Tunnel Lining Research Articles

Numerical simulation method and deterioration analysis of load-bearing performance of tunnel linings containing cold joints in plain concrete

Cracking in tunnel linings is a common issue in tunnel engineering, with the main cause being construction-induced defects. As a construction-induced defect in a lining, a cold joint affects the bearing capacity of the lining, and the effect of cold joints on the bearing performance deterioration of linings remains unclear. In this study, 180 high-speed railroad tunnels built in Grade III surrounding rock areas were investigated to determine their degradation states, and the distribution of lining cracks in these tunnels was explored on the basis of different factors. Subsequently, three-point bending experiments were conducted on concrete components with different pouring interval cold joint. Based on the experimental results, a computational unit applicable to cold joint simulation was proposed, and the unit parameters were inverted. Finally, the unit was applied to establish a tunnel model with cold joints and to analyze the deterioration effect of cold joints on the bearing performance of the lining. The cracks caused by cold joints in the lining of a structure were found to extend perpendicular to the lining surface, and this can greatly affect the overall strength of the structure. It's important to consider the impact of cold joints on the lining. In order to simulate these cold joints, cohesive elements were used to calculate the maximum stress and stiffness degradation of the lining with and without cold joint elements. The results showed that there were only small differences, indicating that cohesive elements are effective for simulating cold joints. Two cracking patterns were identified, the dorsal tension misalignment model and the medial tension misalignment model, which are related to the stress state of the cold joints. It's necessary to pay attention to cold joints in the inner tensioned area of the lining and those that exceed the final setting time of concrete during pouring.

Effect of laying length on dynamic heat transfer characteristics of capillary heat exchangers in urban subway tunnel lining

The subway tunnel is a typical semi-enclosed underground space, which poses challenges in dissipating the waste heat generated by subway operations and may result in thermal environment deterioration of urban underground spaces. However, by incorporating heat exchangers into the tunnel lining, the subway can be transformed into an “energy tunnel” that effectively addresses this issue. Capillary heat exchanger (CHE) is a common type of tunnel lining heat exchanger. Recent studies have investigated its heat transfer properties and influencing factors under the assumption of homogeneity, neglecting the variability of heat transfer properties along the CHE tube. The present study developed a numerical model of tunnel-lined CHE utilizing water as the circulating medium, based on a demonstration project in Qingdao. Subsequently, an analysis was conducted to investigate the evolution of heat transfer properties for different laying lengths. The simulation results indicate that as the laying length increases from 2 to 10 m, the fluctuation range of outlet temperature decreases significantly from 10.6 °C to a mere 0.4 °C. Moreover, there is a noticeable decrease in average heat transfer per unit length from 1.9 W/m to only 0.4 W/m; however, this is accompanied by an impressive increase in average heat transfer efficiency from 28 % up to an impressive level of around 61 %. Based on the aforementioned results, it is recommended that the optimal length range for a tunnel-lined CHE should fall within 4 to 6 m. The findings of this study can serve as a valuable theoretical reference for the practical engineering applications of CHEs in urban tunnel lining.

An overview of the research trends on fiber-reinforced shotcrete for construction applications

Abstract In this study, data mining, followed by the scientometric analysis of fiber-reinforced shotcrete (FRS), was carried out for knowledge mapping, co-citations, and co-occurrence. The information needed for the analysis was retrieved from the Scopus search engine. Important publishing sources, keyword analysis, writers with the most contribution in citations and publications, the most-cited articles, and the regions most actively engaged in FRS research were identified throughout the data review process. Moreover, the need for FRS, the major constraints associated with their usage, and their possible solutions were discussed. The analysis of the bibliographic data showed that research publications on FRS progressed inconsistently till 2015, and over the past 6 years (2016–2021), publication numbers increased steadily, which exhibited the interest of academics in fiber-reinforced materials. The analysis of keywords in the field showed that the most common FRS research keywords are shotcreting, shotcrete, steel fibers, FRS, and fiber-reinforced materials. Keyword analysis showed that FRS is typically used for tunnel rock support and lining. Based on the review of relevant literature, research gaps have been identified, and future research has been suggested.

Novel corrugated tube–rubber–concrete flexible joint for lining water conveyance tunnels crossing reverse Faults: Numerical analysis of dislocation resistance performance

When water conveyance tunnels cross seismic fault fracture zones, significant deformation may occur, threatening the structural integrity of the tunnel. To resolve this problem, a novel corrugated tube–rubber–concrete flexible joint (CTRCFJ) for improving fault resistance is proposed for the first time. The effectiveness of the CTRCFJ was evaluated using advanced three-dimensional non-linear finite element analysis. The design parameters of the CTRCFJ, including rubber width, corrugated tube interval, and corrugated tube width, were selected based on the distribution of the axial bending moment of the lining structure. An orthogonal test was performed to determine the optimal combination of parameters. The effects of the number of crests, different steel grades, and wall thickness of the corrugated tube on the fracture resistance of the CTRCFJ are investigated. Results show that the CTRCFJ can effectively improve the dislocation resistance performance of composite lining water conveyance tunnels crossing reverse faults by reducing axial compression and bending strain. This study provides a reference for the structural design of composite lining structures that can cross reverse faults.

Nonlinear seismic response and damage evolution of a mountain tunnel: Multi-scale simulation by IBEM-FEM coupled method

Studying dynamic response and damage assessment of mountain tunnels is paramount in earthquake engineering. This paper proposed a novel method, the indirect boundary element method-finite element method (IBEM-FEM) coupled method, aimed to concurrently simulate the amplification effect of kilometer-scale mountain topography and the damage evolution in a centimeter-scale lining tunnel section. The proposed method involves two fundamental steps. Initially, the input motion on the truncation boundary within the mountain is accurately determined using the indirect boundary element method (IBEM). Subsequently, the nonlinear dynamic behavior of the tunnel structure and its adjacent area is analyzed by the finite element method (FEM) based on the results from the previous step. This study numerically simulates the seismic damage and failure mechanisms of a mountain tunnel considering three influence factors: incident wave types, incident wave intensities, and surrounding rock mass grades. The results indicate that mountain topography amplifies the seismic response, thereby affecting the dynamic behavior of the tunnel. Under the incidence of SV-waves and P-waves, the dynamic damage distribution patterns of the tunnel lining are significantly different. Moreover, as seismic wave intensity increases, the peak values of tunnel stress exhibit a non-monotonic increasing trend. The surrounding rock mass grade also significantly affects the dynamic response and damage distribution of the mountain tunnel. Overall, the proposed IBEM-FEM coupled method can effectively consider complex mountain topography and is applicable for evaluating the nonlinear seismic response of mountain tunnels.

Traditional cultivation and management practices of agarwood (Aquilaria malaccensis) in Golaghat district of Assam

A few plant species of the Thymelaeceae family are highly valuable and demanding because it contains resinous oil in their stem, branches, and roots. Agarwood (Aquilaria malaccensis) is one of them, which is found primarily in Assam and adjoining region of North Eastern parts of India as well as in other countries of South and South East India. In Assam, the plant is profusely cultivated in Golaghat, Jorhat and Sivasagar districts. Naturally, stem of the older plant is infected by fungal consortia via the holes made by stem borer. The blackish infection appears inside the stem along the line of the borer tunnel and valuable resinous oil can be extracted through water distillation from the black, infected wood. The agar oil has great demand in international market and is used in manufacturing perfume, incense stick, fragrant smoke, and pharmaceuticals industry. Since ancient time, people of this region have been cultivating Aquilaria with the methods adopted from traditional knowledge and found better success of infection and oil yield. Documentation of this traditional knowledge of Aquilaria malaccensis is of significant importance for promoting its cultivation among the people of this region before the knowledge is lost forever. The knowledge will also be useful for developing scientific method of commercial cultivation of this perennial tree. In this paper, we are discussing the traditional method of cultivation of Aquilaria malaccensis including seedling preparation, cultivation, intercropping and management practices. Agar is propagated through seeds for growing healthy seedlings; and cultivation practices of the plant are of utmost concern for harvesting valuable oil. Extensive field survey has been conducted at Golaghat district of Assam, India to document the method of cultivation and management practices of the plant. The results obtained from the field study were analyzed and interpreted for understanding the importance of this traditional cultivation practice.

Retracted: Intelligent Edge Computing Detection Vehicle and Detection Method Based on Tunnel Lining Concrete

Retracted: Intelligent Edge Computing Detection Vehicle and Detection Method Based on Tunnel Lining Concrete

Performance of Single-Layer Lining Using Shotcrete and Reinforcement Ribs Employed for Supporting Large-Span Tunnel.

Single-layer tunnel lining using shotcrete has the significant advantages of reducing the tunnel excavation volume and saving construction materials, which has been gradually applied in tunnel construction. The high-performance concretes are generally adopted in single-layer tunnel lining for enhancing the bearing capacity of the tunnel lining, whereas the single-layer tunnel lining may still induce damages due to the adverse conditions such as shallow buried depth of the tunnel, and further study related to its application condition is thus required. This paper presents a study of the single-layer tunnel lining with shotcrete employed for supporting the large-span tunnel, in which the reinforcement ribs are also adopted in the single-layer lining for improving the lining stiffness and strength. The study is implemented using numerical simulation, focusing on the safety and performance variation of the single-layer tunnel lining influenced from the varied lining thicknesses and shallow buried depths of the tunnel. The results shows that the single-layer tunnel lining has the obvious advantage of toughness in significantly absorbing large deformation of surrounding rocks and improving the ability to resist lining cracking. The results also demonstrate that the single-layer tunnel lining with shotcrete and reinforcement ribs can safely support the large-span tunnel, in which the stability and safety of the large-span tunnel are confirmed from both the tunnel deformation and lining stresses. Moreover, the factors related to both the lining thickness and shallow buried depth of the tunnel have great influence on the single-layer tunnel lining with shotcrete and reinforcement ribs, in which the insufficient lining thickness and excessive shallow buried depth of the tunnel can induce the damages of the single-layer tunnel lining due to shotcrete stresses exceeding its strength. This study provides some references of employing the single-layer tunnel lining with shotcrete and reinforcement ribs for supporting large-span tunnel.

Case study of performance assessment of overlapping shield tunnels with a small curve radius

AbstractDue to the network planning of subways and their surrounding structures, increasingly more overlapping shields with a small curve radius have been constructed. A newly constructed upper tunnel partly overlaps a lower one, leading to the extremely complex uplift of the lower tunnel caused by the construction of a new tunnel. Based on the shield‐driven project that runs from the Qinghe Xiaoyingqiao Station to the Qinghe Station in Beijing, which adopts the reinforcement measures of interlayer soil grouting and steel supports on site, in this study, the uplift pattern of the lower tunnel and the stress characteristics of steel supports were investigated through numerical simulations and on‐site monitoring. The study results show that among all tunnel segments, the first segment of the shield witnesses a maximum uplift displacement that increases with the horizontal space between tunnels. On using either interlayer soil grouting or steel‐ring bracing reinforcement, the uplift of the tunnel lining exceeds the control value; by contrast, when these two measures are jointly applied, the uplift of the tunnel lining does not exceed a maximum value of 4.87 mm, which can satisfy the requirements of deformation control. Under these two joint measures, the soil strength between two stacked shield tunnels can be enhanced and the uplift deformation can be restricted with the interlayer soil grouting. Also, the segmental deformation and overall stability of the existing tunnel can be controlled with the temporary steel supports. The deformation of circumferential supports and segments is closely related to each other, and the segmental uplift is controlled by H‐shaped steel supports. With the increase in the horizontal space between twin shields, the effect of the construction would gradually weaken, accompanied by a gradual reduction of the stresses of steel supports. These findings provide a valuable reference for the engineering design and safe construction of overlapping shield tunnels with a small curve radius.

Temperature Condition Analysis for Freezing on Tunnel Lining Back Side According to Tunnel Length

Railway mountain tunnels were constructed in cold regions of Korea recently, and freezing has been generated. Most mountainous railway tunnels are designed with waterproofing membranes since groundwater exists on the backside of the tunnels. The lower air temperature inside the tunnel is transferred to the back of the tunnel lining as the outside air temperature drops below zero in winter, causing the groundwater behind the waterproofing membrane to freeze. There have been cases of freezing-related damage, such as the obstruction of drainage flow and freezing groundwater leakage. Therefore, the freezing conditions inside the tunnel should be analyzed by each tunnel length after the air temperature variation in the tunnel is measured. In this study, the air temperature inside a railway tunnel located in a cold region was measured using thermometers. The inside air temperature over time was changed by the DTR (diurnal temperature range) every 24 h. The DTR inside the tunnel was also reduced far from the entrance. Heat transfer analysis was implemented considering the air temperature variation inside the tunnel. Assuming that the minimum air temperature freezing inside the tunnel lasts seven days, the higher the minimum air temperature the longer the tunnel length. The research results show that the freezing inside a tunnel can be estimated from the tunnel length and the minimum air temperature inside the tunnel.

The deformation and failure characteristics of tunnels in layered rock with gentle dip angles after freeze–thaw cycles: Physical model tests and numerical investigation

When a tunnel passes through layered rock with a gentle dip angle in cold regions, the occurrence of multiple freeze–thaw (F–T) cycles can easily cause fatigue damage to the rock bedding surfaces and seriously affect the rock stability. One of the engineering problems that needs to be solved is to determine the deformation and failure mechanisms of such surrounding rock under F–T cycles. Based on the similarity principle, the mechanical response of the tunnel lining structure and the progressive failure process of the surrounding rock under long-term F–T action were studied by performing physical model tests and numerical simulations. The results show that the model tunnel lining partially separates from the surrounding layered rock with a gentle dip angle under the action of F–T cycles. Moreover, the load bearing capacity of the model weakens after undergoing F–T cycles. Additionally, the bending moment and axial force evolution characteristics of the tunnel and surrounding rock model are consistent with the deformation characteristics, which agree with the actual mechanical and deformation characteristics of a real tunnel under F–T cycles. After establishing numerical calculation models for surrounding rock with three bedding angles (0°, 10°, and 20°) and verifying the numerical models based on the test results, the horizontal and vertical displacements of the surrounding rock in the tunnel entrance section under ground stress conditions at a depth of 400 m were calculated. The research results accurately reflect the long-term deformation characteristics of layered rock with gentle dip angles surrounding tunnels in cold regions and can provide theoretical guidance for the application of corresponding tunnel support measures in cold regions.

Intelligent recognition of voids behind tunnel linings using deep learning and percussion sound

Intelligent recognition of voids behind tunnel linings using deep learning and percussion sound

Performance of Precast FRC Tunnel Lining Segments Reinforced with GFRP Bars under Quasi-Static Cyclic Flexural Loading

Performance of Precast FRC Tunnel Lining Segments Reinforced with GFRP Bars under Quasi-Static Cyclic Flexural Loading

Influence of Collection Parameters on Lining Detection Results in Comprehensive Wave Field Method

For hydraulic tunnel lining detection, a comprehensive wave field method is presented for the detection of hydraulic tunnel lining in this paper, and a 1:1 hydraulic tunnel model is built according to the actual engineering situation. The effects of source, sampling rate, offset and group interval on the detection results are analyzed through experiments, a set of parameters suitable for hydraulic tunnel lining detection is finally derived, which can effectively improve the efficiency and accuracy of lining defect detection in the subsequent work.

Experimental investigation on the influence of portal-blocking speed on fire behaviors in tunnel structure

This work provides a series of fire tests in a 1/7 model tunnel to explore the influence of portal-blocking speed on tunnel fire behaviors. Burning rate, ceiling temperature, temperature distribution inside tunnel and thermal characteristic near tunnel portal are obtained and analyzed. Results shown that the comprehensive effect of portal-blocking speed on fire behavior is related to fuel area of fire source. For the fire scenario with small fuel area (Sfuel≤0.18 m2), the effect of blocking speed is not significant. While for the fire scenario with large fuel area (Sfuel≥0.54 m2), burning rate decreases rapidly, due to the blocking of tunnel portals. A critical blocking ratio existed due to the competitive between two action mechanisms of the reduction of air supplement and heat loss. The larger the fuel area is, the smaller the critical blocking ratio is. There is a delay effect on the burning suppression of fire source. For the fire scenario with large fuel area (Sfuel≥0.54 m2), the ceiling temperature distribution was more “uniform”, compared to that of the fire scenario with small fuel area (Sfuel≤0.18 m2). The faster blocking speed can make the ceiling temperature decay to a relatively low level earlier. The larger the fuel area is, the better the suppression effect of blocking strategy is. Earlier and faster blocking operation can effectively suppress the high temperature region, which is beneficial to the protection of tunnel lining.

A formula for hydrostatic pressure calculation in high-pressure railway tunnels

High hydrostatic pressure can cause common problems such as cracking and leakage in the lining of railway tunnels during operation. A clear understanding of the magnitude and distribution characteristics of hydrostatic pressure in tunnel lining under high-pressure conditions is crucial for optimizing the structural design of tunnel lining. In this study, professional equipment was first selected to measure the lining water pressure of two typical sections of Tunnel A on site, and the pressure distribution characteristics were analyzed; Then, a calculation model of the tunnel under high hydrostatic pressure was established using FLAC3D numerical calculation software. Select several calculation parameters and within a reasonable range of values, select multiple values for each parameter instead of just taking one value to form 60 working conditions, and calculate the corresponding tunnel lining water pressure for each working condition. Analyze the correlation between static water pressure and calculation parameters under various working conditions, propose a preliminary calculation formula for tunnel lining static water pressure, and finally use SPSS statistical calculation software to fit the final calculation formula for lining water pressure. This formula is applicable to the calculation of lining hydrostatic pressure under various parameters and is a universal calculation formula for tunnel lining hydrostatic pressure. Our proposed formula is very consistent with on-site measured data under similar geology conditions, providing a new method for calculating the hydrostatic pressure of tunnel lining.

Prediction of maximum upward displacement of shield tunnel linings during construction using particle swarm optimization-random forest algorithm

Prediction of maximum upward displacement of shield tunnel linings during construction using particle swarm optimization-random forest algorithm

Automatic recognition of defects behind railway tunnel linings in GPR images using transfer learning

Ground-penetrating radar (GPR) is widely used for non-destructive detection of hidden defects behind railway tunnel linings, including non-compactness, air- and water-filled voids, fractures, and insufficient lining thickness. However, manual interpreting a substantial volume of GPR B-scan images is time-consuming, and the results heavily depend on the professional knowledge of the practitioner and the available prior information. This paper presents an automatic recognition algorithm for detecting hidden defects, as well as estimating lining thickness in GPR B-scan images of railway tunnels using a You Only Look Once for Panoptic driving perception network (YOLOP) model. The process mainly contains three steps. Firstly, a real GPR dataset of underground objects is employed for transfer learning to enhance the robustness of the prediction model. Secondly, a dataset containing 2,245 real GPR B-scan images of railway tunnel linings is created. Thirdly, the established dataset is used to retrain the YOLOP model and assess the prediction accuracy for identifying hidden defects and lining thickness in GPR images. Field experiment results demonstrate that the trained hidden defects recognition algorithm achieves an average accuracy of 80.6%, with a detection time of only 0.02 s for a GPR image sizing of 1024 × 512. Therefore, it is concluded that the proposed algorithm is efficient and reliable for automatic recognition of hidden defects behind railway tunnel linings.

Viscos-elastic-plastic solution for deep buried tunnels considering tunnel face effect and sequential installation of double linings

Tunnels excavated in soft rock under high in situ stress are usually accompanied by large time-dependent deformation, slow convergence, and long periods of increased support load due to the strong rheological properties of the surrounding rock. This paper presents a time-dependent solution for deeply buried supported circular tunnels excavated in viscoelastic-plastic strain-softening rock masses, in which both the whole process of longitudinal excavation and the sequential installation of two elastic linings are considered. In the solution, the surrounding rock obeys a Burger-creep viscous elastic–plastic strain-softening model and two stages, referring to the “tunnel face influence stage” and the “creep stage”, are divided to derive the explicit expressions of the time-dependent tunnel convergences and support loads, in which the former stage accounts for the effect of stress release based on the elastic–plastic analysis, and the latter concentrates on the long-term response induced by the viscous behavior of the ground. To account for the different rock qualities, tunnel face advance rates, and lining tunnel support locations, the elastic–plastic strain-softening solution in the former stage is divided into three cases and the viscos-elastic–plastic solution in the creep stage includes two sub-solutions depending on the evolutions of stress paths being considered or not. For validation purposes, the provided analytical solutions are compared with the numerical results by finite-difference simulations and previous solutions. Following that, parametric studies are conducted to compare the stresses, deformations, and support loads under different stages and solutions. Finally, to further verify the applicability of the solutions in practical tunnels, the convergences, support loads and lining stresses of a typical tunnel cross-section in the Saint Martin La Porte access adit are successfully predicted. Overall, the proposed solutions in this study provide a profitable idea for deriving various viscoelastic-plastic or elasto-viscoplastic explicit solutions that can simultaneously account for both the rock rheology and tunnel face effect.

Confining pressure forecasting of shield tunnel lining during construction based on LSTM-PSO models combined with the multi-output recursive strategy

The confining pressure is the main source of the internal force of the shield tunnel. Estimating confining pressure accurately holds a pivotal role in the analysis of the shield tunnel structure. Popular belief prefers to consider the confining pressure constant rather than variable along with time. However, the pressure will change dynamically due to the variation of contact between soil and tunnel, underground water level, or internal load during construction. In this study, the complete time histories of confining pressure during the whole construction period, at the top, middle, and bottom of the shield tunnel lining, were acquired through long-term and high-frequency field monitoring. The raw data were preprocessed and transformed into the training and testing set. The models based on the fusion of the LSTM framework, PSO algorithm, and the multi-output recursive strategy, were constructed to forecast the 7-day history of confining pressure. Results show the proposed models have better prediction performance than other traditional models. The number of output layer units impacts the prediction performance of models greatly. Relatively speaking, the models with 6 ∼ 8 units in the output layer have the more stable prediction performance.