Study On Optimization Of Smooth Blasting Parameters For Tunnel By Developing An Automatic Design Software

The smooth blasting method has been used widely for long-term underground construction,such as mountain tunnels,principal mining excavations and hydroelectric projects,etc.,with the primary purpose of minimizing overbreak or underbreak volume and creating a well-shaped boundary.Auto CAD has been used for drawing almost technical blasting designs.But until now,no software can automatically resolve the complicated work of calculating smooth blasting parameters and the long time consumed in drawing blasting design in Auto CAD,etc.Therefore,to facilitate the design process as well as to study on optimization of smooth blasting parameters for tunnel,an automatic design software which helps resolve the above problems has been developed.Based on the synthesis,analysis and research of basic data,drilling design data,and construction design data involved in the tunnel blasting design process,the tunnel blasthole layout,construction design parameters,relevant data and formulas related to the development of automatic design software,were analyzed and discussed.In addition,the database content,software structure and conditions for integrating traditional blasting design with computer technology were determined.The parallel hole cut method is selected as the main cut method for automatic design software based on the synthesis and analysis of the existing cut methods.Three altered cut designs which are suitable for most tunnel blasting conditions have been proposed.Based on the theoretical study and the graphical analysis result obtained by analyzing the synthesis data from practical research,the parameter calculation principle for proposed cut designs has been determined.Moreover,the improvement in determining contour hole parameters was put forward through the optimal equations of burden and charge concentration.The synthesis and analysis of existing programming languages,computer-aided design software(s),and automatic drawing methods have been conducted to select a suitable method for developing automatic design software.Various algorithms have been created to automatically calculate and draw based on the reasonable schematizing method and computer coding method.The automatic design tunnel smooth blasting software,which is named VOLVN,was successfully developed by using the chosen programming language Delphi.The software can automatically realize the calculation of blasting parameters and the drawing of blasting design.Otherwise,it can also realize the data transmission with Microsoft Excel.The combination of VOLVN software and Auto CAD helps to obtain a complete smooth blasting design within 3 ～ 5 minutes.Compared with similar software(s),this software has outstanding automatic calculating and drawing efficiency advantages.The VOLVN software was applied for the construction of Dak My-3hydropower project and NUI BEO coal mine in Vietnam.Both practical applications and research results indicate that the software helps to increase the hole utilization coefficient by 15-25%,the smoothness of tunnel boundary,the economic and technical indexes by 10-20%,minimizing oversized rocks,rock flies,etc.Otherwise,the practice of multiple blasting constructions shows that various blasting designs given by VOLVN software can be directly applied to engineering construction,achieved the goals of blasting parameter optimization,computer adaptive hole layout,etc.,and the blasting design of the tunnel is completed about 4 minutes.The developed VOLVN software is used to investigate effect of blasting conditions on blasting results for smooth blasting of semi-circular tunnels using parallel hole cut methods.The correlation equation and rule of rock Protodyakonov coefficient,cracks’ distance effecting on blastholes number,specific charge with the variation of blasthole diameter and the semi-circular tunnel face area were obtained.The results showed specific charge increases as rock Protodyakonov coefficient,cracks’ distance,and drillhole diameter increase but decrease when tunnel face area increases.In addition,the number of drillholes increases linearly as tunnel face area increases but decreases when drillhole diameter increases.The thesis also obtained the optimal equation for calculating specific charge value through research.