Search Results (90)

The stability of the intermediate rock wall in the blasting construction of bifurcated small-spacing tunnels directly affects the construction safety of the tunnel structure. Clarifying the damage characteristics of the intermediate rock wall has significant engineering value for ensuring the safe and efficient construction of bifurcated tunnels. Based on the Tashan North Road Expressway Tunnel Project, this paper investigated the damage characteristics of the intermediate rock wall in bifurcated tunnels under different blasting construction schemes, using numerical simulation methods to account for the combined effects of in situ stress and blasting loads. The results were validated using comparisons with the measured damage depth of the surrounding rock in the ramp tunnels. The results indicate that the closer the location is to the starting point of the bifurcated tunnel, the thinner the intermediate rock wall and the more severe the damage to the surrounding rock. When the thickness of the intermediate rock wall exceeds 4.2 m, the damage zone does not penetrate through the wall. The damage to the intermediate rock wall exhibits an asymmetric “U”-shaped distribution, with greater damage on the side of the trailing tunnel at the section of the haunch and sidewall, while the opposite is true at the section of the springing. During each excavation step of the ramp and main-line tunnels, the damage to the intermediate rock wall is primarily induced by blasting loads. As construction progresses, the damage to the rock wall increases progressively under the combined effects of blasting loads and the excavation space effect. In the construction of bifurcated tunnels, the greater the distance between the headings of the leading and trailing tunnels is, the less damage will be inflicted on the intermediate rock wall. Constructing the tunnel with a larger cross-sectional area first will cause more damage to the intermediate rock wall. When the bench method is employed, an increase in the bench length leads to a reduction in the damage to the intermediate rock wall. The findings provide valuable insights for the selection of construction schemes and the protection of the intermediate rock wall when applying the bench method in the construction of bifurcated small-spacing tunnels. Full article

With the development of underground space in urban areas, the demand for tunneling through existing railways is increasing. The adverse effects of cut-blasting during the construction of tunnels under crossing existing railways are investigated. Combined with the principle of blasting seismic wave superposition, LS-DYNA numerical simulation is used to analyze the seismic wave superposition law under different superposition methods. This study also investigates the vibration reduction effect of millisecond blasting for cut-blasting under the different classes of surrounding rocks. The results show that the vibration reduction forms of millisecond blasting can be divided into separation and interference of waveform. Based on the principle of superposition of blasting seismic waves, vibration reduction through wave interference is further divided. At the same time, a new vibration reduction mode is proposed. This vibration reduction mode can significantly improve construction efficiency while improving damping efficiency. The new vibration reduction mode can increase the vibration reduction to 80% while improving construction efficiency. Additionally, there is a significant difference in the damping effect of different classes of surrounding rock on the blasting seismic wave. Poor-quality surrounding rock enhances the attenuation of seismic wave velocity and peak stress in the surrounding rock. In the Zhongliangshan Tunnel, a tunnel cut-blasting construction at a depth of 42 m, the best vibration reduction plan of Class III is 3 ms millisecond blasting, in which the surface points achieve separation vibration reduction. The best vibration reduction plan of Class V is 1 ms millisecond blasting, in which the surface points achieve a new vibration reduction mode. During the tunnel blasting construction process, electronic detonators are used for millisecond blasting of the cut-blasting. This method can reduce the vibration effects generated by blasting. The stability of the existing railway is ultimately guaranteed. This can improve construction efficiency while ensuring construction safety. This study can provide significant guidance for the blasting construction of the tunnel through the railway. Full article

To study the optimization of construction parameters and schemes for complex connecting tunnels in extra-long highway tunnels in granite strata, the research team, relying on the construction project of the complex connecting tunnel between the Xiaolongmen Extra-long Highway Tunnel and the ultra-deep shaft, established an on-site monitoring scheme and a refined numerical simulation model. It systematically analyzed the impact of various construction parameters on the construction process of connecting tunnels and the main tunnel, and on this basis, optimized the construction scheme, improving construction efficiency. The research results show that (1) after the excavation of the connecting tunnel, the confining pressure at the top of the working face decreases rapidly, while the confining pressure on both sides increases rapidly; the extreme point of the confining pressure decrease is located at the central point at the top of the excavated working face. (2) For Class III surrounding rock excavated using the full-face blasting method, the maximum influence range of working face excavation on the stratum along the tunneling direction is approximately 4D (where D represents the excavation step). (3) The larger the excavation step of the connecting tunnel, the more obvious the stress concentration phenomenon at the central point of the working face arch crown, and the excavation step should be optimally controlled within the range of 2–3 m. (4) When explosives in the blast hole adopt decoupled charging, the ratio of borehole diameter to charge diameter can be increased to utilize the air gap to buffer the energy generated by the explosion. Full article

The large-scale reuse of shield tunneling muck remains a major challenge in urban construction. This study proposes a geopolymeric-controlled low-strength material (GC-CLSM) utilizing shield tunneling muck as the primary raw material and a novel alkali-activated binder composed of ground granulated blast-furnace slag (GGBFS) and carbide slag (CS). Emphasis is placed on early-age strength development and its underlying mechanisms, which were often overlooked in previous CLSM studies. Among the tested mixtures, a GGBFS:CS ratio of 80:20 yielded the best balance between early and long-term strength. Its 1-day UCS reached 1.18–1.75 MPa, representing a 6.3–23.6-fold increase over the low-CS reference (90:10), which achieved only 0.05–0.31 MPa. However, excessive CS content (e.g., 60:40) led to a significant reduction in the 28-day strength—up to nearly 50% compared with the 90:10 mix—due to impaired microstructural densification. Microstructural analyses (pore-solution pH, SEM, EDS, XRD, FTIR, LF-NMR) confirmed that higher CS levels enhanced early C–A–S–H gel formation by increasing OH⁻ and Ca²⁺ availability while compromising long-term structure. Additionally, the GC-CLSM system reduced carbon emissions by 68.6–70.3% per ton of treated shield tunneling muck compared with conventional cement-based CLSM. Overall, this study offers a sustainable and performance-driven approach for the valorization of shield tunneling muck, enabling the development of early-strength controllable, low-carbon CLSM for infrastructure applications. Full article

The Tunnel Boring Machine (TBM) method has gained attention as an eco-friendly tunneling technique, effectively reducing noise, vibration, and carbon emissions compared to conventional blasting methods. However, ground settlement and volume loss are inevitable during TBM excavation due to the deformation of the surrounding ground, which may even lead to ground collapse in severe cases. In this study, a Shield TBM model, validated using field data, was employed to perform numerical analyses on parameters such as tunnel diameter, ground elastic modulus, face pressure, and backfill pressure. Based on the simulation results, the influence of each parameter on settlement was evaluated, and a predictive model for estimating maximum settlement was developed. The proposed model was statistically validated using p-value assessment, variance inflation factor (VIF), coefficient of determination (R²), and residual analysis. Furthermore, the prediction model showed high agreement with the field data, yielding a prediction error of 8.25%. This study emphasizes the applicability of verified numerical modeling for accurately predicting ground settlement in Shield TBM tunneling and provides a reliable approach for settlement prediction under varying construction conditions. Full article

Under the “dual-carbon” strategy, accurately quantifying carbon emissions in water conservancy projects is crucial to promoting low-carbon construction. However, existing life cycle assessment (LCA) methods for carbon emissions during the mechanical construction stage often fail to reflect actual processes and are limited by high costs and lengthy data collection, potentially leading to inaccurate estimates. To address these challenges, this paper proposes a carbon emission evaluation method for the mechanical construction stage, based on carbon footprint theory and discrete event simulation (DES). This method quantifies equipment operation time and energy consumption during the drilling and blasting processes, enabling a detailed and dynamic emission analysis. Using the Fumin Pumped Storage Power Station Tunnel Project as a case study, a comparative analysis is conducted to examine the carbon emission characteristics of drilling and blasting operations under different surrounding rock conditions based on DES. The validity of the proposed model is confirmed by comparing its results with monitoring data and LCA results. The results show a clear upward trend in carbon emission intensity as surrounding rock conditions deteriorate, with emission intensity rising from 8405.82 kgCO₂e/m for Class II to 16,189.30 kgCO₂e/m for Class V in the headrace tunnel. The total carbon emissions of the water conveyance tunnels reach 40,019.64 tCO₂e, with an average intensity of 13,565.98 kgCO₂e/m. This study presents a refined and validated framework for assessing the carbon emissions of pumped storage tunnels. It addresses key limitations of traditional LCA methods in the mechanical construction stage and provides a practical tool to support the green transition of hydraulic infrastructure. Full article

This study investigates damage characteristics of red sandstone under dynamic loads to clarify the effects of construction disturbances and blasting on the stability of surrounding rock during mountain tunnel construction in water-rich strata. Dynamic impact experiments at various loads were conducted using the Split Hopkinson Pressure Bar (SHPB) instrument, complemented by simulations of the fracturing process in saturated sandstone using finite element software. This analysis systematically examines the post-fracture granularity mass fraction, stress-strain curves, peak stress-average strain rate relationship, and fracture patterns. The dynamic response mechanism of red sandstone during the process of tunnel blasting construction was thoroughly investigated. Experimental results reveal that the peak stress and failure strain exhibit strain rate dependency, increasing from 45.65 MPa to 115.34 MPa and 0.95% to 5.23%, respectively, as strain rate elevates from 35.53 s⁻¹ to 118.71 s⁻¹. The failure process of red sandstone is divided into four stages: crack closure, nearly elastic phase, rapid crack development, and rapid unloading. Dynamic peak stress and average strain rate in sandstone demonstrate an approximately linear relationship, with the correlation coefficient being 0.962. Under different impact loads, fractures in specimens typically expand from the edges to the center and evolve from internal squeezing fractures to external development. Peak stress, degree of specimen breakage, and energy dissipation during fracturing are significantly influenced by the strain rate. The numerical simulations confirmed experimental findings while elucidating the failure mechanism in surrounding rocks under varying strain rates. This work pioneers a multiscale analysis framework bridging numerical simulation with a blasting construction site, addressing the critical gap in time-dependent deformation during tunnel excavation. Full article

In recent years, geological disasters such as water inrush during drilling and blasting operations have posed significant challenges in tunnel engineering. This paper presents a novel continuous-discrete coupling method based on LS-DYNA, combining the finite element method (FEM) and smoothed particle hydrodynamics (SPH), to simulate the water inrush phenomenon in blasting engineering. The proposed FEM-SPH model effectively captures the propagation of explosion shock waves, simulates small deformation areas with solid grids, and models water behavior using SPH. This study systematically investigates the dynamic evolution of water inrush, divided into three distinct phases: the rupture of the water-resistant rock layer, the emergence of fluid-conducting channels, and the onset of large-scale water influx. Results indicate that under blasting load, the stress of the surrounding rock increases sharply, leading to instantaneous water inrush. The FEM-SPH model demonstrates superior performance in simulating the complex interactions between blasting stress waves, water pressure, and rock mass damage. This research provides new insights and methods for water control in tunnel engineering and offers significant potential for preventing water inrush disasters in underground construction. Full article

Tunnels beneath reservoirs are prone to significant geohazards, such as water and mud surges during excavation. To mitigate construction risks during the excavation of the Dajianshan Tunnel, a three-dimensional refined numerical model was developed. This study employed a fluid–solid coupling numerical model to analyze the temporal and spatial variations of the filtration field during the excavation and drainage of the tunnel section beneath the reservoir, and to assess its impact on pore pressure at the reservoir bottom. The results indicate that excavation and drainage initially cause a rapid decrease in pore water pressure at the tunnel vault, which gradually stabilizes. Furthermore, the extent of disturbance in the surrounding rock’s filtration field increases with distance from the tunnel vault. When the excavation intersects fault zones, water surges significantly affect filtration conditions at the reservoir bottom, resulting in a pore pressure reduction of approximately 5.2 kPa. Additionally, under blasting disturbance conditions, a larger disturbance range and higher permeability in the loosened zone led to greater pore pressure fluctuations, posing increased challenges for excavation safety and drainage management. This study provides a predictive model and methodology to prevent construction accidents during tunnel excavation, offering valuable insights for ensuring safety during the construction process. Full article

In geotechnical engineering, an accurate prediction is essential for the safety and effectiveness of construction projects. One example is the prediction of over/under-excavation volumes during drill and blast tunneling. Using machine learning (ML) models to predict over-excavation often results in low accuracy, especially in complex geological settings. This study explores how the pre-processing of measurement while drilling (MWD) data impacts the accuracy of ML models. In this work, a correlational analysis of the MWD data is used as the main pre-processing procedure. For each drilling event (single borehole), correlation coefficients are calculated and then supplied as inputs to the ML model. It is shown that the ML model’s accuracy improves when the correlation coefficients are used as inputs to the ML models. It is observed that datasets made from correlation coefficients help ML models to obtain higher generalization skills and robustness. The informational content of datasets after different pre-processing routines is compared, and it is shown that the correlation coefficient dataset retains information from the original MWD data. Full article

Risk assessment in tunnel construction using the drilling and blasting method presents a complex multi-criteria decision-making challenge due to numerous interacting factors. This study develops an advanced risk assessment model integrating game theory-based combination weighting with nonlinear fuzzy analytic hierarchy process (FAHP). The methodology establishes a comprehensive risk evaluation system through the systematic coupling of a work breakdown structure (WBS) and a risk breakdown structure (RBS), effectively combining subjective weights from an analytic hierarchy process (AHP) with objective weights derived through principal component analysis (PCA). A specialized nonlinear operator addresses the inherent fuzziness in the risk evaluation processes. The model is applied to the Daliangshan No. 1 Tunnel flat guide entrance drilling and blasting construction section, with the risk level determined to be high. Detailed analysis further revealed that the detonation network reliability and ventilation system performance constituted the most significant secondary risk elements. Comparative validation demonstrates the model’s superior accuracy over conventional methods in both weight determination and risk classification. The results demonstrate the effectiveness of the proposed model in improving risk assessment accuracy and supporting decision-making in complex tunnel construction environments. Full article

Steel arches and shotcrete systems are the most commonly used forms of initial support structures in underground tunnel engineering. Blasting and excavating in tunnels constructed using the drill-and-blast method affect the synergy between the early-age concrete and the steel arch. Research on the performance of commonly used grid steel frames and I-steel frames in tunnel support systems under blasting vibration conducted to date is not sufficient. In this paper, an experimental instrument was developed that can apply displacement and impact loads on concrete at an early age to simulate the stress situation of a steel frame during tunnel blasting excavation, and four groups of steel-grid frame and I-frame experiments were carried out. A numerical simulation of twelve schemes was launched based on ABAQUS, considering the effects of arch curvature and the time of impact load. Results: (1) The synergistic action between the steel frame and concrete has a time effect, and the damage between rebar and concrete caused by the blasting action decreases with the age of the concrete. (2) After the impact load, the ultimate bearing capacity of the two types of steel frame decreases by 25% and 15.5%, respectively, and the bearing capacity of the I-steel concrete arch is higher than that of the grid concrete arch, but the I-steel concrete arch is greatly affected by the vibration load. (3) The impact load and curvature of the steel arch have an impact on the synergy between the steel frame and concrete, while the supporting performance of the I-frame concrete arch is more significantly decreased by the effect of blasting excavation. Full article

Gas control and extraction are essential for energy use and sustainable development. In order to study the gas diffusion and transportation law of high-gas tunnels after excavation and blasting and the influence of ventilation on gas concentration, an engineering example is used as a research object. We put forward the “energy concentrating device + digital electronic detonator”, a new type of peripheral hole in the joint initiation of explosive technology, applied to a tunnel in the plateau, studied through field tests and the original “detonating cord + digital electronic detonator” joint detonation technology after a comparative analysis of the blasting effect. On this basis, the characteristics of gas diffusion and transportation near the palm face were studied by numerical simulation under the two working conditions of ventilated and unventilated, and the law of gas diffusion and transportation near the palm face was obtained. The research shows that: with the “energy concentrating device + digital electronic detonator”, a new perimeter hole joint detonation technology compared to the original “detonating cord + digital electronic detonator” joint detonation technology, the explosive unit consumption reduced by 0.2 kg/m³, half-hole retention rate increased by 5%, average charging time shortened from the original 1.3 h to 1.0 h, and stabilizing the cycle of footage at the same time greatly reduces the cost of consumables, improving the tunnel surface blasting effect; numerical simulation shows that under the condition of no ventilation, the gas accumulation near the arch top and arch waist at the tunnel face is severe, with the gas concentration close to 30%, the gas concentration is higher up to 7 m from the face after the gas state is stabilized, and the gradient of the gas concentration in the area beyond 7 m is small. The gas concentration in the area can be reduced to the safe range after ventilation in about 30 s, but gas accumulation easily occurs in the foot and arch waist on the opposite side of the wind pipe. The results of this study can provide a reference basis for similar gas tunnel blasting construction and ventilation optimization and promote the sustainable development of energy. Full article

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

In evaluating the construction safety of the building in the subway tunnel using the cover-and-cut method, the main objective is to analyze the diaphragm wall, the central pillar, and the roof. This article conducted a blasting vibration test based on the background of the Guiyang Metro Line 3 project and used the FLAC3D software to establish a three-dimensional numerical model. The results showed that the peak particle velocity (PPV) decreased with increasing distance from the blasting center. The PPV measured at the underground diaphragm wall was 1.424 cm/s, while at the bottom of the central pillar it was 1.482 cm/s. The predicted PPV on the roof was up to 1.537 cm/s, which met the safety standards. According to the cloud map of particle vibration velocity and the comprehensive analysis of particle vibration velocity, the degree of impact of artificial structures in the subway tunnel was the central pillar, the underground diaphragm wall, and the roof in order from high to low. After eight blasting operations per day, the vibration velocity trend at the vulnerable point of the central column increases, but it will not exceed the safety standard. Full article