Compared smooth blasting with presplit blasting. For each case, there were production blasts, buffer blasts, and then either a smooth or presplit blast. High Rock Slopes in China – Smooth Blast. Damage is predominately a result of the first two production blasts, penetrating into the rock mass.

In tunnels and underground excavations: Sound-wall blasting …met by the technique of presplitting, developed in the United States in the late 1950s. Basically, this technique consists of creating a continuous crack (or presplit) at a desired finished excavation line by initially firing a line of closely spaced, lightly loaded holes drilled there.

A REVIEW OF THE DESIGN CRITERIA AND PRACTICAL ASPECTS OF DEVELOPING A SUCCESSFUL PRE-SPLIT. Simon St J Tose ... unconsolidated, weathered or highly fissured rocks, problems in obtaining a consistently smooth wall are usually encountered, but the overall result is always much better than the result from production ... As with Smooth Blasting ...

Feb 25, 2011· WALL CONTROL BLASTING TECHNIQUES -----The best approach will be to initially design the presplit shot, using the air-deck approach, on the normal presplit …

Presplit blasting involves drilling a single row of holes along the back of the final excavation zone . Unlike smooth wall blasting, the presplit holes are fired on the first delay of the production blast. The presplit technique is the most commonly used controlled blasting technique for surface operations. 3. Methods 3.1. Line drilling

Preliminary tests on presplitting rock in the presence of an in situ static stress field were undertaken to study the influence of a horizontal static stress field on the creation of a vertical presplit fracture plane. These tests indicated that it is easier to fracture the rock parallel to the

Presplit blasting Spacing = Hole diameter x 12 Burden = 0.5 x production blast burden (B) Uncharged length at top = 10 x D Powder factor = 0.5kg per square metre of face Do not stem holes. Fire all holes on the same delay, or in groups of ≥ 5 holes Smooth Blasting Spacing = 15 x Hole diameter (hard rock) 20 x Hole diameter (soft rock)

A better way to presplit. ... slopes that are close to the planned angle of the final pit wall and benches that are smooth and stable. Unfortunately at other mines, the opposite is a common experience; presplit holes that take off in different directions, a lot of waste rock that has to be blasted and hauled away at great cost and uneven slope ...

smooth blasting at the same distance and direction. For the smooth blasting, the frequency components of peripheral boreholes are inšuenced by the inner free face generated by main boreholes, which makes the dominant frequency of peripheral boreholes with smooth blasting larger than that with presplit blasting at the same distance and direction.

Feb 19, 2017· Blasting a presplit in Granite ... This video gives a brief look at the drilling of the presplit for the garage and the blast. The presplit was drilled 38mm diameter, 4m deep and loaded with 70 ...

Apr 10, 2018· The presplit-smooth blasting approach inherits the advantages of both presplit and smooth blasting and improved the blasting damage control effect significantly. The emphasis of this study is to evaluate the differences in the damage processes of the smooth and presplit blasting …

To explore the applicability of control blasting in underground mining operations, protect the safety of students, faculty, and staff, prevent overbreak, and to ensure the stability of openings and workings, four experimental control blasts, comprising of three smooth blasts and one presplit blast were conducted at the Orphan Boy Mine (an ...

Drilling and blasting is the controlled use of explosives and other methods such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining, quarrying and civil engineering such as dam, tunnel or road construction. The result of rock blasting is …

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 ...

Sep 14, 2013· Among the total damage, the blasting of the production hole is the main resource, followed by the smooth and buffering holes. For the presplit blasting, the final damage of rock slope is mainly induced by presplit blasting itself. The spatial distribution characteristics of the final damage zone of two methods are compared.

This paper focuses on the comparison of damage induced by smooth blasting and presplit blasting based on the excavation of high rock slope. The whole damage process of the smooth blasting and ...

@article{osti_398353, title = {Smooth blasting with the electronic delay detonator}, author = {Yamamoto, Masaaki and Ichijo, Toshiyuki and Tanaka, Yoshiharu}, abstractNote = {The authors utilized electronic detonators (EDs) to investigate the effect of high detonator delay accuracy on overbreak, remaining rock damage, and surface smoothness, in comparison with that of long-period delay ...

correctly designed and executed, smooth blasting can be very beneficial in trimming the final excavation face. Figure 1 illustrates a comparison between the results achieved by a normal blast and a face created by presplit blasting in jointed gneiss. It is evident that, in spite of the fairly

PRESPLIT BLASTING Presplit blasting is an effective technique for stabilizing the final wall in open pit metal mines. This technique is based on the phenomenon that the detonation shock wave is stopped and reflected at any free face. In presplit blasting, an intentional fracture is created at the excavation line prior to the detonation

pre-splitting A method of blasting in which a planar crack is propagated by blasting to determine the final shape of a rock face before holes are drilled for the final blast pattern; firing with a minimum time scatter can then be used. The crack helps to screen the surroundings from ground vibrations during the firing of the main round. Source for information on pre-splitting: A Dictionary of ...

effects of small-scale structures could be controlled through lighter smooth blasting, whereas the impact of larger, more dominant, structures, prevailed even for very light smooth (for open pit operations) blasting. For the footwall, presplit blasting in inclined (70°) …

These techniques are presplit blasting, smooth blasting, and cushion blasting. Presplit Blasting: Presplit blasting, or presplitting, is used before production blasting to protect the final rock face from damage caused by the production blasting. Presplitting creates a fracture plane along the final slope face, which prevents the radial cracks ...

Each type of blasting-presplit, smooth, and cushion blasting-has its own formula. Presplit Blasting. As discussed above, presplit blasting (or presplitting) is most often done before production blasting to create a secondary fracture plane that will protect the final slope face from damage in the main production blast.

smooth-wall blasting and presplitting (also pre-shear) [15]. ... from Fig. 2a, presplit blast leads to generate a fracture plane parallel to free face which is final wall of temporary slope. Fig. 2b illustrates a successful presplit blast with no unwanted damage in other sides. In order to operate a successful presplit

To understand differences of smooth and presplit blasting for the excavation of rock wells, two field experiments using these two techniques are implemented at the same test site, respectively. The ground vibrations induced by them have been monitored with the different distances through the corresponding devices. The vibration results illustrate that at the same monitoring distance and ...

1. Controlled Blasting Techniques-2011 - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online. control blasting techniques

Controlled Blasting Methods Line blasting Smooth blasting Cushion blasting Presplit blasting Presplit Hole Design As a general guide for the presplit holes, spacing can be 8 to 12 times of the hole diameter or about one third to less than one half of the normal spacing used in production blast