Tunnel Lining Research Articles

Numerical Modeling and Optimization Design of Embedded Rubber Waterstops in Tunnel Lining

Tunnel water leakage is a common issue. Embedded rubber waterstops are crucial in ensuring the waterproofing performance of mountain tunnels. The deformation performance of a rubber waterstop directly impacts its effectiveness, with structural parameters playing a key role. This study employs numerical simulation methods to quantitatively assess the impact of structural parameters—such as the central hole, ribs, and flanges—on the deformation performance of waterstops. The parametric analysis reveals significant variations in how different structural components affect the deformation performance, as indicated by the defined deformation stress influence rate. Specifically, the deformation performance of the embedded waterstop under tensile, compression, and settlement deformations shows a correlation with factors such as the ratio of the central hole opening rate to thickness and the inner and outer diameters. Additionally, an optimization analysis, taking both economic and performance factors into account, was conducted on 16 types of waterstops with different central hole parameters, from which the optimal waterstop was selected. This research provides a scientific basis for enhancing the deformation performance of waterstops and optimizing their structure.

Hydro-mechanical behaviour of reinforced concrete linings in hydraulic tunnels: transient

The deregulation of the power market and the growing reliance on electricity generation from variable renewable energy sources have significantly altered the operational dynamics of hydropower plants. The shift from hydropower systems designed to function as base load plants to Pumped Storage Schemes (PSPs) characterized by more frequent load changes and start/stop sequences of operations significantly increased the relevance of transient conditions with respect to static ones. While existing research has predominantly focused on the effects of water pressure on tunnel linings under steady-state conditions, little to no attention has been given to transient conditions. This paper addresses this gap in the current literature by presenting a novel model for evaluating the behavior of reinforced concrete linings in hydraulic tunnels during transient conditions. This approach allows for a comprehensive understanding of the intricate interaction between fluid flow, tunnel structure, and rock mass. The insights gained have the potential to significantly advance the assessment and safeguarding of the structural integrity of hydraulic systems operating in PSPs.

MGSLU-Net: a lightweight network for efficient detection of water leakage in subway tunnel linings

MGSLU-Net: a lightweight network for efficient detection of water leakage in subway tunnel linings

A Teacher-Student Framework Leveraging Large Vision Model for Data Pre-Annotation and YOLO for Tunnel Lining Multiple Defects Instance Segmentation

A Teacher-Student Framework Leveraging Large Vision Model for Data Pre-Annotation and YOLO for Tunnel Lining Multiple Defects Instance Segmentation

In-situ analysis of sprayed concrete in a sewage tunnel lining.

In-situ analysis of sprayed concrete in a sewage tunnel lining.

Interfacial bond properties between polypropylene fiber mortar and rock with different roughness

Abstract Abstract: Effective reinforcement measures for the surrounding rock of the tunnel are crucial to ensure the safety of tunnel engineering. Fibers are very effective in improving the quality of the interface; however, to promote the application of fiber mortar (FM) in tunnel lining reinforcement, it is necessary to study the bonding performance between FM and rock. The mechanical properties of ordinary mortar (OM) and FM were investigated, and bonding performance tests were conducted. The effect of polypropylene (PP) fibers on the mechanical properties and the influence of PP fibers and surface with different roughness on the bond properties were analyzed in detail. A 3D printer was used to print various structural boards to characterize different roughness levels, and the shape of the printed model was effectively controlled, thereby ensuring the consistency and repeatability of the structural board. The test results indicated that the splitting tensile strength and volumetric strain of the mortar were improved significantly with the addition of PP fibers, in which the splitting tensile strength increased by 38%, the elastic modulus and Poisson’s ratio increased, and the deformation and energy absorption capacity were enhanced; however, there was little effect on its compressive strength. The bonding performance between mortar and rock surface were enhanced with the increase in roughness, and the direct shear strength recorded the highest value while the bond specimens with a surface roughness of joint roughness coefficient 18-20, also the PP fibers improved the bond properties. This study will be helpful for promoting the application of fiber mortar in tunnel surface lining engineering.

Analysis of Different Noise Reduction Effects of Ground Penetrating Radar Image of Cavity Behind Tunnel Primary Support Based on Singular Value Decomposition and Wavelet Transform

The cavity behind the lining structure is a typical disease in tunnel engineering. Cavity seriously affects the interaction between lining and surrounding rock, resulting in uneven bearing of lining structure and stress concentration, which can easily induce lining concrete cracking, water leakage and other diseases. Accurate identification of lining structure cavities is the key to ensure the normal operation of the tunnel. However, the ground penetrating radar detection images of lining cavities often contain interference signals such as background noise, which seriously affects the accuracy and clarity of cavity detection. The application effects of wavelet transform and singular value decomposition in image denoising and resolution of tunnel lining cavity ground penetrating radar are studied. Under this background, the model test of regular and irregular cavity detection behind tunnel lining is carried out, in which the irregular cavity is located in the surrounding rock environment of filling soil to simulate the real situation of tunnel. The measured images of lining cavity under different working conditions are obtained, and the image denoising analysis is carried out. The results show that singular value decomposition can effectively suppress noise. The ground penetrating radar image after singular value decomposition denoising is clearer, and the image resolution is effectively improved, thus realizing the accurate identification of cavity diseases behind the primary support of the tunnel

Seismic Response of Tunnels Under Effect of Overburden Depth Using Simplified Pseudo-Static Analysis

Earthquakes are one of the natural occurrences that can lead to massive disasters, either on structures or infrastructure. The seismic response and performance of underground infrastructure such as tunnels against earthquake vibrations is predictably severe due to the complex interaction between tunnels and the surrounding soil, especially one embedded in poor soil material properties. In view of this, previous experiences of tunnel damages subjected to earthquake loads have been reported in the literature. Thus, rigorous analysis is necessary to provide indepth knowledge and understanding of the seismic response of tunnels which beneficial to engineering practitioners in especially in early design stage in order to avoid the future risk of tunnel damage and failure during an unpredictable earthquake event. The aim of this study is to investigate the effect of overburden depth on seismic response of tunnels using the simplified pseudo-static analysis, while simultaneously to emphasize the shortcoming of conventional closed-form solution. This study presents a two-dimensional (2D) simplified pseudo-static analysis of soil-tunnel model embeded at 10m and 20m overburden depth subjected to increasing levels of seismic intensity at the transverse direction of tunnel axis. The numerical investigation was performed using the finite element program PLAXIS 2D. The circular shaped tunnel lining are assumed to be elastic, while the soil is considered as homogeneous, and isotropic in plane strain condition. Considering the complex soil-tunnel interaction, the tunnel lining and soil interface is assumed as no-slip condition. The numerical result of pseudo-static analyses were compared with the conventional closed-form Wang‘s analytical solution to verify the reliability of the obtained results. The results denoted that the tunnel embedded at 10m overburden depth experienced considerable seismic-induced deformation and structural forces than tunnel buried at 20m depth. The deformation and seismic induced structural forces of tunnel increased with increment on the magnitude of earthquake loadings. Thus, it can be concluded that the shallow tunnel suffered more damages compared to the tunnel embedded at deeper depth. Overburden depth of tunnel plays a significant role in modifying the seismic response of tunnel apart of the imposed magnitude of earthquake loadings. The conventional closed-form analytical method tends to overestimate the seismic response of tunnel compared to numerical pseudo-static analysis.

Unveiling the seismic sensitivity of the Himalayan tunnels: a comprehensive assessment through analytical and numerical exploration of P-wave dynamics

This study investigated the seismic sensitivity of tunnels in the Jammu Region (JR) of the northwestern Himalayas, a region characterized by significant seismic activity and complex geological conditions. The research combined both analytical and numerical approaches to assess the influence of site conditions, tunnel lining, and reinforcement properties on tunnel resilience. A key objective is to develop a more reliable seismic assessment method by adopting a P-wave-based approach, which is particularly suitable for mountainous tunnels prone to landslides. The study identified three seismic hazard zones, with peak ground accelerations (PGA) ranging from less than 0.3 g to greater than 0.5 g, providing vulnerability aspects. The major outcomes of this study include guidelines for the design and retrofitting of sustainable and resilient underground structures in the Himalayas, with broader implications for global projects in seismically active and geologically complex regions. The methodologies and insights can be applied to infrastructure projects worldwide, enhancing the safety of communities living in vulnerable areas. This work aligns with the United Nations Sustainable Development Goals (SDGs), particularly in promoting resilient infrastructure and sustainable development, contributing to both structural resilience and the geological safety of the Himalayan region.

A study on critical dislocation of gasket for segmental linings of shield tunnels

Dislocation of segments in shield tunnels significantly contributes to joint leakage, making it crucial to identify the critical dislocation amount of segment linings. To explore the waterproofing mechanism of sealing gaskets under water pressure, a structural coupling finite element analysis model was created. This model simulates water intrusion dynamics at segment joints, analyzing contact stress distribution and waterproof performance across various dislocation amounts. The comparison of finite element calculations with experimental data shows a positive correlation, although simulation results are slightly lower than experimental findings. The analysis demonstrates that lower effective contact stress due to dislocation increases leakage risk. In small deformation ranges, opposite segment constraints can enhance gasket contact, reducing leakage risks. However, exceeding critical dislocation leads to leakage. Findings indicate that as dislocation increases, the effective contact stress between the gasket and groove first decreases, then increases. A dislocation of 9 mm and an opening of 8 mm yield the lowest effective contact stress proportion and worst waterproof performance, marking a critical point for sealing water pressure changes. This study provides a scientific basis for determining critical dislocation amounts, optimizing joint sealing performance, and reducing leakage in shield tunnels.

Study on the mechanics and self-sensing properties of ultrahigh-performance shotcrete containing waste glass aggregates

To promote the recycling of waste glass and satisfy the demands of environmental sustainability for ultrahigh performance concrete (UHPC), in this study, glass sand was employed to partially or entirely replace machine-made sand, and steel fibres were incorporated to fabricate ultrahigh performance shotcrete (UHPS). The effects of glass sand and steel fibres on the mechanical and electrical properties of composite materials were analysed in this study. Furthermore, alkali‒silica reaction (ASR) tests and microstructural analyses were conducted. The results indicate that at higher steel fibre contents, the incorporation of glass sand does not reduce the compressive strength of the UHPS and that glass sand has no significant effect on the split tensile or flexural strength. When the steel fibre content is 2% and the replacement ratio of glass sand reaches 100%, the mechanical properties of the UHPS reach their maximum. The addition of glass sand negatively affects the electrical properties, whereas the use of steel fibres improves them. The results of the alkali‒silica reaction tests confirm that the use of glass sand does not induce harmful expansion reactions. The study revealed the trends in the mechanical and electrical properties of concrete from a microstructural perspective and provided explanations for the alkali‒silica reaction outcomes. This study provides technical support for the application of UHPS to tunnel linings.

Experimental Study on Tunnel Failure Mechanism and the Effect of Combined Anti-Dislocation Measures Under Fault Dislocation

Taking the tunnels crossing active faults in China’s Sichuan–Tibet Railway as the research background, experimental studies were conducted using a custom-developed split model box. The research focused on the cracking characteristics of the surrounding rock surface under the action of strike-slip faults, the progressive failure process of the tunnel model, and the mechanical response of the tunnel lining. In-depth analyses were performed on the tunnel damage mechanism under strike-slip fault action and the mitigation effects of combined anti-dislocation measures. The results indicate the following: Damage to the upper surface of the surrounding rock primarily occurs within the fault fracture zone. The split model box enables the graded transfer of fault displacement within this zone, improving the boundary conditions for the model test. Under a 50 mm fault displacement, the continuous tunnel experiences severe damage, leading to a complete loss of function. The damage is mainly characterized by circumferential shear and is concentrated within the fault fracture zone. The zone 20 cm to 30 cm on both sides of the fault plane is the primary area influenced by tunnel forces. The force distribution on the left and right sidewalls of the lining exhibits an anti-symmetric pattern across the fault plane. The left side wall is extruded by surrounding rock in the moving block, while the right side wall experiences extrusion from the surrounding rock in the fracture zone, and there is a phenomenon of dehollowing and loosening of the surrounding rock on both sides of the fault plane; the combination of anti-dislocation measures significantly enhances the tunnel’s stress state, reducing peak axial strain by 93% compared to a continuous tunnel. Furthermore, the extent and severity of tunnel damage are greatly diminished. The primary cause of lining segment damage is circumferential stress, with the main damage characterized by tensile cracking on both the inner and outer surfaces of the lining along the tunnel’s axial direction.

Analysis of the influence of different types of anti-slide piles on lining structures under landslide loading

Investigating the selection of corresponding support methods for tunnel lining structures with different burial depths under landslide loads has strong practical significance. This paper analyzes the influence of anti-slide piles on the lining support of tunnels at different depths through scaling experiments combined with numerical simulation methods. The conclusions of this study are as follows: Under the same anti-slide pile cross-sectional conditions, when the tunnel is at a shallower depth (above the slip surface), due to the influence of the landslide load, a significant bias stress phenomenon occurs in the tunnel lining. When the tunnel is buried at a greater depth (below the slip surface), the impact of the anti-slide pile cross-sectional shape and landslide load on the tunnel lining diminishes. The bias stress ratio gradually approaches 1. Under the same tunnel lining burial depth conditions, h-type anti-slide piles exhibit the best anti-slide performance, followed by square piles, with circular anti-slide piles demonstrating relatively poorer performance. However, h-type anti-slide piles also have the highest cost, whereas circular piles are the most cost-effective. An analysis based on value engineering theory indicates that when a tunnel is positioned above the slip surface, square piles or h-type anti-slip piles offer the most cost-effective support. When a tunnel is buried at a greater depth, circular anti-slide piles represent a cost-effective solution. This study holds certain reference significance for the selection of tunnel support methods at different burial depths within tunnel landslide systems.

Study on the Vibration Propagation Law and Stress Distribution Characteristics in Double-Arch Tunnels During Blasting

Highway tunnel construction in mountainous areas of China has been developing rapidly. The influence of drilling and blasting on the existing tunnel structure has become a key factor affecting the safety and stability of tunnel construction. The double-arch tunnel has unique structural characteristics. The propagation characteristics of blasting vibrations and the resulting stress responses exhibit a certain level of complexity. There is little research on the influence of single-line blasting excavation of double-arch tunnel on the other line tunnel. This paper analyzes the blasting vibration of a double-arch tunnel by ANSYS/LS-DYNA. The propagation law of blasting vibration velocity and stress distribution law of blasting vibration in different sections of the tunnel is revealed. At the same time, the relationship between the peak particle velocity (PPV) and tensile stress is established, and the threshold vibration velocity is proposed. It provides a scientific basis for tunnel design and construction. The propagation of blasting vibration in the adjacent roadway is affected by the middle pilot tunnel. The peak vibration velocity of different parts decreases with the increase in distance. The monitoring of vibration velocity and stress in section A of the right line of the adjacent tunnel should be strengthened, especially in the tunnel vault, blast-facing side wall, and arch foot. The difference in vibration strength across different tunnel parts provides a basis for optimizing the structure. It helps strengthen the parts susceptible to vibration during the design stage of the multi-arch tunnel, improving the tunnel’s safety and stability.

Rebar Recognition Using Multi-Hyperbolic Attention in Faster R-CNN

Rebar constitutes a crucial element within tunnel lining structures, where its precise arrangement plays a pivotal role in determining both structural stability and load-bearing capacity. Due to the rebar’s high dielectric constant approaching infinity, radar signal reflections are intensified, manifesting as distinct hyperbolic patterns within radar imagery. By performing convolutional operations, these hyperbolic features of rebar can be effectively extracted from radar images. Building upon the feature extraction capabilities of the ResNet50 model, this study introduces a Deformable Attention to Capture Salient Information (DAS) mechanism, employing deformable and separable convolutions to enhance rebar localization and concentrate on hyperbolic features resulting from multiple reflections. Before the Region Proposal Network (RPN) and region of interest (ROI) pooling stages in Faster R-CNN, this study integrates a hyperbolic attention (HAT) module. Through refined distance metrics, the hyperbolic attention mechanism enhances the network’s Precision in identifying rebar hyperbolic features within feature maps. To ensure robustness across diverse conditions, this study utilizes a simulated public dataset for tunnel linings, alongside real data from the Husa Tunnel, to create a comprehensive ground-penetrating radar image dataset for tunnel linings. Experimental results indicate that the proposed model achieved an Average Precision of 94.93%, reflecting a 3.14% increase compared to the baseline model. Lastly, in a random selection of 50 radar images for testing, the model achieved a rebar detection accuracy of 93.46%, representing an enhancement of 0.94% over the baseline model.

A Roughness, Feature-based Algorithm of Point Cloud Segmentation of the Secondary Lining in NATM Tunnel

A Roughness, Feature-based Algorithm of Point Cloud Segmentation of the Secondary Lining in NATM Tunnel

A Preprocessing Method to Improve Edge Crack Detection from Railway Tunnel Lining Images

A Preprocessing Method to Improve Edge Crack Detection from Railway Tunnel Lining Images

Performance evaluation method for measuring crack width of tunnel lining detection instruments

Performance evaluation method for measuring crack width of tunnel lining detection instruments

Numerical investigation on failure mechanism of tunnel lining with different fault dip angles and Geological Strength Index under geohazard of fault movement and seismic action

In this article, the failure mechanism of the tunnel under geohazard fault movement and non-uniform seismic load was studied. The study area considered was Atal Tunnel in Himachal Pradesh, India, in the North-West of the Himalayas. A normal fault of 10 m width was considered by varying the fault dip angles of 30°, 45°, 60°, 75°, and 90° along with Geological Strength Index (GSI) values of 20, 40, 60, and 80. The finite element models were analysed under fault movement and 4 ground motions. A fault movement of 0.5 m was applied at the bottom of the fault and hanging wall area. The results showed that fault with 60° dip angle produced more structural forces in tunnel lining under fault movement. The fault with 20 GSI rock mass exhibited higher structural forces in the tunnel lining, irrespective of dip angle. In the case of seismic load, a smaller dip angle generates more structural forces. The tunnel lining in the hanging wall experienced more tensile damage, especially in the direction of seismic wave propagation. The left and right sides of the lining in the footwall area underwent tension, whereas the tunnel crown and bottom experience compression under seismic load.

Analysis on the effect of buried depth-initial water content of the tunnel in expansive rock

There are countless engineering disasters induced by expansive strata in the tunnel project. Nowadays, most of the research focuses on the basic characteristics of expansive rock and soil, while the influence about coupling buried depth and different initial water content of surrounding rock on the tunnel lining is still rarely involved. Based on the principle of temperature and humidity equivalence, this paper discusses the behavior of rock as well as the mechanical properties of lining under the interaction of different buried depth and initial water content by using FLAC3D numerical simulation. It was found that the initial water content show an obvious effect on the evolution about the plastic area of rock compared with the buried depth of the tunnel. For shallow tunnels with a water content of less than 10 %, the plastic zone of the vault will penetrate to the surface after water absorption and expansion. Under the coupling effect, buried depth inhibits the development of the plastic zone to a certain extent. For different initial water contents of the surrounding rock, the displacement of the tunnel adds with the burial depth. The swelling of rock will significantly reduce the safety of the primary support, and when the burial depths of the tunnel increase to 150 m, the security coefficients of some primary support structures are less than 2, which does not meet the need in standard. The safety factor of secondary support is mainly influenced by the expansion force, not the ground pressure (represented by buried depth). The findings may be valuable reference for the analysis as well as evaluation of the security as well as stability of tunnels in expansive mudstone.