To reduce the vibration intensity of wedge-shape excavation blasting in tunnel, the precisely controlled delay time technology of tunnel V-cut blasting was proposed based on the Mohr-Coulomb strength criterion, the maximum tensile stress, and Anderson superposition theory. Firstly, the mechanism of segmental blasting of V-cut is revealed through theoretical analysis. Secondly, the function of blasting vibration waves was obtained by fitting the Gauss function. Finally, the precise delay time of reducing blasting vibration was obtained by superimposing different delay times with Matlab. The results show that: The stepped V-cut blasting improves the free surface conditions of blasting, and weakens the vibration propagation energy by reducing the amount of blasting charge in a single stage. Based on the Qi Jiazhuang tunnel of National Highway 109, the vibration strength of V-cut blasting was reduced by about 60% when the delay time was 13 ms. The engineering practice showed that the relative error between the theory and the field monitoring data was 13.9%, which verified the validity of the technology.

To attain precise regulation of the smooth blasting effects during tunnel excavation, this paper employs the LS-DYNA fluid-solid coupling algorithm and a cubic polynomial ignition and growth equation of state to develop a numerical model of shaped charge jet initiation of explosives. A study on the optimal detonation distance for emulsified explosives within an axially shaped charge configuration was conducted. Additionally, field experiments on axial energy-focused charge structures were performed based on the tunnel blasting excavation project of the Hongshimen Tunnel on the Chengping Expressway(Beijing section). The research results indicate the following: (1) When employing the commonly used axial energy-focused charge structure in industry, approximately 25 cm of movement occurs at the tip of the energy-focused jet 110 μs after the main charge detonation. At this point, the jet separates from the plug. Subsequently, the energy-focused jet becomes discontinuous and fragmented during its motion, which may adversely affect the initiation of the explosive charge. Therefore, selecting an appropriate explosive spacing is crucial for the successful detonation of the initiated explosive by the energy-focused jet. (2) Based on the analysis of jet head pressure and explosive reaction characteristics, it is observed that when the explosive spacing exceeds 50 cm, the impact pressure exerted by the jet on the initiated explosive is less than the critical initiation pressure of the emulsified explosive. As the explosive spacing increases, the distance that the jet penetrates the explosive during detonation also gradually increases. When the explosive spacing exceeds 90 cm, the jet fails to initiate the explosive charge. (3) Field tests were conducted based on the tunnel blasting project of the Chengping Expressway(Beijing section) with explosive spacings of 50 cm and 70 cm. The test results revealed that better control of over-excavation and under-excavation was achieved at a spacing of 70 cm. Therefore, under the conditions of this project, a reasonable detonation distance is determined to be 70 cm. The findings of this study can provide valuable references for similar smooth blasting efforts in tunnel engineering.

To accurately predict the peak particle velocity(PPV) and effectively reduce the hazards of blasting vibration, a prediction model was built by BP neural network based on the blasting project of Xingguang No.1 open-pit mine. Seven influencing factors as core distance, plugging length, minimum resistance line, explosives unit consumption, maximum single-hole charge, total extension time, and maximum single-delay charge, were selected as input variables, and the correlation between each factor and PPV was evaluated by using the grey correlation analysis method. The Sparrow Search Algorithm(SSA) optimized the BP neural network to predict the three-way peak vibration velocity. By comparing and analyzing the prediction results of the BP neural network model, the average errors of the prediction results of the SSA-BP neural network model were 6.08%, 7.34%, and 1.91%, respectively, and that of the prediction results of the BP neural network model was 22.19%, 54.01%, and 25.29%, respectively. The results show that the SSA-BP neural network model comprehensively considers the influence of multiple blasting design parameters on the peak vibration velocity. The sparrow search optimization algorithm can effectively solve the problem of the traditional BP neural network model, which quickly falls into the local optimum. The prediction results are more accurate, and the vibration velocity monitoring value is more consistent with smaller errors. Meanwhile, it can significantly shorten the learning and training time of the sample data to speed up the convergence speed of BP. Additionally, it can also significantly shorten the training time of sample data and accelerate the convergence speed of the BP neural network prediction model.

In order to study the vibration response of the interlaid rock in the small clear distance tunnel under the blasting load, a field blasting vibration test was carried out based on the blasting project of the Xiaolongmen tunnel. The improved variational mode decomposition(VMD) and multi-scale permutation entropy(MPE) algorithm were employed to denoise the blasting vibration signal. Subsequently, the differences in vibration characteristics between the left arch waist(non-interlaid rock area) and right arch waist(interlaid rock area) of the tunnel were analyzed, along with a comparison and analysis of seismic wave attenuation characteristics generated by cut hole blasting and surrounding hole blasting. The results demonstrate that the improved adaptive VMD-MPE algorithm enables automatic determination of modal number K and penalty factor α while effectively eliminating noise from the vibration signal, reducing subjective decision-making influence. During posterior excavation tunnel face blasting, interlaid rock exhibits significant amplification effects on blast vibrations. Peak particle velocity(PPV) values are higher in interlaid rock compared to non-interlaid areas. However, vibrations attenuate faster within interlaid rock regions. Additionally, analysis reveals that low-frequency vibrations below 40 Hz account for a substantial proportion of energy within interlaid rock areas when comparing frequency characteristics at measuring points between non-interlaid and interlaid regions. Attention should be given to these low-frequency vibrations as they are more likely to induce resonance in supporting structures, posing higher risks of damage or destruction within interlaid rock zones. By analyzing the blasting vibration characteristics of the cut hole and the surrounding hole, it can be found that the vibration velocity generated by the surrounding hole blasting in the surrounding rock behind the tunnel face is greater than that of the cut hole blasting within the range of the scale distance(SD) which is less than or equal to 11.57 m kg^1/3 due to the effect of 'corner weakening' and the influence of the seismic wave propagation path. After exceeding the critical value of SD, the vibration velocity generated by the cut hole blasting is greater.