Tunnel Structure Research Articles

Fracture evolution in steel fiber reinforced concrete (SFRC) of tunnel under static and dynamic loading based on DEM-FDM coupling model

The frequent or occasional impact loads pose serious threats to the service safety of conventional concrete structures in tunnel. In this paper, a novel three-dimensional mesoscopic model of steel fiber reinforced concrete (SFRC) is constructed by discrete element method. The model encompasses the concrete matrix, aggregate, interfacial transition zone and steel fibers, taking into account the random shape of the coarse aggregate and the stochastic distribution of steel fibers. It captures microscopic-level interactions among the coarse aggregate, steel fibers, and matrix. Subsequently, a comprehensive procedure is formulated to calibrate the microscopic parameters required by the model, and the reliability of the model is verified by comparing with the experimental results. Furthermore, a coupled finite difference method-discrete element method approach is used to construct the model of the split Hopkinson pressure bar. Compression tests are simulated on SFRC specimens with varying steel fiber contents under static and dynamic loading conditions. Finally, based on the advantages of DEM analysis at the mesoscopic level, this study analyzed mechanisms of enhancement and crack arrest in SFRC. It shed a light on the perspectives of interface failure process, microcrack propagation, contact force field evolution and energy analysis, offering valuable insights for related mining engineering applications.

Study on Anti-Dislocation Performance of a Novel Composite Anti-Dislocation Tunnel Structure Crossing Strike-Slip Faults

ABSTRACT A novel composite anti-dislocation tunnel structure (CATS) is proposed as an anti-dislocation measure for tunnels crossing strike-slip faults. The anti-dislocation performance of CATS is verified through numerical simulation. Parameter analysis is presented for CATS, including the circumferential length of the buffer layer, the buffer layer thickness, segment length, fault dip angle, and fault displacement. The results highlight that CATS can effectively reduce both the peak value and the longitudinal damage distribution range of compressive and tensile damage to the secondary lining. The buffer layer in CATS helps reduce compressive damage to the secondary lining, while the flexible joint in CATS aids in reducing tensile damage to the secondary lining. CATS demonstrates good anti-dislocation performance compared to tunnels without anti-dislocation measures or those with only flexible joints. The buffer layer thickness has little effect on the anti-dislocation performance, while a smaller segment length is more conducive to enhancing the anti-dislocation performance of CATS. The anti-dislocation performance of CATS increases with an increasing fault dip angle; conversely, it decreases as the fault displacement increases. These results can provide valuable references for tunnel anti-dislocation design.

The strategy used by naïve anti-PEG antibodies to capture flexible and featureless PEG chains.

Polyethylene glycol (PEG) is widely used as a standard stealth polymer, although the induction of anti-PEG antibodies and consequent effects have drawn attention in recent years. To date, several anti-PEG antibodies induced by PEG-modified proteins via the T cell-dependent (TD) pathway, in which affinity maturation occurs, have been reported. In contrast, structures of the naïve anti-PEG antibodies before affinity maturation have not been described in the literature. Here, to understand the details of the naïve anti-PEG antibodies capturing PEG, we studied a naïve anti-PEG antibody induced by a PEG-modified liposome in the absence of affinity maturation via the T cell-independent (TI) pathway. The mutation levels, structures as well as in vitro and in silico binding properties of TI and TD anti-PEG antibodies were compared. The TI anti-PEG antibody showed no mutation and a low binding affinity toward PEG, meanwhile, it allowed PEG chain sliding and weak interaction with the terminal group. Furthermore, the naïve anti-PEG antibodies may obtain high affinities by forming tunnel structures via minimal mutations. This research provides new insights into polymer-antibody interactions, which can facilitate the development of novel stealth polymers that can avoid antibody induction.

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.

Assessing the role of deep eutectic solvents in Yarrowia lipolytica inhibition

Yarrowia lipolytica has gained recognition as a microorganism with biological relevance and extensive biotechnological applications. Some of its features include a high enzyme secretion capacity and a high cell-density fermentation mode. Hexokinase (YlHxk) is a vital enzyme in Y. lipolytica growth since it catalyzes glucose metabolism through phosphorylation in the glycolytic pathway. Given the potential application of deep eutectic solvents (DES) as novel solvents in biotechnological processes, this study evaluated the influence of eighteen DES on the growth of Y. lipolytica. Furthermore, this work examined the effects of individual ions on the YlHxk enzyme by analyzing its enzymatic tunnel structure, molecule transport, and molecular docking. The results revealed a significant reduction in yeast growth in the presence of most DES compared to the control (medium without DES), with the exception of the [N8881]Cl: hexanoic acid (1:1) DES. The growth varied between 11.95 ± 0.60 and 0.68 ± 0.17g dry cell weight L-1. According to the enzymatic tunnel analysis, DES components associated with the lowest microbial growth values were transported through tunnel 1. On the other hand, DES components had their pathway facilitated through tunnel 2 ([N8881]+ and hexanoic acid) and showed growth values close to the control. Molecular docking analysis identified a similarity between all the ligands in this tunnel (including substrate and product), presenting binding interactions with the ASN273 amino acid of the YlHxk active site. Combining experimental results with computational tools provided promising insights at the molecular level, while also potentially reducing analysis costs and time, paving the way for similar approaches in broad biocatalytic reactions.

Nanoscale nonlocal thermal transport and thermal field emission in high-current resonant tunnel structures

We present a nonlinear model of thermal field emission in resonant tunneling nanostructures with multiple barriers and potential wells, based on an accurate determination of the quantum potential shape and a rigorous solution of the Schrödinger equation, while considering thermal balance. The model applies to vacuum and semiconductor resonant tunnel diode and triode structures with two and three electrodes and to the general case of two-way tunneling with electrode heating. The complete balance of heat release and transfer is accounted for, with heat transport considered ballistic. This approach can also be extended to the non-stationary case, incorporating the influence of space charge. The short flight time of electrons in such structures makes them promising for the fabrication of THz devices.

Opening measurement of rubber gaskets in tunnel segmental joints based on impedance analysis using piezoelectric sensors

Abstract The segmental joint with rubber gaskets is the weakest part of the shield tunnel structure. Poor assembly quality or prolonged loading conditions can compromise the effectiveness of these gaskets, leading to issues such as leakage, seepage, and reduced load-bearing capacity. Currently, there is a lack of effective methods for directly monitoring the state of rubber sealing gaskets. This paper proposes a novel monitoring method for rubber sealing gaskets by integrating flexible piezoelectric sensors (PVDF), based on the principle of structural impedance analysis. First, the mechanical performance equation of the rubber sealing gasket is derived, and a piezoelectric material-rubber sealing gasket impedance model is proposed based on existing research. Subsequently, experiments are conducted on single-set rubber sealing gaskets using piezoelectric impedance analysis, as well as on dual-set rubber sealing gaskets in both series and parallel configurations. The results demonstrate that the impedance magnitude, phase angle, and real part of the impedance of the piezoelectric sensor-rubber sealing gasket structure can effectively reflect the opening state of the rubber sealing gaskets. For the rubber sealing gaskets selected in this study, for every 1 mm of opening, when the applied AC frequency is near the resonant frequency, the impedance magnitude increases by 0.23 Ω, the real part of the impedance increases by 0.3 Ω, and the phase angle decreases by 0.42° at an AC frequency of 300 MHz. In multi-set rubber sealing gasket simultaneous monitoring, the monitoring performance with series-connected internal sensors is found to be superior to that with parallel connections. When both sets of rubber sealing gaskets open simultaneously, compared to a single set of gaskets opening, the impedance magnitude curve generates an additional extreme point near the resonant frequency. This additional extreme point can serve as a signal to determine the opening of multiple sets of rubber sealing gaskets.

Experimental study on modal analysis and vibration response of tunnel structures under different damage conditions due to subway train loads

Based on a prototype of the Beijing subway tunnel, this research conducts large-scale model experiments to systematically investigate the vibration response patterns of tunnels with different damage levels under the influence of measured train loads. Initially, the polynomial fitting modal identification method (Levy) and the model test preparation process are introduced. Then, using time-domain peak acceleration, frequency response function, frequency-domain modal frequency, and modal shape indicators, a detailed analysis of the tunnel’s dynamic response is conducted. The results indicate that damage significantly amplifies vibration acceleration, with the amplification increasing with the severity of the damage. When the crack lengths are 2 cm, 4 cm, and 6 cm, the peak acceleration increases by 25.12%, 36.35%, and 50.29%, respectively, while adjacent segments show increases of 13%, 29%, and 45%. Damage decreases the tunnel structure’s modal frequency, with the first two modal frequencies showing the most significant reductions of 9.87% and 7.34%, respectively. The adjacent segments show reductions of 7.7% and 4.2%. As the severity of the damage increases, the amplitude of the modal shape at the damaged location also increases, with the first modal shape rising by 43.37% for 4 cm damage compared to 2 cm damage and by 72.21% for 6 cm damage. The second modal shape increases by 9.04% and 26.51%, respectively. Additionally, the effectiveness of the polynomial fitting modal identification method (Levy) for tunnel structural damage detection was validated. Finally, based on the methods outlined above, the tunnel responses measured on-site in the Beijing metro were also analyzed. The findings of this study provide important theoretical support for the assessment and routine maintenance of metro tunnels.

Field Monitoring and Analysis of Factors Influencing Existing Tunnels Laterally Adjacent to Foundation Pit Excavations

To investigate the factors influencing existing tunnels adjacent to foundation pit excavations, this paper focuses on a case of excavation of MTR station foundation pits near an existing tunnel. Monitoring data are collected and analyzed, and a two-dimensional numerical model of the pit–tunnel system is established using ABAQUS (2022) software. This study examines the effect of excavation factors on the tunnel, including excavation depth, horizontal spacing between pit and tunnel, support pile wall dimensions, support structure insertion ratio, horizontal support stiffness, and geological conditions. The research results indicate that for tunnels in silty clay formations, the depth of pit excavation should be limited to 20 m. When the horizontal spacing between a foundation pit and tunnel in a silty clay formation is within 1.5 times the depth of excavation, the tunnel is more significantly affected by tunnel excavation works in the adjacent pits. Increasing the horizontal support stiffness has the greatest effect on controlling deformation and stress in the tunnel structure. The degree of influence on deformation and stress in the tunnel due to laterally adjacent excavation of a foundation pit varies with geological conditions. Among them, tunnels in muddy-silty clay and silty soils are the most affected, and it is recommended that reinforcement measures be optimized and monitoring be strengthened. The conclusions of the present study can provide a reference point and guidance for the optimal design of similar pit projects.

Preparation of sandwich-structured V6O13via direct current magnetron sputtering for high-capacity zinc-ion batteries.

Aqueous zinc-ion batteries are an appealing electrochemical energy storage solution due to their affordability and safety. Significant attention has been focused on vanadium oxide cathode materials for ZIBs, owing to their high specific capacity, unique layered or tunnel structures, and low cost. Compared to traditional methods for preparing and assembling electrode materials, direct current (DC) magnetron sputtering allows direct synthesis and uniform deposition on current collectors, offering advantages such as simplicity, mild reaction conditions, and strong film adhesion. Therefore, we synthesized sandwich-structured vanadium oxides (V6O13) with a V-O framework on stainless steel using this method, and for the first time, employed them as cathode materials for zinc-ion batteries. The unique crystal structure of V6O13 features numerous ion diffusion channels, providing ample sites for zinc ion embedding. Additionally, the multiple valence states of vanadium in V6O13 contribute to its high specific capacity and excellent coulombic efficiency during the charge/discharge process. The V6O13 synthesized at 400 °C in 3% O2 exhibits the highest specific capacity (550 mA h g-1 at 100 mA g-1). This synthesis strategy demonstrates significant application potential and offers a new pathway for the fabrication of other oxide thin-film electrode materials.

Analysis of Environmental Vibrations in Suburban Railways Affected by Adjacent Bidirectional Tunnels

Train-induced environmental vibrations are a common issue in urban rail transit systems, particularly in suburban railways operating at high speeds, where the impact of these vibrations is more pronounced. This presents significant challenges for urban planners and engineers. Existing research has mainly focused on the impact of single tunnel structures on ground vibrations, with limited understanding of the vibration propagation characteristics of adjacent bidirectional tunnels. To address this gap in knowledge, this study investigates the ground vibration attenuation characteristics induced by train operations in the underground sections of suburban railways, with a focus on the amplification effects of adjacent tunnels on ground vibrations. The results show that the vibrations induced by the trains are concentrated in the 20–50 Hz frequency range and exhibit similar characteristics in all directions. The maximum vertical vibration acceleration and peak acceleration occur directly above the train tunnel. Additionally, adjacent tunnels significantly amplify the maximum peak acceleration at measurement points in directions perpendicular to the track, including both horizontal and vertical directions. Furthermore, the soil within the adjacent tunnels also exhibits amplification of the vertical power spectral amplitude in the 40–100 Hz frequency range. The findings of this study provide new insights into the influence of adjacent bidirectional tunnels on environmental vibrations in suburban railway operations. These results are of significant importance for optimizing railway design and vibration mitigation measures.

Construction of advanced Nb9VO25 electrode material by introducing graphene quantum dot for high energy supercapacitors with exceptionally high diffusive capacitance

Unreasonable tunnel structure and low intrinsic conductivity limit practical applications of niobium oxide in high-performance supercapacitors. The study reports the construction of Nb9VO25 electrode material via coordination of Nb(V) and V(V) with histidine and serine-functionalized and boron-doped graphene quantum dot (HSBGQD) and subsequent annealing. The introduction of HSBGQD and rambutan peel leads to formation of small Nb9VO25 nanocrystal and low valent Nb and V species. The combination of small size and more reasonable tunnel structure accelerates the ion diffusion. The Nb(IV) and V(IV) double doping optimizes the tunnel structure, narrows the bandgap and creates new pathways for high-speed electron transfer. The integration of defect engineering with graphene surface modification enhance the intrinsic conductivity. The Nb9VO25 electrode shows exceptionally high specific capacitance of 2925.3 F/g, which is more than 142 times that of Nb2O5. The symmetrical supercapacitor with Nb9VO25 electrodes and PVA/Li2SO4 gel electrolyte offers high specific capacitance (263 F/g at 1 A/g), high-rage capacity (138 F/g at 50 A/g), cycling stability (capacitance retention of 99.4 % after 10000-cycle), energy density (146 W h Kg−1 at 996 W Kg−1 and 77 W h Kg−1 at 50181 W kg−1) and broad application prospect in wearable electronic devices.

Impact of foam metal hoods on pressure waves generated by high-speed trains traversing tunnels

The high-speed trains traveling at 400 km/h will generate severe alternating pressure and potential sonic boom when passing through tunnels. This paper proposed foam metal hoods (FMH) to mitigate the pressure waves induced by trains traversing tunnels. 1:20 scaled moving-model experiments were conducted to investigate the mitigation mechanisms of FMH on micro-pressure waves (MPW), residual pressure, and aerodynamic loads on the train and tunnel. The impact of FMH's installation position and length on MPW and residual pressure were discussed. The results indicate that the entrance FMH can weaken the expansion wave generated by the tail train entering the tunnel, thereby reducing the pressure amplitude on the train surface and tunnel wall. FMH can reduce the reflection intensity of pressure waves, effectively lowering the root mean square (RMS) of residual pressure. Installing FMH at both ends can reduce the RMS of residual pressure in the middle of the tunnel by 25%. The exit FMH enables the initial wavefront to gradually release pressure outward, thereby reducing MPW intensity. The radiation range of the MPW iso-surface is narrowed by energy consumption as the wavefront passes through the porous structures. The mitigation ratio of MPW intensifies as the length of the exit FMH increases. Using a 4-m-long exit FMH can decrease the MPW amplitude by 83.2% at 20 m from the FMH exit. The FMH facilitates a low-noise environment near tunnel portals, reducing the aerodynamic loads on the tunnel structures, and mitigating the train aerodynamic loads.

MoO3 based nanocomposites for the photocatalytic degradation of colourants – A review

BackgroundPhotocatalysis is the most environmentally friendly method for reducing and mineralizing organic contaminants because of its high efficacy, low toxicity, and low cost. Semiconductor photocatalysts are one of the most intriguing catalysts because they are safe and produce no secondary pollution, making them one of the best at removing pollutants from water. MethodsTransition metal oxide molybdenum trioxide (MoO3) is a widely used photocatalyst because of its tunnel structure and one-dimensional behaviour. Because it is common, has strong electrochemical activity, is non-toxic, and kills bacteria, MoO3 also plays a big role in semiconductor photocatalysts. MoO3 outperformed other oxide semiconductors as photocatalysts owing to its superior adsorption properties. MoO3 is commonly found in three polymorphs: orthorhombic, monoclinic, and hexagonal. In addition, the efficacy of various experimental settings on the deterioration of various colourants was investigated. Scientific findingsAs a result, the current study examines the photocatalytic activities of various MoO3-based nanocomposites as well as the results of various experimental conditions, with a particular emphasis on extensive colourants.

Sustained Tl(I) removal by α-MnO2: Dual role of tunnel structure incorporation and surface catalytic oxidation.

Manganese oxide-based filtration technologies are considered cost-effective for thallium (Tl) removal in engineered systems. However, current gaps in understanding the heterogeneous adsorption and oxidation mechanisms of typical tunneled α-MnO2 may lead to a serious underestimation of its long-term Tl removal potential. In this study, α-MnO2 could continuously remove Tl(I) during the 584-h reaction, with its irreversible removal eventually increasing to 81 %-95 % in different anionic environments. The adsorbed low-loaded Tl(I) is preferentially oxidized, whereas the high-loaded Tl tends to be adsorbed in a nonoxidative pathway by α-MnO2. The nonoxidized Tl(I) was gradually immobilized in the stable thalliomelane-like tunnel structure. More importantly, the synergism of surface Mn(III)-oxygen vacancies (Ov) on α-MnO2 could catalyze the oxidation of Tl(I). Furthermore, the oxidized Tl(III) was bound to the tunnel surface via double edge-sharing and double corner-sharing. In addition, the phosphate anion occupied the surface active site and inhibited the oxidation of Tl(I), thereby reducing the binding strength of Tl. This study provides a new perspective on the effectiveness and stability of Tl(I) removal by MnO2 and highlights the neglected mechanism of Mn(III)-Ov mediating Tl(I) oxidation, which expands our understanding of the removal and transformation fate of Tl in MnO2-engineered systems.

Expansion counteraction effect assisted vanadate with rich oxygen vacancies as a high cycling stability cathode for aqueous zinc-ion batteries.

In this study, a novel tunnel structure vanadate NaVO (Na0.465V2O5) cathode for aqueous zinc ion batteries (AZIBs) is facilely fabricated by thermal decomposition of polyoxovanadate containing NH4+ ions. The NaVO cathode is characterized by abundant oxygen vacancies and nanometer dimensions. These attributes can offer extra reaction sites and suppress structural collapse during circulation. In the charge-discharge process, a unique phenomenon occurs where NaVO undergoes opposite expansion (positive vs. negative expansion) along its different crystal planes. This opposite expansion produces an "expansion counteraction effect", which effectively buffers the volume change of NaVO. Additionally, the irreversibly inserted Zn2+ ions as "pillars" are maintained in the framework after the first discharge, further improving the structural stability of NaVO. Consequently, the NaVO cathode exhibits superior cycling stability. The capacity retention rate can reach 87.3% after 350 cycles at 0.1 A g-1. With a high current density of 2 A g-1, the specific capacity can be maintained at 206.3 mA h g-1 with a capacity retention of 95.5% after 2100 cycles. This study not only provides a novel approach for synthesizing nanoscale vanadate cathodes with rich oxygen vacancies, but also proposes the "expansion counteraction effect" theory, offering innovative insights into the design of high cycling stability cathodes for AZIBs.

Mechanical behavior and damage evolution of tunnel lining structure under the impact of derailment of high-speed train

In deep-buried long tunnels, train derailment accidents pose a serious threat to the stability of the tunnel lining structures and the safety of personnel along the line. To address the impact damage to the secondary lining caused by high-speed train derailments, a three-dimensional nonlinear dynamic analysis model of the Electric Multiple Unit (EMU) − lining − soil system was established. The advantages of this model include: it fully considers the complex streamlined design of the EMU front end, the nonlinearity of lining materials, and the M−C elastic structural model of the soil, allowing for accurate simulation of the contact and deformation between the EMU and the lining. The results indicate that the first 30 ms of the collision process are extremely intense, primarily involving the first three train vehicles. Among these, the head vehicle experiences the greatest reduction in kinetic energy and plastic dissipated energy, resulting in the most severe plastic deformation of the vehicle body. The impact load exhibits a distinct multi-peak characteristic, mainly composed of lateral impact force components. The area of displacement change in the lining expands continuously along the direction of the train, with peak displacements stabilizing after 30 ms. The lining primarily suffers from tensile failure, with multiple tensile cracks appearing in areas distant from the collision, while compressive damage is mainly concentrated at the point of direct impact. As the collision angle increases, the range of compressive damage along the longitudinal direction becomes narrower. The ratio of tensile damage area to compressive damage area is mainly influenced by the collision angle. In the design of tunnel structures for impact resistance, special attention should be paid to the lateral impact resistance and tensile failure capacity of the tunnel structure.

Geophysical methods reveal a subsurface historic wastewater tunnel exposed by a sinkhole: a case study in Bandung City, Indonesia

Bandung City, the capital of West Java Province in Indonesia, has changed its physical face rapidly due to the many constructions of office buildings, hotels, and other facilities until now. To avoid the instability of existing buildings and for building construction in the future, knowledge of the subsurface conditions in the city must be enhanced. A sudden soil collapse in the yard of the PAG Building occurred in early 2018 and resulted in a sinkhole with a diameter of 5 m, which revealed a historic wastewater tunnel structure in the subsurface. Non-invasive, low-cost, and time-effective geophysical methods to solve those problems are proposed. Ground-penetrating radar (GPR) and Electrical Resistivity Tomography (ERT), widely applied to identify artificial objects underground, came to be used for these purposes. A research to know the suitability of both methods for application began with numerical simulation, followed by field measurement on 4 GPR and ERT lines and analysis of each method. The results show that GPR data, through both numerical and field data, could identify and locate the tunnel in a radargram due to its hyperbola shape, whereas ERT data provided the property contrast between the tunnel and its host. The results suggest that GPR and ERT techniques are effective for revealing water tunnels in the study area with a maximum depth of 1.8 m and a 65% reduction in size. These findings can be used as a guide to using both methods to reveal the water tunnel network in the central part of Bandung City for sustainable urban planning.

Discovery of Novel 4,5,6,7-Tetrahydro-7H-pyrazolo[3,4-c]pyridin-7-one Derivatives as Orally Efficacious ATX Allosteric Inhibitors for the Treatment of Pulmonary Fibrosis.

Pulmonary fibrosis (PF) is a progressive, fatal lung disease lacking effective treatments. Autotaxin (ATX) plays a crucial role in exacerbating inflammation and fibrosis, making it a promising target for fibrosis therapies. Herein, starting from PAT-409 (Cudetaxestat), a series of novel ATX inhibitors bearing 1H-indole-3-carboxamide, 4,5,6,7-tetrahydro-7H-pyrazolo[3,4-c]pyridin-7-one, or 4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine cores were designed based on the structure of ATX hydrophobic tunnel. The optimal 31 and 35 inhibited ATX with IC50 values of 2.8 and 0.7 nM, respectively. In a bleomycin-induced mouse PF model, both compounds significantly reduced fibrosis by regulating the TGF-β/Smad signaling pathway and downregulating collagen deposition. Furthermore, 35 exhibited both negligibly low hERG channel inhibition (IC50 > 30 μM) and remarkable microsomal stability. Notably, 35 was characterized by favorable pharmacokinetic properties (F = 69.5%) and excellent safety in vivo. Overall, 35 turned out to be a well-characterized potent and safe ATX inhibitor warranting further investigation for the treatment of PF.

Unified Elasto-Plastic Solution for High-Speed Railway Tunnel in Cold Regions Considering Dual Transverse Isotropic Model of Frozen Rock Mass

Frost damage is one of the main influencing factors for the deterioration of support structures in cold-region tunnels. A new dual transverse isotropic model of frozen rock mass is first proposed based on parameter strain and elastic modulus to serve as the theoretical basis for tunnel operation safety in cold regions. Subsequently, a unified elasto-plastic solution for high-speed railway tunnels in cold regions is derived based on the new dual transverse isotropic model, and the accuracy of the analytical solution is verified by comparisons with existing models and experimental results. Finally, the effect of the model parameters on stress and displacement is explored. The results reveal a significant negative correlation between the plastic radius of the frozen rock mass zone and the pressure acting on the inner surface of the support structure, the influence coefficient of intermediate principal stress, radial-gradient influence coefficient of the frozen rock mass, and anisotropic frost heave coefficient of the frozen rock mass, as well as between the frost-heaving force and the influence coefficient of intermediate principal stress parameter. However, the frost-heaving force is positively correlated with the pressure acting on the inner surface of the support structure, the radial gradient influence coefficient of the frozen rock mass, and the anisotropic frost heave coefficients of the frozen rock mass. Therefore, the pressure acting on the inner surface of the support structure, the radial gradient influence co-efficient of the frozen rock mass, and the anisotropic frost heave coefficients of frozen rock mass should be reasonably considered, but the strength theory of the surrounding rock should be strongly considered in the design of tunnel structures in cold regions.