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.     

Application Technology of Spray applied Waterproofing in  Unloading Tunnel of an LNG Receiving Terminal（液化天然气接收站LNG工艺隧道喷膜防水应用技术）

The application of a spray applied waterproof membrane in the case of the liquefied natural gas (LNG) unloading line tunnel constructed via the New Austrian Tunneling Method (NATM) is described. The waterproof standards for the LNG unloading line tunnel are stricter than those for regular tunnels based on the consideration of safety and environmental protection during operation. A double layer waterproofing system including radial grouting, systematic drainage facilities, an EVA sheet membrane, a spray applied acrylate waterproof membrane and other waterproofing and drainage facilities are designed based upon comparisons among several possible waterproofing solutions. The application results and consequential observations prove that the outcome of this waterproof system is satisfactory. The important issues for the successful application of the sprayed membrane in this case are summarized, including a reasonable design for the waterproofing system, performance of the sprayed membrane, proper training for the operators, adequate preparations, careful execution, and complete quality control and acceptance. The successful application of the spray applied acrylate waterproof membrane combined with other waterproofing and drainage facilities in this case has been demonstrated according to the inspection results and provides alternative solutions to improve the waterproof quality of similar tunnels under high standards.     

Some Key Technical Issues on Construction of Ultra long Deep buried Water Conveyance Tunnel under Complex Geological Conditions（复杂地质条件下跨流域调水超长深埋隧洞建设需研究的关键技术问题）

For the water conveyance tunnels in the long distance water diversion projects constructed or planned in China, most of them have to pass through mountain areas with complex geological conditions, due to the constraints of route selection. These tunnels might face engineering problems such as harsh natural environment, high seismic intensity and steep terrain, leading to difficulties in construction and high operational risks. In this paper, some key technical issues on the construction of ultra long deep buried water conveyance tunnels under complex geological conditions are summarized into 5 aspects, namely, (1) exploration and testing techniques for deep buried tunnels, (2) prediction and prevention for large deformation and rock burst in the surrounding rock masses, (3) failure mechanism and anti faulting techniques of the surrounding rock masses and lining for tunnels crossing active faults, (4) synergistic load bearing mechanism and life cycle design theory for rock support system of deep buried tunnels, (5) disaster treatment for deep and long tunnels such as prevention of high pressure water inrush. The scientific and technical problems to be solved and their development directions are pointed out, which can provide some reference for engineering construction of ultra long deep buried tunnels.     

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.     

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.     

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.     

Key Techniques for Construction of Sanyang Road Cross riverTunnel of Wuhan Rail Transit Line 7（武汉轨道交通7号线三阳路越江隧道施工关键技术）

The author focuse on the great challenges encountered during the tunneling process in the Wuhan Sanyang Road Tunnel, and the key techniques adopted to solve those problems. When tunneling in composite strata, engineers inevitably face problems such as inefficient excavation, excessive tool wear, excavation face instability and the risk of clogging. The TBM used in the project allows tool change under atmospheric pressure, which improves the efficiency of tool change and eliminated the risk of casualties during hyperbaric interventions. In terms of the tool wear and clogging, the authors propose technical solutions as follows: the optimization of the tool′s type and configuration, improvement of the central flushing system and chemical dissolution of clogging. The results indicate that through the countermeasures proposed, the tunneling efficiency can be improved effectively. They also reduce the cutter change frequency and eliminate the risk of TBM downtime. The technical achievements obtained in the construction of the Wuhan Sanyang Road Tunnel can provide technical reference for the construction of large diameter shield tunnels in composite strata in the future.     

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.     

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.     

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.     

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.     

Study of Collaborative Management of Intelligent Highway Tunnel（智慧公路隧道协同管理研究）

Aiming to solve the problems of collaborative management of intelligent tunnel and tunnel management under different traffic conditions, the tunnel is regarded as a part of highway, and five features of the intelligence are proposed from the definition of intelligence. In order to realize a collaborative management of intelligent highway tunnel, the spatial extent of tunnel is defined at first. Then, a collaborative management road topology based on road critical nodes is proposed; and a holographic collaborative control information system based on tunnel structure, facilities, vehicle, operation, management, and environment is established. Finally, collaborative control of people, cars, roads and environment could be realized, so as to improve the management level of the intelligent highway tunnels.     

Heat Exhaust Ventilation for Ultra long GIL Tunnel（超长GIL管廊排热通风研究）

The GIL chamber in the utility tunnel under Tanxinpei Road in Wuhan is an ultra long closed structure. Heat exhaust ventilation is the controlling problem in engineering design for the project, especially the heat transfer between the tunnel and the surrounding soil in the long term. A one dimensional model for the GIL chamber is established by using the IDA tunnel simulation software to analyze the short term and long term heat exhaust, respectively. The short term heat exhaust is analyzed for the typical climate of summer/winter/transitional seasons and the long term analysis is carried out under the seasonal changes in 1 year/ 10 years/ 30 years. The short term analysis results indicate that the slope of the utility tunnel and the temperature gradient lead to lower ventilation efficiency in certain areas. The long term analysis results show that the air temperature in the GIL chamber and the wall temperature rise most pronouncedly during the first 5-6 years of operation and remain stable for the remaining time within 30 years. It also is found that around 10%-40% of the heat is released to the surrounding soil. A three dimensional model of the GIL chamber is established using the fluid mechanics based program, OpenFOAM, for 3D simulation. The effects of cables and brackets on the temperature and velocity fields in the chamber are analyzed. The effect of non uniformity of velocity distribution and the stack effect on the temperature distribution in the GIL chamber are revealed. The results can provide some reference for the design and specification revision of heat exhaust ventilation for similar utility tunnels in the future.     

锦屏二级水电站深埋特大引水隧洞关键技术

Seven tunnels across Jinping Mountain are arranged for Jinping Ⅱ Hydropower Station, with a total length of about 120 km. Among them, four headrace tunnels have a length of 16.67 km, an excavated diameter of 12.4-14.6 m, and a cover depth of 1 500-2 000 m in general. The maximum cover depth is 2 525 m, and the maximum external water pressure is more than 10 MPa. The tunnels are featured by great length, great depth and large diameter. It is the largest and most difficult among the underground tunnel groups built or under construction in China and even the world. With complex hydrogeological conditions and special topographical conditions along the tunnels, many challenging problems, such as rock burst under high in situ stresses, groundwater inrush in karst strata and failure of loading bearing structure, were encountered during construction. A great amount of groundbreaking studies were carried out regarding these problems. The key technical problems during construction of extremely large and deep tunnels were solved successfully. Safe and rapid tunnel construction and stable operation were achieved. The hydropower station started operation in 2014 and has been in a safe and stable operation state. The successful construction of headrace tunnels of Jinping Ⅱ Hydropower Station can provide some experiences and reference for deep tunnel projects in the world.     

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.     

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.     

Reflections on Construction of Bohai Bay Crossing Corridor（对兴建渤海海峡跨海通道有关问题的思考）

The author discusses the necessity and urgency of constructing the Bohai Bay Crossing Corridor from the following aspects such as the increasing traffic volume, the convenience of the transportation after the corridor is constructed, and the regional benefit brought by the corridor. As for the timing of the construction of the sea crossing corridor, the author thinks that as long as the national economic situation permits and relevant conditions are basically available, the preliminary work should be carried out as soon as possible so as to promote the early commencement of the construction. Regarding the proposal of building another coastal national highway/high speed railway along the Bohai Bay coast, the author puts forward his viewpoints. In the aspect of construction risks, the author thinks that the geological risks in the construction of the Bohai Bay Crossing Corridor are very difficult to be dealt with; therefore, strict and detailed risk assessment should be carried out, and effective safety measures should be taken to mitigate the risks. The author also briefly describes the technological advantages of the tunnel proposal selected for the Bohai Bay Crossing Corridor, and briefly analyzes some key technological issues in the tunnel construction. The author describes the construction scheme and construction period estimation for the sea crossing corridor in details. The author makes the following proposal are given: (1)the hard rock tunnel boring machine (TBM) assisted by the drilling and blasting method should be used for the construction of the long sea crossing tunnel of Bohai Bay Crossing Corridor; (2) a parallel service tunnel shall be arranged between the twin main tunnel tubes; (3) in Proposal 2, the diameters of the twin main tunnel tubes and the service tunnel should be 8.0 m and 55 m, respectively. The proposal has two optional solutions: Solution 1: The service tunnel ( 55 m) located between the main tunnel tubes will be constructed first; for the main tunnel tubes, the disassembled TBMs ( 8 m) and the backup gantries are assembled for tunneling after arriving at the main tunnel tubes through the service tunnel and the cross passage; Solution 2 (alternative): Tunneling with  55 m TBM is carried out; the  55 m TBM will be dismantled to pass through the cross passage, and then be re assembled after arriving at the main tunnel; the start section (180 m) of main tunnel tube will be formed by  55 m TBM before it is enlarged to  8 m by drilling and blasting method; or the cross passage is enlarged to a large curved space to allow the 5.5 m TBM passing throught without disassembly. Comparison and contrast will be made and the preferred solution will be adopted. According to the rough estimation on the construction period of the 125 km long sea crossing tunnel, the total construction period of "completed tunnel" will be about 19 years (including 5 years of detailed offshore investigation) in Solution 1.     

Research on Heat Transfer Model of Asphalt Pavements Subjected to Microwave Heating Recycling

In　order　to　assess　temperature　field　in　microwave　heating　for　recycling　asphalt　pavements,a　2D　mathematic　heat　transfer　model　was　developed　based　on　Fourier　heat　transfer　theory　The　microwave　internal　heat?generation　was　researched　by　using　surface　field　of　pyramidal　horn　replacing　approximate　radiation　field　In　addition,the　boundary　conditions　were　built　and　normalization　processing　was　implemented　The　control　volume　based　finite　differential　method　(CV-BDM)　was　used　to　establish　the　implicit　discrete　scheme　of　the　conservation equations,and　the　numerical　value　simulation　was　employed　By　continuous　or　intermittent　 radiation　heating　technique,a　microwave　heating　experimental　system　at　2　145　GHz　was　carried　out　to　investigate　temperature　variation　characteristics　of　asphalt　pavements　along　with　heating　time　The　result　shows　that　(1)　the　increase　of　temperature　of　asphalt　mixture　during　microwave　heating　is　obviously　nonlinear,the　temperature　rises　slowly　in　the　initial　stage　of　the　heating　but　increases　rapidly　in　the　late　heating　period;　(2)　the　temperature　distribution　is　non-uniform　that　the　temperature　in　central　area　of　the　surface　is　higher　while　it　is　lower　on　edge;　(3)　the　uniformity　of　temperature　within　asphalt　mixtures　can　be　improved　by　using　intermittent　heating　technique,and　the　heating　time　must　be　reasonable　The　simulation　results　are　in　preferable　agreement　with　the　experiment     

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.     

Research Progress and Prospect on Dynamic Response of SFT Structures(悬浮隧道结构动力响应研究进展与展望)

Construction of submerged floating tunnel （SFT） is one of the major solutions for fjord crossing projects and deep sea crossing projects in the future. Aimed to solve the key problems in SFT construction, the authors present an overview on the progress of the researches made in China and other countries in recent years on cross section of SFT, dynamic response of SFT segment structure, vortex induced vibration of anchor cable, testing technique and applicability of SFT, summarize the critical problems in the dynamic response research of SFT structures and make prospect on the trend of further SFT research. Conclusions are drawn as follow: (1) In the aspect of cross section design, SFT with ear shaped or elliptical cross section has good stability in the complex environment of flowing water, with factors comprehensively considered, such as cross section of SFT segment structures, buoyancy weight ratio and layout. (2) In the aspect of dynamic response of structures and anchor cables, the current research methods are mainly based on theoretical derivation and numerical simulation, and poorly rely on model based testing technique; therefore, it is necessary to perform model tests under combined loads from the environment, traffic and SFT, for mutual check between the theoretical analysis and numerical model. (3) In the aspect of applicability, it is necessary to build small SFT in feasible water conditions to make research on the physical SFT in the static waters, to identify problems and to lay a foundation technically for building large SFTs in the complex sea conditions.