China's transportation infrastructure is facing severe challenges such as serious structural defects, short life, aging, and the absence of a long-life security strategy. Therefore, this paper complies the advancements in developed countries regarding these issues and proposes the overall objectives, strategic tasks, and related recommendations for constructing a long-life security system for China’s transportation infrastructure. It also presents systematic research into construction of long-life security systems for transportation infrastructure. This research has a very significant strategic significance in ensuring the safe long-life service of transportation infrastructure and safe and smooth traffic arteries, supporting sustainable development of the national economy, protecting people’s lives in a stable and orderly manner, and contributing to national security and social stability.
China has built the largest scale traffic infrastructure in the world. Owing to many factors, the security of major structures is becoming extremely challenging. This paper analyzes the current development of China’s transportation infrastructure, reviews research progress in related fields at home and abroad, discusses ways to guarantee the safety of the major civil structures during long service lives, and proposes the implementation objectives of a safety plan and key issues to be resolved.
This paper reviews the history and events related to urban underground space (UUS) exploitation in the world, focusing on the status and achievements of UUS exploitation and utilization in China. Further, it proposes development strategies for issues with regard to UUS that need to be resolved urgently, including ① planning UUS in coordination with urban planning and realizing synergetic planning between surface space and UUS; ② refining policies and laws based on China’s national conditions and completing the management mechanism and law system for UUS utilization; and ③ formulating an information platform for UUS, improving the efficiency of using big data, and eliminating the information isolation phenomenon. Finally, with the development of urbanization and information technologies, UUS utilization is poised for a bright future.
Based on the explosion theory of point source, this study obtains the solution of a strong explosion of one-dimensional TNT point source charge, line source charge, and plate source charge blasting in a close-in flow field. Furthermore, this study investigates the propagation characteristic in the close-in field of a shock wave of the TNT spherical charge explosion in real air condition by using the dimensional state equations of real air and the detonation products of a TNT spherical charge. Based on the analysis of the examples, the study results are largely consistent with that of some existing literature. These research results provide an important reference for studying explosion mechanics and protection engineering.
With the continuous increase in bridge service life, problems regarding the safety, durability, and maintenance management are becoming increasingly serious. Safety guarantee issues will become increasingly prominent. In this study, the current safety situation and trends in bridge structure are investigated, along with domestic and foreign scientific and technological developments. The present situation of bridges in China in the field of safety and its challenges are also discussed in this paper. The status and advantages of China’s bridge security technologies, measures, and policies, as well as the main differences between China and foreign countries are analyzed. Furthermore, policies, technologies, and measures for bridge safety and security are proposed. This paper can provide a reference for the development of a major infrastructure security plan.
The bridge deck is the most vulnerable part of a bridge during its entire life cycle. The deck pavement is often adversely affected by improper construction methods, the aging of concrete, and corrosion of steel bars. This then has an adverse effect on the structure and overall performance of the bridge. Therefore, it is necessary to determined defects related to the bridge deck and to conduct relevant quality evaluations. This article describes the mechanism, application methods, and testing equipment of four mainstream nondestructive testing technologies used worldwide: ground penetrating radar, half-cell potential, impact echo, and infrared thermography. The use of one or more of these methods can accurately assess the deterioration of the bridge deck and make a rapid, nondestructive evaluation, which provides technical support for rapid detection and accurate evaluation of the deck situation, leading to reduced structural defects and an extended bridge life cycle.
This paper analyzes four aspects of the safety problems in tunnel lining structures: design and construction, environmental erosion, sudden natural disasters, and sudden accidents. A survey of underwater tunneling such as the Huangpu River’s cross-river tunnel and the underground traffic tunnel in Shanghai was carried out, and the status quo of China’s underwater tunnel lining structure was analyzed. Based on these analyses, countermeasures guaranteeing the long-life security of underwater tunnel structures are being sought regarding tunnel construction, structural performance degradation, sudden natural disasters, and sudden accidents. These countermeasures are being sought to effectively protect and ensure the service performance of the tunnel structures during their entire life cycle. These security measures can ensure the safe performance of the structure during its entire life cycle, even under long service times. This research can serve as a reference for enhancing the structural security of underwater tunnels and other major tunnel structures.
The segment joint is the weak link in the lining structure of subsea tunnels, as it is under the continuous coupled effect of high water pressure and the corrosive seawater environment. If its performance deteriorates, it will seriously affect the safety of the lining structure of entire subsea shield tunnels. Based on an analysis of existing research into segment joint erosion and deterioration, a tunnel service time factor is introduced. Considering the influence of seawater pressure infiltration and chloride ion erosion and migration, a model analyzing the erosion and deterioration of the segment joint over its whole life cycle was subsequently established. The law governing the progressive erosion and deterioration of the segment joints of subsea tunnels over the entire life cycle was analyzed. The effects of seawater pressure and ion concentration on the erosion, deterioration, and steel corrosion of segment joints were studied. Based on the analysis of erosion and deterioration over the entire life cycle, economic and rational measures to ensure the long-term safety of the segment lining structure of subsea shield tunnels were proposed.
This study is presented in view of the current tunnel monitoring maintenance status and existing problems, and proposes reliability-centered maintenance (RCM) as a maintenance concept. RCM can be introduced into tunnel management. Accordingly, a preliminary study on the application of the RCM method in tunnel monitoring maintenance is performed through the tunnel equipment failure mode and a reliability analysis. Finally, by adopting a case, this study shows that a tunnel using the RCM analysis method can effectively reduce the maintenance cost, and has certain economic and social benefits.
Although significant progress in the development of rail transportation infrastructure has been achieved in China, operational safety management and efficient maintenance still has numerous complicated problems to be solved, especially relating to insufficient service life. Therefore, it is particularly urgent to organize and implement a long-life security plan for railway track engineering. This paper first reviews recent achievements in the field of railway track engineering in China, and then introduces advancements in this field in developed countries. Compared to developed countries, current research into long-life safety in the field of railway track engineering in China has much room for improvement; there is the absence of a top-level design, a lack of systematic research work, and insufficient depth and breadth of research. This paper concludes by providing suggestions in terms of theoretical research, talent cultivation, intelligent information management, and performance improvement and recovery.
At present, China is faced with major problems in infrastructure management, such as improper scheduling and belated implementation of maintenance work or huge maintenance budget outlays. As such, it is essential to implement rapid and effective management measures to ensure road safety, prevent catastrophic damage, and increase economic growth. In this paper, five nondestructive road testing methods and their associated testing equipment are introduced according to the American Society for Testing and Materials. These include the falling weight deflectometer, ground penetrating radar, macro texture depth, international roughness index, and spectral analysis of surface waves. The operating principles and applications of each testing method are elaborated to guide relevant personnel to make a reasoned choice according to their actual situation. The application of these testing methods will accelerate the assessment of projects without traffic closures, likely provide a new approach for establishing a high-efficiency intelligent road network monitoring system, and will provide a practical and feasible method for sustainable road development and the efficient utilization of capital.
This paper analyses a pavement fatigue life prediction method for asphalt and cement concrete pavements. A detailed frequency domain analysis of fatigue life was carried out. Using the vehicle-road coupled vibration system model, the random vibration between the vehicle and road caused by road roughness was analyzed. In this paper, it is proposed that the random power spectral density of the vehicle-road coupling vibration is a useful tool to predict the fatigue life of pavements, and corresponding prediction procedures are proposed, which are aimed at providing some reference for long-life pavement design and performance evaluation.
The stability of sandy slopes is poor, as are the protective effects of conventional protection measures. To effectively protect sandy slopes with chemical sand consolidation technology, a new type of sand consolidation agent, TD-1, was developed. In order to study the effect of sand consolidation, proportion optimization tests, penetration tests, wetting-drying cycle tests, and field tests were carried out. The results showed that the strength of the sand samples increases with the increase in the potassium water glass modulus when the ratios of the incorporated silica phosphate, lithium silicate, and silica sol remain the same; the optimum amount of potassium water glass added was 3 % of the solidified sand. The strength of the samples containing the modifier obviously increases, and the permeability of samples with low-modulus potassium water glass is relatively better; the strength of the samples decreases gradually with the increase in the wetting-drying cycle index, and after three cycles, the strength tends to be stable. TD-1 can be used with soil spraying technology for slope greening protection, and the solidified product is good for plant growing.
Urban underground space has become the fastest growing area in global engineering construction and commercial operation. The scale and level of China's urban underground engineering have reached considerably advanced, but ensuing security accidents in urban underground spaces have also significantly increased, and the necessary security monitoring and emergency rescue measures are seriously lacking. This paper focuses on the security issues pertaining to terrorism, explosions, and nuclear biological or chemical attacks in urban underground spaces and analyses the challenges faced by infrared imaging technology when implemented in disaster monitoring and emergency search and rescue. The key technologies and applications presented include shortwave infrared imaging, multi-scale infrared imaging preprocessing, adaptive image enhancement, adaptive infrared environment imaging, and disaster location and alarm. This paper discusses the applications of infrared imaging technology in underground space emergencies such as fires. The research presented here can provide references for security legislation and the strategic planning of urban underground space in China.
Parking problems have become increasingly prominent, thereby seriously affecting the urban environment and traffic order. At present, better utilization and transformation of parking lots and building new lots to vigorously promote the construction of urban underground parking lots are undoubtedly the most effective methods of solving parking problems. This study mainly analyzes the existing problems in construction management, planning, design, and construction of underground parking lots through a typical case investigation on the construction of domestic and foreign city underground parking lots. To address these problems, corresponding development suggestions regarding planning and design proposals, operating model, and investment and financing mode are proposed to guide the scientific and effective development of underground parking lots and solve the urban traffic congestion.
With the increasing developmental scale of urban underground space, the main contradiction of the urban underground space development has gradually turned from the stability of the foundation pit to the deformation control of the environment around the foundation pit. The underground space development surrounding a complex environment may easily lead to uneven surface subsidence and building cracking, resulting in great economic losses. Therefore, the environmental effect of various excavation foundation pits and environmental effect control technology must be systematically studied. This study introduces and reviews the application of statistical, numerical simulation, and model test methods in the study of the environmental effects caused by excavation foundation pits. This study also summarizes the advantages and disadvantages of each research method, introduces the existing environmental control technology and application cases, summarizes the research results on the environment effect of the underground space development, and proposes some suggestions for future research in this field.
The main prospects of the urban underground development in China are a greater depth and a wider dimension. Advanced devices and technologies require the development of new materials. From the aspects of excavation mechanical materials, support materials, and environmental protection materials, this study summarizes the status of the main materials in use and the prospects of new materials. Aside from the strength requirement, an environment-friendly feature is the main requirement of new materials. Thus, self-healing, biological, and green support materials are demonstrated as future prospects.
The intensive development of urban space provides a good opportunity for the development of underground engineering. At the same time, it also demands higher requirements in terms of underground construction technology. In this paper, combined with the advantages of the shield method and shallow tunneling method, a mobile support technology suitable for soft soil tunneling is proposed, and its control effect on ground deformation is also studied. Numerical analysis and field tests show that this technique has a strong ability to control ground deformation. This technique has remarkable advantages in urban short-distance crossing engineering and tunnel construction in districts where there is a strict surface subsidence demand, and as such, it is worth applying and popularizing.
Compared with traditional cast-in-place structures, fabricated structures have the characteristics of saving energy, protecting the environment, eliminating mold, and short construction times. Fabricated structures have been developed rapidly in above-ground buildings. However, the use of underground fabricated structures in China has only recently begun. Owing to the complexity of the underground environment, waterproofing underground fabricated structure joints remains a problem. In this paper, based on an analysis of the joints of an underground fabricated building and of the current state of waterproofing technology, we propose the use of an epoxy grouting material, which is used to pot the prefabricated structure joint, and study the mechanical properties of the epoxy grouting material and its bonded concrete. At the same time, we introduce backfilling technology for prefabricated solidified soil in the foundation pit, and expound the effect of the prefabricated solidified soil on the waterproofing of the underground engineering structures. The research results are good references for similar engineering projects.
This study collects the maintenance history, reconstruction material, and disease data of the Qinghai–Tibet Highway (QTH) over the past 60 years. The QTH is then divided into a stable region, a basically stable region, an unstable region, and a highly unstable region according to the road disease rate. Subsequently, 134 km typical disease sections are selected, and the relations between the road diseases and the mean annual ground temperature (MAGT), permafrost degradation rate, and ice content are studied based on the survey data. The average road service life is also determined. Newly developed diseases and their temporal effect are analyzed using the treatment measure. Furthermore, new stabilizing technologies adaptive to large-scale permafrost subgrade (e.g., distributed ventilation subgrade, unidirectional heat conduction board subgrade, and integrated pavement-subgrade heat drainage structure) are introduced. The results show that the MAGT, degradation rate of permafrost tables, and ice content are negatively related to the road service life. In all kinds of treatment measures, thermosyphon, crushed-rock, insulation board, and ventilation duct plus flag and block stone have a higher effective rate in heat prevention compared to other measures.
This Issue
Dec 2017, Volume 19 Issue 6