Experiment and Analysis of Wedge Cutting Angle on Cutting Effect

In the process of tunnel excavation, large charge wedge cutting blasting is widely used to improve the effect of cut blasting and speed up the excavation rate, which is tantamount to increasing the construction cost. In order to save economic cost and improve cutting blasting effect, wedge cutting models with five different cutting angles were experimented and studied by using concrete materials on the basis of similarity theory analysis. The relationships among cutting depth, blasting volume, blasting fragment, and cutting angle are studied and deduced by the dimensional analysis method. The polynomial fitting of cutting depth, blasting volume, blasting fragment, and cutting angle is carried out according to the experimental data, and the corresponding fitting formula is obtained. The optimum cutting depth, hole utilization rate, blasting volume, and blasting fragment were obtained when the wedge cutting angle was 67° under the same charge. The values were 1.665 × 10−1 m, 92.5%, 8.390 × 10−3 m3, and 49.07 mm, respectively. With the use of TC4850N type blasting vibration meter, the blasting vibrations on the wedge in four directions are tested and analyzed. The results show that when wedge cutting inclination is 65 degrees, the peak vibration velocity is the minimum and the vibration intensity of the wedge cutting inclined side is generally smaller than that of the vertical side. Considering the cutting depth, blasting volume, blasting fragment, blasting vibration hazard, drilling error, tunneling construction cost, and other factors, the 65°∼69° wedge cutting blasting in engineering practice can improve the blasting tunneling rate and increase economic benefits. The experimental results show that the blasting tunneling rate is increased and the economic benefit is increased with the minimum construction tunneling cost, which has certain engineering significance.

Tunneling radiation of fermions with 1/2 and 3/2 spins from a charged axisymmetric nonstationary black hole

In this paper, we derived Hamilton–Jacobi equation for spin 1/2 and 3/2 fermions from Dirac equation and Rarita–Schwinger equation. Then, by using the Hamilton–Jacobi equation and general tortoise coordinate transformation, the tunneling rate and Hawking temperatures of a nonstationary axisymmetric symmetry black hole are investigated. The result shows that the tunneling rate, temperature and surface gravity are all related to the properties of horizons of the black hole, the cosmological constant [Formula: see text], the charge [Formula: see text], mass of black hole [Formula: see text] and the Eddington time [Formula: see text].

Polymer deformation and particle tunneling from Schwarzschild black hole

In this paper, we investigate a tunneling mechanism of massless particles from the Schwarzschild black hole (S-BH) in the framework of polymer quantum mechanics. According to the corresponding invariant Liouville volume, we determine the tunneling rate from S-BH by the polymeric quantization procedure. In this regard, we show that the temperature and tunneling radiation of the black hole receive new corrections in such a way that the exact radiant spectrum is no longer precisely thermal.

Instanton interaction in de Sitter space–time

Because of the presence of a cosmological horizon, the dilute instanton gas approximation used for the derivation of the Coleman–De Luccia tunneling rate in de Sitter space–time receives additional contributions due to the finite instanton separation. Here, I calculate the first corrections to the vacuum decay rate that arise from this effect and depend on the parameters of the theory and the cosmological constant of the background space–time.