Search

The use of pre-split controlled blasting and blast pattern optimisation is described for the horseshoe-shaped main opening for the Faryab mine in Iran. The controlled blasting parameters used were a hole diameter of 45 mm, hole length 3 m, burden 0.7 m, spacing 0.6 m, stemming 0.45 m, explosive concentration 0.17 kg/m, explosive per hole 0.4 kg, number of dynamite charges per hole 3, number of contour holes 24, total charge 10 kg and 93 m of detonating cord. Compared with results obtained with the previous patterns the amount of overbreak was reduced by up to 40%, the advance rate increased by to up to 96% and the half-cast factor by up to 40%., The use of pre-split controlled blasting and blast pattern optimisation is described for the horseshoe-shaped main opening for the Faryab mine in Iran. The controlled blasting parameters used were a hole diameter of 45 mm, hole length 3 m, burden 0.7 m, spacing 0.6 m, stemming 0.45 m, explosive concentration 0.17 kg/m, explosive per hole 0.4 kg, number of dynamite charges per hole 3, number of contour holes 24, total charge 10 kg and 93 m of detonating cord. Compared with results obtained with the previous patterns the amount of overbreak was reduced by up to 40%, the advance rate increased by to up to 96% and the half-cast factor by up to 40%.

Conventional design techniques such as the Swedish method cannot be used to design the blast pattern when employing short holes of less than 2 m. Tests were carried out at the Hamkar and Pabedana coal mines, Kerman, Iran, in order to determine the relationship between burden and relief hole diameter. Trials were first conducted to determine the optimum pattern of the cut section in tunnel blasting and the results validated using full face tests. The results showed that in cuts with hole lengths of less than 1.5 m, the first quadrangle burden may increase to 4 times the relief hole diameter, in contrast to the Swedish blasting method in which the burden of the first quadrangle is 1.5 times the relief hole diameter, indicating that a reduction in drilling and blasting costs can be achieved. The advance rate was used to evaluate the results of full-face tests. The results showed that with a burden of 4 times the relief hole diameter advance rates of more than 90% can be achieved in full face blasting., Conventional design techniques such as the Swedish method cannot be used to design the blast pattern when employing short holes of less than 2 m. Tests were carried out at the Hamkar and Pabedana coal mines, Kerman, Iran, in order to determine the relationship between burden and relief hole diameter. Trials were first conducted to determine the optimum pattern of the cut section in tunnel blasting and the results validated using full face tests. The results showed that in cuts with hole lengths of less than 1.5 m, the first quadrangle burden may increase to 4 times the relief hole diameter, in contrast to the Swedish blasting method in which the burden of the first quadrangle is 1.5 times the relief hole diameter, indicating that a reduction in drilling and blasting costs can be achieved. The advance rate was used to evaluate the results of full-face tests. The results showed that with a burden of 4 times the relief hole diameter advance rates of more than 90% can be achieved in full face blasting.

The economic benefits are discussed of employing controlled blasting instead of diamond wire cutting. Tests were carried out on blocks of granite 5 m wide, 11.3 m long and 2.5 m-5.8 m high from the Shahkooh quarry in Iran using split controlled blasting. A total of 102 holes with a diameter of 32 mm were drilled, of which 37 were horizontal with a spacing of 30 cm and 65 were vertical with a spacing of 25 cm. Blasting was carried out using 60 g/m of PETN detonating cord, with a detonation velocity of 6 000 m/s, density of 943 kg/m3 and diameter of 10 mm. The amount of damage to the intact rock and the half-cast factor (HCF), defined as the ratio of the total length of half-cast holes to the total length of the holes drilled, were used to evaluate the results. Good breakage was obtained, leaving very flat excavation surfaces and an HCF of 85%., The economic benefits are discussed of employing controlled blasting instead of diamond wire cutting. Tests were carried out on blocks of granite 5 m wide, 11.3 m long and 2.5 m-5.8 m high from the Shahkooh quarry in Iran using split controlled blasting. A total of 102 holes with a diameter of 32 mm were drilled, of which 37 were horizontal with a spacing of 30 cm and 65 were vertical with a spacing of 25 cm. Blasting was carried out using 60 g/m of PETN detonating cord, with a detonation velocity of 6 000 m/s, density of 943 kg/m3 and diameter of 10 mm. The amount of damage to the intact rock and the half-cast factor (HCF), defined as the ratio of the total length of half-cast holes to the total length of the holes drilled, were used to evaluate the results. Good breakage was obtained, leaving very flat excavation surfaces and an HCF of 85%.

We present several improvements of the full-Newton step infeasible interior-point method for linear optimization introduced by Roos (SIAM J. Optim. 16(4):1110–1136, 2006). Each main step of the method consists of a feasibility step and several centering steps. We use a more natural feasibility step, which targets the ?+-center of the next pair of perturbed problems. As for the centering steps, we apply a sharper quadratic convergence result, which leads to a slightly wider neighborhood for the feasibility steps. Moreover, the analysis is much simplified and the iteration bound is slightly better., Software Technology, Electrical Engineering, Mathematics and Computer Science

Interior-point methods for semidefinite optimization have been studied intensively, due to their polynomial complexity and practical efficiency. Recently, the second author designed a primal-dual infeasible interior-point algorithm with the currently best iteration bound for linear optimization problems. Since the algorithm uses only full Newton steps, it has the advantage that no line-searches are needed. In this paper we extend the algorithm to semidefinite optimization. The algorithm constructs strictly feasible iterates for a sequence of perturbations of the given problem and its dual problem, close to their central paths. Two types of full-Newton steps are used, feasibility steps and (ordinary) centering steps, respectively. The algorithm starts from strictly feasible iterates of a perturbed pair, on its central path, and feasibility steps find strictly feasible iterates for the next perturbed pair. By using centering steps for the new perturbed pair, we obtain strictly feasible iterates close enough to the central path of the new perturbed pair. The starting point depends on a positive number ?. The algorithm terminates either by finding an ?-solution or by detecting that the primal-dual problem pair has no optimal solution (X *,y *,S *) with vanishing duality gap such that the eigenvalues of X * and S * do not exceed ?. The iteration bound coincides with the currently best iteration bound for semidefinite optimization problems., Software Technology, Electrical Engineering, Mathematics and Computer Science

In the theory of polynomial-time interior-point methods (IPMs) two important classes of methods are distinguished: small-update and large-update methods, respectively. Small-update IPMs have the best theoretical iteration bound and IPMs with full-Newton steps belong to this class of methods. Within each of these classes one has feasible and infeasible interior-point methods (IIPMs). In this thesis we first deal with full-Newton step IIPMs, and we consider feasible full-Newton step IPMs., Electrical Engineering, Mathematics and Computer Science

Pre-splitting controlled blasting tests were carried out at the Sarcheshmeh, Iran, Cu mine using a long hole diameter of 251 mm. The optimum values for parameters such as spacing, charge length (decoupled or decoupled-deck), coupling ratio and stemming were determined for different types of rock. Good results were obtained with decoupling and continuous charging using 3 m spacing between holes in the pre-split row and 2.5-3.5 m of stemming. Continuous rather than deck charging is preferred when using bulk explosives in wet conditions. Cartridged rather than bulk explosives are recommended when using the pre-splitting decoupled method in wet conditions., Pre-splitting controlled blasting tests were carried out at the Sarcheshmeh, Iran, Cu mine using a long hole diameter of 251 mm. The optimum values for parameters such as spacing, charge length (decoupled or decoupled-deck), coupling ratio and stemming were determined for different types of rock. Good results were obtained with decoupling and continuous charging using 3 m spacing between holes in the pre-split row and 2.5-3.5 m of stemming. Continuous rather than deck charging is preferred when using bulk explosives in wet conditions. Cartridged rather than bulk explosives are recommended when using the pre-splitting decoupled method in wet conditions.

Vibrations resulting from 39 blasts were monitored at different distances from the blasts in the Sar Cheshmeh, Iran, Cu mine. The results were analysed to determine peak particle velocities, acceleration, displacement, frequency, signal length and duration. The dynamic effects of the vibrations on slope stability were studied and the maximum block size on the western wall that could be coherently displaced by vibration was determined. Blasts which could potentially cause overbreak in the final pit wall were analysed and the minimum distance to the final wall within which production blasting should not be permitted was determined. The results indicated that production blasts could be carried out 50 m away from the final wall without any risk of overbreak on the final wall., Vibrations resulting from 39 blasts were monitored at different distances from the blasts in the Sar Cheshmeh, Iran, Cu mine. The results were analysed to determine peak particle velocities, acceleration, displacement, frequency, signal length and duration. The dynamic effects of the vibrations on slope stability were studied and the maximum block size on the western wall that could be coherently displaced by vibration was determined. Blasts which could potentially cause overbreak in the final pit wall were analysed and the minimum distance to the final wall within which production blasting should not be permitted was determined. The results indicated that production blasts could be carried out 50 m away from the final wall without any risk of overbreak on the final wall.

The use is discussed of controlled blasting close to the final wall of open-pit mines, and the results are presented of investigations into the optimisation of pre-splitting patterns at the Sarcheshmeh, Iran, Cu mine for different rock conditions. The results showed that continuous charging for the pre-splitting row was easy to achieve compared with deck charging. For small diameter holes, decoupling was not feasible. A salt- ANFO mixture was preferred for continuous charging as it was easy to use and the operation was less time consuming., The use is discussed of controlled blasting close to the final wall of open-pit mines, and the results are presented of investigations into the optimisation of pre-splitting patterns at the Sarcheshmeh, Iran, Cu mine for different rock conditions. The results showed that continuous charging for the pre-splitting row was easy to achieve compared with deck charging. For small diameter holes, decoupling was not feasible. A salt- ANFO mixture was preferred for continuous charging as it was easy to use and the operation was less time consuming.