OVER BREAK ANALYSIS OF ROCK MASS IN SMOOTH.pptx

over break

1. OVER BREAK ANALYSIS OF ROCK MASS IN SMOOTH BLASTING TECHNIQUE IN OPEN CAST BENCH BLASTING A project Submitted In partial Fulfilment of the Requirements for the degree of Bachelor of Technology In Mining Engineering By Aniket Gupta ,Soumyadip Biswas Under the guidance of Mr. Himadri sekhar Mahata Department of Mining Engineering , Kazi Nazrul University

2. CONTENT Introduction Literature Review Scholarly work of different Researches Research Gap Work plan Methodology Reference

3. INTRODUCTION This project provides an introduction to over break analysis of smooth blasting in open cast bench blasting . The mining industry's most common excavation method for removing rock fragments is drilling and blasting (DAB). Due to blasting some inevitable negative effects are often encountered under the blasting loads, such as blast-induced damage ,vibration, stability of slope , under break and over break. The task of quality evaluation of smooth blasting is highly challenging due to the complicated site conditions and varying blasting operations which is focused on the overbreak or underbreak evaluation, rock damage, and ground vibration assessment, as well as the blasting control , which might considerably deteriorate the physical and mechanical properties of surrounding rock masses, and thus result in safety or stability as well as construction delay.

4. Over Break & Under Break - * Overbreak*: This occurs when the actual excavation extends beyond the intended boundaries. It might result from factors like excessive explosive force or poor control during the blasting process, leading to more material being removed than originally planned.- * Underbreak*: This happens when the excavation falls short of the intended dimensions. Factors such as insufficient explosive force or improper drilling can contribute to underbreak, causing less material to be removed than originally intended.

5. Blasting Technique

6. What is Smooth blasting ? Fig 1 : Smooth-Blasting Smooth blasting is a controlled and systematic mining technique that involves using carefully measured explosives to break rock efficiently. This method aims to minimize vibrations, reduce flyrock, and enhance fragmentation, contributing to safer and more productive mining operations

7. What is Pre- Split Blasting? Fig 2 : Pre – Split Blasting Pre-splitting blasting in the mining industry refers to a technique where a row of closely spaced, smaller diameter blast holes is drilled along the perimeter of a larger main blast hole. This creates a protective barrier or "pre-split" that helps control the direction of the main blast, minimizing damage to the surrounding rock and improving fragmentation. The goal is to create a clean, well-defined rock face, reducing the risk of overbreak and improving overall stability in the mining operation

8. OBJECTIVE OF THE STUDY: 1. To find out the most important parameter to reduce over break and under break. 2. Reduction of crack generation in the excavation wall. 3. Make the blasting process more economical.

9. Compression in excavation line in between pre –split blasting and smooth blasting : Fig 4 : (a) Pre- Split Blasting (b) Smooth Blasting

10. GRAPH ANALYSIS:

11. Blast Geometry : Influence of Face Length. Influence of Burden. Influence of Spacing. Influence of Depth of Hole. Inclination of hole .

12. Smooth Blasting and Pre-Split Blasting:

13. Research Gap : The improvement of Theoretical concept to understand plan and design smooth blasting pattern may be done :- Insitu stress and Re- distribution of longitudinal wave . Modification the Empirical Formula Uniformity index (Rosin – Rammler equation). The Rosine Rammler equation used by Cunningham (1983) for blasting analysis is R =e ^ -(x/ xc) * n where R is the fraction of material retained on screen, x is the screen size, xc is a constant called characteristic size, and n is a constant called uniformity index. Slabs and Beam theory of structural dynamics. Using some suitable strength of explosive according to the UCS of the rock mass. Quasi – static , the slow growth rate of racks due to re distribution of Stress and Computer Simulation method (CSM) to find outline the damage limit and linear charge .

14. Rosine Rammler equation : The Rosine Rammler equation used by Cunningham (1983) for blasting analysis is R =e ^ -(x/ xc)*n , where R is the fraction of material retained on screen, x is the screen size, xc is a constant called characteristic size, and n is a constant called uniformity index. The uniformity index typically has values between 0.6 and 2.2 (Cunningham, 1983). A value of 0.6 means that the muck pile is non-uniform (dust and boulders) while a value of 2.2 means a uniform muck pile with majority of fragments close to the mean . The importance of the uniformity index is size distribution curves having the same characteristic size but different values of uniformity index.

15. Work plan Work plan : We are proposed to presents the construction of a smooth blasting quality control system for open cast bench blasting: I ntroduces a process quality control technology into quality control of smooth blasting construction . C ollects control index data of over break based on field investigation Experimental work. By using the comparative analysis of index utilization, and principal component analysis, and selects the main control indexes.

16. Methodology Here, our work is development of theoretical concept of reducing the distribution of breaking energy. Our work’s decision variables are damage scale, extensional strain, detonating velocity, pattern of smooth blasting, damage factor, uniformity index. As per our study we have consider four different waves longitudinal wave, transverse wave, damage modelling, LS – Dyna code analysis. Modification of uniformity index (Rosin – Rammler equation), dynamic loading analysis. Then we get a optimizing result.

17. Methodology

18. Conclusion

19. Reference: S. K. Mandal Æ M. M. Singh Æ S. Dasgupta (2008), Theoretical Concept to Understand Plan and Design Smooth Blasting Pattern . Wanmao Zhang, Yu Tang, Dunwen Lun, Weichiao Qui Multifractal Characteristics of Smooth Blasting Overbreak in Extra-Long Hard Rock Tunnel, DOI : https://doi.org/10.3390/fractalfract7120842 Baoping Zou,1,2,3 Zhipeng Xu , 4 Jianxiu Wang,2 Zhanyou Luo,1 and Lisheng Hu5, Numerical Investigation on Influential Factors for Quality of Smooth Blasting in Rock Tunnels(2020) P.K. Singh, M.P. Roy, R.K. Paswan, Md. Sarim , Suraj Kumar, Rakesh Ranjan Jha (2015) Rock fragmentation control in opencast blasting, DOI: 10.1016/j.jrmge.2015.10.005 Bert-Olof Svanholm , Per-Anders Persson and Bernt Larsson SMOOTH BLASTING FOR RELIABLE UNDERGROUND OPENINGS, Swedish Detonic Research Foundation, Stockholm, Sweden Nitro Nobel AB, Gyttorp , Sweden

20. Reference: P. K. Singh, M. P. Roy, and R. K. Paswan, “Controlled blasting for long term stability of pit-walls,” International Journal of Rock Mechanics and Mining Sciences R. N. Gupta, M. M. Singh, and B. Singh, “Application of presplitting and smooth blasting for excavation of a large power house cavern,” in Proceedings of the 28th US Symposium on Rock Mechanics (USRMS), American Rock Mechanics Association, Tucson, AZ, USA, June-July 1987. W. Lu, M. Chen, X. Geng , D. Shu, and C. Zhou, “A study of excavation sequence and contour blasting method for underground powerhouses of hydropower stations,” Tunnelling and Underground Space Technology

21. Thank You