A Numerical Study on the Screening of Blast-Induced Waves for Reducing Ground Vibration

Zhu

et al. 2019

Shock and Vibration

Radial cracks may exist around tunnel edge, and these cracks may propagate and weaken tunnel stability under nearby blasting operations. In order to study the blast-induced fracture behavior of radial cracks emanating from a tunnel spandrel, a tunnel model containing a spandrel crack (TMCSC) with different inclination angles was proposed in this paper. Crack propagation gauges (CPGs) and strain gauges were used in the experiments to measure crack initiation moment and propagation time. Finite difference models were established by using AUTODYN code to simulate crack propagation behavior and propagation path. ABAQUS code was used to calculate dynamic stress intensity factors (SIFs). The results show that (1) crack inclination angles affect crack initiation angles and crack propagation lengths significantly; (2) critical SIFs of both mode I and mode II decrease gradually with the increase of the crack propagation speed; (3) the dynamic energy release rates vary during crack propagation; and (4) there are “crack arrest points” on the crack propagation paths in which the crack propagation speed is very small.

Section: Numerical Simulation Analysis Under Explosive Loadmentioning

confidence: 99%

“…For this paper, the aspects will be researched. In terms of the simulation study of rock dynamic fracture rule, nite di erence AUTODYN code has been largely used, and moreover, its feasibility has been widely proved [16][17][18][19][20][21][22][23][24][25][26]. erefore, in the simulation study of crack fracture rule, it will be used.…”

Section: Introductionmentioning

confidence: 99%

Study on the Fracture Behavior of Cracks Emanating from Tunnel Spandrel under Blasting Loads by Using TMCSC Specimens

Zhu

et al. 2019

Shock and Vibration

“…In an open-pit coal mine, the profile of the slope is generally controlled by the presplit blasting, so as to obtain a smooth slope and reduce ground motion induced by production blasting [4][5][6]. Presplit blasting is commonly used to reduce the back impact and produce smooth bench slopes after blasting in the mines applying cast blasting which causes severe damage to slopes due to the large quantities of charge used and violence of the blasting technology.…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Study on the Design Method for Large‐Diameter Deep‐Hole Presplit Blasting and Its Vibration‐Isolation Effect

Xiao

Wang

Dong

2019

Shock and Vibration

Presplit blasting can reduce vibration and back impact induced by cast blasting, thus resulting in a smooth bench slope. To design reasonable presplit blasting parameters, this research investigated the formation of presplit faces based on the explosion mechanics and revealed the cracking mechanism of presplit blasting. According to the stress distribution in the vicinity of the blast holes under the action of explosive stress waves and blasting gas, we deduced theoretical formulae for parameters including charge mass in blast holes, hole spacing, and distance from presplit blast holes to cushion holes. On this basis, a method was proposed for the design of large-diameter deep-hole presplit blasting. Field testing was conducted by setting different spacing for presplit blast holes, to monitor the blasting-induced vibration. The results showed that appropriate hole spacing can reduce the particle vibration velocity and the attenuation index of blasting-induced vibration changed slightly while the attenuation coefficient decreased significantly; the formed presplit faces were smooth and had a high half-cast factor. Finally, the reasonable hole spacing for presplit blasting, distance from presplit blast hole to the cushion hole, and the charge mass in blast holes in the Heidaigou open-pit coal mine were determined, respectively.

“…Shin [3] investigated the characteristic behavior of existing tunnels by utilizing the numerical method. Parametric analyses were conducted under various conditions to analyze the screening effectiveness of line-drilling [4]. The results of vibration analysis induced by blasting were performed to obtain the particle vibration velocities, the empirical relationships between scaled distance and peak particle velocity and the interaction between shotcrete and rock influenced by propagating stress waves [5].…”

Section: Introductionmentioning

confidence: 99%

The stability analysis of blasting excavation in short distance on water diversion tunnel underpassing Jinduicheng Molybdenum Mine

Han¹,

Li²,

Mei³

2019

J. vibroeng.

To investigate effect induced by blasting in Jinduicheng molybdenum mine on the Dongchuan river diversion tunnel, the tunnel vibration has been monitored. According to the actual conditions, the corresponding numerical simulation is performed in FLAC 3D , and dynamic response of the lining and surrounding rock of the diversion tunnel caused by blasting load is analyzed. The variation of vibration velocity in the later stage of tunnel under the action of existing blasting scale is predicted, when the vertical distance between blasting source and diversion tunnel is 50 m, the velocity of tunnel vibration reaches the critical value. The blasting scheme of mine production can be modified according to the practical distance between the explosion source and the diversion tunnel.