From the perspective of the surrounding medium, loose blasting occurred in coal seam, while that for pre-splitting blasting and deep hole blasting occurred in rock strata. Mine MS events may occur in coal seam or in rock strata. The physical and mechanical properties of coal and rock of this working face are shown in Table 3. …
is absorbed by the rock structural face, ... face of the pre-splitting hole. (3) The pre-splitting hole and main lasting hol e is detonated sequentially a few milliseconds ahead .
Pre-splitting can be defined as 'a technique using lightly charged, closely spaced holes to induce a fracture plane along a required design profile, which isolates the rock to be blasted from the surrounding rock mass'.
Are there rules of thumb for Pre-Splitting in non-competent rock geology? Non-competent can be many things. In order to keep this response broad, I'll just say that the more a geologic unit is non-competent, the smaller scale you may want the design. For a good presplit to be successful, you might need to reduce the hole diameter charge ...
Pre-split in the rock forms a discontinuous zone that minimizes or eliminates overbreak from the subsequent primary blast and produces a smooth-finish rock wall. Pre-splitting …
The key parameters of pressure relief pre-splitting blasting technology (PRPBT) contribute to the implementation effect of goaf-side entry by roof cutting (GSERC). This study is an attempt to design the key parameters including the roof cutting height, the roof cutting angle, the spacing between blasting boreholes, the charge structure and the …
Free faces can be any pre-existing joint or bedding plane within the rock mass, fractures created by the neighboring blast, or the opening face. The concept of rebound is important when considering blast damages because it can be used as a means to reduce any further fracturing to a final face, which will be covered in greater detail later.
A study was conducted to evaluate the effect of air deck (pipe deck), water deck technique to control induced ground vibration in production blasting and pre-splitting at Tata west Bokaro, Colliery. Bulk explosive and shock tube initiation was normally used in mines. The study was aimed at optimization of blast parameters to enhance over all blasting …
Pre-splitting may be thought of as a special case of blasting where the blasthole pressures are deliberately kept below the normal levels which cause significant crushing around …
The aim is to analyze the costs associated with the different blasting techniques, conventional and pre-split, especially the costs of support, which depend on …
2. Pre-Splitting . The pre-splitting blasting involves a single row of holes drilled along the excavation line. Pre-split in the rock forms a discontinuous zone that minimizes or eliminates overbreak from the subsequent primary blast and produces a smooth-finish rock wall. Pre-splitting is also used to reduce ground vibration in some critical ...
The large explosion pressure cracks the weak connection between the left rock masses of the well contour, forming the overbreak area. However, when charges in the smooth holes are fired, the internal rock has been broken, reducing the resistance force of the inner rock masses, making more explosion pressure squeeze to the center of the rock well.
Pre-split blasting is a primary technique for creating slopes with a minimum amount of unwanted damage to the remaining rock mass. Rock slopes created in such a …
Pre-splitting is a controlled blasting technique with applications in open pit mines. The main objectives of pre-splitting in open pit mining are: preventing/controlling back-break; controlling
According to the pre-splitting design method of rock beam, the maximum and average microseismic energy of the 10303 working face after pre-splitting construction are reduced by 25.6% and 6.4%, respectively, with excellent prevention and control effect of thick roof.
Julian Cleeton, director of Stemtek, examines the conventional and alternative methods for achieving a stable face. Pre-splitting can be defined as 'a technique using lightly charged, closely spaced holes to induce a fracture plane along a required design profile, which isolates the rock to be blasted from the surrounding rock …
Semantic Scholar extracted view of "Application of deep borehole blasting on fully mechanized hard top-coal pre-splitting and gas extraction in the special thick seam" by L. Jian et al. ... In view of the ground drilling of the N2206 working face in Shanxi Wangzhuang Coal Mine, the gas concentration is low and the extraction effect is not …
Under the influence of roof cutting, the gangue in goaf along the roadway quickly connect the roof noncaving, which limits the movement of overlying strata and weakens the influence of mining stress on the surrounding rock of the roadway. (2) The pre-splitting before the working face mining can make the rock layer in the goaf along the roadway ...
During the initial evaluation period of pre-splitting results, it is recommended that the presplit blast be its own blast that way the results can be evaluated. ... The crack is intended to protect the new rock cut face, or some other perimeter. When well executed, the exposed rock face may contain "half casts" of the boreholes used for ...
According to the structural characteristics of the surrounding rock of the roof and gob of the AFR in the process of advancing the working face, and combined with the mechanical effects of a pre-splitting on the rock mass of the roof, the roadway is divided into three zones: the pre-splitting implementation zone, the pre-splitting influence …
In order to solve the problem,that the hard rock fault with a large throw hinders the advance of a fully mechanized mining face,this paper analyzes the disadvantages of the traditional method for passing through the fault and the existing technologie. Also,the paper carries out a systematic study on the deep hole pre-splitting blasting technology for passing …
According to the development requirements of green mining of coal resources, it is imperative to improve the extraction rate of coal and the application of safe and efficient mining technology. Pre-splitting and roof cutting technology is widely used in reducing residual coal pillars and safe pressure relief mining, which has become the …
Blasting is a major method of excavation in mining, civil construction and infrastructure projects. The integrity of the rockmass of the final wall after excavation is important for the stability and economics of the operation. Perimeter blasting achieves a planned surface of the rockmass. The pre-split is one such technique, deployed when …
Hole diameters for pre-splitting were 89 mm, and hole spacing ranged from 0.8 to 1m. ... Both the numerical and test results indicate that because of highly confined rock mass and restricted free ...
Energies 2022, 15, 6489 3 of 20 forming roadway technology; 6 Research on gas and rock explosion in the process of the pre-fractured roof. 1XVXXð1W[ð1¡1 1 1 1 Y1 1 XW1 1 1 1 ...
the presplitting method of producing a plane of split rock along the face of the slope prior to any primary drilling or blasting is described. this sheared area from hole to hole along slope line may be formed for the entire depth of the cut, or if the cut is too deep the plane is made to a predetermined bench level and repeated in lifts of of ...
Unfortunately, a presplit is normally necessary in a weaker rock to increase safety and prevent overbreak of the face. The new form of precision presplitting is …
The compressive strength of the rock is the ability of the rock to withstand compression. The way a precision presplit functions is: 1. A rapid buildup of gas …
The rock mechanics parameters (see Table 2) and contact parameters (see Table 3) were defined, and the boundary conditions were set after pre-splitting. Pre-splitting and roof cutting are achieved by …
In this study, a three-dimensional experimental model for the non-penetrating pre-splitting of small-coal-pillar roadway roofs was established, the apparent resistivity change in the rock layer during mining of the working face was determined, the propagation law of high-frequency electromagnetic waves in the overlying rock was studied, and the ...
