2.2 The Exploring Support Technology Related to Ca...
Zhou Enlai,Premier of the State Council stated clearly in the report that all construction projects must implement the principle of small-scale,decentralized and covert on October 29,1964.The basic principle of the site selection has always been effective throughout the third-front construction.The blind expansion of caverns has caused a huge amount of contradictions,such as wasteful collaboration of technological processes,inconvenience of employees'daily life and difficult urbanization.
If we treat caverns independently,we can see the development of underground large-span and large-scale space technology under a certain level of mechanization.Look firstly at international experience,Germany got ready 96 million m2 of underground buildings,of which 14 million m2 were put into use in World War II.[4]Enterprises that stored and produced aircraft engines along with instrumentations preferred to enter caverns.The United States responded creatively to the risks that the country may encounter.15 huge buildings were built 500m in the Cheyenne Mountain Cavern in the southwestern suburbs of Colorado.They were delivered to the North American Air Defense Combined Headquarters(NORAD)in May 1965.It is still the most modern equipment military facility in the world today.The bunker structure belongs to special engineering thus is related closely to geological conditions,excavation technology,ventilation,lighting,communications and drainage.China has always regarded inherited and international character of technology as an important role.The Institute of Building Science of the Ministry of Construction and Engineering translated the latest special research timely from the United States instead of the Soviet Union's in 1964.(https://www.daowen.com)
Reinforced Concrete support is a main point to prevent the collapse of the cavern,and it is also the highlight of engineering practice to the national standard.Chengdu-Kunming Railway won the Special Prize of the 1978 China Science and Technology Congress.Among them,seventeen tunnels were partially covered with bolt shotcrete support.Firstly they removed the gravel,then sprayed the concrete on the stone wall,added the anchor bolt in the third step,finally made the reinforced concrete and the natural earth along with stone into one.The Rocks Shotcrete Supporting Technology was published for railway tunnels in 1985(GJB86).In order to complete the task perfectly,the compiling team conducted extensive investigations.China's independent technological research has set up many demonstration models,which have benefited and have so far played an undisputed role in international railway and subway bidding.
The rocks shotcrete supporting can't be separated from the builders.There were a total of eight engineer corps in China which belonged to labor-intensive ministries such as metallurgy,mining,railways,water conservancy and construction.The corps was mainly concentrated in the southwest and northwest areas,that was,the main battlefield for the third-front construction,also used to be included in the PLA's engineering sequence before 1985.The 54th Division was a well-equipped special force,it participated in almost all grand projects of the National Committee for Science and Technology from the Two Bombs City in Jinyang,Sichuan Province to the Lop Nur Atom Bomb Base in Xinjiang Uygur Autonomous Region.China's first atomic bomb exploded successfully in Lop Nor,which symbolized the modernization of national defense entered a new stage on October 16,1964,followed by explosion of the hydrogen bomb independently in 1967.The development of a series of nuclear bombs involved various aspects including mining,scientific research,equipment manufacturing,transportation and security.It was characterized by unified leadership,clear division of labor and efficient coordination.The Atomic City in Qinghai Province is the first nuclear weapon research base in China.It was built in May 1958 and fully retired in May 1995.The base has kept the completely physical testimony of the nuclear industry from its creation to decommission since 1995.Another case was the Chongqing 816 nuclear engineering base,which was nominated as the modern architectural heritage in China in 2016.32 large-scale caverns had been built by 1975.The main cavern was 79.6m high,32m wide and horizontally 80m long.It was excavated in four levels so that a giant underground construction like a vertical spider web.In order to solve support issues,a conference was held on the 816 project site to conduct a full theoretical discussion on the two main technologies of side wall support and vault backfilling of the tall caverns on March 13,1972.The achievement was published in a professional journal named Engineering Force Scientific and Technical Information in June 1974.The 54th Division has made blueprint a reality and helped engineers solve puzzles of large-span tunnel construction.The Chongqing 816 was inevitably costly.What a pity it is that it has become ruins before it was actually occupied.Today only a small amount is used for tourism.Security must have its uniqueness,as China's leading telecommunications firm Tencent preferred the highly concealed qualities of the Chongqing 816 thus used to consider placing its data storage center in the cavern.However,Tencent changed its mind.The ultra-higher data centers and distribution facilities were moved to a new cavern in Gui'an County,Guizhou Province in 2015.The reasons are very complicated.One is that the cavern is suffering from structural deterioration due to water seepage defects.The Chongqing 816 is in urgent need of systematic conservation and rehabilitation in the future.