Numerical analysis in rock blasting.
Date of Issue2011
School of Civil and Environmental Engineering
The drill and blast process, which is the most common technique for rock excavation, has been used not only in mining and quarrying but also in tunnelling and dam construction. Compared to heavy machinery excavation such as using tunnel boring machines, rock blasting is more reliable, economical and flexible in their applications. In this report, parametric studies were conducted to evaluate the effect of blast sequence and delay time on the rock mass damage induced by underground explosions. Besides, ground vibration prediction model, measured as peak particle velocity (PPV), was also developed using the curve-fitting technique. The numerical simulations were carried out using Discontinuous Deformation Analysis (DDA) method. A 13m x 27m model with 52 blasting boreholes was built to study the rock fragmentation patterns under three different ways of detonation explosives. In the first study, all the explosives were blasted simultaneously. For the second case, the blasting was conducted in sequence with 2ms delay. In the third simulation, the detonation time was reduced and the delay time was shortened to 0.4ms. Crack propagation patterns were compared for the three cases to evaluate whether the cracks extended adequately to form detached bodies that could be removed without another firing. In addition, the PPV damage criterion was adopted to study the damage zone around the charge hole. Empirical formulas considering the distance from the blast centre and weight of charge were obtained to estimate the particle velocity based on the numerical results. From the analysis, it was concluded that the sequenced blasting was more effective than simultaneous blasting as it produced better crack propagation results but less ground vibration. In addition, the PPV prediction model could be used to predict the blast-induced ground vibration.
Final Year Project (FYP)
Nanyang Technological University