Accurate prediction of blasting vibration associated with tunnel engineering is essential to ensure the safety and stability of tunnel excavation and to prevent any damage or distress to adjacent existing tunnels. Based on the dimensional analysis principle, this paper deduces the classical Sadovsky formula, analyzes its limitations from a mathematical point of view, and proves the feasibility of using this principle to derive a prediction model of blasting vibration. On this basis, considering the influence factors of blasting vibration such as the rock density, delay initiation time, and number of free surfaces, a new prediction model that can simultaneously consider the influence of the vibration in near-field and far-field blasting is proposed, and its rationality is explained. Combined with a case study, comparative analysis, variance analysis, and Akaike information criterion, the results show that the new prediction model can effectively solve the difference in blasting vibration in different types of blast holes and different areas, and the calculated results are in better agreement with the monitoring data than is the Sadovsky formula. Overall, this study provides a new solution and reference for more accurate prediction of blasting vibration.

The artificial freezing method can effectively improve the stability of strata and provide favorable conditions for the construction safety of shield tunnel in water-rich strata. Based on the frozen shield tunneling project of a metro station, which is close to important buildings, a reasonable freezing method and parameters are proposed in this paper. The simulation model was established by using Plaxis 3D finite element software (Version 2017). The numerical model was verified based on a large amount of field data. The characteristics of segment deformation, ground surface settlement and vertical displacement of buildings were compared between frozen layer and nonfrozen layer during shield tunnel excavation. It was found that segment deformation in the nonfrozen layer is three times that in the frozen layer. The surface settlement above the frozen layer is less than 2 mm. Expansion excavation of shield tunnel was carried out to meet the space function of subway station using artificial freezing method. The deformation of frozen layer was compared between full section excavation and partial excavation. It was found that the deformation of the former is 4.5 times that of the latter, so the partial excavation was chosen as the main research object. Subsequently, the characteristics of vertical displacement and surface settlement of buildings under partial excavation were studied. It was found that the vertical settlement of buildings away from the frozen layer is greater than that of buildings near the frozen layer. All settlement values meet the requirements, thus ensuring the feasibility of partial excavation and ensuring the safety of construction.

Loosened rock circle is formed around the tunnel when the tunnel is constructed by the drilling and blasting method. The size of the loosened rock circle around the tunnel and the degree of internal rock fragmentation has an important influence on the support parameters, durability, and safety of the tunnel. Firstly, referencing an existing tunnel project, blasting tests using nonelectronic and electronic detonators were carried out to determine the influence of blasting construction on the scope of the rock loose circle and the degree of rock fragmentation. Then, a numerical simulation was used to study the contribution of the blasting impact and surrounding rock stress redistribution on the loosened rock circle around the tunnel. The results showed that the range of the loosened rock circle around the tunnel generated by the normal blasting of nonelectronic detonators was 1.5~2.3 m, and the wave velocity of the rock mass in the loosened rock circle around the tunnel decreased to 23~36%. The size of the loosened rock circle around the tunnel generated by the blasting impact was 0.66 m, accounting for 33% of the range of the loosened rock circle around the tunnel. The range of the loosened rock circle around the tunnel produced by electronic detonator blasting was 0~1.4 m. The wave velocity of the rock mass in the loosened rock circle around the tunnel decreased to 12~17%. The range of the loosened rock circle around the tunnel was approximately 60~76% of that of detonator blasting, and the broken degree of the surrounding rock in the loosened rock circle around the tunnel was small. The research results can provide a reference for the optimization design of preliminary support parameters of tunnels, such as anchors and steel arches in blasting construction.

In order to address the issue of limited excavation footage in the drilling and blasting of a water diversion tunnel with a cross-section of approximately 10 m², which is unable to meet the demands of rapid construction, a blasting method combining long and short straight-hole cutting was proposed based on the theories of elastic mechanics, blasting craters, explosive gas and stress waves. A mechanical model was established to elucidate the parameter design method and cavity formation principle of the combined cutting. Numerical simulation and field tests were employed to analyze the rock-breaking process of combined cutting, with a view to comparing the blasting effect differences between the traditional inclined cutting method and the combined cutting method. The research results indicate that during the blasting process with combined long and short straight-hole cutting, the uncharged portion of the deep hole can serve as an empty hole during the subsequent blasting of the shallow hole. The concentration of stress at the wall of the empty hole and the superposition of reflected and incident waves serve to enhance the rock-breaking effect of the shallow hole, with the enhancement being influenced by the diameter of the hole and the distance between it and the empty hole. The preferential detonation of the shallow hole can provide a smaller resistance line and free surface distance for deep hole detonation, creating favorable conditions for rock fragmentation in deep hole blasting, making it easier for the rock in the cutting area to be thrown out and increasing the utilization rate of the blast holes. The shape of the formed cavity is a long strip-shaped cube, with its volume being influenced by the spacing between each group of deep and shallow holes. The rock mass damage is most severe in the vertical direction, while the rock mass damage at the center of the upper and lower edges is relatively weaker. In order to optimize the utilization of blasting energy, it is essential to select an appropriate spacing between each group of blast holes. In comparison to the utilization of traditional inclined cuts, the implementation of combined long and short holes has been observed to result in a greater extent of blasting footage and relatively lower explosive consumption. These research findings provide a reference point for the rapid and efficient construction of small-section tunnel engineering, as well as the design of straight-hole cut blasting with reduced consumption.

In this study,criteria and blast ing technologies are introduced in order to control the stability ofsurrounding rock of tunnel built using drill and blast safety . The paper is composed of three parts,namely, a blast vibration propagation law in roof surrounding rock in close proximity to tunnel face,two formulae to calculate particle critical vibration velocity of shotcrete and key structural element atthe roof of tunnel, and innovative technologies of tunnel blasting . The blast vibration propagationlaw is the base to control the sta bility of surrounding rock during tunnel blast ing Based onMorhr Coulomb criterion and the dynamic analys is, two formulae to calculate the critical particlevibration velocity are proposed Based on a series of trial blasts using electronic detonators, tw oinnovative blasting technologies are derived. One is the blast holes detonated one by one by usingelectronic detonator , and another is the blast holes detonated by combining initiation system ofelectronic detonators and nonel detonators T he use of ele ctronic detonators in tunnel blasting notonly leads to a smaller blast vibration but also to a smaller extent of the EDZ (excavation damagedzone)