 1,680 square kilometers, mastered a large amount of first-hand data, and recompiled the "Special Report on Karst Hydrogeology of the Jinping II Hydropower Station." This report is China's first comprehensive, systematic, and in-depth research achievement analyzing the karst hydrogeology of the Jinping Mountain area. It provides a scientific basis for solving major problems in the construction of the Jinping II Hydropower Station, provides experience for engineering construction in karst areas of high mountain and gorge regions, enriches the theory and practice of karst research, and has played a major role in promoting the construction of infrastructure such as highways, railways, and tunnels in the entire region.
　　The results were appraised and reached the international leading level.
　　Cutting the Bend and Straightening It, Piercing Through Jinping
　　After 2000, closely following the firm pace of the national Western Development strategy, the people of the East China Investigation and Design Institute once again set foot on this land of "half a century of dreams, three generations of hard work." In order to solve the project's external transportation problem and conduct advance exploration for the four world-class water diversion tunnels, the East China Investigation and Design Institute innovatively proposed the idea of building the Jinping auxiliary tunnel in advance, which is now the Jinping traffic tunnel.
　　In eight years, in order to solve the water inflow problem of the auxiliary tunnel, technical experts and designers of the East China Investigation and Design Institute moved into the damp and cold tunnel and ate and lived with construction workers for more than several months;
　　In order to grasp first-hand information, each of them took a bottle of water and a few steamed buns, entered the site of the sudden water inrush point by a rope to observe, soaked in the icy inrushing water, and stayed for a whole day;
　　In order to ensure the rationality and safety of on-site construction, geologists often risked rockbursts that could occur at any time, and conducted on-site inspections and geological sketches of newly excavated caverns every day;
　　They left their homes and children, devoted themselves to research, attacked camps and pulled out strongholds, bravely overcame difficulties, accompanied by the mountains and the great river. Black hair turned white, white hair mixed with black hair. Together with Yalong River Hydropower Development Co., Ltd., they wrote a magnificent chapter in the history of Jinping construction, setting multiple national and even world records.
　　On August 8, 2008, the first tunnel successfully crossing Jinping Mountain—the Jinping Auxiliary Tunnel B—was the first to break through. The builders used sweat, blood, and even life to pierce through Jinping Mountain for the first time, pushing China's long tunnel construction technology to a new peak. They summarized and formed the "Treatment Method for High-pressure Large-flow Stable Underground Water Inrush Sealing" and the "Shunting and Pressure-reducing Treatment Method for Ultra-high-pressure Sudden Underground Water Spray," and obtained national invention patents, effectively guiding construction operations to deal with sudden water inrushes, providing important technical support for solving the problem of sudden water inrushes, and laying a solid foundation for the construction of the four most difficult water diversion tunnels in the world.
　　Piercing the Mountain and Diverting Water, Dream Realized at Jinping
　　The successful breakthrough of the auxiliary tunnel greatly boosted the morale of all participating personnel. With the smooth breakthrough of the auxiliary tunnel, the Jinping II project advanced faster and faster.
　　In less than three years thereafter, the four Jinping water diversion tunnels and one construction drainage tunnel were successively completed, successfully achieving "five breakthroughs in one year"! The world's largest hydropower tunnel group was born here!
　　"This is a miracle on earth!" commented Wang Huisheng, then chairman of Yalong River Hydropower Development Co., Ltd.
　　During the project implementation, nearly 400 people from 15 specialties including geology, construction, water diversion, and powerhouse of the East China Investigation and Design Institute worked on the front line year-round on various aspects of Jinping project design, survey, and research. Even so, designers worked overtime almost every day to race against time.
　　Zhang Chunsheng, design project manager of the Jinping II Hydropower Station and now president of the East China Investigation and Design Institute, was both the front-line "commander" and the rear "guarantor." Whenever problems arose, he always rushed to the site at the first opportunity. Upon arriving at the construction site, he would go directly into the tunnel. Especially during the period of dealing with water inrush problems, he often wore a raincoat, waterproof pants, and rain boots, leaned on a bamboo pole, held a searchlight, and groped forward hand in hand with other designers in waist-deep sewage, surveying and discussing construction measures at the same time.
　　"Since we have undertaken the engineering design work, we must be responsible to the end for every link," Zhang Chunsheng said. Over more than a decade, Zhang Chunsheng led the establishment of a mechanical model and analysis method for marble under ultra-high stress excavation unloading that can accurately describe the behavior, invented the ultra-high-pressure underground sudden water shunting and pressure-reducing treatment technology, established a tunnel formation design method centered on suppressing the time-dependent fracture propagation of surrounding rock, constructed a composite seepage-control and load-bearing structure system for hydraulic tunnels under ultra-deep burial and ultra-high external water pressure conditions, and developed a numerical simulation system for hydraulic transient flow calculation and a differential surge chamber type with multi-well integration, double-arch partition, multi-orifice impedance, and shunting and span reduction, etc., playing an important role in the technological progress of the country's ultra-deep buried extra-large tunnels.
　　In November 2014, the Jinping II Hydropower Station, which has the world's largest comprehensive scale and highest comprehensive construction difficulty hydropower tunnel group, was fully completed and put into operation. The people of the East China Investigation and Design Institute "pierced the mountain and diverted water," and the Jinping dream pursued for more than half a century finally came true.
　　After decades of overcoming difficulties, relying on the construction of the Jinping II Hydropower Station, Yalong River Company and the East China Investigation and Design Institute, together with multiple scientific research units, closely focused on the key technical needs for long tunnels with deep burial, high in-situ stress, and high external water pressure in the National Energy Science and Technology "12th Five-Year Plan." Supported by the National Natural Science Foundation and the Yalong River Joint Research Fund, they carried out joint scientific and technological research in the "industry-university-research-application" mode, and successfully overcame worldwide technical difficulties such as ultra-deep burial and ultra-high in-situ stress, ultra-high-pressure large-flow karst groundwater, ultra-deep buried tunnel formation, and complex hydraulic transient flow. They created an integrated technology system for predicting and preventing strong rockburst risks in ultra-deep buried extra-large tunnels, proposed a complete set of technologies for predicting, warning against, and preventing ultra-high-pressure large-flow karst sudden water inrush disasters, established a design method for ultra-deep buried extra-large tunnel formation, and innovated the electromechanical integrated hydraulic design method and regulation method for long and large water diversion and power generation systems, etc.
　　Using the results of this project, China's first and the world's deepest underground laboratory—the China Jinping Underground Laboratory—was built, which is of great significance for promoting major basic frontier research. The research results won 2 special prizes, 4 first prizes, and 2 second prizes for provincial and ministerial science and technology progress; 37 authorized invention patents and 6 software copyrights; 7 published monographs, 118 papers indexed by SCI and EI, and incorporated into 6 national (industry) standards and 2 industry manuals, greatly promoting scientific and technological progress in this field, and were written into the "13th Five-Year Plan for Power Development" as a successful example of technical breakthroughs.
　　"The mountain is still that mountain, the river is still that river, but the Jinping Hydropower Station is like a dazzling pearl, shining ever more brightly with the nourishment of time."