Development and Thinking of Tunnels and Underground Engineering in China in Recent 2 Years （From 2017 to 2018）（近2年我国隧道及地下工程发展与思考（2017—2018年））

The author gives an overview of the development of tunnels and underground engineering in China in the past two years, including railway tunnel, high speed railway tunnel, highway tunnel, metro tunnel, hydraulic tunnel and utility tunnel, and introduces some key and representative railway, highway and municipal tunnels projects, i.e. Muzhailing Tunnel on Lanzhou Chongqing Railway, Dangjinshan Tunnel on Dunhuang Golmud Railway, immersed tunnel of Hong Kong Zhuhai Macao Bridge, China Laos Railway Tunnel, Gaoligongshan Tunnel on Dali Ruili Railway, Yuelongmen Tunnel on Chengdu Lanzhou Railway, Tianshan Shengli Tunnel on Urumchi Yuli County High speed Railway, Shenzhen Zhongshan Passage, Su′ai Tunnel in Shantou, Ka Shuang Tunnel of Ertix River Water Diversion Project, Qianhai underground integrated hub in Shenzhen and underground integrated structure of Optics Valley Square in Wuhan. The author also introduces the development and progress in the fields of engineering investigation technology, BIM technology, mechanized and intelligent tunnel construction technology, shield/TBM manufacturing and remanufacturing technology, offshore immersed tube tunnel construction technology, non circular shield tunnel construction technology, tunnel big data platform construction technology, etc. According to the operation of series national strategies and planning such as Sichuan Tibet Railway, coordinated development of Beijing, Tianjin and Hebei, the Yangtze Economic belt, and the Guangdong Hong Kong Macao Greater Bay Area, following technical demands are proposed, namely, sea crossing tunnels, construction of complex and long distance tunnels, environmental protection technology for tunnel construction in ecologically vulnerable areas, development of large scale urban underground complexes, research and development of new materials in alpine environment, intelligent diagnosis of tunnel diseases and rapid repairs, intelligent disaster prevention of ultra long complicated tunnels and underground engineering, etc. Some thoughts and suggestions are put forward in two aspects of engineering construction management mode and mechanization supporting in combination with the development status of the industry.     

Representative Projects and Development Trend of Underwater Shield Tunnels in China（我国水下盾构隧道代表性工程与发展趋势）

In the 21st century, the underwater tunnels have advanced rapidly in China. A large number of projects, completed or ongoing, have greatly promoted the advancement of underwater shield tunnel technologies in China and in the world. The development history of the underwater tunnels in China is summarized, and the technical challenges and breakthroughs encountered and achieved during the construction of many tunnels are presented, as represented by Nanjing Yangtze River Tunnel and Shiziyang Tunnel of Guangzhou Shenzhen Hong Kong High speed Railway. The characteristics and challenges of some representative underwater tunnels during construction, including Road Railway Yangtze River Tunnel in Sanyang Road, Shiziyang Tunnel of Foshan Dongguan Intercity Railway, Yangtze River Tunnel of Suzhou Nantong UHV Power Transmission and Transformation Project; and projects to be constructed, such as Pearl River Estuary Tunnel of Shenzhen Maoming Railway, Shantou Bay Subsea Tunnel of Shantou Shanwei High speed Railway, and Nanjing Heyan Road Yangtze River Tunnel, are presented as well. The development trend of China′s underwater shield tunnels, including from single soft soil formation to complex soil formation, from large diameter to super large diameter, from medium water pressure to high and ultra high water pressure, from ordinary to special and unfavorable geological conditions, from seismic regions with moderate intensity to those with high intensity, and from single construction method to combination of multiple methods, are analyzed. It is pointed out that the technical fields still require further study and innovation, and the areas still require further enhancement and innovation, such as the norms, codes, designs, constructions, equipment, materials and management.     

Innovation and Practice of Parallel Dual mode Slurry/EPB Shield Construction Technology and Freezing Cutterhead Opening Technology（并联式泥水/土压双模式盾构施工技术与冷冻刀盘开舱技术的创新与实践）

Two major concerns have been drawn in the process of shield construction: one is the difficulty in selecting a shield machine; the other is the high risk of opening for cutterhead changing. Based on the existing shield systems, a parallel dual mode shield with freezing cutterhead is developed by optimising internal structure and equipment and carrying the freezing device. The dual mode shield construction technology and freezing cutterhead technology are successfully carried out on project cases including Guangzhou Metro Line 9, Guangzhou Metro Line 21 and 220 kV Shijing Huanxi Electric Tunnel (Xiwan Road Shisha Road Section). The parallel dual mode slurry/EPB shield not only has the functions and advantages of slurry shield and EPB shield but also can switch into slurry/EPB mode for different strata and environments easily. Thus, it can achieve rapid shield tunneling. By combining the shield with the freezing system, the soil around cutterhead can be frozen to provide conditions for chamber opening under atmospheric condition. Meanwhile, it is also compatible with dual mode shield.     

Design Method and Application of Rock and Support System for Super large Span Tunnel（超大跨度隧道围岩支护体系构件化设计方法及其应用研究）

In order to guarantee the stability of surrounding rock and support structure of super large span tunnel and realize quantification of support structure design, the optimal excavation contour line shape is obtained based on study of influence of initial ground stress on bearing arch of surrounding rock; a new quantitative design method, in which the surrounding rock is regarded as an arch structure, bolts, cables, shotcrete and lining are designed to satisfy the intensity, rigidity and stability of the arch structure, is presented to design the support structure system. The method has been successfully applied to super large span tunnel of Badaling Great Wall Station on Beijing Zhangjiajie High speed Railway; and the applicable results show that the maximum accumulative settlement of crown top of large span section is only 17.3 mm, and the relative subsidence of crown top is only 0.09%, which can meet safety requirements.     

Key Technology of Sea crossing Interval Tunnel in Complex  Environment Design of Xiamen Rail Transit Line 3（厦门轨道交通3号线复杂环境过海区间隧道设计关键技术）

A sea crossing tunnel is generally large in scale, having a complex site environment, and lack of engineering experience. The success of the project is directly related to the design plan. At present, no metro sea crossing tunnel havd been built in mainland, and the design standard and technology of the sea crossing tunnel are not studied throughly. The key technology of long and large sea crossing metro tunnel design, including construction method selection, cross section design, waterproofing and drainage system design, response to complex environment in sea area, durability design, ventilation and evacuation are analyzd with methods of geological analysis, engineering analogy and comprehensive comparison based on the sea crossing tunnel of Xiamen Rail Transit Line 3. A combination of shield and mining methods is proposed for the geological conditions of different sections. The drainage system of the mining section can be maintained by applying advanced grouting to control displacement. The complex geology of the sea area is considered in the targeted design, including a deep weathering trough, a water rich sand layer, a hard rock and uneven stratum, and the development of solitary rocks. The durability design of the tunnel structure and the limit of the bearing capacity are treated equally to consider safety reserve. The tunnel adopts sectioned longitudinal ventilation and smoke extraction mode, and contains ventilation shafts and civil smoke extraction air shafts on shore to prevent disasters. The conclusions can provide technical support for tunnel scheme decision and reference for similar projects.     

Analysis of Adaptability of TBM in Trial Boring Stage of Super long Tunnel（超特长隧洞TBM集群试掘进阶段适应性分析）

The total length of the 2nd stage water transfer project in the northern area of Xinjiang of China is 540 km. The project consists of three tunnels, namely Xi Er (XE) Tunnel, Ka Shuang (KS) Tunnel and Shuang San (SS)〖HJ6.5mm〗 Tunnel, with lengths of 139.04 km, 283.27 km and 92.15 km respectively. All of these three tunnels have deep cover and are super long tunnels, and 95.6% of the total length of these three tunnels is constructed by TBMs. KS Tunnel is the longest water tunnel built or under construction in the world. In the paper, the trial TBM boring scheme and schedule of the water transfer project are introduced; the geological conditions revealed are statistically analyzed; and main project difficulties, i.e. durability of key equipment in long distance driving, passing through fault and fracture zones, water inrush, single head ventilation and transportation in long distance tunneling, anti slope drainage, and rock breaking efficiency and boring efficiency, are put forward. The adaptability of the TBMs used is analyzed from the aspects of adaptability to different surrounding rocks, adaptability to bad geological conditions and countermeasures, long distance ventilation and belt conveyor mucking and countermeasures, and TBM boring stability (such as equipment availability, boring time proportion, system malfunction and operation time). The following conclusions are obtained: (1) Accurate geological survey is the precondition of efficient tunneling. (2) The open type TBM can better adapt to Grade Ⅱ and Ⅲ of surrounding rocks, jointed and fractured zones and small faults; the adaptability of the TBMs used to the large scale fault fracture zones and water rich strata in this project is poor, and it needs to be improved in aspects of TBM equipment, supporting and construction technology. (3) The average availability of the TBM equipment in the trial boring stage is 89.9%, however, the malfunction rate of some ancillary equipment is high, particularly oil leakages occur to the main bearing seals; in order to achieve long distance tunneling, it is necessary to further improve the reliability and durability of the TBM equipment. (4) The average net boring efficiency in the trial boring stage is 296%, and TBM1 in Section Ⅱ of SS Tunnel achieves up to 45.2 % net boring efficiency; and highest monthly progress rate is 1 280 m, which created the highest record of the open type TBM boring in China. (5) TBM need to make great efforts to achieve 90% of the equipment system′s availability and over 40% of the tunneling efficiency.     

Key Construction Technologies for Overlapping Twisted Shield bored Tunnels in Weak Water rich Strata(富水软弱地层中麻花型盾构隧道群施工关键技术)

The project under study is an overlapping twisted shield bored tunnels in weak water rich strata. The purpose of the study is to solve the key technological problems in the construction of the project. The optimal construction sequence of the overlapping twisted shield tunnels is determined according to the engineering geological conditions, the surrounding working environment, and theoretical analysis on the spatial relationship of the four tunnels, and verification control are carried out via monitoring means. The tunnel construction is properly timed, smart self propelled movable support jumbo is adopted, and grouting reinforcement technology is used to ensure the construction safety of the overlapping twisted shield bored tunnels. The grouting pre reinforcement technology and the clay shock technology are adopted to ensure the safety of the surrounding buildings. The technologies for the construction of the overlapping twisted shield bored tunnels described in this paper is of great significance for the construction of similar overlapping tunnels with high shield launching/receiving risks and crossing under important structures with small clearance.     

Innovation and Practice of Hard Rock TBM in China（我国硬岩掘进机的创新与实践）

In recent years, with the help of good national policy support, the design, manufacturing and construction technology for tunnel boring machine (TBM) in China have been greatly improved; but compared with foreign relatively proven technology, there is still a certain gap for domestic technology development and engineering application. Based on the situation analysis of research and application of TBM in China and abroad, the research work for TBM design is carried out according to the complex geological conditions of Gaoligongshan Tunnel on Dali Ruili Railway as follows. (1) The prototype disc cutter rock breaking and scaled disc cutter wearing experiment are carried out to provide reference for adaptable design of TBM cutterhead and key parameter calculation. (2) The TBM design scheme is discussed from the aspects of high efficiency rock breaking of cutters and cutterhead, TBM over excavation, integrated support system, etc. (3) Two kinds of advanced geological prediction technology, i.e. HSP method and RTP method, are researched. The study results can provide reference for design and manufacture of TBM with high adaptability in complex geology and construction application in Gaoligongshan Tunnel.     

Design and Application of Double shield TBMs  for Urban Metro Tunnels（城市地铁双护盾TBM设计及应用）

With reference to the construction conditions and features of metro tunnels, the design features of double shield TBMs are analyzed and key issues to be considered and settled when a double shield TBMs is used for metro tunnel construction are proposed. The issues include cutterhead′s rock breaking capacity, small curve excavation, selection of backfill grouting technology and jamming prevention and release function in fault and fracture zone, etc., which all have a direct effect on the geological adaptability, tunnel lining quality and tunneling performance of double shield TBMs. Subsequently, the specific design and optimization scheme, which includes the design of cutterhead thick steel plates, tapered shield, monorail hoist and pea gravel backfill and cement slurry grouting, etc., are studied. The success of double shield TBMs in Shenzhen Metro project well proved its remarkable geological adaptability and advantages in efficient mechanized construction.     

Innovation and Future Application of Mechanized and Intelligentized Construction Technology for High speed Railway Tunnels: A CaseStudy of Hubei Section on Zhengzhou Wanzhou High speed Railway（高速铁路隧道机械化修建技术创新与智能化建造展望——以郑万高速铁路湖北段为例）

To ensure the safe, rapid and high quality construction of Zhengzhou Wanzhou High speed Railway, a series of exploration and innovation of construction technology, structural design and information management under the condition of large scale mechanization is used in the whole construction process. The technology includes: （1）A set of advanced geological prediction, advanced pre reinforcement technology of excavation face, mechanized construction technology of primary support, wide waterproof board trolley operation technology and intelligentized full face lining trolley of large scale mechanized construction technology are formed. （2）A classification method of surrounding rock stability is established based on the mechanized construction technology, and the design parameters of the tunnel support structure are optimized under the guidance of New Austria Tunneling Method. （3）To realize informatized management of tunnel construction, the tunnel construction management system, construction information record system, construction safety management system, quality management system of concrete mixing station and quality credit evaluation system are established. Finally, on the basis of mechanized and informatized construction, exploration and outlook of the tunnel intelligentized construction technology are given from the aspects of the dynamic intelligentized design system of tunnel support system, the intelligentized robot construction technology of tunnel support system and the intelligentized monitoring system of tunnel structure, to promote China′s tunnel construction technology.     

Main Construction Technical Difficulties and Solutions of  Shenzhen Chunfeng Tunnel（深圳春风隧道主要施工技术难题与解决方案）

Shenzhen Chunfeng Tunnel is one of the shield tunnels under construction with the largest diameter in mainland of China. The whole tunnel passes through the coastal composite stratum, with rock from broken to integral, and the strength of some sections reaches 173 MPa. The tunnel under crosses the railway, subway, bridge and multiple buildings closely in a complex and sensitive environment. Combining the stratum situation and characteristics of large diameter shield machine, the problems that will be faced during the construction process, including low rock breaking efficiency of shield machine, discharge stagnation and jamming of the chamber, settlement control in sensitive environment, and impact of large diameter shield segment floating, cracking and construction on urban traffic, are analyzed. Based on the engineering experience, the following solutions are proposed: a shield rock breaking efficiency solution for the complete extremely hard rock section, settlement control measures for adjacent buildings and structures of shield driven tunnels, solutions for jamming and discharge stagnation of large diameter slurry shield, comprehensive measures for prevention and control of shield segment floating and cracking, and a slag treatment plan for downtown areas. Chunfeng Tunnel tests the wisdom of Chinese builders with its tremendous volume and strict construction standards, and it also has certain reference significance for other similar projects.     

Scientific and Technological Innovation and Operation related Issues for Island Tunnel of Hong Kong Zhuhai Macao Fixed Link Project（港珠澳大桥岛隧工程建设的科技创新和 运营后应关注的若干问题）

The author explains why a giant undersea immersed tube tunnel was selected for the sea area of the main channel of the east side of the Hong Kong Zhuhai Macao Fixed Link Project, instead of employing a bridge or shield tunnel; and summarizes several domestic and international leading innovative technologies applied in the island tunnel construction of the Hong Kong Zhuhai Macao Fixed Link Project, including the use of huge self stabilized steel cylinders as retaining structure of foundation pits for constructing the artificial islands, the large area and ultra deep "sand compaction pile (SCP) composite foundation" reinforcement technology, "semi rigid segment joints", "sandwich" steel RC combined inverted trapezoid closure joints, and crack control and anti corrosion/durability design for RC tube structure. All these technologies reflect Chinese wisdom and Chinese speed. The author also points out some technical issues to which attention should be paid after the immersed tube tunnel of the project is put into operation: （1） Will the post construction settlement and differential settlement of the immersed tube tunnel further develop after the project is open to traffic? How much is the final convergence value? If it exceeds the limit, what control measures should be taken?（2） How to deal with the issue that the joints of large/small elements or segments are open? How to ensure that all the large and small joints between segments of the tube are "watertight"? Furthermore, the author presents some suggestions and control measures: （1） For excessive post construction settlement (especially differential settlement) spotted on large joints, it is suggested to incorporate "micro disturbance grouting" for post treatment. （2） If a joint opens under the excessive positive bending moment at the floor slab, it is believed that the open joint on the floor slab can be closed again by cutting off some prestressed tendons in the roof slab of the segment to reduce the positive bending moment of the section.     

Great Revolution in Maritime Transportation: Discussion on Preliminary Work and Operation Plan of Bridge/Tunnel Projects for Vacuum HTS Maglev Train at High Speed（畅想海上交通运输建设的伟大革命——真空高温超导磁浮高速列车桥隧工程前期工作与运行方案探讨）

The improvement in the operation speed of the transportation project means the progress and development of the construction technologies in transportation projects. In this paper, the following factors restricting the further improving of the speed of high speed railway are analyzed: as the operation speed increases, the trains in the dense atmosphere are subject to the wind induced resistance and various resistances caused by the friction between the wheels and the rails and by the irregularity of tracks, and the noise will also increase with a high power. Therefore, the economy and safety issues involved in the operation have become the main factors restricting the further improving of the speed of high speed railway. A scheme of vacuum pipelines of underwater vacuum tunnel and/or subwater bridge is proposed in this paper: the pipelines and cars are sealed and vacuated to form the quasi vacuum. The transportation system of the vacuum maglev train at ultrahigh speed with the HTS maglev technology can achieve the operation speed more than 4 times that of the existing HSR train (about 1 200 km/h). Key technologies for constructing the vacuum maglev tunnels/subwater bridges in respect of construction plans, vacuating and sealing, as well as maglev trains are introduced in this paper. The subjects to be further studied on the vacuum HTS maglev tunnels (pipelines) are analyzed from the aspects of technology, management, construction costs, operation expenses, candidate project, airtight materials for cars and evacuation in case of emergencies. It is recommended that "cross sea maglev train in vacuum tunnel" should be developed in the eco tourism project between the coastal cities and their neighboring islands and a series of necessary technical tests should be conducted during the trial operation, so as to obtain related experience. Based on the experience and lessons learned, the transportation system at ultrahigh speed may be implemented for strait crossing projects in China. Finally, a brief introduction to the research on HSR trains at ultrahigh speed in countries such as China, the United States and the Netherlands is presented in this paper. The development of vacuum pipeline transportation can drive the development of China′s transportation modes in a faster, safer and more energy efficient manner, facilitating the development of the fifth generation of transportation industry and its driving role in the social and economic development, and promoting the integration and progress of the economy of China or even the world at a higher speed.     

Achievements and Challenges of Tunneling Technology in China over Past 40 Years（中国隧道工程技术发展40年）

In this paper, the current situation of tunnel engineering in China is introduced, especially the achievements obtained in the field of tunnel construction since the reform and opening up over 40 years. The 34 708 km long traffic tunnel built after reform and opening up takes 96% of the total length. The challenges met and achievements obtained during the key tunnel projects construction in China are presented emphatically from the aspects of extra long tunnel, deep tunnel, large tunnel, tunnel at high altitude and tunnel in complex environment. It is pointed out that: the main technological challenges during extra long tunnel construction are the accuracy of geological investigation, rapid construction and running disaster prevention; the main challenges during deep tunnel construction are high geostress, high waterpressure and high geothermal; the large tunnel faces high design and construction challenges; the challenges during tunnel construction at high altitude are freezing thawing and hypoxia; but still, many tunnels have been built under complex environments, including karst, gas, high geostress, high waterpressure, expansive rock, etc., and many technological breakthroughs have been achieved. The development trend of tunnel projects in China is proposed from the aspects of investigation, design, construction and operation, turning the development speed into development quality. It is generally acknowledged that the tunnel engineering achievements in China over the past 40 years benefit significantly from the development of international tunnel technology. Meanwhile, the development of tunneling technology in China has also greatly contributed to the international tunnel engineering development.     

盾构隧道结构耐久性问题思考

Structural durability of shield tunnel lining is a trans scale problem from mesoscopic material to macroscopic structure. With increasing amount of shield tunnel construction in China, the issues related to structural durability become more prominent. In this paper, the typical applications of shield tunnel lining in China and other countries are introduced. The service conditions and diseases of shield tunnel lining structure are then analyzed. The factors affecting the structural durability of shield tunnel lining, such as material, design, environment, construction, management and maintenance, are summarized. The research results and progress related to structural durability of shield tunnel lining are then reviewed in terms of tunnel durability, durability evaluation and prediction, durability ensuring techniques. Finally, the existing problems and future research directions in structural durability of shield tunnel lining are discussed in terms of durability ensuring techniques, impact of diseases and accidents, tunnel evaluation and rehabilitation, arrangement of secondary lining and establishment of dynamic evaluation system for structural durability.     

Study of Engineering Geological Conditions and Railway Tunnel Scheme across Qiongzhou Strait（琼州海峡工程地质条件及铁路隧道方案研究）

The cross sea channel for the Qiongzhou Strait not only provides a solution for transportation, but also plays an important role in the political and economic development of the region. In addition, the project has an extensive impact on many fields, such as energy, national defense, science and technology, opening up and reform, comprehensive utilization and so on. It is a significant project to enhance China′s comprehensive national strength, defend the country′s territorial integrity and promote regional economic development. The geological conditions across the Qiongzhou Strait are complex. A large amount of existing engineering geological information and hydrogeological data are collected, based on which the seismic impact on subsea tunnels and the main geological conditions including tectonic structures are analyzed. Different options crossing the Qiongzhou Strait have been considered and compared in terms of engineering geology, environmental condition, as well as the construction feasibility. The analystical results indicate that a subsea tunnel has more advantages over a bridge. Because more complicated technical difficulties have to be solved for a highway tunnel which would potentially increase construction and operation costs, a railway tunnel scheme is recommended. Vehicles can be carried by trains through the Qiongzhou Strait railway tunnel. Based on the seabed topography and geological conditions, four preliminary railway tunnel routes are proposed. After a comprehensive comparative analysis, the railway tunnel route Ⅱ is identified to be superior to other alternatives and should be the basis for determining the final tunnel layout. The proposed tunnel cross section includes two railway tunnels and one service tunnel. All the three tunnels have the same structural form and dimension and will be constructed by shield.     

The Current Status and Some Problems of Slurry Shield in China（中国泥水盾构使用现状及若干问题）

For recent ten years, the slurry shield tunnelling technology has been widely used in major underneath river/ocean tunnels and urban metro constructions in China. With the gradual maturity of the slurry shield technology, especially the large diameter slurry shield technology, the numbers of projects and shield machines have been among the highest in the world. However, great challenges arise during the construction of the slurry shield projects under complex geological conditions, such as the stability of the excavation face, cutting tool abrasion, opening the chamber and repairing the machine, slurry circulation with slag, and remanufacturing of the shield. Therefore, it is necessary to investigate the development of slurry shield construction technology in China. Based on typical cases of slurry shield projects, this study analysed the main problems of the slurry shield in the construction process and summarised the current experiences and key technologies. Considering the actual situation of the slurry shield technology, this study clarifies its development direction in China, which is significant to promote the development of the slurry shield technology in the world.     

Key Design Technologies for Cutter Replacing of Super large  Slurry Shield under Atmaspheric condition: Case Studies of Shantou Gulf Tunnel and Shenzhen Chunfeng Tunnel（超大直径泥水盾构常压换刀设计关键技术——以汕头海湾隧道及深圳春风隧道为例）

By analyzing the application cases of super large diameter shield machine in the world and taking China Shantou Gulf Tunnel and Shenzhen Chunfeng Tunnel construction for examples, the problems encountered in the research and development and construction are proposed and the key technologies to solve a series of problems, such as cutterhead maintenance and cutter changing technology under high soil and water pressure, boring in long fractured zone, are explored. More specifically, the technologies mainly involve cutterhead design, atmospheric cutter changing, main drive with telescopic and swinging function, reliable sealing system, anti blockage technique by applying double crushers, which are of great significance to the development and application of super large diameter shield machine.     

Construction Technologies for Tunnels in Special and  Complicated Geology of Lanzhou Chongqing Railway（兰渝铁路特殊复杂地质隧道修建技术）

Lanzhou Chongqing Railway is located in the uplift margin of the Tibetan Plateau, where the geological environment is very complicated and special. Based on numerical analysis and field tests, the physical and mechanical properties, micro structure, and complicated water related stability of the Tertiary sandstone are studied. A comprehensive dewatering system integrating deep surface wells and vacuum light well points in tunnel is used and the construction technique featured with advance reinforcement by horizontal jet grouting for the full face of aquiferous silty fine sand tunnels is invented to solve the problem of the Tertiary quick sand. In addition, the classification method for deformation potentiality in design and dynamic adjustment in construction of tunnels in high geostress soft rock is established, the deformation control technology combining active stress release and passive control according to the deformation mechanism is developed, an automatic real time monitoring system for operation is invented, and a complete technological system of design, construction, and operation management of soft rock tunnels is built. Moreover, the TBM equipment parameter design principles are put forward, the parallel lining and multi stage belt conveyor mucking system is researched, the phased ventilation technology is invented and thus the problem of safe and fast long distance construction by large diameter TBMs is solved. The technological achievements have filled in gaps and facilitated development of the tunnel construction technology.     

Study of Tunneling Technology in Tertiary Sandy Mudstone Strata with Rich Water under High Pressure: Case Study of Shuangfeng Tunnel of Mudanjiang Suifenhe Railway（第三系高压富水砂泥岩地层隧道技术研究——以牡绥铁路双丰隧道为例）

In order to deal with the technical problems of Shuangfeng Tunnel passing through water rich Tertiary sandy mudstone strata with long distance and big overburden, such as dewatering, advance reinforcement, structural design and construction method etc., reducing tunnel deformation, preventing water inrush, gushing mud and tunnel collapse, the technical route of "stereo exploration, pressure reduction by water releasing, pre grouting, supporting timely, overall monitoring" is established after the field test and data analysis. Methods of full dimensional exploration and water pressure reducing are proposed, which form the preceding reinforcing technology that are different between inside the excavation contour and outside the excavation contour. Support linings are constructed immediately after excavation of upper bench. Safety performance of tunnel structure is evaluated according to the monitoring results. The research is conducted based on Shuangfeng Tunnel and the study results are applied in the construction of the tunnel. Results indicate that it can make sense to control deformation and ensure safety by using methods of reducing pressure through full dimensional water release, adopting advance reinforcement measures that are different between inside the excavation contour and outside the excavation contour, proposing mini bench method during tunnel construction and supporting timely after excavation for tunnels passing through water rich Tertiary sandy mudstone strata.