Fault Displacement Research Articles

Displacement of Dongducheon and Wangsukcheon Fault Observed by Gravity Field Interpretation

Displacement of Dongducheon and Wangsukcheon Fault Observed by Gravity Field Interpretation

Coupled Microstructural EBSD and LA-ICP-MS Trace Element Mapping of Pyrite Constrains the Deformation History of Breccia-Hosted IOCG Ore Systems

Electron backscatter diffraction (EBSD) methods are used to investigate the presence of microstructures in pyrite from the giant breccia-hosted Olympic Dam iron–oxide copper gold (IOCG) deposit, South Australia. Results include the first evidence for ductile deformation in pyrite from a brecciated deposit. Two stages of ductile behavior are observed, although extensive replacement and recrystallization driven by coupled dissolution–reprecipitation reaction have prevented widespread preservation of the earlier event. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) element maps of pyrite confirm that many pyrite grains display compositional zoning with respect to As, Co, and Ni, but that the zoning is often irregular, patchy, or otherwise disrupted and are readily correlated with observed microstructures. The formation of ductile microstructures in pyrite requires temperatures above ~260 °C, which could potentially be related to heat from radioactive decay and fault displacements during tectonothermal events. Coupling EBSD methods with LA-ICP-MS element mapping allows a comprehensive characterization of pyrite textures and microstructures that are otherwise invisible to conventional reflected light or BSE imaging. Beyond providing new insights into ore genesis and superimposed events, the two techniques enable a detailed understanding of the grain-scale distribution of minor elements. Such information is pivotal for efforts intended to develop new ways to recover value components (precious and critical metals), as well as remove deleterious components of the ore using low-energy, low-waste ore processing methods.

A Review of Historical Volcanic Tsunamis: A New Scheme for a Volcanic Tsunami Monitoring System

Tsunami monitoring and early warning systems are mainly established to deal with seismogenic tsunamis generated by sudden seafloor fault displacement. However, a global tsunami triggered by the 2022 Tonga volcanic eruption promoted the need for tsunami early warning and hazard mitigation of non-seismogenic tsunamis in coastal countries. This paper studied the spatiotemporal distribution characteristics of historical volcanic tsunamis and summarized high-risk areas of volcanic tsunamis. The circum southwestern Pacific volcanic zone, including the Sunda volcanic belt and the Indo-Australian plate, is a concentrated area of active volcanoes and major volcanic tsunamis. In addition, the challenges associated with adapting seismogenic tsunami techniques for use in the context of volcanic tsunamis were elucidated. At the same time, based on historical records and post-disaster surveys, typical historical volcanic tsunami events and involved mechanisms were summarized. The results show that a majority of volcanic tsunamis may involve multiple generation mechanisms, and some mechanisms show geographical distribution characteristics. The complexity of volcanic tsunami mechanisms poses challenges to tsunami early warning by measuring tsunami sources to evaluate the possible extent of impact, or using numerical modeling to simulate the process of a tsunami. Therefore, a concise overview of the lessons learned and the current status of early warning systems for volcanic tsunamis was provided. Finally, a conceptual scheme of monitoring systems for volcanic tsunamis based on historical volcanoes, real-time volcanic eruption information and sea level data, as well as remote sensing images, was presented.

Analysis of faulting destruction and water supply pipeline damage from the first mainshock of the February 6, 2023 Türkiye earthquake doublet

In 2023, two consecutive earthquakes exceeding a magnitude of 7 occurred in Türkiye, causing severe casualties and economic losses. The damage to critical urban infrastructure and building structures, including highways, railroads, and water supply pipelines, was particularly severe in areas where these structures intersected the seismogenic fault. Critical infrastructure projects that traverse active faults are susceptible to the influence of fault movement, pulse velocity, and ground motions. In this study, we used a unique approach to analyze the acceleration records obtained from the seismic station array (9 strong ground motion stations) located along the East Anatolian Fault (the seismogenic fault of the MW7.8 mainshock of the 2023 Türkiye earthquake doublet). The acceleration records were filtered and integrated to obtain the velocity and displacement time histories. We used the results of an on-site investigation, jointly conducted by China Earthquake Administration and Türkiye’s AFAD, to analyze the distribution of PGA, PGV, and PGD recorded by the strong motion array of the East Anatolian Fault. We found that the maximum horizontal PGA in this earthquake was 3.0 g, and the maximum co-seismic surface displacement caused by the East Anatolian Fault rupture was 6.50 m. As the fault rupture propagated southwest, the velocity pulse caused by the directional effect of the rupture increased gradually, with the maximum PGA reaching 162.3 cm/s. We also discussed the seismic safety of critical infrastructure projects traversing active faults, using two case studies of water supply pipelines in Türkiye that were damaged by earthquakes. We used a three-dimensional finite element model of the PE (polyethylene) water pipeline at the Islahiye State Hospital and fault displacement observations obtained through on-site investigation to analyze pipeline failure mechanisms. We further investigated the effect of the fault-crossing angle on seismic safety of a pipeline, based on our analysis and the failure performance of the large-diameter Thames Water pipeline during the 1999 Kocaeli earthquake. The seismic method of buried pipelines crossing the fault was summarized.

Improved semi-analytical solution for longitudinal mechanical response of tunnels crossing active faults considering nonlinear soil-tunnel interactions and shear effects

Tunnels crossing active faults are susceptible to severe damage. This study establishes an improved semi-analytical methodology for analyzing the mechanical responses of tunnels subjected to active fault dislocation. The methodology incorporates nonlinear axial, transverse, and vertical soil-tunnel interactions, shear effects, and geometric nonlinearity within its governing equations. Compared with existing methods, the proposed method has a significantly extended application range with improved accuracy, and the solution procedure demonstrates exceptional computational efficiency, with each case typically being solved in less than 1 s. The proposed methodology demonstrates outstanding qualitative and quantitative agreement with 3D FEM results across various fault types, as well as with the results obtained from the model test. Additionally, neglecting shear effects results in approximately 1.11 to 1.20 times higher bending moments and 1.13 to 1.19 times higher shear forces of the tunnel. Finally, a parametric analysis was conducted based on the proposed methodology to investigate the influence of critical parameters, such as fault displacement, buried depth, tunnel diameter, soil cohesion, and soil friction angle, on the tunnel response under fault dislocation. The results suggest that the tunnel responses positively correlate with the fault displacement, buried depth, and soil cohesion. Increasing the fault displacement amplifies the vertical shear force and bending moment asymmetry while increasing buried depth reduces this asymmetry. An increase in the tunnel diameter and soil friction angle is associated with a decrease in the peak axial force and an increase in the vertical shear force and bending moment. Additionally, variations in the friction angle do not exert a significant effect on the transverse shear force and bending moment.

Design displacement for lifelines at fault crossings: the code-based approach for Europe

The earthquake-resistant design of lifelines, such as pipelines, tunnels and bridges, is based on the reliable representation and estimation of the seismic loading. In the case of lifeline–fault crossings, the design fault displacement is typically derived from estimates based on fault dimensions via empirical fault scaling relations for a given “design” scenario event. This approach comes with an unknown level of safety because the fault productivity and the actual distribution of earthquake events are essentially disregarded. To overcome this challenge, a simplified approach is proposed by statistically analyzing the outcome of probabilistic fault displacement hazard analyses (PFDHAs). A selection of faults from the 2020 European Fault-Source Model is used to build the logic tree and to set the range of parameters considered in the PFDHAs. The methodology allows the (mostly conservative) approximation of the fault displacement corresponding to any given return period based on readily available data, namely fault productivity, fault mechanism, fault length, and lifeline crossing location on the fault. The proposed methodology has been proposed and adopted as an informative Annex in prEN 1998-4:2022.

A mechanical analysis model for tunnels under strike-slip faulting considering the fault zone width and nonlinear tunnel-stratum interaction

Tunnels crossing active fault zones are seriously damaged under the action of faulting. However, the influence of the fault zone width or nonlinear tunnel-stratum interaction is neglected in existing analytical models, resulting in incorrect estimation of the tunnel mechanical response. To aid in the seismic design of tunnels, a mechanical analysis model for tunnels under strike-slip faulting considering the effect of fault zone width and nonlinear tunnel-stratum interaction is first proposed in this work. The calculation results of the proposed model agree well with those obtained from the model test and numerical simulation, and the accuracy is obviously higher than that of the existing analytical methods. Compared with the FEM numerical model, the average errors of the peak bending moment, shear force and axial force calculated by the proposed model are 6.37 %, 11.00 % and 9.91 %, respectively. Neglecting the effect of fault zone width or nonlinear tunnel-stratum interaction, the tunnel response will be misestimated, e.g., when the fault displacement is 3 m and the crossing angle β is 90°, the overestimated value is approximately 40–110 %. Finally, the results of parameter analysis show that under the condition of 0° < β < 90°, the tunnel failure scope caused by the left-lateral strike-slip faulting is obviously larger than that caused by the right-lateral strike-slip faulting, while the conclusion is opposite under 90° < β < 180°; the maximum strain within the tunnel correlates directly with fault displacement and the strength of the fault zone, exhibiting an inverse correlation with the width of the fault zone; meanwhile, the scope for tunnel failure is directly influenced by fault displacement, fault zone width, and the crossing angle (where 90° <β < 180°), while inversely affected by the crossing angle (where 0° <β < 90°) and the strength of the fault zone.

Active‐Source Seismic Imaging of Fault Re‐Activation and Leakage: An Injection Experiment at the Mt Terri Rock Laboratory, Switzerland

AbstractWe conducted a time‐lapse seismic experiment utilizing automated active seismic source and sensor arrays to monitor a reactivated fault within the Opalinus clay formation at the Mont Terri Rock Laboratory (Switzerland), an analog caprock for geologic carbon storage. A series of six brine injections were conducted into the so‐called Main Fault to reactivate it. Seismic instrumentation in five monitoring boreholes on either side of the fault was used to continuously probe changes in P‐wave travel‐times associated with fault displacement and leakage. We performed time‐lapse travel‐time tomography on five hundred sequential data sets; this revealed a zone of decreased P‐wave velocity, up to 16 m/s, during each injection cycle, followed by a velocity increase during shut‐in. These results demonstrate varying elastic property perturbations, both spatially and temporally, along the fault plane during reactivation. We then interpreted these velocity changes in terms of fault dilation induced by pressurized fluids along the fault.

Fault-displacement models for aggregate and principal displacements

New fault-displacement models (FDMs) are developed for the aggregate and principal net surface displacement using the database developed by the Fault Displacement Hazard Initiative Project. An FDM for the aggregate displacement is developed, which is then partitioned into principal and distributed displacements. The model for the aggregate displacement is first formulated in the wavenumber domain to incorporate seismology-based constraints for the extrapolation of the magnitude scaling of median displacements to large-magnitude events. The results from the wavenumber-domain model are then adjusted to fit the empirical moderate-magnitude scaling (M &lt; 7) and the shape of the displacement profile at the ends of the rupture. Segments are used in the model development to better capture the complexity of the variability of the surface-displacement profile along strike, including regions with zero displacements. For applications in which segments cannot be identified, simplified FDMs without segments are developed that treat the number, lengths, and locations of the segments as aleatory variability. The principal-displacement FDM is then developed as an adjustment to the aggregate-displacement FDM. The segmentation and the magnitude dependence of the taper length of individual segments lead to non-self-similar scaling of the median profile along the entire rupture that can have a significant impact on probabilistic fault-displacement hazard analysis (PFDHA) for sites near the ends of faults. A key feature of the new FDMs is the use of a power-normal [Formula: see text] distribution for the aleatory variability, which leads to narrower distributions of the displacement for large-magnitude earthquakes compared to the commonly used lognormal distribution. For large-magnitude earthquakes, the expected maximum displacements computed using the power-normal distribution of the FDM are consistent with the observed maximum displacements along strike, supporting the narrower shape of the upper tail of the power-normal distribution for large-magnitude events.

Impact of structural geometry of tilted fault blocks on hydrocarbon entrapment and deposition of syn-rift clastic reservoirs: Belayim Marine field (Gulf of Suez rift)

Belayim Marine oilfield is representative of the Gulf of Suez fields with hydrocarbon production from pre-rift and syn-rift reservoirs. Detailed subsurface mapping using a complete 3D seismic and borehole dataset throws light on the trapping mechanisms of tilted fault blocks in rift basins where the strike of the tilted block is parallel to the bounding fault. For such one-way tilted fault traps, linkage of rift-parallel and rift-oblique faults at the updip sides of the tilted blocks is necessary for trap integrity of laterally continuous reservoirs like the Nubia Sandstone. For laterally discontinuous reservoirs like tidal sand bars aligned normal or oblique to the block-bounding faults, a combination trap can be laterally closed by lateral change in facies of the reservoir unit along fault strike. Fault sealing of the proved hydrocarbon traps is mainly through juxtaposition. Shale smearing is valid for thick shale units with reasonable fault displacement and shale gouge is a proven sealing mechanism especially in clay-rich units. The ductile nature of syn-rift sediments leads to fault-propagation folding above the main-bounding faults of tilted fault blocks where folding is the trapping mechanism of these syn-rift reservoirs.The structural geometry of tilted fault blocks also controls the distribution of syn-rift reservoirs as the linkage of rift-parallel and rift-oblique faults controls the entry of main valleys transporting syn-rift clastics into the basin. Longitudinal depressions sculptured at the crests of tilted fault blocks represent another location for deposition of syn-rift reservoirs.

Methodology for quantitative prediction of low-order faults in rift basins: Dongtai Depression, Subei Basin, China

In eastern China, oil and gas reservoirs mainly have fault block traps. Low-order, small-scale faults are well developed, with small fault displacements and short extension lengths, but are difficult to identify by traditional seismic methods. Based on paleotectonic interpretations, rock mechanics experimental results and stratigraphic data, combined with seismic interpretation, structural evolution and fault activity analysis, a geomechanical model of the Majiazui area in the Dongtai Depression in the Subei Basin is established to construct a three-dimensional model of the paleostress field. Finally, the control of the principal stress, shear stress, and strain energy on the occurrence and development of low-order faults is quantitatively analyzed. This research shows that fault activity was weak during the Funing period (65-53 Ma), became strong during the Dainan period (53-46 Ma) and was strongest during the Sanduo period (46-37 Ma). The Sanduo period was the main period during which the low-order faults in the Majiazui area were formed. The minimum principal stress and strain energy controlled the development of low-order faults in the Majiazui area. The low-order faults are most developed in areas that experience high minimum principal stress and strain energy. In the Sanduo period, the minimum principal stress in the Majiazui area was tensile in the north–south direction, and the maximum principal stress was vertical. In an extensional stress environment, lateral shear stress controls the strike of faults, while vertical shear stress controls the inclination of faults. The faults in the northern Majiazui area are inclined mainly to the south, and the faults in the southern Majiazui area are inclined mainly to the north. These results are of practical importance for evaluating the oil–water relationship in oil-bearing fault blocks, solving the conflict between injection and production wells and improving oil recovery.

Method of co-seismic fault displacement estimate based on peak ground acceleration

Based on the results of the seismic hazard survey in Yunnan Province, four exceedance probabilities of peak ground acceleration were converted into earthquake magnitudes using the empirical relationship between epicentral intensity and magnitude. By using logistic regression, earthquake magnitude, source depth, cover layer thickness, and fault type were used as independent variables to calculate the probability of co-seismic displacement for different earthquake magnitudes. Using the magnitude-displacement empirical model in the southwestern region of China, horizontal and vertical displacements were obtained with a 95 % confidence level. The results show that all Holocene faults have the ability to produce surface displacement, but from the perspective of probabilistic hazard, the probability of surface rupture in the short term is low, while the probability of surface rupture for each fault significantly increases over a long time scale. Buildings with different service lives should adopt different avoidance strategies, and buildings with shorter service lives (&lt;50a) can consider not avoiding active faults.

Least cost path analysis as an objective and automatic method to define the main fault trace for probabilistic fault displacement hazard analyses

Least cost path analysis as an objective and automatic method to define the main fault trace for probabilistic fault displacement hazard analyses

Mechanical Properties of Buried Steel Pipe With Polyurethane Isolation Layer Under Strike-Slip Fault

Abstract Long-distance buried pipelines are one of the most common and economical transportation methods for oil and gas, but the fault movement will pose a threat to the safety of pipelines. The main challenge of pipeline under strike-slip faults is to improve the ability of resistance to fault dislocation, and the main aim of the study is how to improve the critical fault displacement of pipelines with the help of polyurethane isolation layer. Three-dimensional finite element models were proposed for mechanical analysis of X80 buried steel pipe with polyurethane isolation layer under strike-slip fault. The influence of factors on the mechanical properties of pipelines were studied, such as thickness of isolation layer, internal pressure, fault displacement, diameter-thickness ratio, and the angle of pipe and fault line. The simulation results indicate that with the increase of the thickness of the isolation layer, the development of the maximum tensile and compressive strain of the pipeline is significantly reduced for the same fault displacement, resulting in a significant increase in the critical fault displacement corresponding to the three failure modes of the pipeline. As the ratio of diameter to thickness and internal pressure decrease, the critical displacements decrease. When designing and planning the pipeline, pipeline is recommended with the seismic isolation layer, large wall thickness, and the crossing-angle at 70 deg∼80 deg. The research provided a reference for judgment of earthquake resistance, failure analysis, and safety design of pipelines with polyurethane isolation layer crossing strike-slip faults.

Hydrogeochemical Evaluation of Aquifer Storage and Recovery in Edwards Aquifer, New Braunfels, Texas.

This study examines the potential for aquifer storage and recovery (ASR) in the brackish portion of the Edwards aquifer in New Braunfels, Texas. Successful ASR relies on understanding hydraulic properties, aquifer heterogeneity, water geochemistry, and geochemical processes during operations. The research aims to investigate the chemistries of native groundwater and injectant during ASR operation, estimate the hydraulic properties of the aquifer layers, and assess the recovery rate for the recovered groundwater meeting the total dissolved solids (TDS) threshold. The study found that native groundwater is of Na-Cl facies due to halite dissolution and a possible basinal brine migration associated with the zone of greatest fault displacement. High sulfate ions in background native groundwater result from sulfate-bearing minerals' dissolution in the Kainer and Person Formations. The injectant water is of Ca-Mg-HCO3 facies due to the carbonate-rich composition of the aquifer host matrix and interaction with the Guadalupe River riverbed. During ASR operations, mixing controlled the shift in hydrochemical facies from Na-Cl to Ca-Mg-HCO3.The study also suggests a possible connection between Kainer and Person Formations and preferential pathways in the targeted storage zone aquifer. The estimated conductivity values also indicate dominant horizontal flow via possible fracture pathways in both the Person and Kainer Formation storage zones. Recovery of groundwater meeting the TDS of 1000 mg/L requires a recovery rate of 0.03 m3/s for 60 days after 40-day storage. This research emphasizes that understanding the hydrogeological conditions and geochemical processes is critical to ASR feasibility in brackish carbonate multi-aquifer fractured systems.

Mechanical response and failure characteristics of tunnels subjected to reverse faulting with nonuniform displacement: Theoretical and numerical investigation

Tunnels subjected to reverse fault dislocation undergo severe structural damage, and their mechanical response and failure characteristics play a key role in seismic fortification efforts. This paper investigates the mechanical responses and failure characteristics exhibited by tunnels subjected to reverse faulting using theoretical analysis and numerical simulations. A theoretical model is established for analysing the bending moment, shear force, and safety factor of the tunnels under reverse fault dislocation. The nonuniform fault displacement, fault zone width, and nonlinear soil-tunnel interaction is applied in the proposed theoretical model, significantly improving the analysis accuracy and range of applicability. The corresponding numerical simulation based on the XFEM (extended finite element method) is carried out, and the proposed theoretical model is verified by the numerical results. The theoretical results demonstrate excellent agreement with the numerical results when nonuniform fault displacement is considered. A parametric analysis is presented in which the effects of the maximum fault displacement, fault zone width, and ratio of the maximum fault displacement of the footwall to the hanging wall are investigated. The results show that the ultimate fault displacement for compression-bending failure of the tunnel subjected to reverse fault dislocation is estimated to be approximately 30 cm, while the ultimate displacement for shear failure stands at 20 cm. Variations in the fault displacement ratio yield alterations in the distribution pattern and peak values of internal forces, together with shifts in the potential failure ranges of the footwall and hanging wall. Additionally, an initial crack emerged on the tunnel crown near the fault plane, followed by a second crack on the tunnel invert. Upon reaching a fault displacement of approximately 40 cm, the crack fully traverses the entire tunnel lining.

Nucleation Mechanism and Rupture Dynamics of Laboratory Earthquakes at Different Loading Rates

The loading rate of tectonic stress is not constant during long-term geotectonic activity and significantly affects the earthquake nucleation and fault rupture process. However, the mechanism underlying the loading rate effect is still unclear. In this study, we conducted a series of experiments to explore the effect of the loading rate on earthquake nucleation and stick–slip characteristics. Through lab experiments, faults were biaxially loaded at varying rates to produce a series of earthquakes (stick–slip events). Both shear strain and fault displacement were monitored during these events. The findings indicate a substantial effect of the loading rate on the recurrence interval and the shear stress drop of these stick–slip events, with the recurrence interval inversely proportional to the loading rate. The peak friction of the fault also decreases with the increasing loading rate. Notably, prior to the dynamic rupture of earthquakes, there exists a stable nucleation phase where slip occurs in a quasi-static manner. The critical nucleation length, or the distance required before the dynamic rupture, diminishes with both the loading rate and normal stress. A theoretical model is introduced to rationalize these observations. However, the rupture velocity of these lab-simulated earthquakes showed no significant correlation with the loading rate. Overall, this study enhanced our comprehension of earthquake nucleation and rupture dynamics in diverse tectonic settings.

Response of prefabricated-polyurethane reinforced ballasted track to dislocation in tunnels through active fault zone

ABSTRACT The dislocation of the active fault zone may cause some threat to the track structures passing through it, in order to investigate the response of prefabricated-polyurethane reinforced ballasted track and CRTS III slab track to different forms of fault and to compare their adaptability in fault zone, a finite element model of the track-tunnel-surrounding rock system and a dynamic model of vehicle-track system were integrated together in this study. Based on the models, the changes of track geometry of the two track structures were studied, the mechanical behaviour of track components was revealed, and the effect of irregularity caused by fault dislocation on vehicle dynamic response was studied. Results show that the components of CRTS III slab track are damaged at a smaller dislocation displacement than those of prefabricated-polyurethane reinforced ballasted track. With the increase of the train speed and dislocation displacement, the derailment coefficient and wheel load reduction rate also increase. The safe speed limits for travelling under different types of fault and different dislocation displacements are obtained, which can provide reference for similar engineering applications.

Evaluation of landslides, accretion circumstance and riverbank slope stability analyses in the Mekong Delta

This study presents the current situation of landslides and accretion on the Tien and Hau riverbanks in the Mekong Delta over time. Simultaneously, the riverbank slope stability was assessed and showed some related effects. Statistical methods, combined with field surveys and GEOSlope analysis, were used to assess the circumstances of landslides and accretion. Results show that the most landslides have occurred in the An Giang and Dong Thap areas. In the prior 2015 period, 23 and 7 riverbank sections with frequent landslides were excavated and inventoried on the Tien and Hau rivers, respectively. Meanwhile, 28 and 9 sections where accretion occurred during this period were inventoried on the Tien and Hau riverbanks, respectively. Since 2015, 248 locations of landslides and accretion occurring in the area have been investigated. The study also indicates that the displacement of active tectonic faults and instability of riverbank slopes have been demonstrated and complemented the landslide causes in the area. These results are intended to warn and help local authorities to promptly take positive measures to prevent and orient appropriate socio-economic development for the region.

Study of Mechanical Response of Tunnels Crossing Active Faults in Different Burial Depths

There are numerous tunnels worldwide that cross active fault zones. These tunnels are situated in complex geological environments and are subjected to intense seismic activities. When active fault zones experience displacement, tunnels are susceptible to varying degrees of damage. Over the past few decades, many scholars have researched tunnels crossing active fault zones using numerical simulation methods, including finite element analysis, discrete element analysis, and finite difference methods. However, certain aspects have been overlooked, such as the influence of burial depth on tunnels crossing active fault zones. Most prior studies have primarily omitted consideration of tunnel depth and high-stress effects, resulting in disparities between research findings and practical engineering outcomes. In light of these issues, this paper analyzes the impact of ground stress fields at different burial depths on tunnels crossing active fault zones. It compares the mechanical response characteristics of deep-buried and shallow-buried tunnels after experiencing fault displacement, elucidating variations in displacement patterns, stress, and strain at different burial depths. The results indicate that: (1) Deep-buried and shallow-buried tunnels exhibit an “S”-shaped deformation pattern. (2) Regarding the strain distribution within the tunnel, the affected regions are predominantly concentrated within the fault zone. (3) Regarding the stress distribution within the tunnel, deep-buried tunnels experience a broader range of stress variations distributed across the fault zone. In contrast, shallow-buried tunnels predominantly exhibit stress concentration at the fault slip plane. (4) By analyzing the patterns of tunnel damage at different burial depths, it is observed that burial-depth effects notably influence tunnels with a burial depth less than 200 m. In comparison, tunnels exceeding 300 m gradually reduce the impact of burial depth. These findings can be essential theoretical references for studying tunnels crossing active fault zones in deep-buried environments.