The major principal stress direction of the tunnel is one of the most important factors affecting the stability of an underground tunnel. This paper is devoted to the quantitative analysis of the effect of the major principal stress direction respect to the tunnel long axis on the stability of an underground tunnel. A total of thirty-two loading levels with three physical models combined with the numerical

In this work, comprehensive numerical modelling was conducted on the full-scale linear cutting test with a TBM disc cutter. Several numerical techniques, including local particle refinement and the coupling of different numerical methods (4D-LSM, DDA, and NMM), were adopted to more realistically reproduce the actual experimental loading conditions. The coupled numerical method was first calibrated

Metro system as the most effective transportation method in urban area, greatly relieve the traffic pressure. The fire safety problem of metro system cannot be ignored as it is easy to develop into a large-area fire due to the relatively closed condition of the metro system. Double fire source is an important process in the development to large-area fire, however, there is still no relevant researches

The purpose of this study is to present an efficient and reasonable methodology to evaluate the seismic fragility of shield tunnels based on investigating the seismic performance of segments and joints in detail. The finite element model of segments and joints is established using appropriate constitutive models and elements. A pseudostatic soil-tunnel interaction analysis approach based on the multimodal

As urban environments densify and cities across the world employ urban underground metros for the effective rapid movement of millions of people a day, there is an essential need to ensure the safe continued presence and operation of those metros. To achieve this, the authors argue there is a need for a more detailed qualitative analysis of how urban underground metro infrastructure and its environment

Water and mud inrush is one of the most important geohazards in underground engineering. The paper presents a state-of-the-art review of the current understanding of this type of geohazard. Emphasis is placed on recorded the geneses and evolution processes of water and mud inrush, as well as relevant prevention methods. In particular, the geneses of this inrush hazard are initially discussed, by providing

This results presented in this paper follow the basic principles and methodology developed for horizontal Single Hole Blast (SHB) testing using terrestrial laser scanning (TLS), introduced in Part 1, and shows specific SHB test applications as a mean to investigate rock blasting behavior. Part 1 introduced a detailed procedure for consistent and systematic SHB testing to provide the means for reproducible

The rock muck is the direct product of a rock-cutter interaction in the tunnel boring machine (TBM) tunnelling. It indicates both the TBM performance and rock mass quality. To investigate the relationships between the rock muck and the TBM operational parameters/rock mass parameters, the most important work is how to characterize the morphological properties of rock blocks reliably. Traditionally,

Large scale Single Hole Blast (SHB) testing is used to characterize blasting behavior in a cost-effective manner. SHB testing provides the means to assess the effect of blasting specifications (e.g. burden dimension, explosive used, borehole diameter) on rock cratering and blast efficiency. The observed behavior depends significantly on the testing procedure and measurements recorded. Crater characteristics

This paper considers the applicability of remote laser sensing to reinforced concrete tunnel linings with suspected corrosion of the reinforced steel. As an alternative to the hammering test, this approach represents a non-contact inspection method that provides quantitative evaluation. Remote laser sensing uses two types of lasers: an impact laser to induce vibrations in the measurement target by

This study investigated the mechanical properties and failure patterns of the steel fiber reinforced concrete (SFRC) lining segments with different fiber parameters using a three-dimensional mesoscale model. The research highlights a sophisticated mesoscale model of the SFRC tunnel segment with randomly distributed steel fibers and considers the nonlinear mechanical behaviors of steel fiber, concrete

A series of numerical simulations were carried out to investigate the effectiveness of a fly-wing smoke screen in improving smoke exhaustion performance in a naturally ventilated urban road tunnel with vertical shafts. The fly-wing smoke screens with different included angles (0°<θ≤180°) were installed under the tunnel ceiling. The numerical results showed that plug-holing was prevented effectively

With rapid rates of urbanisation and significant improvements in construction technologies, the number of subsurface infrastructure projects has drastically increased in recent years. In addition to their primary functions, these structures have shown great potential as energy geo-structures, exchanging heat with the ground to heat and cool spaces. Given their large contact area with the ground, energy

Soil deposits inevitably affect the seismic performance of underground structures, and underground tunnels are commonly constructed on sites composed of layered soil deposits. In this study, dynamic centrifuge tests and numerical modelling are conducted to enhance the fundamental understanding of the kinematic soil-tunnel interaction for tunnels constructed in layered soils that consist of muddy clay

For biogenic gas-rich ground tunneling, control and prevention of gas explosion is an arduous task. Until now, there is still a lack of reliable technologies to eliminate security emergencies such as explosion and combustion. In the present study, geotechnical investigations associated with the biogenic gas-rich ground at Sutong GIL Yangtze River Crossing Cable Tunnel have been summarized. The potential

Maximum temperature rise is an important parameter in tunnel fires. It is noted that classical models of maximum temperature rise in previous studies are limited to single tunnel. However, in real situations, there is cross-passage between two neighboring tunnels. The studies about the effect of distance between fire source and cross-passage on the temperature rise is limited. In this study, numerical

This investigation deals with numerical solution of complex aerodynamic interactions induced by a high-speed train (HST) entering and passing through tunnels with a closely adjacent gap and without in between. We present evidences that included pressure transient on the train surface and tunnel wall and comparisons between slipstreams and aerodynamic loads. The results show that two closely adjacent

A novel precast horseshoe segmental tunnel (PHST) structure was applied in the construction of the west extending project of Beijing Subway Line 6. The seismic performance of the PHST was one of the critical difficulties for the engineering project. A series of investigations were conducted to deal with the problem, including the 1-g shaking table model tests of the PHST buried in sand. In the present

High in-situ stress can limit the generation of rock fractures induced by blasting, which usually shows different states of rock fragmentation with those under low-stress conditions. In this paper, the stress distribution around the blasthole under coupled in-situ stress and blasting load was theoretically analyzed. Then, the single-blasthole blasting process, which is calibrated by field blasting

This study aims to investigate drivers’ visual characteristics under different radii and turning conditions in small-radius optically long tunnels on rural roads. Fixation and saccade were our main research objectives. We conducted real vehicle tests in optically long tunnels under four different radii. Using the distribution of gaze points, fixation duration, and fixation frequency, the drivers’ fixation

Coal has dominated the energy structure in China for a long time. In recent years, dynamic disasters such as rockbursts have affected the safety of coal mine in production with the increase of coal mining depth. Microseismic monitoring is a non-intrusive monitoring technique that can be used to collect much key information: it has been widely applied in coal mine safety monitoring. In this paper, the

This paper proposes a parameter calculation method for the mixed initiation circuit with both nonel detonators (NDs) and electronic detonators (EDs) to increase the detonator delay for reducing the blast-induced vibration in tunnel blasting and to ensure safe circuit operation. The circuit involves the outside-hole delay for increasing the delay numbers under the premise of safe circuit operation.

As a new form of urban traffic, extra-long undersea tunnels have emerged as an important means of transportation to promote the development of coastal cities in recent years. Owing to the black hole effect and the special alignment at the entrance of these tunnels, the occurrence of a traffic accident can often lead to casualties and traffic paralysis. This study analyzed the main characteristics of

A systematic but straightforward probabilistic approach was adopted for the preliminary design using a tunnel case in Egnatia Odos Highway. This tunnel was excavated in a heterogenous molassic formation in Northern Greece, and more specifically in tectonically undisturbed but lithologically varied sedimentary series. This research aimed to identify sources of uncertainty and evaluate its governance

Serviceability limit states (SLS) of segmental circular tunnel rings, subjected to symmetric loading, may experience asymmetric deformations. This is investigated herein, based on real-scale experiments and structural analysis. Single segmental rings, consisting of six tubbings and six joints, were subjected to 24 point loads, simulating ground pressure until convergence-related SLS were reached. Structural

Shield tunnels with great longitudinal differential deformations will adversely affect the service performance and optional safety of the metro system. Previous studies on the longitudinal mechanical behavior of shield tunnel are mostly carried out within the framework of elastic or elastic–plastic theory. However, assuming the concrete as elastoplastic body cannot properly reflect its nonlinear mechanical

An analytical model is developed to simulate the load-displacement performance of rock bolts under axial loading based on Modified Continuously Yielding Criterion. Such a model accounts for various surface geometries of rock bolt as well as the various confining pressures at the rock bolt to the grout interface which play significant roles in the behaviour of grouted rock bolts under axial loading

In this study, based on the construction of a large-span triple-arch tunnel, the authors focus on the surrounding rock mass deformation characteristic, evolution process of rock mass load, and mechanical behaviors of tunnel linings. Numerical modelling is used for rock mass deformation analysis. The leading tunnel excavation would disturb the rock mass of the lagging tunnel and cause its pre-deformation

This article exposes, through the case study of the IFEMA Trade Fair and Exhibition Centre in Madrid (Spain), the benefits of using a multi-utility tunnels (MUTs) system as a smart and sustainable solution for the distribution of utility networks in buildings, or in complexes made up of several buildings, to enable their quick and continuous adaptation. The saturation of the health system in the capital

Predicting the face support pressure and understanding the failure mode for shield tunnel with different longitudinal inclination, δ, in dense sand strata are crucial. Six laboratory model tests are conducted to explore the failure mechanism of tunnel face with δ = 15°, 0°, and −15°. It shows that the face support pressure declines sharply to the elastic limit value, and further decrease slowly to

This paper presents a longitudinal dislocation detection method using an accurate tunnel segment joint labeling algorithm featured by deep CNNs (Convolutional Neural Networks). This method is proposed to be four steps. First, a mobile scanning system is used to acquire 3D point clouds of metro shield tunnels. Then, we use cylinder projection to generate tunnel surface depth images from 3D point clouds

There has been an increasing demand for underground construction due to urbanization and limited land in metropolitan cities in the recent years. However, the behavior of underground structures in soils and rocks is often not completely understood. The emergence of Artificial Intelligence (AI) techniques is envisaged to have a huge potential in addressing geotechnical problems that involve complex

Water inrush is one of the most serious geological disasters threatening tunnel construction. Generally, complexity and multi-sources feature of physical information existing in tunnel construction make disaster prediction very difficult, how to accurately predict the disaster becomes a hot topic in the field of tunnel engineering. Dempster-Shafer (DS) theory of evidence is a widely used method for

Underground logistics systems (ULSs) has been an important topic and research hotspot for urban underground space use in China, especially for implementation in new cities and districts, as it is a necessary element to be considered for city underground space planning. Since these newly planned areas will face many challenges, including increasing logistics volume, spatial constraints etc. if we use

In this paper, the deformation characteristics of tunnel lining structures in different soils are studied by theoretical analysis, numerical modelling and field monitoring. The deformation of segmental lining was monitored by distributed optical fiber sensors in the tunnels of Foshan Metro Line 2 during EPB shield tunnelling. The structural deformation characteristics, including the longitudinal strain

For old pipes that have been in service for a long time in disrepair conditions, it is common to find internal and external defects in the pipelines. The repair technologies for internal defects inside the pipes are well-established, but these technologies for the defects around the pipe are still in the early stage. In this study, an innovative trenchless pretreatment technology for concrete pipes

With the rapid growth of the population density, the above-ground transportation mode cannot withstand the drastic increase in travel pressure. Therefore, the construction of river-crossing tunnels has gradually become an effective way to alleviate traffic dilemmas. To further investigate the ventilation and smoke extraction systems in tunnels, four different kinds of practical river-crossing tunnels:

Slurry shield TBMs with full-face mechanized excavation and active face support using slurry suspension are increasingly being employed for the construction of underwater tunnels. When tunneling in permeable sandy ground, the choice of suitable excavation management system and volume calculation method is extremely important to prevent security emergencies such as face collapse, water inflow and ground

‘Clogging’ is a common issue encountered during tunnelling in clayey soils which can impede tunnel excavation, cause unplanned downtimes and lead to significant additional project costs. Clogging can result in a drastic reduction in performance due to reduced jacking speeds and the time needed for cleaning if it cannot be fully mitigated. The data acquired by modern tunnel boring machines (TBMs) have

The number and complexity of tunnel systems will surely increase with ever increasing population and urbanization. Although most tunnel construction projects have been completed safely, there have been several incidents that have resulted in delays, cost overruns, and sometimes more significant consequences such as injury and loss of life. In this paper we present a database of tunnel accidents that

Historical data indicate that tunnel fires often cause casualties and damage to both vehicles and tunnels. These severe consequences suggest that (1) humans seldom effectively learn from history, and (2) people lack optimal safety response strategies for tunnel fires. To investigate the root causes of accidental tunnel fires and learn from them, we first surveyed the literature on historical tunnel

Protecting existing utility lines in congested urban centers is considered a major challenge especially in cases of new construction bridging over these lifelines. Several innovative techniques have been proposed lately to bridge over existing pipes. This study discusses the use of stiff three-dimensional geogrids to reinforce sandy soils bridging over existing buried Polyvinyl Chloride (PVC) pipe

Due to the complex geological structure and abundant groundwater system in karst areas, the gushing water disasters of mines in karst areas are characterized by large flow rate, high velocity and frequent occurrence, which have become an unavoidable social problem, further caused huge economic losses and casualties. In this paper, a novel treatment method and construction technology were summarized

Development and utilization of Urban underground space (UUS) is one of the key ways for developing sustainable cities. However, the development and utilization of UUS is currently occurring in a passive manner, lacking proactive and quantitative planning. In this paper, an intelligent planning model was established to guide the future development and utilization of UUS. The proposed model, in which

Smoke layer thickness is a key parameter in tunnel fire research. In this paper, the effects of the dimensions of the tunnel cross-section and Heat Release Rate (HRR) in naturally ventilated short tunnel fires were studied. A series of numerical simulations with Fire Dynamics Simulator (FDS) were carried on, and some tunnel model experiments were conducted in a 1/10 scaled short tunnel model to verify

A series of experiments was performed to investigate the evacuation speed distribution in a darkened smoke-filled full-scale tunnel where participants are expected to perform urgent evacuation, the results of which provide fundamental patterns for evacuating pedestrian traffic in the event of tunnel fires. The extinction coefficient was divided into levels, namely, 0 (no smoke), I (0.01–0.5 m−1), II

Rock abrasivity is an important factor that affects tool wear and tool parameter design, construction efficiency, and cost budgeting during rock excavation. The Cerchar abrasivity index (CAI) is used as a standard parameter to characterize the abrasiveness of rocks. It can be obtained through the Cerchar abrasivity test in a laboratory. However, conventional laboratory Cerchar abrasivity tests and

The fires in underground indoor space often result in limited field of vision, thus revealing the characteristic of exit-selecting behavior under the influence of fire and limited view is the basis for optimizing exit layout and emergency evacuation strategies for the underground spaces. In this study, an interactive virtual environment is presented and using which an evacuation experiment is carried

As one of the effective way of smoke exhausting method, the lateral mechanical exhaust system is gradually being adopted in more and more scenarios. While compared to the numerous investigations on the ceiling exhaust system, the of influence of plug-holing and the key factors that affect the smoke exhaust effect of lateral system are quite insufficient. During the smoke exhaust process, the plug-holing

Mine gas explosion accident is one of the most harmful coal mine disasters. Usually, it will cause a lot of property losses and casualties, which seriously restricts the healthy development of the coal mining industry. In this paper, Fluent software is used to simulate gas explosions in straight roadways of different sizes and it is concluded that Fluent software can be used to accurately simulate

The ground displacements with complicated distribution induced by metro shield crossing and overlapping construction can significantly influence the stability of surrounding tunnels and structures, which really need to be monitored in practice systematically and exactly. In the present work, a high-accuracy monitoring system at the observation station was developed to precisely and real-timely monitor

When the shaft-tunnel junction is subjected to vertically propagating SH-waves, the dominant factor is the discrepant responses between the shaft and the tunnel. However, in the case of inclined SH-waves, the travelling wave effect also has a significant influence, especially on the tunnel. To address this issue in an analytical fashion, the displacement field of the ground under travelling SH-wave

Road tunnels are critical components in road transportation networks. In their service life they may subject to explosion loads from terrorist bombing attacks, engineering blasting for construction and accidental explosions from transported flammable goods. These extreme loading conditions might not only lead to catastrophic damages to tunnel structures, severe casualties and economic losses, but also

The understanding of temperature distribution in a railway tunnel caused by train fire can help to optimize the design of ventilation and rescue systems. In this study, a series of experimental tests were conducted in a 1/11 reduced-scale tunnel to investigate the effect of train blocking and internal fire of the carriage on the maximum temperature distribution. Different fire scenarios were discussed

In this work, the collapse conditions of shallow tunnel faces are studied using the Numerical Limit Analysis (NLA) and the Material Point Method (MPM). A particular form (based on a mixed representation of velocities and stresses) of the lower bound formulation of numerical limit analysis was used. The solution using NLA is evaluated considering finite elements for the volume discretization in conjunction

When a shield tunnel is subjected to earthquakes and longitudinal deformation of the stratum, the segment ring may open along the longitudinal direction, thereby rendering the circumferential joint more vulnerable when being pulled. In this study, a self-made loading device was adapted to analyze the mechanical characteristics and failure process of a circumferential joint with a straight bolt in a

Flexural behavior of segmental joints plays a crucial role in the design of lining structure of shield tunnels, and many novel joints are proposed to enhance its flexural behavior. This paper presents a comprehensive investigation of the flexural behavior of a new segmental joint containing double rows of bolts, proposed for a deep-buried shield tunnel in Shanghai, via the full-scale experimental tests

The ground penetrating radar (GPR) is an effective tool to detect the grouting layer behind shield tunnel linings, yet to estimate the thickness from GPR data is always difficult. We herein present a probabilistic inversion method to infer the grouting layer thickness together with its relative permittivity and electric conductivity values from GPR waveform data. This method uses a sliding window and