Study rock mass characterisation helps in selection and optimum usage of explosive in bench blasting. There are various methods to characterize the rock mass but use of Schmidt hammer in rock characterization before blasting may be a good option. The Schmidt hammer, due to its simplicity and capability of instant data production, has so far been a powerful tool utilized by many researchers to predict compressive strength of rocks. In this light, the present study was conducted in opencast phosphate mines to see the effect of Schmidt hammer rebound number or transformed compressive strength of rocks on the powder factor. The correlation was found sufficiently reliable to enable the determination of an optimum powder factor for surface bench blast in different rock types, maintaining the required blasting results regarding fragmentation

The rock fragmentation reflects the degree of control of blasting. Despite the accuracy of screening analysis to determine the size distribution of blasted rocks, this technique remains complex and long because of the large volume of blasted rocks. The digital image processing method can overcome these constraints of accuracy and speed. Our method uses the empirical model of KuzRam and numerical method (Digital image processing) through two image processing software's (WipFrag and Split-Desktop) to analyze the particle size distribution of rocks fragmented by explosives in Jebel Medjounes limestone quarry. The digital image processing is based on the photography of the pile of blasted rock analyzed using image processing techniques. The objective of this work is to evaluate and compare the results obtained for each blast from the two methods and to discuss the similarities and differences among them. Three different blasts with the same design were analyzed through the two methods. The result of the KuzRam model gave idealistic results due to the heterogeneity of the structure of the rocks; although, this model can be used for an initial evaluation of blast design. For better efficiency of the explosion, we proposed a new fragmentation indicator factor in order to compare the fragment produced to the estimated ideal size obtained from the KuzRam model by incorporating the blast design parameters and the rock factor. Both image processing gives close results with more accuracy for the Split-Desktop software. Our method can improve the efficiency and reduce crushing costs of the studied career.

In this study, a numerical verification of the performance of preliminary tunnel support systems suggested by rock mass classification methods is performed. The Rock Mass Rating (RMR) method and the Quality Index (Q Barton) show a succession of a moderately jointed and jointed quality of Kherrata Tunnel 3. The numerical assessment combining the Finite Element Method (FEM) with the Discrete Fracture Network (DFN) models; involves the jointed area of the tunnel, in which the Voronoi model represents the joints distribution. During numerical simulations, particular attention focused on the evolution of the total displacement and the extension of the plastic zone. In addition, a parametric study was carried out to study the effect of the length and spacing of rock bolts on tunnel deformation. Results showed that the combined FEM and DFN models represent a solution for the stability analysis of underground excavations. The Voronoi model is suitable for representing the global distribution of joints in the rock mass. The parametric study carried out revealed pertinent conclusions. Thus, increasing the length of bolts (4 m to 6 m) decreases the total displacement of the tunnel; and reduces the extension of the plastic zone. However, the spacing between rock bolts does not improve the stability. The empirical method remains a reliable tool for the recommendations of preliminary support systems.

It is recommended to feed the cattle and poultry with grain fodder in the form of feed mixture balanced according to the content. Feeding of grain fodder in the form of stock feed is inefficient and economically unreasonable. The article is devoted to actual problem – the preparation of mixed fodder in the conditions of agricultural enterprises. Review and critical analyses of mixed fodder assemblies and aggregates are given. Structural and technical schemes of small-size mixed fodder aggregate with intensified attachments of vibrating and percussive action for preparation of bulk feed mixture in the conditions of agricultural enterprises were developed. The mixed fodder aggregate for its preparation in the places of direct consumption from own grain fodder production and purchased protein and vitamin supplements is also suggested. Mixed fodder aggregate allows to get prepared mixed fodder of high uniformity at low cost of energy and price of production that is becoming profitable for livestock breeding. Model line-up of suggested mixed fodder aggregate with different productivity both for small and big agricultural enterprises is considered.

The study of blast effect on bench stability is indispensable, because the overall stability of the quarry’s slope is directly linked to it. For this purpose, a study is conducted in a limestone quarry. Before the stability analysis, a fragmentation evaluation is carried out by two methods, by the Kuz-Ram model and the Digital Image analysis method using the WipFrag program, this part of the work aims to establish a more efficient blast design that assures a better fragmentation and a higher stability for the quarry’s structure. Afterwards, a numerical stability analysis approach is adopted, by employing the Finite Element Method (FEM) through the Phase² software. A 2D numerical model of the quarry’s profile is constructed, on which simulations are carried out for two cases: 1-static conditions; 2-Dynamic conditions using the proposed blast design. This analysis goals are to define the possible deformation that the blasting process could engender to the benches and its effect on bench’s stability as an individual case and on the overall stability of the slope in general.