In engineering blasting, the slope surfaces in the blasting area exert various effects on the blast vibration velocity. For example, the slope effect and the whipping effect are generated in the slope area, which will influence the blast vibration velocity. The slope area is the key protection area for many projects; therefore, it is of practical value to explore the influence of slope surface on blast vibration speed for the prediction of blast vibration and protection against it. The influence of slope effect and whipping effect on blast vibration velocity in the slope area was analyzed by numerical simulation and fitting. The field monitoring data were fitted to the blast vibration velocity prediction formula. According to the obtained fitting formula, we inferred that vibration speed amplification occurred in the slope area. Numerical simulation was carried out using the ANSYS/LS-DYNA program. Using the above two methods, whether the slope effect and whip tip effect occurred in the study area was verified. By numerical simulation, we established three-dimensional (3D) slope models for four different working conditions. We simulated the complete blasting process and the consistency between the simulation results, and the field data proved the reliability of the numerical simulation. Based on the results of the numerical simulation, we explored the variation of blasting vibration velocity under different height difference conditions. Finally, we explored the distribution law of blasting vibration at the slope surface and inside the slope.

The inversion of the Rayleigh wave dispersion curve is a crucial step in obtaining the shear wave velocity (V_S) of near-surface structures. Due to the characteristics of being ill-posed and nonlinear, the existing inversion methods presented low efficiency and ambiguity. To address these challenges, we describe a six-layer deep neural network algorithm for the inversion of 1D V_S from dispersion curves of the fundamental mode Rayleigh surface waves. Our method encompasses several key advancements: (1) we use a finer layer to construct the 1-D V_S model of the subsurface, which can describe a more complex near-surface geology structure; (2) considering the ergodicity and orderliness of strata evolution, the constrained Markov Chain was employed to reconstruct the complex velocity model; (3) we build a practical and complete dispersion curve inversion process. Our model tested the performance using a random synthetic dataset and the influence of different factors, including the number of training samples, learning rate, and the selection of optimal artificial neural network architecture. Finally, the field test dispersion data were used to further verify the method’s effectiveness. Our synthetic dataset proved the diversity and rationality of the random V_S model. The results of training and predicting showed higher accuracy and could speed the inversion process (only ~15 s), and we proved the important effect of different factors. The outcomes derived from the application of this technique to the measured dispersion data in the Yellow River Delta exhibit a strong correlation with the outcomes obtained from the integration of the very fast simulated annealing method and the downhill simplex method, as well as the statistically derived shear wave velocity data of the sedimentary layers in the Yellow River Delta. From a long-term perspective, our method can provide an alternative for deriving V_S models for complex near-surface structures.

Silt liquefaction can occur due to the rapid cyclic loading of sediments. This can result in the loss of the bearing capacity of the underlying sediments and damage to the foundations and infrastructure. Therefore, assessing liquefaction hazards is an important aspect of disaster prevention and risk assessment in geologically unstable areas. The purpose of this study is to assess the liquefaction hazards of silt sediments by using the horizontal-to-vertical spectral ratio method. Single-station noise recording was carried out in the northern plain of the Yellow River Delta, and a new method was adopted to identify the fundamental frequency. The dynamic parameters of the silt, such as the fundamental frequency, amplification, and vulnerability index, were used as indicators to assess the liquefaction potential. The results show that the silty soils in different areas have different stable ranges of values of the fundamental frequency. Moreover, the distribution of the observations is in good agreement with the geological conditions in the area, which indicates the potential applicability and reliability of the new method for identifying fundamental frequency. The vulnerability index is inversely related to the fundamental frequency, with the southwestern part of the study area having a lower fundamental frequency and a higher vulnerability index, meaning a greater liquefaction risk compared to other areas. The horizontal-to-vertical spectral ratio method has great advantages in characterizing subsurface dynamic parameters and can be applied to liquefaction hazard assessments of silt sediments in large areas, which is critically important in terms of providing information and guidance for urban construction and planning.

In order to reveal the evolution of bonding performance of HIRA (High Intensity and Rapid Agent) anchor solids with maintenance time, the evolution characteristics of bond strength and stress distribution at the interface between HIRA-based anchor solids and a geotechnical body under different maintenance times and the fine damage pattern of anchor solids were studied by an indoor pull-out test of anchor solids. The comparative analysis was performed with 42.5 grade ordinary Portland cement (hereinafter referred to as P.O 42.5). The results show that the early strength and rapid setting characteristics of HIRA type material are obvious, and the difference between its average peak bond strength and that of cement is 10.45 times. The shear stress distribution has obvious stress concentration characteristics, and the peak value will appear and shift with the increase in load, and the peak shift of the HIRA anchor solid occurs earlier than that of cement. Due to different stress levels, the damage of the HIRA anchor solid after being pulled out increases with the increase in maintenance time, while that of cement gradually becomes more severe. The overall damage of the HIRA material is generally lower than that of cement in the same period.