Mechanical blasting mixed excavation method suitable for large section and long footage of subway station

Abstract

The invention discloses a large-section long-footage mechanical blasting mixed excavation method suitable for a subway station, and relates to the technical field of underground rail transit engineering, and the method comprises the following steps: obtaining a tunnel section contour, a geologic structure and blasting parameters, building a three-dimensional blasting wave propagation inversion model, and combining geology and material heterogeneity to obtain a three-dimensional blasting wave propagation inversion model; and identifying a closed space region forming reflection interference, and predicting a space point location where blasting wave energy is abnormally accumulated. Based on the three-dimensional blasting wave propagation inversion model, the abnormal wave energy accumulation area is predicted in combination with geological heterogeneity, the high-risk blasting section is recognized, parameters are reconstructed, vibration real-time monitoring and model feedback correction are assisted, a closed-loop control system is constructed, local wave crest abnormity is effectively restrained, and the safety and controllability of large-section tunnel blasting construction are improved.

Description

Technical Field

[0001] This invention relates to the field of underground rail transit engineering technology, specifically to a mechanical blasting and mixed excavation method suitable for large-section, long-expansion subway stations. Background Technology

[0002] "Mechanical-blasting hybrid excavation suitable for large-section, long-distance subway station construction" refers to a hybrid construction method that combines mechanized excavation (such as tunneling machines and hydraulic breakers) with controlled blasting (such as micro-delay blasting and directional blasting) in complex situations involving large cross-sections and long excavation lengths during subway station construction. This method leverages the advantages of both machinery and blasting techniques, combining the precision and continuity of mechanical excavation with the efficient breaking capacity of blasting on hard surrounding rock. It is particularly suitable for underground space engineering projects with complex rock types, high-strength surrounding rock, limited construction sites, or tight deadlines. By rationally controlling blasting energy and sequence, and coordinating with mechanical equipment for auxiliary excavation and shaping, the overall excavation efficiency is effectively improved, surrounding rock disturbance is reduced, structural stability is enhanced, and the multiple requirements for safety, efficiency, and quality in the construction of large-section, long-distance subway stations are met.

[0003] The existing technology has the following shortcomings: During the excavation of large-section, long-distance tunnels in subway stations, especially in areas with complex cross-sectional structures (such as sidewall recesses, deep arch grooves, locally thickened or sunken areas), conventional blasting can easily trigger abnormal changes in the propagation behavior of local blast waves. Specifically, the high-energy shock waves generated by blasting tend to undergo nonlinear, interlaced reflections and multiple energy superpositions within these closed or semi-closed geometric structures. This results in blast wave amplitudes in local areas far exceeding design expectations, forming high-intensity energy concentration zones, i.e., "local peak anomaly zones." These anomaly zones not only cause uncontrollable over-fracture or disturbance damage to the surrounding rock structure, leading to structural safety risks such as arch collapse and sidewall collapse, but may also impact the initial support structure (such as shotcrete layers or steel arches), inducing support failure, contour deformation, and connection errors. Furthermore, the formation mechanism of such local blasting effects is characterized by its suddenness and high degree of concealment, making it difficult to avoid through conventional blasting parameter configurations. This seriously threatens the stability of the tunnel structure and construction safety, becoming one of the key hidden risks affecting the quality control of large-section, long-distance mixed excavation.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a mechanical blasting and mixed excavation method suitable for large-section, long-expansion excavation of subway stations, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a mechanical blasting and mixed excavation method suitable for large-section, long-expansion excavation of subway stations, comprising the following steps: S1. Obtain the tunnel cross-sectional profile, geological structure and blasting parameters, establish a three-dimensional blasting wave propagation inversion model, combine geological and material heterogeneity, identify the closed spatial region that forms reflection interference, and predict the spatial location of abnormal accumulation of blasting wave energy. S2. Based on the predicted spatial locations of abnormal accumulation of blasting energy, structural resonance path analysis is performed to calculate the reflected wave path, energy superposition time sequence and amplitude amplification factor, and to determine the high-energy change region with a local amplitude amplification trend. S3. Based on the identified high-energy change region, construct an excitation coupling interference assessment index, and identify high-risk blasting sections by comprehensively considering the blast source layout, detonation sequence and cross-sectional geometry. S4, for high-risk blasting sections, reconstructs blasting parameters, adjusts the blast source location, delay time and charge structure, and controls the wave propagation path to deviate from the energy superposition zone; S5, during the implementation of the reconstructed blasting parameters, a vibration sensing device is deployed to collect the propagation behavior and surrounding rock response in real time, and to determine whether the peak distribution meets the expected adjustment direction. S6. Based on the difference between the vibration response data and the three-dimensional blast wave propagation inversion model, the model parameters and evaluation indicators are corrected to optimize the subsequent blasting design and achieve closed-loop control of local peak anomaly effects.

[0007] Preferably, step S1 includes: Acquire tunnel cross-sectional contour point cloud data, geological structure parameters, and blasting design parameters; A geometric model of the tunnel cross section was established based on point cloud data, and a 0.1-meter unit mesh was divided in FLAC3D, which was further refined to 0.02 meters in the high-energy superposition region. Different material constitutive parameters and boundary conditions are set according to geological zones, and detonation excitation loads are applied. The closed spatial region that forms reflection interference is identified by wave velocity field analysis and kinetic energy contour tracing method, and the spatial location of the abnormal accumulation of blast wave energy is determined by combining the third-order spline interpolation method.

[0008] Preferably, step S2 includes: Establish a local propagation behavior observation area with each point of abnormal accumulation of blast energy as the spatial center, and obtain wave propagation path, particle velocity and energy density distribution data within the area; By tracing the multiple reflected wave paths of the target point in reverse, points with highly overlapping reflection paths can be identified. Energy superposition time series analysis and amplitude amplification factor calculation were performed on the points where the reflection paths highly overlapped to screen out key points for resonance enhancement. The key points of resonance enhancement are projected onto the three-dimensional structural model and clustered into high-energy change regions.

[0009] Preferably, step S3 includes: Acquire data on the spatial location, delay time, charge structure, and excitation method of all explosion sources within a 2.5-meter radius of the high-energy change area; Analyze the angle between the propagation path of the explosion source and the reflection direction of the target structure, and calculate the spatial coupling degree; Analyze the time difference between the arrival of each explosion source wavefront in the target area and calculate the temporal overlap. By combining cross-sectional geometric parameters, a structural response sensitivity index is constructed, and the three indices are weighted to form an excitation coupling score to identify high-risk blasting sections.

[0010] Preferably, step S4 includes: The spatial location of the blast source was rearranged, and a staggered and layered distribution method was adopted to keep the propagation path of the blast wave away from the weak parts of the structure. Based on the new layout results, the detonation delay time is set, and electronic detonators are used for zoned control to increase the detonation interval between adjacent detonation sources and disrupt wavefront synchronization. The charge structure was optimized for each structural part, and cavity partitions and energy-blocking fillers were set to limit the continuous increase of wave amplitude. The effects of amplitude reduction, phase misalignment, and energy shift were verified through three-dimensional simulation, confirming the effectiveness of the reconstruction parameters.

[0011] Preferably, step S5 includes: Three-dimensional vibration sensing devices are deployed at the corners of the arch, the grooves of the side walls, the broken lines of the inverted arch steps, and the connection nodes of the steel arch frame to form a high-density spatial monitoring network. During the blasting process, all vibration sensing devices were activated to collect three-dimensional particle velocity time history data within 150 milliseconds and transmit it synchronously to the data master station. A point-by-point comparative analysis was conducted between the measured data and the simulation prediction results, focusing on three aspects: peak arrival time, propagation direction, and peak amplitude. The analysis results determine whether the peak conforms to the predicted path direction. If more than 80% of the monitoring points meet the standard and the amplitude decreases by more than 30%, the reconstruction is considered effective.

[0012] Preferably, after the reconstruction is deemed valid, the following steps are performed: Based on the measured data of blast wave propagation obtained by the three-dimensional vibration sensing device, a spatial distribution map of the measured-predicted difference is generated. By overlaying and comparing the spatial distribution map of the differences with the identification results of high-risk blasting sections, local areas with significant deviations in peak time, direction, or amplitude are marked. Export the blast source location, delay time and charge parameters corresponding to the deviation area for subsequent blasting scheme optimization modeling input; All vibration monitoring data will be archived into the blasting construction database as a historical reference for subsequent blasting designs in geological sections.

[0013] Preferably, step S6 includes: The measured wave peak arrival time, particle velocity amplitude, propagation direction and equivalent energy density are compared one by one with the predicted values ​​of the three-dimensional simulation model at the same coordinate point to identify model deviation points with significant errors in wave velocity, wave amplitude and direction. For the deviation points in the model, the elastic modulus, shear modulus and wave impedance parameters of the corresponding surrounding rock area were adjusted, and the reflection boundary conditions and joint structure parameters were corrected. Wave propagation simulation was then performed again. Based on the corrected simulation results, the excitation coupling scoring matrix was reconstructed, the spatial focusing coefficient, the time superposition coefficient and the structural amplification sensitivity coefficient were quantified, and the first-level high coupling interference zone was calibrated. The scoring results are fed back to subsequent blasting designs. For the first-level high-coupling interference zone, optimized control strategies are implemented, including offsetting the blast source layout, increasing the delay time, and configuring the three-stage charge structure.

[0014] The technical effects and advantages provided by the present invention in the above technical solution are as follows: This invention, based on a three-dimensional blast wave propagation inversion model and combined with the heterogeneous characteristics of geological structure and materials, accurately predicts the abnormal accumulation points of blast wave energy. Through resonance path analysis and excitation coupling indices, it systematically identifies high-risk blasting sections and achieves targeted reconstruction of blasting parameters. More importantly, the method incorporates on-site vibration sensing devices for real-time monitoring and dynamic comparison with simulation models. Through a parameter feedback mechanism, it continuously corrects design strategies, constructing a closed-loop control system integrating "prediction-verification-correction-redesign." Compared with traditional blasting schemes, this method significantly reduces engineering risks such as arch collapse, sidewall collapse, and support failure caused by coherent superposition of blast waves, enhances the ability to suppress local peak anomalies, and effectively ensures the construction safety and controllability of blasting operations in large-section subway tunnels under complex geological conditions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1 This is a flowchart illustrating the method of mechanical blasting combined with excavation for large-section, long-distance excavation of subway stations, as described in this invention. Detailed Implementation

[0017] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that the description of this disclosure will be more complete and fully convey the concept of the exemplary embodiments to those skilled in the art.

[0018] This invention provides, for example Figure 1 The mechanical blasting and mixed excavation method shown is suitable for large-section, long-expansion excavation of subway stations and includes the following steps: S1. Obtain tunnel excavation cross-sectional contour data, geological structure parameters, and construction blasting parameters. Based on the acquired data, establish a three-dimensional blasting wave propagation inversion model, considering the heterogeneity of geological structure and surrounding rock materials, identify closed spatial regions that form reflection interference in the geometric structure, and predict the spatial locations of abnormal accumulation of blasting wave energy. To address the problem of anomalous superposition of blast wave energy caused by complex cross-sectional structures, a technical approach is proposed to construct a three-dimensional blast wave propagation inversion model based on refined geometric and geological information. This is achieved through the following steps: Three types of core input data were acquired as the basis for model construction: First, a portable 3D laser scanner was used to conduct on-site mapping of the tunnel to be excavated, obtaining point cloud data of the cross-sectional contour, ensuring that the acquisition accuracy was better than 5 mm. The data covered all structural features of the tunnel, including the main arch section, the transition zone between the arch waist and the sidewall grooves, the deep grooves of the invert arch, the reserved pipe slots, and the area surrounded by the steel arch frame. Second, combined with the results of borehole sampling, seismic wave velocity testing, and CT scan analysis, detailed geological structural parameters were extracted, including the rock mass layering structure, joint surface orientation, lithology calibration, structural surface spacing, weathering degree, and fault influence range. The elastic modulus, shear modulus, Poisson's ratio, density, and damping coefficient of each rock layer were also determined. Third, the pre-set blasting parameters were extracted from the construction design documents, including the spatial coordinates of each blast hole, the length of the charge column and the length of the empty charge section, the charge amount per hole, the type of explosive (such as No. 2 rock emulsion explosive), the detonation sequence (such as millisecond delay), the type of detonator (electric detonator or electronic detonator), and the arrangement of the blast holes (linear array or ring array).

[0019] Based on the above data, a three-dimensional blast wave propagation inversion model was constructed. This model was built in the commercial finite difference simulation platform FLAC3D. First, based on the point cloud data, a precise cross-sectional geometric model was generated using CAD modeling software (such as SolidWorks or Rhino), and then divided into tetrahedral or hexahedral meshes with a minimum element side length of 0.1 meters in the preprocessor. In high-energy-sensitivity regions (such as the transition zone between the sidewall and the arch foot), the mesh was refined to 0.02 meters. Second, geological zones were imported, and different regions such as granite, sandy mudstone, tuff, and fractured soft rock were assigned their respective material constitutive relations. An elastoplastic dynamic material model was used, and Coulomb frictional contact boundary conditions were set for the joint zones. Third, the blast source point was mapped to the excitation load input position in the model, and the instantaneous pressure loading (usually 10) at each initiation moment was set according to the blasting design. 7 Pa (lasting 0.1ms) is used to achieve multi-point directional excitation input; finally, absorbing boundary conditions are set to prevent boundary reflection interference, and the blast wave propagation simulation is performed with a total duration of not less than 150ms.

[0020] During the simulation, the reflection behavior of blast waves in geometrically discontinuous regions was analyzed to identify closed spatial regions forming reflection interference. Wave velocity field analysis and kinetic energy contour tracing were used to extract wave propagation path trajectories at locations such as the arch corner, the concave area at the wall foot, and the thickened section of the invert arch. By comparing the energy attenuation slope and velocity vector coincidence on different paths, regions exhibiting wave path intersections of three or more times were identified, and their occurrence times and maximum amplitude locations were recorded. Further analysis of the peak particle velocity and cumulative kinetic energy density in these regions within the 0-50 ms range of the blast was conducted, identifying spatial bodies with a wave field overlap greater than 80% and an amplitude increase exceeding three times the original excitation value as closed reflection interference regions. Furthermore, multi-time snapshot synthesis analysis was used to reconstruct the dynamic change trend of these spatial bodies, confirming their energy focusing capability over time and providing a basis for subsequent point calibration.

[0021] The "wave velocity field analysis and kinetic energy contour tracing method" refers to a method used in three-dimensional blast wave propagation simulations to dynamically identify the propagation, reflection, and accumulation paths and trends of waves in space by observing the velocity distribution and kinetic energy spatial distribution at different time points. Its role in this blast inversion model is to locate and analyze the actual propagation trajectory of blast waves within areas of geometric abrupt changes in tunnel structures, particularly identifying dangerous areas where multiple reflections and energy superposition may occur, such as arch crown turning points, sidewall recesses, and thickened sections of inverted arch steps.

[0022] The specific steps are as follows: In the three-dimensional simulation results, wave velocity distribution data are extracted at multiple time points after the blast initiation to generate a "wave velocity field" image. The wave velocity field shows the magnitude and direction of particle velocities at different spatial locations. Higher wave velocity regions indicate that the wavefront has just passed, while lower wave velocity regions are attenuated areas that have not yet arrived or have been reflected.

[0023] Overlaying kinetic energy contour maps involves drawing contour lines with the same kinetic energy density within the model to identify spatial regions where energy is concentrated. By continuously tracking the evolution of these contour lines over time, it is possible to observe trends in which fluctuations bend, focus, or repeatedly reflect in specific structural areas (such as arch corners).

[0024] By comparing these characteristic regions over time and analyzing the evolution path of the kinetic energy contour lines at structural corners, combined with the wave velocity vector direction, the propagation trajectory of the blast wave in these irregular structures can be clearly depicted. For example, if the wave velocity vector reverses direction multiple times within the groove of the side wall, and the kinetic energy contour lines repeatedly accumulate at that location, it indicates the presence of a high-frequency reflection path in this area, which is a closed space where energy accumulates abnormally.

[0025] By projecting the trajectory lines and superimposed areas onto the tunnel cross-section diagram, the convergence point of the reflection path can be accurately located, serving as the input basis for subsequent analysis of high-risk areas of "local peak anomalies".

[0026] Within the identified closed spatial region, key points exhibiting strong energy accumulation trends were extracted. By comparing the particle velocity time history curves at each point, a third-order spline interpolation method was used to fit the amplitude change rate curve. The amplitude growth slope, superposition time sequence consistency coefficient, and instantaneous power density of each point were calculated. Ultimately, points exhibiting strong nonlinear growth trends and multiple simultaneous reflections within the initial stage of blasting excitation (0-20ms) were selected as abnormal accumulation points of blasting waves. Furthermore, the coordinates of these points were projected back into the tunnel excavation cross-section geometric model to locate their corresponding component locations in the actual structure (such as the sprayed concrete zone at the arch crown, steel arch connection nodes, and concrete joints at the invert arch). These locations served as key control points for high-risk areas, providing a spatial input basis for subsequent blasting structure resonance path analysis, excitation interference control, and fine parameter reconstruction.

[0027] Third-order spline interpolation is a commonly used smoothing fitting technique in data analysis. Its basic idea is to connect a series of cubic curve segments to create a smooth transition between each data point, thereby accurately reproducing the continuous trend of data change over time or space. In this invention, the third-order spline interpolation method is used to finely fit the amplitude variation data at various points during the simulation of blast wave propagation, in order to capture the dynamic change characteristics within the initial stage of blast excitation (0~20 milliseconds) and identify spatial points where local peak anomalies may exist.

[0028] In practice, the particle velocity time history data at each monitoring point during the initial stage of blasting excitation is first extracted from the simulation results, and a discrete data point sequence is constructed at equal time intervals. Then, a third-order spline interpolation method is used to fit these discrete data points into a continuous and smooth amplitude variation curve, ensuring that the curve satisfies both the data trend and good derivative continuity within each time period, avoiding drastic jumps or inaccurate fluctuations. Next, the slope change of the fitted curve on the time axis is analyzed to extract the amplitude growth rate of each point within a short time period, used to determine its energy concentration. Simultaneously, the temporal overlap of multiple reflected waves arriving at the point is compared, and the "superposition temporal consistency coefficient," reflecting the synchronicity of multiple wave superposition, is calculated to further determine whether it belongs to a reflection focus of multi-wave synergistic enhancement. Finally, combined with the local kinetic energy change rate at the point within the same time period, its instantaneous power density level is estimated. The amplitude growth rate, temporal overlap, and energy density are used to jointly determine whether the point has a significant nonlinear growth trend and abnormal accumulation characteristics of blasting waves.

[0029] This method can effectively screen out key points that exhibit obvious energy anomalies in the early stages of excitation from thousands of model calculation points, serving as the core basis for subsequent dangerous section identification and blasting parameter reconstruction, thus effectively improving prediction accuracy and intervention targeting.

[0030] The purpose of this step is to provide a fundamental model for blast wave propagation with high spatial accuracy and geological responsiveness for subsequent prediction and control of local blast wave peak anomalies in large-section, long-distance tunnels in subway stations. By acquiring tunnel excavation cross-section contour data, geological structure parameters, and construction blasting parameters, a comprehensive understanding of the geometric morphology, surrounding rock structure, and actual blasting boundary conditions of the construction area can be obtained, thus providing a realistic input basis for numerical simulation. The three-dimensional blast wave propagation inversion model established on this basis can dynamically simulate the propagation, reflection, refraction, and interference processes of blast waves after blasting excitation under different lithological zones, cross-sectional geometric changes, and charge layouts, realistically reproducing the spatiotemporal evolution path of blast waves in complex spatial structures. In particular, by introducing the modeling of the heterogeneity of the surrounding rock material (such as impedance differences between different rock layers and the degree of fracture development), the nonlinear and asymmetric behavior of energy propagation in actual engineering can be effectively captured, making the model closer to the real construction scenario. The ultimate goal of this model is to identify closed spatial regions formed by multiple wave reflections and interference in complex geometric areas (such as arch crown recesses, sidewall corners, and thickened invert arch areas), and to locate points within these regions where the energy superposition intensity is significant and the propagation paths highly overlap, indicating anomalies in the accumulation of blasting waves. These points are often the core source areas for the formation of local wave peak anomalies in subsequent blasting, and are highly susceptible to inducing arch crown collapse, sidewall damage, or initial support failure. Therefore, accurate prediction through this step in advance is not only a necessary prerequisite for achieving optimized blasting design, but also a key control measure to ensure the stability of complex tunnel structures and construction safety.

[0031] S2. Based on the predicted spatial locations of abnormal accumulation of blasting energy, perform blasting wave structural resonance path analysis, calculate the reflected wave path, energy superposition time sequence and amplitude amplification factor at the corresponding locations, and determine the high-energy change area with local amplitude amplification trend. To further identify the multipath reflection and local energy enhancement behavior of blast waves in complex geometries, structural resonance path analysis of blast waves is conducted based on the predicted spatial locations of blast energy anomalies. This analysis includes the following steps: All accumulated points of blast energy anomalies identified in the previous stage using the 3D blast wave propagation inversion model were extracted, and local propagation behavior observation areas were established for each point. A cubic analysis unit with a side length of 2.0 meters was set up with each point as the spatial center, divided into a spatial grid with an accuracy of no less than 0.05 meters. Within each local analysis unit, particle velocity data, energy density distribution data, and direction vector data from the entire blast simulation timeline were retrieved to construct a complete wave propagation record for that point within a time window of 0 to 100 milliseconds after blast excitation. Based on this, the main propagation path of the blast wave from the initial excitation point to the target point was analyzed, tracing the wavefront propagation direction, propagation speed, and arrival time, and a path trajectory diagram was plotted for subsequent reflection behavior analysis.

[0032] Reflection path identification is performed for each target point. Using a 3D visualization analysis platform, the target point is used as the receiving point, and the paths of the main wave and reflected waves received at multiple time points are traced in reverse. Each propagation path is comprehensively judged based on spatial angle, incident boundary attributes, and propagation duration. For example, if the path originates from the tunnel arch corner, the invert arch depression area, or the sidewall inflection surface, and the number of reflections is not less than two, and the propagation paths intersect at a high angle in space, then this path is marked as a multiple reflection path. If a target point receives reflected waves from three or more different directions, and the difference between the incident angle and the reflection angle of the reflected path is less than 15 degrees, and the angle between the propagation paths is less than 30 degrees, it indicates that the point is in a multi-path coupling focal region with obvious resonance focusing characteristics, and is recorded as a "highly coincident reflection path point."

[0033] At identified points exhibiting multipath reflection characteristics, energy superposition time-series analysis and amplitude amplification factor calculations were performed. Specifically, the particle velocity variation curve at this point was extracted from the model data, and the waveform was smoothly fitted using third-order spline interpolation to determine the main peak positions and corresponding times. The time interval between adjacent peaks was calculated to determine if they were concentrated within 20 milliseconds after the explosion. If two or more peaks with similar heights and time intervals less than 2 milliseconds occurred within this time period, it indicated a synchronous superposition trend. Furthermore, the maximum peak amplitude was compared with the peak value at the initial excitation point within the same time period to calculate the amplitude amplification factor. If the amplitude amplification factor was greater than 3.0 and the time interval between superimposed peaks was less than 1 millisecond, it indicated that this point had a significant local amplitude amplification effect and was identified as a "key point for resonance enhancement."

[0034] All key resonance enhancement points are projected back into the 3D tunnel structure model, and their corresponding structural locations are determined based on their spatial coordinates. Points located in the concave corner area at the lower edge of the arch, the connection between the steel arch frame and the shotcrete support, the abrupt change section of the concrete bottom of the invert arch, or the transverse transition zone of the sidewall are classified as structurally vulnerable high-energy variation areas. Using spatial grouping and cluster analysis, multiple adjacent high-energy points are merged into a single "high-energy variation area," and the mean amplitude amplification factor, energy superposition frequency, and reflection path density within this area are calculated. These calculations serve as quantitative references for subsequent blasting interference control and optimization of parameters in hazardous sections.

[0035] This step aims to further analyze the reflection and propagation characteristics and energy temporal superposition mechanisms of the structural space where these points are located, based on the identified spatial locations with abnormal energy accumulation of blast waves. This allows for the precise identification of key areas most likely to experience resonance focusing and abnormal local amplitude amplification during the blasting process. By calculating the reflected wave path at each point, the specific direction, propagation sequence, and path overlap of multiple reflections of the blast wave in areas of abrupt structural geometry change (such as arch foot, sidewall grooves, and invert arch steps) can be determined, indicating the presence of high-frequency convergence of reflected waves in space. Combined with the temporal arrival sequence analysis of these reflected waves, it can be further identified whether multiple wavefronts arrive at the same location synchronously within a very short time, forming a high degree of consistency in the energy superposition temporal sequence. If the calculated amplitude amplification factor is significantly higher than the initial excitation value, it indicates a significant resonance effect at that point, and the surrounding space is highly likely to develop into a high-energy impact zone. In actual tunnel excavation, such high-energy change areas are often the triggering source of risk events such as arch collapse, support cracking, or profile deviation. Therefore, this step of identifying and quantitatively evaluating these areas in advance not only provides a scientific basis for the precise control of subsequent blasting parameters, but also lays a technical foundation for structural reinforcement and support early warning in high-risk sections. This analysis acts as a bridge in blasting control, transforming the results of preliminary simulation predictions into implementable and interventionist spatial objects, achieving a crucial shift from "identifying problems" to "preventing risks."

[0036] S3. Based on the identified high-energy change area, construct an excitation coupling interference assessment index, comprehensively quantify the coupling relationship between the blast source location, the detonation delay sequence and the tunnel cross-sectional geometry, and identify high-risk blasting sections that are prone to nonlinear concentration of blasting energy. To effectively identify high-risk areas where nonlinear energy concentration of blast waves may occur during blasting operations, potentially leading to structural disturbances, a vibration coupling interference assessment index is constructed based on previously identified high-energy variation areas. This assessment method comprehensively analyzes the spatial distribution of blast source points, the configuration of detonation delay time, and the energy-concentrating characteristics of the tunnel cross-sectional geometry to determine the blasting risk level point by point. The process includes the following steps: The coordinates of the high-energy variation regions identified in the 3D simulation analysis are projected back onto the tunnel entity structure corresponding to the construction design drawings. Combined with the 3D laser measurement model, these regions are determined to be located in areas of structural geometric abrupt changes, such as the circumferential concave corner of the arch crown, the connection between the sidewall and the invert arch, the variable cross-section of the arch waist, and the step-turning section of the invert arch. Based on this, information on all blast sources within a 2.5-meter radius is retrieved, including the 3D spatial coordinates of the blast source point, the detonation delay time, the type of explosive used (e.g., emulsion explosive, MF-fueled explosive), the charge structure (cylindrical or segmented charge), the charge amount per hole (in kg), and the detonation method (e.g., millisecond electric detonator, electronic detonator). This data serves as the complete set of excitation input factors around the high-energy region. A corresponding data list is established and entered into the simulation analysis platform for subsequent coupled modeling.

[0037] A dual spatial and temporal analysis was conducted on the coupling relationship between the aforementioned explosion source data and the high-energy variation region. Spatially, the Euclidean spatial distance between each explosion source point and the center point of the high-energy region was calculated. Simultaneously, the wave propagation direction vector was extracted, and its direction of propagation was analyzed to determine if it aligns with the main reflection path direction of the target region. If the path angle is less than 20 degrees, it is considered to exhibit a directional focusing trend. Temporally, the delayed detonation sequences of all relevant explosion sources were analyzed, a delay time axis diagram was plotted to form a time series array, and the time nodes for the propagation of each explosion source wave to reach the target region were calculated to determine whether multiple explosion source waves superimpose within a time window of no more than 5 milliseconds. If both spatial directionality and temporal coincidence are satisfied, the target region is considered to be potentially affected by multi-point coordinated excitation, posing a risk of nonlinear energy concentration.

[0038] An excitation coupling interference assessment index was constructed to quantify the aforementioned coupling relationships. Three indices were specifically defined: the first is the spatial coupling degree index, reflecting the consistency between the propagation path of the blast source and the main reflection path of the target structure, normalized using the cosine of the direction angle; a value closer to 1 indicates a higher spatial coupling degree. The second is the temporal overlap index, reflecting the synchronicity of overlapping wavefronts from multiple initiation points in the target area, uniformly normalized using a Gaussian weighting factor based on the wavefront arrival time difference. The third is the structural response sensitivity index, modeled based on the geometric abrupt changes in the target area in a three-dimensional cross-sectional model, including parameters such as radius of curvature, indentation depth, and variable cross-sectional angle, to obtain its structural response index to the blast wave reflection and focusing capability. After standardization, the three indices were linearly superimposed with weighted coefficients to form a comprehensive excitation coupling score, ranging from 0 to 1; a higher score indicates a stronger coupling effect and a greater risk of structural disturbance.

[0039] Based on the excitation coupling score, a risk assessment threshold is set, typically 0.75, to classify all high-energy areas. Areas with a score greater than or equal to 0.75 are classified as "Level 1 High-Risk Blasting Sections," those with scores between 0.5 and 0.75 are "Level 2 Intervention Sections," and the rest are "Conventional Control Sections." For Level 1 High-Risk Sections, subsequent blasting designs must prioritize control measures such as repositioning of the blast source, optimizing the charge structure, and adjusting the detonation sequence. Simultaneously, the support thickness, material strength, and joint rigidity of the area must be strengthened, and multiple vibration monitoring points must be deployed for real-time feedback control. This process not only achieves quantitative identification of high-risk blasting sections but also provides a decision-making basis for subsequent precise control blasting.

[0040] The purpose of this step is to further identify high-risk blasting sections that may be induced by nonlinear energy concentration effects due to unreasonable excitation source configuration, based on the identified high-energy variation areas, by establishing an excitation coupling interference assessment index with multi-dimensional analysis capabilities of spatial, temporal, and structural responses. By analyzing the spatial distribution of the blast sources and the angle between the propagation path of the excitation direction and the high-energy region, it can be determined whether the excitation energy has a spatial focusing trend. Furthermore, by analyzing the time difference of the detonation delay sequence, it can be determined whether the blast waves released by multiple blast sources are superimposed within an extremely short time window, thus forming the temporal synchronization of the instantaneous energy peak. On this basis, combined with the geometric characteristics of the tunnel cross-section structure, such as the curvature of the arch foot, the abrupt change of the invert arch step, and the spatial configuration parameters such as the angle of the sidewall groove, the sensitivity of the target area to the reflection and focusing of blast waves can be further determined. By comprehensively quantifying the above three factors, the constructed excitation coupling interference assessment index can not only be used to assess the structural disturbance risks hidden in the current blasting design scheme, but also provide a reliable basis for subsequent optimization of blasting parameters, reconstruction of the detonation sequence, and rearrangement of blast sources. By using this indicator to classify risks, high-risk blasting sections most likely to experience abnormal energy accumulation, excessive rock fragmentation, initial support failure, or contour deformation during blasting can be identified in advance. This allows for a shift in construction risk management from "passive response" to "proactive prediction." This step plays a crucial role in the entire closed-loop control process of blasting design, serving as a fundamental analytical step for achieving precise blasting, controlling structural disturbance, and ensuring construction safety.

[0041] S4. For the identified high-risk blasting sections, the blasting parameters are reconstructed, the spatial layout of the blast source, the initiation delay time, and the charge structure configuration are reset, and the propagation path of the blast wave is controlled to move away from the high-energy superposition area, so as to achieve the diffusion and phase misalignment of the blast wave energy. For identified high-risk blasting sections, to avoid multi-source coupling and superposition of blast waves in structurally complex areas, resulting in abnormally enhanced local amplitudes and causing construction hazards such as over-fractured surrounding rock, damage to initial support structures, or excavation profile deviation, a blasting parameter reconstruction strategy based on energy path regulation and peak misalignment control needs to be implemented. This strategy includes resetting the spatial layout of blast sources, the configuration of initiation delay time, and the composition of the charge structure to ensure that the blast wave propagation path avoids high-energy superposition zones, achieving directional diffusion and phase difference control. Specifically, it includes the following steps: Based on the spatial coordinates of the three-dimensional high-risk blasting section, the original blast source layout scheme was globally adjusted. Taking construction sections as units, the blast source arrangement was redesigned on the cross-sections to avoid concentrating multiple blast sources in structurally weak areas, such as the upper edge of the arch, the junction of sidewall recesses, or the corner of the invert arch steps. In the optimized design, a "staggered arrangement + layered distribution" method was adopted: in the circumferential arrangement, blast sources were arranged in a spiral cross pattern, with a longitudinal offset of 0.6 meters between each adjacent row; in the axial direction, the spacing between each blast source row was maintained at no less than 1.5 meters, and an asymmetrical configuration was set according to the structural direction. This guided the blast wavefront during propagation towards areas with relatively higher structural strength (such as straight sections of sidewalls or the bottom surface of the invert arch), reducing the wavefront concentration tendency at structural geometric transitions.

[0042] Based on the rearranged blast source locations, a new detonation delay time program was developed. A millisecond-level electronic detonator control device was employed, assigning each blast source point an independent delay configuration. The detonation sequence strictly adhered to the principles of "staggered main reflection directions" and "delayed critical structural nodes": the blast source delay time corresponding to the concave corner area of ​​the arch was set to +80 milliseconds after the reference blast source, +60 milliseconds at the sidewall recess, and +100 milliseconds in the invert arch turning-back area. This ensured that the blast wave fronts generated by blast sources at different locations were staggered as much as possible on the time axis, preventing them from synchronously reaching high-risk structural areas. The detonation interval between adjacent blast source points was no less than 20 milliseconds. By "spacing out" the timing, synchronicity was disrupted, effectively dispersing the focused energy in the time domain.

[0043] Based on the reconstructed blast source locations and delay sequences, a specific design optimization of the charge structure was implemented for each blast hole. Regarding the selection of charge materials, low-velocity emulsion explosives were used in the arch and invert areas, with detonation velocities controlled between 3,000 and 3,200 meters per second; while ammonium nitrate explosives were used in the sidewalls and structurally sensitive areas, reducing the detonation velocity to 2,500 to 2,800 meters per second, thus slowing wavefront propagation. In terms of the charging method, a "spaced-cavity charge + energy-blocking filler" structure was adopted, meaning that each blast hole contained two sections of explosive charge with a non-explosive high-density polyethylene inert material layer inserted in between, with a length not less than 10 centimeters. This structure creates an energy interruption zone during detonation, significantly reducing wavefront continuity and minimizing the possibility of phase interference. Simultaneously, the total charge amount per hole was controlled to not exceed 80% of the original design charge amount. By reducing the peak blast energy release rate and increasing waveform amplitude differences, the convergence conditions of the reflection path were further intervened.

[0044] Based on the above reconstruction results, a three-dimensional blast wave propagation simulation platform (such as a dynamic analysis model based on FLAC3D or LS-DYNA) was used to simulate the propagation path of the new scheme. The changes in the blast wave propagation path, amplitude distribution curve, and energy concentration area location were compared between the original design and the reconstructed scheme. The focus was on monitoring whether the peak amplitude of the original high-risk blasting section decreased by more than 30%, whether the phase arrival time difference was greater than 5 milliseconds, and whether the location of the maximum energy density deviated from the original identification point by more than 0.5 meters. If all three indicators were met, it indicated that the reconstructed scheme effectively broke the energy coupling path, achieved peak misalignment and diffusion control, and verified that the interference control target was achieved. Finally, this reconstructed scheme will serve as the basis for optimizing the construction drawing design, and will be simultaneously fed back to the support design department for synchronous reinforcement design coordination. It will also be transmitted to the on-site blasting process guidelines as the basis for executing blasting construction control parameters.

[0045] The purpose of this step is to fundamentally intervene in the propagation path and interference characteristics of blast waves in structurally complex areas by reconstructing blasting parameters for identified high-risk blasting sections. This avoids engineering risks such as structural disturbance, excessive rock fragmentation, or initial support failure caused by multi-source superposition and energy focusing of blast waves in space. In traditional blasting design, blast sources are often arranged symmetrically and equidistantly, and the charge structure and delay time are configured based on experience, ignoring the amplification effect of different cross-sectional structures on the combination of wave propagation direction and phase. Especially in geometrically discontinuous areas such as concave corners of tunnel arches, bends in sidewalls, or steps of inverted arches, high-amplitude local wave peaks can easily form due to the convergence of blast waves along multiple paths in a short period of time, leading to excessive structural stress. This step redefines the spatial distribution of blast source points to avoid areas of high energy coupling. At the same time, by staggering the detonation delay time, the wavefronts generated by each blast source are phase-shifted on the time axis, avoiding synchronous energy superposition. Furthermore, by adjusting the charge structure, such as using cavity charges, segmented charges, and combinations of low-velocity explosives, the release of blast energy is made discontinuous and dispersed, effectively reducing peak amplitude, disturbance concentration, and reflection overlap rate. Ultimately, the blasting scheme, after parameter reconstruction, allows the blast wave to propagate within the structure with directional diffusion and temporal misalignment characteristics, achieving energy interference control over the original high-risk blasting sections. This process not only optimizes the blast energy release pattern but also provides a precise design basis for subsequent blast monitoring and structural response control during construction, making it a key technical step in achieving high-precision, low-disturbance, and safe controllable blasting operations.

[0046] S5. During the implementation of the reconstructed blasting parameters, multiple vibration sensing devices are deployed to collect blasting wave propagation behavior and surrounding rock vibration response data in real time, and to determine whether the actual blasting wave peak distribution conforms to the predicted path adjustment direction. To verify whether the reconstructed blasting parameters effectively controlled the propagation path of the blast wave, high-precision vibration sensing devices need to be deployed on-site to monitor the wave propagation behavior and surrounding rock vibration response in real time during the blasting process. By comparing the measured data with the simulation prediction results point by point, closed-loop verification of the wave crest propagation trajectory deviation, energy concentration trend, and directional control effect is achieved, ensuring that the blast energy does not refocus in high-risk areas. This process includes the following steps: High-density vibration sensing devices were deployed in the tunnel construction section to collect real-time responses to blast wave propagation. Based on the main propagation path and energy reflection focal points identified in the 3D blasting simulation model, priority was given to selecting sensing point locations, focusing on covering arch corners, sidewall recesses, invert arch step sections, and steel arch connection nodes. Each sensing point used a triaxial electrodynamic velocity sensor (model SVS1000, frequency range 0.5Hz–1kHz) and a high-precision data acquisition unit with a sampling frequency of 20kHz and a sampling accuracy of ±0.1mm / s. The sensing points were spaced 3 meters apart circumferentially and 2.5 meters apart longitudinally, employing a staggered layout. Three layers of vertical sensing panels were installed in typical structural sections to form a three-dimensional multi-point spatiotemporal monitoring network. The sensors were all mounted on the outer surface of the shotcrete layer in a waterproof enclosure, using a double-fixation method of chemical anchors and steel supports to ensure continuous and reliable data acquisition under blasting loads.

[0047] During the blasting phase, a unified blasting command system issues the activation command, simultaneously initiating the data acquisition programs of all vibration sensing devices. Each device collects complete wave response data from the moment of blasting to within 150 milliseconds, including the three-dimensional component time history curves of particle velocity, the first arrival time of the blast wavefront, the peak amplitude time, and the frequency response energy spectrum. The acquired data is transmitted in real-time to the on-site data processing main station via fiber optic communication lines for multi-channel synchronous processing. The processing software generates wave crest propagation animations, constant amplitude line distribution maps, and structural response energy maps in real time, forming a unified visual image and data result for simultaneous analysis by the construction technical team.

[0048] The collected measured data and the simulation model prediction results established before and after the reconstruction of blasting parameters were compared and analyzed point by point. The comparison included three core indicators: first, the time error between the first arrival time of the wave crest and the predicted time, with a control target of no more than ±3 milliseconds; second, the directional deviation between the measured propagation direction and the predicted main propagation path, with a directional angle deviation of no more than ±15 degrees; and third, the difference in amplitude between the peak particle velocity and the simulation result, with a control target of within ±25%. If the measured data met the above standards, the blasting wave propagation behavior at that point was considered to conform to the expected control path; if it exceeded the limits, further evaluation was needed to determine whether it was an abnormal phenomenon caused by local geological changes or coherent interference of blasting waves, and the area was marked as requiring further intervention. All monitoring point results were integrated and output in the form of spatial coordinates to generate a "Spatial Distribution Map of Measured-Predicted Differences", which was then overlaid with the original high-risk area identification results for comprehensive comparative analysis.

[0049] Based on the comparative analysis results, the effectiveness of the blasting parameter reconstruction strategy is assessed. If more than 80% of the monitoring points meet the control targets for wave crest time, direction, and amplitude, and the measured wave amplitude at sensing points in high-risk areas decreases by more than 30% compared to the original design scheme, and the wavefront synchronous arrival probability decreases to below 20%, then the blasting parameter reconstruction scheme for this round is considered effective, and the wave field control target is achieved. Otherwise, the blast source layout or detonation delay scheme needs to be adjusted based on monitoring feedback, and simulation modeling and on-site verification need to be carried out again. The assessment results are compiled into a special analysis report by the construction unit and submitted to the supervisor, design, and safety technical leaders for joint review, serving as the basis for subsequent optimization of blasting section parameters or revision of support structure design. At the same time, all monitoring data are archived into the blasting construction database as prior data for the configuration of blasting design parameters in future sections with similar geological conditions.

[0050] The purpose of this step is to construct a three-dimensional sensing network covering key structural areas by deploying multiple high-precision vibration sensing devices at the blasting construction site. This enables real-time monitoring and data acquisition of the entire process of blast wave propagation behavior and surrounding rock vibration response, allowing for the determination of whether the reconstructed blasting parameters have achieved the preset control targets of "energy diffusion" and "wave crest misalignment." In complex tunnel construction, even after theoretical optimization and simulation verification, blasting parameters may still be affected by factors such as geological heterogeneity, construction disturbances, and equipment precision, causing the actual wavefront propagation trajectory to deviate from the original set path, resulting in unexpected local amplitude enhancement. Therefore, this step, through on-site monitoring to reinforce the design model, is a crucial link in achieving closed-loop control of "prediction-verification-optimization." Specifically, the vibration sensing devices can collect dynamic data such as particle velocity, acceleration, and kinetic energy density at each point after blasting excitation, clarifying the actual propagation path, arrival time, and peak amplitude of the blast wavefront in three-dimensional space. By comparing the measured data with the predicted path in the blast wave propagation inversion model, it is possible to accurately determine whether the wave peak successfully avoided high-energy change regions, whether a time misalignment occurred in sensitive structural parts, and whether the preset control intervention effect was achieved. If the measured wave peak direction, timing, and amplitude all match the prediction results, it indicates that the blasting parameter reconstruction scheme is effective; otherwise, it needs to be fed back to the parameter design stage for secondary optimization. This step not only improves the verifiability of blasting design but also enables blasting control to have data-driven adaptive capabilities, which is the core technical guarantee for achieving high-quality, safe, and controllable blasting construction.

[0051] S6, based on the comparison results between the collected vibration response data and the three-dimensional blast wave propagation inversion model, dynamically corrects the propagation model parameters and excitation coupling interference evaluation index, and optimizes the subsequent blasting design strategy to achieve full-process closed-loop control of the abnormal effect of local blast wave peaks in complex cross sections. To achieve closed-loop control of the local blast wave peak anomaly effect in complex cross-sections, after completing the blasting operation and on-site vibration response data acquisition, it is necessary to dynamically correct the key parameters of the model and the excitation coupling interference evaluation index based on the comparison results of the measured data and the three-dimensional blast wave propagation inversion model, further optimizing the subsequent blasting design strategy to ensure the effective and continuous achievement of the control objectives. This process includes the following steps: The measured data collected by vibration sensing devices deployed at the tunnel arch edge, sidewall junction, bottom of the invert arch step, and steel arch frame node area were standardized. Key parameters extracted for each monitoring point included the first arrival time of the wave crest (in milliseconds, accuracy 0.1 ms), wave crest particle velocity amplitude (in mm / s, accuracy 0.01 mm / s), main propagation direction (in azimuth, range 0° to 360°), and equivalent energy density (in J / m³). 3 The total number of data points collected should be no less than 30, categorized and stored in the database according to the construction section number, and compared one-to-one with the predicted values ​​of the same coordinate points in the 3D simulation model. If the difference between the peak arrival time and the model prediction at a certain monitoring point is greater than 3 milliseconds, the particle velocity difference is greater than ±0.8 mm / s, and the propagation direction angle error is greater than 20°, it is marked as a "model deviation point". The proportion of each type of deviation point in the entire section is statistically analyzed for error trend analysis.

[0052] Using the identified model deviation points as the core, the physical parameters in the propagation model were corrected item by item. For regions where the measured wave velocity was faster than the model value, the elastic modulus of the corresponding surrounding rock was adjusted from 3.5 GPa to 4.2 GPa, the shear modulus from 1.4 GPa to 1.8 GPa, and the wave impedance was increased to 4000 kg / m. 2 •s; For points where the amplitude is significantly higher than the model value, check the local reflection boundary condition settings and add an equivalent rigid structure to the simulation model, set to a thickness of 0.3m and a density of 2.6t / m³. 3 A high-stiffness material element with a Poisson's ratio of 0.32 was used. Furthermore, the jointed areas were structurally discretized, and three sets of tangential joint interfaces were set within a 0.8m radius around the deviation points, with a joint spacing of 0.25m, a friction angle of 28°, and a cohesion of 500kPa, to reflect the actual geological discontinuities. The corrected model was then re-simulated for wave propagation, outputting particle velocity time histories and wave energy isosurface distributions, requiring that the simulation results at key points match the measured values ​​by at least 90%.

[0053] Based on the revised simulation results, the parameters of the excitation coupling interference evaluation index were reconstructed. Centered on the high-energy response point, the spatial distance (accuracy 0.1m) to the three nearest blast source points, the detonation delay difference (in milliseconds, time interval based on actual detonator configuration), and the geometric radius of curvature at the location (in meters, directly extracted from the CAD structural profile) were statistically analyzed. After normalizing these three types of data, a new "excitation coupling scoring matrix" was constructed, where the spatial focusing coefficient was weighted at 0.4, the time superposition coefficient at 0.35, and the structural amplification sensitivity coefficient at 0.25, with a total score range of 0 to 1. Areas with scores greater than 0.75 were identified as Level 1 high-coupling interference zones, requiring focused control in subsequent designs. This scoring matrix will be integrated with the blasting design software via a data interface, serving as input parameters for blast source rearrangement and detonation sequence setting.

[0054] The revised results were fed back into the subsequent blasting section design phase, serving as the core basis for dynamic optimization control strategies. During construction design adjustments, the blast source points within the primary high-coupling interference zone were forcibly relocated. Specifically, the original blast source points were shifted 0.5 meters along the normal direction, the detonation delay was set to a difference of no less than 60 milliseconds between adjacent blast sources, and the charge structure adopted a three-section structure: "main charge - cavity - isolation filling." The main charge section was controlled to be 0.3 meters long, the cavity section 0.1 meters, and the filling section used high-density polyurethane energy-damping material. The adjusted blasting scheme was submitted to the design review group for expert evaluation, and implementation only proceeded after the evaluation was approved. Subsequent blasting data was collected after each blast, and the propagation model and control strategy were iteratively optimized according to the above process, forming a dynamic update mechanism to achieve a three-in-one closed-loop control of the blast wave propagation behavior: "measurement-simulation-design."

[0055] The purpose of this step is to establish a dynamic closed-loop mechanism of "data feedback - model correction - index reconstruction - strategy optimization," ensuring that blasting design not only remains at the theoretical prediction level but can be continuously adjusted and optimized based on on-site measurement results. This enables precise control over the entire process of local blasting wave peak anomalies in complex cross-sections. In the construction of large-section, long-distance subway station tunnels, due to objective conditions such as geological heterogeneity, fluctuations in surrounding rock physical parameters, and complex structural geometry, blasting waves are prone to deviations, focusing, or interference behaviors exceeding the prediction model during actual propagation. This leads to a surge in local wave amplitude and abnormal energy concentration, resulting in major engineering hazards such as surrounding rock damage, support deformation, and over-excavation. Therefore, static blasting simulation design alone cannot meet the requirements for full-process control; a dynamic adjustment mechanism based on measured data must be introduced.

[0056] By deploying high-density vibration sensing devices to collect blast wave propagation data and comparing it point-by-point with the prediction results of the three-dimensional blast wave propagation inversion model, it is possible to clearly identify areas with propagation path deviations, wave peak arrival time errors, and uncontrolled energy response. Based on this, key parameters in the model, such as surrounding rock wave velocity, impedance, boundary conditions, and joint structure, are dynamically corrected, making the model more realistically reflect the geological environment and structural characteristics of the construction site. Simultaneously, by combining the corrected simulation results, the excitation interference index system between the blast source location, detonation sequence, and cross-sectional geometric coupling is reconstructed, identifying new high-risk sections and providing a scientific basis for the iterative design of blasting parameters.

[0057] Ultimately, by incorporating the modified model and optimized indicators into the blasting design process, the coordinated optimization of the spatial arrangement of the blast source, the delay scheduling, and the charge structure is achieved. This enables precise control of the propagation direction and phase of the blast wave within the structure, avoiding local amplitude overlap and high-frequency focusing effects, and improving the quality of the blast profile formation and the safety redundancy of the support structure. This step is not only a core component for achieving closed-loop verification of the predictive model but also a key technical support for constructing a high-precision, adaptive blasting control system, demonstrating significant engineering practicality.

[0058] The mechanical blasting hybrid excavation method for large-section, long-distance tunnels in subway stations proposed in this invention enables precise control of the propagation behavior of blast waves throughout the complex cross-sectional structure, significantly improving the safety, stability, and quality of tunnel excavation. Based on a three-dimensional blast wave propagation inversion model, and combined with the heterogeneous characteristics of geological structure and materials, this method accurately predicts the abnormal accumulation points of blast wave energy. Through resonance path analysis and excitation coupling indices, it systematically identifies high-risk blasting sections and reconstructs blasting parameters accordingly. Crucially, the method incorporates on-site vibration sensing devices for real-time monitoring and dynamic comparison with simulation models. Through a parameter feedback mechanism, it continuously corrects the design strategy, constructing a closed-loop control system integrating "prediction-verification-correction-redesign." Compared with traditional blasting schemes, this method significantly reduces engineering risks such as arch collapse, sidewall collapse, and support failure caused by coherent superposition of blast waves, enhances the ability to suppress local peak anomalies, and effectively ensures the construction safety and controllability of blasting operations for large-section subway station tunnels under complex geological conditions.

[0059] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A mechanical blasting and mixed excavation method applicable to large-section, long-expansion excavation of subway stations, characterized in that, Includes the following steps: S1. Obtain the tunnel cross-sectional profile, geological structure and blasting parameters, establish a three-dimensional blasting wave propagation inversion model, combine geological and material heterogeneity, identify the closed spatial region that forms reflection interference, and predict the spatial location of abnormal accumulation of blasting wave energy. S2. Based on the predicted spatial locations of abnormal accumulation of blasting energy, structural resonance path analysis is performed to calculate the reflected wave path, energy superposition time sequence and amplitude amplification factor, and to determine the high-energy change region with a local amplitude amplification trend. S3. Based on the identified high-energy change region, construct an excitation coupling interference assessment index, and identify high-risk blasting sections by comprehensively considering the blast source layout, detonation sequence and cross-sectional geometry. S4, for high-risk blasting sections, reconstructs blasting parameters, adjusts the blast source location, delay time and charge structure, and controls the wave propagation path to deviate from the energy superposition zone; S5, during the implementation of the reconstructed blasting parameters, a vibration sensing device is deployed to collect the propagation behavior and surrounding rock response in real time, and to determine whether the peak distribution meets the expected adjustment direction. S6. Based on the difference between the vibration response data and the three-dimensional blast wave propagation inversion model, the model parameters and evaluation indicators are corrected to optimize the subsequent blasting design and achieve closed-loop control of local peak anomaly effects.

2. The mechanical blasting and mixed excavation method for large-section, long-expansion subway station excavation as described in claim 1, characterized in that, Step S1 includes: Acquire tunnel cross-sectional contour point cloud data, geological structure parameters, and blasting design parameters; A geometric model of the tunnel cross section was established based on point cloud data, and a 0.1-meter unit mesh was divided in FLAC3D, which was further refined to 0.02 meters in the high-energy superposition region. Different material constitutive parameters and boundary conditions are set according to geological zones, and detonation excitation loads are applied. The closed spatial region that forms reflection interference is identified by wave velocity field analysis and kinetic energy contour tracing method, and the spatial location of the abnormal accumulation of blast wave energy is determined by combining the third-order spline interpolation method.

3. The mechanical blasting and mixed excavation method for large-section, long-distance excavation of subway stations according to claim 1, characterized in that, Step S2 includes: Establish a local propagation behavior observation area with each point of abnormal accumulation of blast energy as the spatial center, and obtain wave propagation path, particle velocity and energy density distribution data within the area; By tracing the multiple reflected wave paths of the target point in reverse, points with highly overlapping reflection paths can be identified. Energy superposition time series analysis and amplitude amplification factor calculation were performed on the points where the reflection paths highly overlapped to screen out key points for resonance enhancement. The key points of resonance enhancement are projected onto the three-dimensional structural model and clustered into high-energy change regions.

4. The mechanical blasting and mixed excavation method for large-section, long-expansion subway stations according to claim 3, characterized in that, Step S3 includes: Acquire data on the spatial location, delay time, charge structure, and excitation method of all explosion sources within a 2.5-meter radius of the high-energy change area; Analyze the angle between the propagation path of the explosion source and the reflection direction of the target structure, and calculate the spatial coupling degree; Analyze the time difference between the arrival of each explosion source wavefront in the target area and calculate the temporal overlap. By combining cross-sectional geometric parameters, a structural response sensitivity index is constructed, and the three indices are weighted to form an excitation coupling score to identify high-risk blasting sections.

5. The mechanical blasting and mixed excavation method for large-section, long-expansion subway station excavation as described in claim 4, characterized in that, Step S4 includes: The spatial location of the blast source was rearranged, and a staggered and layered distribution method was adopted to keep the propagation path of the blast wave away from the weak parts of the structure. Based on the new layout results, the detonation delay time is set, and electronic detonators are used for zoned control to increase the detonation interval between adjacent detonation sources and disrupt wavefront synchronization. The charge structure was optimized for each structural part, and cavity partitions and energy-blocking fillers were set to limit the continuous increase of wave amplitude. The effects of amplitude reduction, phase misalignment, and energy shift were verified through three-dimensional simulation, confirming the effectiveness of the reconstruction parameters.

6. The mechanical blasting and mixed excavation method for large-section, long-expansion subway station excavation as described in claim 5, is characterized in that... Step S5 includes: Three-dimensional vibration sensing devices are deployed at the corners of the arch, the grooves of the side walls, the broken lines of the inverted arch steps, and the connection nodes of the steel arch frame to form a high-density spatial monitoring network. During the blasting process, all vibration sensing devices were activated to collect three-dimensional particle velocity time history data within 150 milliseconds and transmit it synchronously to the data master station. A point-by-point comparative analysis was conducted between the measured data and the simulation prediction results, focusing on three aspects: peak arrival time, propagation direction, and peak amplitude. The analysis results determine whether the peak conforms to the predicted path direction. If more than 80% of the monitoring points meet the standard and the amplitude decreases by more than 30%, the reconstruction is considered effective.

7. The mechanical blasting and mixed excavation method for large-section, long-expansion subway station excavation as described in claim 6, is characterized in that... Once the reconstruction is deemed valid, perform the following steps: Based on the measured data of blast wave propagation obtained by the three-dimensional vibration sensing device, a spatial distribution map of the measured-predicted difference is generated. By overlaying and comparing the spatial distribution map of the differences with the identification results of high-risk blasting sections, local areas with significant deviations in peak time, direction, or amplitude are marked. Export the blast source location, delay time and charge parameters corresponding to the deviation area for subsequent blasting scheme optimization modeling input; All vibration monitoring data will be archived into the blasting construction database as a historical reference for subsequent blasting designs in geological sections.

8. The mechanical blasting and mixed excavation method for large-section, long-expansion subway stations according to claim 7, characterized in that, Step S6 includes: The measured wave peak arrival time, particle velocity amplitude, propagation direction and equivalent energy density are compared one by one with the predicted values ​​of the three-dimensional simulation model at the same coordinate point to identify model deviation points with significant errors in wave velocity, wave amplitude and direction. For the deviation points in the model, the elastic modulus, shear modulus and wave impedance parameters of the corresponding surrounding rock area were adjusted, and the reflection boundary conditions and joint structure parameters were corrected. Wave propagation simulation was then performed again. Based on the corrected simulation results, the excitation coupling scoring matrix was reconstructed, the spatial focusing coefficient, the time superposition coefficient and the structural amplification sensitivity coefficient were quantified, and the first-level high coupling interference zone was calibrated. The scoring results are fed back to subsequent blasting designs. For the first-level high-coupling interference zone, optimized control strategies are implemented, including offsetting the blast source layout, increasing the delay time, and configuring the three-stage charge structure.

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