The deep-buried tunnel has the characteristics of high in-situ stress, high osmotic pressure and rich sources of disasters. These factors can significantly increase the risk of water-inrush. Drilling-and-blasting excavation method must be adopted in some sections. The water-inrush in drilling-and-blasting excavated deep-buried tunnel are commonly characterized by concealment, complexity, suddenness and destructiveness and the disaster mechanism is more complicated. There are still some problems in the existing researches, such as the detection and identification of disaster source are inaccurate, the constructed disaster mechanism is unclear, the prevention and control of malignant disasters are inadequate. The existing theories and technologies are not fully applicable anymore, thus, the prevention and mitigation of geological hazards are the key scientific issues remained to be solved. The existing research status are analyzed from three aspects: the advanced geological prediction, the disaster mechanism of water-inrush, and the evolution and mitigation of constructed disaster. Three suggestions were put forward about the key points and directions of the research on the water-inrush in deep tunnel. First of all, it is necessary that comprehensive application of big data analysis and the latest research results of other subjects in order to achieve quantitative and accurate detection. Furthermore, the catastrophic model of disaster sources should be established from the perspective of energy storage and release. The occurrence conditions and emergency mechanism of engineering disasters need revealing. In addition, the method of calculating the safety of impermeable silt layers should be developed and the existing research results also should be applied to practical engineering. Last but not least, the risk assessment theory of the water-rich soft rock section of deep-buried tunnel should be studied seriously. According to the actual conditions of the tunnel, the different technologies of disaster control should be combined organically to maximize the benefits of technology, economy, resources and environment.

Due to the long length of the tunnel, the low efficiency of manual detection and the strong subjectivity, automated and information-based monitoring and detection methods were required for daily operation and management maintenance, and timely diagnosis and prevention. This study introduced several common defects in tunnels and several commonly used monitoring and detection technologies at home and abroad, and analyzed their respective characteristics and detection capabilities. Three common inspection system equipments- UAV, inspection vehicle, and inspection robot were presented, and the applicable conditions and environment were analyzed. The future development trend of tunnel intelligent monitoring and detection was prospected. It was proposed that the development of a variety of comprehensive detection technologies, combined with artificial intelligence and big data analysis is the future trend of intelligent development of tunnel monitoring and detection.

The prevention and treatment of tunnel drainage pipe crystal blockage is very important to the safety of tunnel structure and normal operation of tunnel. Based on the systematic review of domestic and foreign research data, the crystallization process and mechanism of tunnel drainage pipe were analyzed and summarized. The crystallization process in tunnel drainage pipe was summarized as three main stages: the penetration process of groundwater into shotcrete, the dissolution process of calcium in concrete, crystal deposition process in drainpipe. Meanwhile, based on the source of the crystalline material and the crystallization process, the factors affecting the clogging of the tunnel drainpipe were divided into internal and external factors. Internal factors include three types of groundwater quality, surrounding rock types, and shotcrete characteristics. External factors include the characteristics of the aqueous solution in the drainpipe(including the CO₂ content, pH value, salt content in the solution, flow velocity), environmental factors(temperature, pressure)and engineering factors, and elaborated in detail on them. In addition, the prevention technology of drainpipe crystallization blockage was discussed from the aspects of drainage system design, drainage pipe material and concrete mix ratio. Finally, the mechanical, physical, chemical, and biological disposal methods for the crystallization of the tunnel drain pipe were discussed and analyzed in detail. The research can provide a theoretical reference for the prevention and treatment of crystal blocking disease of tunnel drainage pipe.

The construction of railway projects in China is still in the ascendant, and the construction of tunnel projects under complex geological conditions will face more and more challenges. Seven typical engineering disasters during the construction period of railway tunnels were introduced including water inrush, collapse, large deformation, rock burst, harmful gas, high ground temperature and frost damage. According to the types of disasters, a preliminary summary of each disaster case was given. In addition, for some typical disaster prevention and control cases in recent years, the disaster occurrence process, disaster mechanism and specific disposal methods were introduced detailedly to provide reference for future similar project disaster prevention and control. On the basis of summing up the experience and lessons learned from disaster prevention and control of railway tunnels, it was suggested that future disaster prevention and control should focus on the following areas, emphasis on the macro geological analysis of the tunnel site area, development 2019年 - 第1卷第2期田四明,等:中国铁路隧道建设期典型灾害防控方法现状、问题与对策 \=-of comprehensive advanced geological forecasting technologies, improvement of tunnel disaster monitoring and early warning systems, and improvement of the level of disaster risk information management and control, development of large-scale mechanized supporting construction, and reinforcement of the safety quality management of tunnel construction.

The background of the invention of the double-mode shield machine/TBM was reviewed, the multi-mode shield machine/TBM was defined and classified. The working principle of the double-mode shield machine/TBM was explained. The applicable geology formation and environment of the double-mode shield machine/TBM was clarified. The effects of application of the double-mode shield machine/TBM were summarized. The paper has an important reference for the construction of tunnel boring machines under similar strata and environmental conditions.

In recent years, in some super-long water diversion tunnels, construction methods of multi-headed excavation using multiple TBMs have emerged, forming the characteristics of TBM cluster tunneling. The northern Xinjiang Water Supply Phase II Project is a typical representative. The geological condition of this project is extremely complex. Tunnel  construction is faced with many disaster risks such as collapse, water inrush, soft rock deformation with high groundwater, and TBM jamming. There are many high-risk sections and it is of great necessary to carry out geological forward-prospecting. In views of the construction characteristics of TBM cluster and the challenges faced by geological forward-prospecting, the geological conditions and major disaster risks of the project were analyzed, and the features of commonly used geological forward-prospecting techniques were compared. The applicability of forward-prospecting methods under TBM cluster construction conditions as well as the corresponding technical challenges were discussed in detail, and the countermeasures were proposed accordingly. The development direction of TBM geological forward-prospecting technology was further discussed. Recommendations were proposed from the following five aspects: expert decision-making and fusion diagnosis of forward-prospecting for TBM clusters, robust and efficient real-time geological forward-prospecting technology, correct utilization and construction permit of geological forward-prospecting results, TBM intelligent excavation based on “transparent” geological rock mass information and standardization of TBM geological forward-prospecting, etc. These recommendations will be focused and deployed in advance, which will provide guidance for future forward-prospecting in tunnel construction with TBM cluster.

With the development of urban accelerated construction, “urban disease” is becoming more and more prominent, and the development and utilization of underground space is more and more important. By transforming the mode of urban development, scientifically planning the development and utilization of underground space, drawing on international successful experience and paying attention to the development of quality, we can realize the multifunctional utilization of underground space development, realize the “urban diseases” such as urban disaster, traffic congestion, air pollution and urban inland inundation, and take the construction of underground pipe gallery and sponge city construction as an opportunity to resolve the existing problems in the construction of legal system and the reform of management system in a timely manner, realize the harmonious coexistence of man and nature, promote the construction of urban ecological civilization towards a new height, and promote the construction of beautiful cities.

Deep underground rocks are in a complex geomechanical environment featuring high in situ stress, high temperature, and high osmotic pressure. The mechanical responses and failure mechanisms of deep rocks under dynamic loading due to excavation, blasting and earthquakes cannot be explained by traditional rock mechanics theories due to these factors. In recent decades, significant progress has been made in the characterization of dynamic properties of rocks, including compression, tension, fracture and shear. Due to the complex geomechanical environment of deep rocks, extension of these investigations to deep rocks is desirable by considering high in situ stress, high temperature and high osmotic pressure, which is a critical issue in deep rock engineering. This study reviewed existing rock dynamic studies considering such three factors, summarized the influence of these factors to dynamic responses of rocks. Experimental systems, data analytical methods, and experimental results were summarized. In the last, future directions in deep rock dynamics were proposed.

In many cases of shield tunnel collapse accidents occurred both domestically and internationally, the development process of the collapse showed the characteristics of progressive collapse, leading to serious economic losses and casualties. However, the research is still in its primary stage. The lack of understanding of the triggering conditions, development process, and effective prevention measures of the progressive collapse of shield tunnels restricted the high-quality development of urban rail transit in China. Based on the statistical analysis of nearly one hundred cases of tunnels accidents all over the world and focused investigation into 23 typical cases of progressive collapse from 2003 to 2020, the characteristics of progressive collapse of shield tunnels was analyzed. Using statistical methods, the initial damaged location, stratum, damage degree and other factors of shield tunnel progressive collapse accidents and their relationships were categorized and evaluated. The main characteristics were clarified. Based on the comprehensive analysis of multiple cases, the development process of the shield tunnel lining structure damage in the accident was generalized, and it corresponded to the damage degree of the tunnel structure. Finally, considering the interaction between the tunnel structure and the surrounding stratum, the response of the surrounding water and soil during the collapse was analyzed, and it was pointed out that the progressive collapse of the shield tunnels was a fluid-solid coupling dynamic problem. The research results are helpful to improve the relevant understanding of the progressive collapse of shield tunnels, and provide guidance for the prevention and control of the progressive collapse of shield tunnels.

Hydraulic tunnels are widely adopted for water conveyance purpose in the mountainous region of western China. The tunnels usually pass through various stratum with complex occurrence environment and geological conditions, including active faults. Currently, both domestic and foreign codes and regulations regarding tunnel design fail to provide any specifications and recommendations on design philosophy and countermeasures for tunnels crossing active faults and therefore potential threat is posed on the long term stability of water conveyance tunnels. Based on the definition, the classification and the influences of active faults to tunnels, the engineering examples were collected and comprehensive comparisons were made. Totally ten cases regarding tunnels crossing active faults were summarized and the emphasis was placed on the discussion of the design philosophy adopted in each case. It was found that the primary countermeasures consists of four approaches, which were setting up flexible connection section, enlarging excavation dimension, using tubes placed inside the tunnel, and application of composite lining or new materials. Then, the adaptability evaluation of countermeasures for tunnels crossing active faults was reviewed. Some concerning topics and their research progress were summarized and commented. The issues that required further study and improvement were mentioned. Finally, combining the research project “Disaster mechanism of surrounding rock mass and lining structure and countermeasure technology for tunnels crossing active fault”, which was a research program of the National Key Research and Development Program “Efficient Use of Water Resources”, the problems of tunnels crossing active faults were discussed and the potential achievements were prospected.