The tunnel is located between Lupan Station and Shangxipu Station in the Wei (She) Hong (Guo) Section. The total length of the tunnel is 4975 meters. 1085 meters of the tunnel body are coal strata, with 14 main coal seams. The measured gas pressure values ??of each coal seam mostly exceed 0.6Mpa, with the highest reaching 1.34Mpa. The Coal Department's "Detailed Rules for the Prevention and Control of Coal and Gas Outbursts" points out that when the coal seam gas pressure exceeds 0.6Mpa, there is a risk of coal and gas "outbursts". According to calculations, when tunnel construction passes through coal seams, the gas emission volume can reach up to 349 cubic meters per hour. Therefore, the Jiazhuqing Tunnel is a tunnel with high gas outburst risk, and its construction difficulty and danger have no precedent in the history of railway tunnel construction in my country.
In the design of the Jiazhuqing Tunnel, a series of safety precautions were taken, including pre-extraction and pre-drainage, sealing the pit walls, strengthening ventilation, eliminating fire sources, spray cleaning, and reducing coal dust. In order to reduce the ventilation resistance and allow as much fresh air to enter the tunnel as possible to reduce the gas concentration, a parallel guide pit and two inclined shafts are set up in the entrance work area and the inclined shaft work area of ??the tunnel, and a powerful ventilation hole is formed through the suction action of a large ventilator. Tunnel ventilation. During construction, the gas concentration in the excavation working face shall not be greater than 1% after ventilation, the gas concentration in the return air duct (parallel guide pit) shall not be greater than 0.75%, and the wind speed at any point in the tunnel shall not be less than 0.5m/s. In order to prevent gas from gathering and staying in the corners of the tunnel, feng shui sprayers are installed on the excavation working surface to disperse the gas and reduce coal dust. During the construction of the Jiazhuqing Tunnel, the outburst prevention measures of "one detection, two testing, three rows and four testing, vibration and blasting, and safe evacuation." were adopted.
The Nankun Railway uses electric locomotives for traction. High-voltage arc sparks often occur between the pantograph of the locomotive and the contact network. In addition, friction sparks are generated by the train brake shoes and open flames generated by the passenger car dining car are harmful to gas. All words are dangerous sources of fire. For high gas tunnels like Jiazhuqing, although a series of sealing measures have been taken on the lining structure, considering that there may be some imperfections in the design and construction, some gas will still leak into the tunnel. And gradually accumulate. And because the length of the Jiazhuqing Tunnel is nearly 5 kilometers, natural ventilation is not enough to dilute and bring out the gas in the tunnel. Over time, if the accumulated gas concentration exceeds 0.5%, it will pose a threat to driving safety. Therefore, the inclined shaft in the middle of the tunnel is used for extractable mechanical ventilation. Gas probes are installed at the vaults at regular intervals in the tunnel. When the central control room finds that the gas concentration in the tunnel has risen to a dangerous value, the inclined shaft fan is started for ventilation. The tunnel construction started in 1993 and the track was laid on May 11, 1996.
Small Dictionary - Gas. The gas in the formation is the gas produced by the decomposition of ancient underground organic matter. The main component of gas is methane, which is a colorless, tasteless and odorless flammable gas. Under standard conditions, 1 cubic meter of gas weighs 0.716 kilograms. Since it is lighter than air, it often accumulates at the top of the tunnel. Under normal circumstances, when the gas concentration in the air is between 5% and 16%, it can cause an explosion if exposed to an open flame. When the gas concentration is 9.5%, the explosion is most powerful. When the concentration exceeds 16%, it loses its explosiveness, but it can still burn in case of fire. It is worth noting that when the air contains coal dust, the gas concentration of 3% can explode. Since gas exists in the coal seam at a certain pressure, when the tunnel is excavated, the pressure is suddenly reduced. In a very short time (a few seconds), a large amount of gas together with coal powder and rock blocks will suddenly erupt, and the number can reach dozens or hundreds. tons, causing the tunnel to collapse and become submerged, causing personal casualties. This is the so-called "outburst" of coal and gas. It can be seen that gas is the most dangerous "enemy" in tunnel construction. The tunnel is located in Bantao Township, Tianlin County, Guangxi Zhuang Autonomous Region, with a total length of 9,392 meters. The tunnel passes through the Jiuwei Mountains, the watershed between the Youjiang and Nanpanjiang river systems. The mountains in the area are rolling, with undulating peaks, steep slopes and deep ravines. This area has a subtropical humid monsoon climate, and the trees in the mountains are evergreen all year round, with flowers and fruits growing all year round. Every winter, rice flowers bloom all over the mountains and fields, white and fragrant, hence the name Mihua Ridge.
The mountainous terrain the tunnel passes through is complex in geology. There are 3 main faults that pose a great threat to the tunnel, 16 small faults that have a certain impact, 6 folds, and 10 water storage zones, of which 4 water-rich zones may cause water and mud inrush. The water inflow volume of the entire tunnel is 17,000 cubic meters every day and night. The plane of the tunnel line is S-shaped, with a curve at the entrance and exit. The length of the entrance curve is 258 meters, the radius of the curve is 1000 meters, and the curve length accounts for about 6% of the entire tunnel.
The curves at the two entrances are mainly due to the stations at both ends of the tunnel and the terrain conditions. Before the tunnel enters the tunnel, it is Bantao Station, and after exiting the tunnel, it is Genlong Station. The tunnel support structure is designed according to the New Austrian Method principle, using a curved wall composite lining section. The Type II and III surrounding rock sections are curved wall invert fully enclosed linings. The Type IV surrounding rock section does not have inverts, and the bottom is made of reinforced concrete. The bottom plate strengthens the bottom of the tunnel to improve the stress state of the supporting structure, prevents the mudstone from softening under the repeated force of the train, and avoids diseases at the bottom of the tunnel. The water inflow volume of this tunnel is large, and the water control principle in the design is mainly drainage, combined with plugging and drainage. For the Class II surrounding rock sections where water and mud may inrush, long conduits are used to grout the entire section to plug the water before excavation. The tunnel support structure adopts the method of water control with top blocking and bottom drainage, that is, non-woven fabrics and polyethylene waterproof boards are installed between the secondary supports on the arch, drainage blind ditches are installed at intervals on the walls, and double-sided drainage ditches are installed longitudinally in the tunnel to ensure smooth water flow. , to prevent water accumulation from harming the bottom of the tunnel and causing diseases. The key project of this tunnel is the three main faults in the exit section of the middle part of the tunnel. The total length of the fault fracture zone and influence zone is 575 meters, which is equivalent to a small tunnel. A nearly 600-meter "rotten hole" will take one to two years to construct. Moreover, the 600-meter "rotten hole" is embedded deep in the tunnel, so the construction difficulty can be imagined. Based on the treatment of three main faults and drawing lessons from several previous long tunnels, the construction auxiliary tunnel scheme of "two inclined and one flat" was adopted. The tunnel adopts advanced construction equipment such as a rail-mounted gantry-type four-arm rock drilling rig, a vertical claw ballast loader, and a 14 cubic meter shuttle mine car for transportation. The formwork trolley is equipped with concrete pump lining and other advanced construction equipment, creating conditions for rapid tunnel construction. . According to the geological conditions, the excavation method is mainly normal section excavation, and the short step method is used in weak surrounding rock areas. The tunnel construction started on November 1, 1992 and was completed on September 6, 1996. China Railway Tunnel Group (CTG) is the largest enterprise group in the field of tunnels and underground engineering in China. In May 1978, in order to build the Yellow River underwater tunnel, the Ministry of Railways submitted to the State Council for approval, and the Ministry of Railways 4501 Project Headquarters was established in Luoyang, Henan. In October of the same year, the State Council approved the reorganization of the 4501 Project Headquarters into the Tunnel Engineering Bureau of the Ministry of Railways. In 1999 In September 2009, the Tunnel Engineering Bureau decoupled from the Ministry of Railways and was renamed "China Railway Tunnel Engineering Bureau". In May 2001, the Tunnel Engineering Bureau implemented corporate restructuring and established China Railway Tunnel Group Co., Ltd. with China Railway Tunnel Group Co., Ltd. as the core enterprise and integrating the four major functions of survey and design, construction, scientific research and development, and machinery repair. It is affiliated to China China Railway Co., Ltd. The group currently has 10 construction subsidiaries (branch), 1 survey and design institute, 1 scientific research institute, 1 manufacturing company, and 6 regional headquarters in Beijing, Nanjing, Guangzhou, Xi'an, Chengdu, and Wuhan. There are 300 construction projects, with construction teams spread all over the country. The main business scope and qualifications of the group (construction qualifications only include first-level and above qualifications) include: special-level general contracting for railway project construction; first-level general contracting for highway project construction; first-level general contracting for municipal public engineering construction; and general contracting for housing construction projects. Level 1; Level 1 General Contracting for Mechanical and Electrical Equipment Installation Engineering Construction; Level 1 Professional Contracting for Tunnel Engineering, Bridge Engineering, Hydraulic Tunnel Engineering, Highway Subgrade Engineering, Mechanical and Electrical Equipment Installation Engineering, Foundation and Foundation Engineering, Professional Contracting Qualification for Urban Rail Transit Engineering ( Not classified); Comprehensive Class B for highway water transport engineering testing and testing institutions; Professional Class A for municipal industry (bridge engineering, urban tunnel engineering, rail transit engineering, road engineering), Professional Class A for highway industry (extra long tunnels), Professional Class A for highway industry (highway) Professional Grade B, professional Grade A design in the railway industry (tunnels); comprehensive engineering survey Grade A; surveying and mapping qualification Grade A; engineering consulting Grade A (railway tunnels, highway tunnels, urban rail transit, municipal public works (bridges, tunnels), Geotechnical engineering, engineering surveying, hydrogeology); Class B engineering consulting (construction, municipal public works); scientific research, design and technical services, etc. The group company and its main business subsidiaries have successively passed the GB/T19001 standard quality management system, GB/T24001 environmental management system and GB/T28001 occupational health and safety management system certifications.
The group currently has 15,116 employees, 7,437 professional and technical personnel of various types (501 with senior professional titles, 1,381 with intermediate professional titles), and more than 7,000 technical workers of various types, including academicians of the Chinese Academy of Engineering and national-level intellectuals. There are 1 expert each with outstanding contributions, 12 people enjoying special government allowances from the State Council, and 596 qualified project managers (construction engineers). The registered capital of the group company is 1.11 billion yuan, the group's total assets are 12.3 billion yuan, fixed assets are 2.4 billion yuan, and owners' equity is 1.93 billion yuan. The group maintains 4,856 pieces of machinery and equipment, with an original value of 2.42 billion yuan, a net value of 1.31 billion yuan, and a total power of 491,000 KW. There are 46 TBM and shield machines in stock. The technical equipment rate is 126,500 yuan/person, the power equipment rate is 54.18KW/person, and there are currently 46 TBMs and shield machines. It is the construction enterprise with the most complete categories and the largest number of shield machines and TBMs in China, with an annual tunnel construction capacity of 500 kilometers. above.
In the past 30 years, the scale of business operations and production has continued to expand, and the market has continued to expand from within the railway to outside the railway, and from within the country to overseas. A large number of national key project construction tasks with high scientific and technological content have been completed. Railway projects have successively participated in Donglonghai, Hengguang, Daqin, Houyue, Baocheng, Jingjiu, Nankun, Shuohuang, Xikang, Neikun, Zhuliu, Meikan, Shenyan, Xi'an Nanjing, Chongqing Huai, and Jiangxi Long, Qinghai-Tibet, Lanwu, Yiwan, Dali, Luozhan, Shitai, Wuguang, Hewu, Wukang, Xiangyu, Wenfu, Ningbo-Taiwan, Taizhongyin, Qinghai-Tibet Second Line, South Xinjiang Tukuu Second Line, Guangzhou Shenzhen-Hong Kong, Beijing Underground Diameter Line, Longxia, Xiamen-Shenzhen, Zhanliu, Jingshi, Chongqing, Guiguang, Xiping, Nanguang, Lanyu, Yumeng, Ku'er Branch Line, Shenyang Hub Northeast Ring Line, Northeast Eastern Irrigation Line The famous long tunnels that have been completed or participated in the construction of double-track railways include: the longest double-track railway tunnel in China, the Dayaoshan Tunnel on the Heng-Guangzhou Double-track Line (14.3 kilometers), and the Wushaoling Tunnel on the Lanwu Second Line, the longest single-track railway tunnel in China. Tunnel (20.5 kilometers), Xi'an Ankang Qinling Extra-long Tunnel (18.5 kilometers) built for the first time in China using TBM boring machines, the longest karst tunnel in China, the Yuanliangshan Tunnel (11.1 kilometers), the first long tunnel of Yuhuai Railway, and the longest gas tunnel in China Tunnel Yuntaishan Tunnel (8.2 kilometers) is the longest tunnel of Houyue Railway. Famous long tunnels that have been completed or participated in the construction of highway projects include: the Partridge Mountain Tunnel of National Highway 317, the highest in China (4.4 kilometers, 4,000 meters above sea level), the Erlangshan Tunnel (4.2 kilometers), the longest on the Sichuan-Tibet Highway, Guangyu The longest Huayingshan Tunnel on the expressway (4.7 kilometers), the longest Fangdoushan Tunnel on the Chongqing Zhongshi Expressway (7.6 kilometers), the Wuhan Yangtze River Highway Tunnel (3.63 kilometers), etc. Urban subways have successively built a large number of stations and sections in Beijing, Shanghai, Tianjin, Nanjing, Guangzhou, Shenzhen, Shenyang, Xi'an, Hangzhou, Wuxi, Chongqing, Chengdu, Wuhan and other subways.
Since its restructuring in May 2001, China Railway Tunnel Group has aimed at the overall development goal of "domestic leadership and world-famous", carried forward the corporate philosophy of "big industry, big school, big family, big stage" and comprehensively Implement the Scientific Outlook on Development, keep pace with the times, face difficulties, seize opportunities, improve capabilities, use reform as the driving force, management as the foundation, science and technology as the guide, culture as the soul, constantly strengthen and improve corporate management, and promote The management is scientific and modern, and a new enterprise management system is built that meets the requirements of modern enterprise systems, adapts to the needs of market competition, and is conducive to improving the competitiveness of enterprises. Operations and production reach a new level every year, and the competitiveness of enterprises has been significantly enhanced, achieving the goal of China Railway Tunnel Group Sustained and rapid development in the fiercely competitive market environment of survival of the fittest.
The Group firmly adheres to the technology research and development strategy and is committed to the research, development and application of new technologies and new processes in the field of tunnels and underground engineering. It is the first to introduce, absorb and fully master the new Austrian construction technology in China. Especially in tunnel and underground engineering construction under complex and special geological conditions such as fault fracture zones, weak surrounding rock, expansive surrounding rock, high ground stress, coal and gas strata, water inflows, karst, rock piles, quicksand, loess, etc., it has its own Exquisite craftsmanship and unique technology.
In recent years, breakthroughs have been made in the use of large-scale advanced equipment construction technology. 51 shield tunneling projects with a length of 195 kilometers have been constructed; 8 TBM projects with a length of 140 kilometers have been constructed. To date, ***351 scientific research achievements have passed the review, appraisal and acceptance by scientific and technological authorities at the enterprise or provincial and ministerial levels, including 2 items at the internationally leading level, 32 items at the international advanced level, 63 items at the domestic leading level, and 51 items at the domestic advanced level. item. It has won 9 National Science and Technology Progress Awards (including 1 special prize), 2 "Zoomlion Cup" Huaxia Construction Science and Technology Awards, and 70 provincial and ministerial level Science and Technology Progress Awards. It has obtained 26 patents, including 6 invention patents and 20 utility model patents. It has created 17 national-level construction methods, 43 ministerial-level construction methods, and 111 enterprise-level construction methods. The Group adheres to the enterprise spirit of "precision, sincerity, better and newer" and carefully forges high-quality projects. It has won 12 National Construction Engineering Luban Awards, 12 National Civil Engineering Zhan Tianyou Awards, and 3 National Quality Project Gold Awards and Silver Awards. 11 projects, 3 National Design Gold Awards, 2 Silver Awards, and 68 provincial and ministerial quality engineering awards. The Ministry of Science and Technology of the People’s Republic of China has established the “National Key Laboratory of Shield Tunneling and Tunneling Technology” in our group company. The China Civil Engineering Society’s Tunnel and Underground Engineering Branch has been established in our group company. The Henan Provincial Department of Science and Technology has recognized our group company as a high-tech enterprise in Henan Province. , Henan Enterprise Technology Center. The group company has successively won the titles of "Excellent Enterprise of China Railway Engineering Corporation", "Excellent Construction Enterprise of Henan Province", "Excellent Ideological and Political Work Enterprise of Henan Province", "National Excellent Construction Enterprise", "National First Batch of AAA Credit Enterprises in the Construction Industry", "China's Excellent Enterprise", "China's Integrity Unit", "National Customer Satisfaction Construction Enterprise", "National Model Workers' Home", "National Ankang Cup Competition Winning Enterprise", "National Advanced Unit for Corporate Culture Construction", "National Five "Labor Certificate" and other honors.