The development of large cross-section tunnels is an inevitable trend driven by the intensification of coal mining activities and advancements in mining equipment technology. However, the disturbance stress exerted by adjacent caverns has a more pronounced impact on weakly cemented rock strata in the vicinity of neighboring tunnels. To mitigate deformation in weakly cemented tunnels, grouting and the installation of long anchor cables were employed to reinforce the self-supporting capacity of the surrounding rock, thereby establishing an active support layer. Additionally, U-shaped steel frames combined with the subsequent application of flexible filling materials were utilized to aid the surrounding rock in mobilizing its self-supporting capacity, which resulted in the formation of a passive support layer. A layered collaborative control methodology integrating both active and passive support mechanisms was developed and implemented in engineering practice. The findings demonstrate that the vertical stress was alleviated after cavern excavation and was predominantly transferred toward the adjacent tunnel, with the influence zone extending approximately 7 to 12 times the tunnel height. Conversely, the horizontal stress is primarily dispersed laterally, affecting a region approximately 3 to 6 times the tunnel width. Following the infilling of pebbles between the U-shaped steel frame and the adjacent rock mass, the maximum compressive stress experienced by the U-shaped steel frame decreased by 50%. Additionally, the spatial extent of the maximum axial force was reduced by 65%, whereas the stresses within the rock bolts and cable bolts increased by 30% and 40%, respectively. Grouting reinforcement contributed to bonding and compaction effects on the delamination and fracturing of the roof strata, with the grout predominantly distributed within a range of 1.5 to 5 m from the central region of the roof. The research outcomes presented in this paper can provide valuable reference for a large-section weakly cemented tunnel.

This study investigated the long-term settlement behaviour of piled buildings induced by shield tunnelling in soft ground conditions within urban environments. By integrating a detailed case study with advanced numerical modelling techniques, this study provided a nuanced understanding of the interactions between tunnel construction and existing pile foundations. Central to the investigation is the role of soil consolidation, which significantly contributes to the settlement of piled buildings. To address this, this study emphasizes the critical need for the precise calibration of tunnelling parameters such as face pressure and grouting pressures. These parameters are meticulously controlled to mitigate the adverse effects on nearby piled buildings, ensuring their stability and integrity. It is established that an optimal face pressure, set at 90% of the lateral earth pressure, consistently minimizes the settlement of piled buildings, primarily due to the minimal reduction in the pile toe resistance observed near the tunnel. Similarly, the ideal grouting pressure was identified to be within the range of 120%-160% of the vertical earth pressure, with the smallest building settlement and decrease in pile toe resistance observed at a grouting pressure of 150% of the overburden pressure. This finding elucidates the load transfer mechanism within piled buildings. This study further demonstrated that the settlement induced by the second tunnel excavation is smaller than that caused by the first tunnel excavation owing to the sheltering effects of the adjacent first tunnel and pile foundations. During the consolidation phase following tunnel excavation, the settlement caused by the second tunnel is smaller than that caused by the first tunnel, which is attributed to the dissipation of the negative excess pore pressure around the first tunnel, leading to soil volume expansion. These insights not only validate the effectiveness of the numerical model but also contribute significantly to the field of geotechnical engineering by providing actionable guidelines for future tunnelling projects.

Leakage disasters in shield tunnels frequently occur, leading to severe consequences such as tunnel collapse, road collapse, and building destruction. Since it is difficult to record the accident evolution process onsite, it is necessary to reproduce it through credible numerical simulations. However, traditional numerical methods face technical bottlenecks when simulating water-sand inrush in shield tunnels due to challenges such as large deformation analysis and fluid-structure coupling, making it difficult to simulate the process of disaster progression. To address this issue, a Coupled Eulerian-Lagrangian (CEL) method incorporating seepage analysis, referred to as the S-CEL method, was proposed to simulate the interaction between water, soil, and a shield tunnel during a disaster. A refined three-dimensional numerical model was developed using the S-CEL method to simulate the water-sand inrush process. The generation sequence of new leakage points at the segment joints and the mechanisms driving the progression of the disaster were revealed. New leakage points were progressively generated along the longitudinal direction of the tunnel. As the number of leakage rings increased, the amount of soil loss increased rapidly. This led to severe uneven settlement and dislocation deformation of the tunnel. A channel steel was introduced to reinforce the tunnel in the numerical simulation to mitigate or decelerate the progression of the leakage disaster. The connection method between the channel steel and tunnel segments was found to be pivotal to the strengthening effect. Employing only bolt anchoring showed limited efficacy, while enhancing the segment-steel interface with epoxy resin achieved much better performance in mitigating disaster progression.

Despite the thriving development of metro-led urban underground public space (UUPS) and its significant benefits and costs, there remains a critical research gap in understanding and evaluating its efficiency. This paper intends to improve the post-evaluation system of metro-led UUPS by proposing an efficiency evaluation framework based on data envelopment analysis. The public and the private sectors are taken as different coexisting decision-makers, and a pair of linear programming is built accordingly (with different assignments of discretionary and non-discretionary inputs) for each decision-making unit. The directional vector is calculated based on CRITIC weights to model the searching process of referential cases in terms of urban renewal. The empirical study of twenty metro-led UUPSs in central Shanghai reveals that (1) the proposed evaluation framework is feasible and discriminative, (2) the efficient form of metro-led UUPS in Shanghai is mainly limited to a compact pattern with a low proportion of pure public space, (3) the essential solution to promote efficiencies is closer cooperation between different parties, and (4) efficiency evaluation is crucial to avoiding the "the-more-the-better" type of development. The findings of this study are expected to shed light on the future planning and operation of metro-led UUPS.

Accurate TBM performance estimation is essential for effective tunnel design and planning. This study introduces a one-dimensional (1D) estimation model that estimates thrust, torque, power, cutterhead speed, and tool count using only excavation diameter. The model was developed across four TBM types—open, single shield (SS), double shield (DS), and earth pressure balance (EPB)—to isolate the influence of diameter from other variables. Validation against existing models and a 52-case independent dataset confirmed strong correlations: torque scales with the cube of the excavation diameter (R² = 0.89 for EPB), power grows faster than linearly (R² = 0.83 for EPB), thrust increases supra-linearly (R² = 0.79 for EPB), and cutterhead speed decreases with diameter (R² = 0.87 for open TBM). Tool count grows proportionally. A reliability matrix compares model accuracy and data support, aiding selection based on both fitness and robustness. This 1D model offers fast, consistent estimates for early-stage assessments. While it excludes detailed geological input, it is suited for feasibility studies and preliminary design. Future work will incorporate additional ground and machine parameters and extend validation across a broader range of tunneling conditions to enhance generalizability.

The seismic response of underground structures within integrated underground-aboveground structure system (IUASS) is influenced by both kinematic effect from the surrounding soil and inertia effect from aboveground structures, leading to complex dynamic responses. This paper investigates the seismic response of underground structures in IUASS. Dynamic simulations are conducted using both elastic and elastoplastic constitutive models. The results show that the mean period of input motion and the fundamental period of the free field significantly influence the drift ratio of the underground structure, while the force at the base of the aboveground structure is also strongly correlated with the drift ratio of the underground structure. The vertical displacement of the underground structure is strongly affected by the weight of the IUASS and excess pore pressure generated in the soil. Simplified analysis methods for predicting drift ratio and vertical displacement are subsequently proposed taking these factors into consideration. The proposed methods exhibit excellent agreement with dynamic analysis results across a wide range of input motion and structure conditions, providing important tools for seismic design of IUASS.

Burial depth and spacing are key factors influencing the stability of compressed air energy storage chamber groups. However, methods for determining safe burial depth and spacing in aligned multi-chamber systems remain underexplored. This study introduces a modified linear superposition method (M-LSM) for calculating elastic stress tensor fields in the surrounding rock around multiple chambers. The method analyzes the distribution of elastic stress under varying design parameters and surrounding rock conditions, identifying the most critical stress locations, which are the sidewalls affected by adjacent chambers, and providing deeper insights into stress concentrations caused by chamber interactions. The relationship between safe burial depth and spacing follows an approximately inverse proportionality, with the safety criterion of no plastic zones developing in the surrounding rock. A closed-form solution for safe burial depth and spacing is derived, which can be used to quickly determine the design parameters. The M-LSM is applicable to a wide range of internal pressurized chamber groups and borehole problems, capturing mutual interactions between adjacent chambers more realistically. Compared to finite element method simulations based on a practical engineering case, the results show errors that are typically negligible, validating the reliability of the analytical approach. This fully analytical method is mesh-free, iteration-free, and offers infinite resolution, making it highly efficient for both computations and practical applications. The closed-form solution derived from this method provides significant value for trend analysis, practical calculations, and engineering applications.

To mitigate the defects of shield tunnels in operation, a reinforcement method using corrugated plates was proposed. This paper aims to present a comprehensive investigation of the effectiveness of this method. Taking into account the corrugated plate joints, full-scale tests were designed and conducted on two specimens of segmental joints: one unreinforced and one reinforced. The test results revealed that the failure mode of the reinforced specimen was characterized by shear failure of the chemical anchors, followed by concrete crushing. The effectiveness of reinforcement highly depends on the shear capacity of the chemical anchors. After reinforcement, the flexural stiffness and ultimate bearing capacity of the specimen increased by 112.4% and 32.5%, respectively. Two refined numerical models, developed at both the joint scale and full-ring scale, were validated for corrugated plate reinforced shield tunnels. The numerical results indicated that, with full-ring reinforcement, the overall stiffness and the bearing capacity increased by 341.4% and 39.6%, respectively. Notably, shear stress in the chemical anchors was more pronounced at the tunnel vault and haunch, suggesting the need for localized optimization of the chemical anchors in these areas.

Reliable data sources are essential for intelligent tunnel construction, yet on-site data are often insufficient to meet sample require-ments. Previous numerical modeling studies have seldom considered the combined effects of different excavation methods' spatial effects and the distribution characteristics of joints. This paper develops a method to construct a stability database for jointed rock tunnels with primary support systems using a computational framework combining the finite difference method-discrete element method (FDM-DEM). The framework constructs a 2D model using the Mohr-Coulomb criterion and a 3D model with the Hoek-Brown failure criterion, enabling the stress release process to accurately replicate the influence of joint distribution features and excavation space effects in the 2D calculations by utilizing the longitudinal deformation profile parameters of the bench sections and fine-grained ground reaction curves. The computational circle is determined by grid research and data analysis, while the performance differences of various primary support components and their correlations with surrounding jointed rock are analyzed using the control variable method. The validity of the framework is initially confirmed by case comparisons and macroscopically validated using the Mantel test and Spearman analysis on the constructed simulation database—containing tunnel construction information, joint distribution, rock mechanics parameters, and stability indices—thereby establishing a reliable foundation for machine learning and transfer learning applications.

An earthquake with a magnitude of 6.6 (M_W) occurred in Menyuan County, Qinghai Province, China, on January 8th, 2022. The Daliang Tunnel, which traverses the seismogenic fault, was severely damaged during this seismic event. The seismic damage investigation of the tunnel is introduced, and the damage characteristics along the tunnel are also presented. It is found that the damage severity of the tunnel is highly correlated with the distance to the fault. Damage modes for different tunnel zones (cross-fault zone, portal zone, and ordinary zone far from the fault and the portal) are quite distinct. Based on the understanding of seismic damage to the Daliang Tunnel in 2022 Menyuan Earthquake, as well as other damaged tunnels during the 2008 Wenchuan Earthquake, the critical influence factors for damage to cross-fault tunnels are discussed. From the seismic investigation, coupling effects of strong ground motions and fault dislocations are highlighted, which pose significant risks to cross-fault tunnels and should be considered in the seismic design for such tunnels. The deformation joints of the tunnel could help the tunnel adapt to the deformation caused by fault dislocation, and thus protect the main structure, but inversely an added local deformation may be expected around the deformation joints. The instability of the overlying slope may have contributed to the local amplification of the fault dislocation along the Daliang Tunnel. Finally, the requirements of seismic resilience for cross-fault tunnels are proposed, and detailed suggestions are provided to enhance the seismic performance of such cross-fault tunnels.