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.

Fire is one of the main threat for tunnel safety. Because of their long and narrow shape, fire in tunnels commonly induces fast temperature rising and smoke concentrations,with the consequent loss of life and negative economic impacts. How to control tunnel fires refers to several topics such as traffic monitoring and risk evaluation,fire recognition,emergency evacuation and system control,assisting fire extinction,and updating accident database. To improve the safety and fire emergency response capacity of the tunnel,this work was presented based on the latest metadata system,machine learning strategy,fast fire recognition method,and robot equipment. We discussed the key points for building intelligent fire emergency and evacuation system of highway tunnel, and focused on the composition and function of each sub-part of the system. The proposed ideas and routines can help the designer and engineers to design the corresponding intelligent system for specific tunnels,which will improve the safety of the structure and assure the normal working performance of the tunnels.

When the Yuejiang section of Wuhan Metro Line 8 used the mud-water shield construction method to cross the soft and hard soil-rock composite stratum, the serious tool wear had become an important problem affecting the progress of the project. Through the statistics of the wear data of the typical tool of the engineering shield, the wear coefficient and tool change were used to analyze the adaptability of different types of tools in different layers in different layers. The results showed that, entering the soil-rock composite stratum, the tool was severely worn, and the tooth cutter and the front tearing tool were not suitable for cutting the stratum. after the hob was replaced, the tool wear was still serious, mostly due to uneven wear, chip ring cracking and other abnormal wear; traditional tools. The calculation formula of wear coefficient was not suitable for calculation when the tool was extremely worn. Carrying out research on tool alloy materials and developing new tough tools that are more resistant to impact may be the direction to solve this problem.

Based on the finite element software ABAQUS, taking buried carbon steel pipes and ductile iron pipes as the research objects, and considering the operating load of pipelines, a full-circumferential foundation spring model of the buried water supply pipeline was established. The impact of erosion void on the mechanical behaviors of two kinds of pipelines was studied systematically by the above model. The results showed that erosion void was an important factor affecting the safety performance of buried water supply pipelines. And when the length of the erosion void increased to a certain extent, the axial stress of the pipelines caused by the erosion void would be greater than the hoop stress, which would become the controlled stress that the pipelines bear. Internal pressure was one of the main factors causing the stress of pipeline, but its influence on the longitudinal nonuniform settlement of pipeline was very small and could be ignored. Burial depth and surface load are two important causes of the stress and displacement of pipeline. When the pipelines were buried in the carriageway, attention should be paid to pipelines with a buried depth of less than 1.0 m, and special attention should be paid to pipelines with a buried depth of greater than 4.0 m and less than 0.5 m. The research results of this paper could provide support for the safety assessment and operation management of buried water supply pipelines.

Traditional blasting design is mainly based on experience, and lacks systematic automatic layout algorithm for blas-thole design when smooth blasting is used for rock tunnel. Combined with the design code of blasting and the existing algorithm of blast-hole pattern, this paper introduced a programmatic automatic algorithm of blast-hole pattern suitable for various cross-section shapes from the aspects of computer graphics, simplex integration and automatic layout. Through the characterization of data structure for tunnel cross-section, calculation of geometric parameter and the streamline of division blasting, algorithm of blast-hole pattern for each area was introduced in details. The algorithm was applied to automatic blast-hole pattern design for rock tunnels with four cross-section forms of irregular trapezoid, semicircle arch, circle and ellipse, which verified the feasibility of the algorithm.

Seismic responses of tunnel structures are closely related to the surrounding strata properties. Currently, long tunnel construction develops fast and the tunnel length may reach up to several or even scores of kilometers. The strata parameters along the tunnel have significant spatial variability and correlation. However, the strata data used in the longitudinal seismic design of the tunnel was based on limited borehole data, and thus the random field characteristics of strata parameters between the boreholes have not been considered yet, or at least not well addressed. In this paper, a stochastic field model describing spatial variability and correlation of strata parameters was established based on the random field theory, and the covariance matrix decomposition method was used to generate random field distribution of strata parameters, which were employed into the simplified three-dimensional finite element model to characterize the dynamic interaction between stratum and structure. A series of simulation cases of tunnel longitudinal seismic response considering the influence of random field of stratum parameters were carried out to study the influence of horizontal correlation distance, variation coefficient and mean value of stratum on the seismic response of tunnel structure. Results indicated that: the correlation distance, variation coefficient and mean value all had a significant impact on the seismic response of the structure, and the change of horizontal correlation distance and mean value had a negative influence on the seismic response of the structure while the coefficient of variation had a positive influence. The influence of variation coefficient on the structural response was significantly greater than correlation distance; compared with the mean field without consideration of the randomness, the random field could significantly amplify the moment response amplitude of the tunnel structure by about 80%, and the mean field results would lead to unsafe design under the confidence level of 0.005.

Aiming at the engineering problems of collapse caused by circular tunnel construction in sand, the influences of cover depths, ground loss ratio, particle size and gradation on the stratum deformation in sand were numerically simulated by PFC^2D based on the physical model test results. The results showed that the transmission of disturbance force, which was caused by the circular tunnel construction in sand, was a gradual process, the deeper the buried depth was, the larger the width of settlement trough was, the smaller the maximum settlement value of the ground surface was, and the easier to form the completed arch-shaped stable zone and the “Λ” instability zone; the settlement trough width and the maximum settlement value of the ground surface became large with the increase of the ground loss ratio and there was a linear relationship between the ground loss ratio and the maximum settlement value of the ground surface; the larger the particle size was, the larger the width of settlement trough was, the smaller the maximum settlement value of the ground surface, the faster the disturbance force transmit and the less likely to form the arched stable zone; the influence of particle gradation on the settlement trough width and the maximum settlement value of the ground surface was not significant. The results are of great reference significance for the circular tunnel construction in sand.

When the tunnel crossed the fault fracture zone, it was easy to cause water and mud inrush, the minimum safe thickness of water resisting rock mass is an important guarantee to avoid water and mud inrush. The influence of fault dip angle and strike was considered, the lateral ground stress in the tunnel area adjacent to the faults was solved based on the theory of Terzaghi. The calculation model of mechanical characteristics analysis of water resisting rock mass for tunnel crossing fault was established, and the calculation formula of the minimum safe thickness of water inrush prevention was obtained. The formula was used to calculate the minimum safe thickness in Qilianshan Tunnel, and compared with the actual thickness, which proved the reliability and feasibility of the theoretical solution. The influence factors of the minimum safe thickness were analysed. The results showed that the minimum safe thickness of water inrush prevention increased with the increase of tunnel radius, water head height, fault width and fault strike angle, increased with the decrease of fault dip angle, and decreased with the increase of friction angle and cohesion in water resisting rock mass.

With the start of a series of major underground projects in western China, more and more rockburst disasters bring serious harm to the safety of construction personnel and machinery. However, rockburst has complex failure types and fracture surface characteristics in the specific geological structure. Therefore, a correct understanding of the characteristics of rockburst failure process has become an urgent problem to be solved. GDEM software was used to simulate and reproduce three typical stress-structure rockburst, and the rockburst gestation process, rockburst block movement characteristics and rockburst system energy characteristics were discussed. The study showed that there were great differences in the failure form and energy evolution of bending-bulging, cracking-sliping and splitting-dumping rockburst under different rock mass structures. In addition, the numerical simulation directly showed that the rock burst would not only produce block ejection phenomenon, but also lead to rock mass damage and fragmentation in a certain depth of the rockburst pit. The research results can provide some reference basis for the gestation mechanism of stress-structure rockburst, as well as the macroscopic understanding of rockburst failure phenomenon and the design of rockburst protection measures in construction.

At present, the underwater shield tunnels in China are developing towards large-scale cross-sections, consequently, problems such as large buried depth and high waterpressure had brought great challenges to the safety of the segment lining. Accordingly, the load-bearing performance and failure characteristics of segment lining under high water pressure need to be investigated. In view of this, based on the experimental failure results of two prototype large-sectional segment linings used in the Shiziyang Tunnel and the Sutong GIL UHV Power Pipe Gallery Project, the failure characteristics of the large-section segment lining under high-water-pressure were clarified. In addition, the evaluation indexes for the load-bearing performance of the segment lining was proposed and the recommended control parameters based on the test results were given.