Overview of fine blasting

(A) the concept of fine blasting

Fine blasting, that is, through the quantitative blasting design and careful blasting construction, the release of explosive blast energy and media crushing, throwing and other processes of precision control, not only to achieve the intended effect of blasting, but also to achieve effective control of the harmful effects of blasting, and ultimately to achieve a safe, reliable, environmentally friendly and economically rational blasting operations. [1]

Fine blasting is the emergence and development of market demand, with the national economy soaring, urbanization process accelerated, engineering blasting technology is increasingly playing an important role. The proposal of fine blasting is not only the inevitable result of technological development, but also from the huge demand of engineering blasting market. In the field of earth and rock blasting, the demand for fine blasting is increasing, for example, in the construction of major national projects and western development, facing complex geological conditions, the construction of large-scale hydropower hub projects, long-distance water transfer or transportation tunnels, high and steep slopes, large-scale mines and other difficult tasks, are involved in the problem of fine blasting.

(B) the meaning of fine blasting

From the definition of fine blasting, fine blasting can be seen, fine blasting adheres to the traditional concept of controlled blasting, but with the traditional control of blasting there are obvious differences. The goal of fine blasting and traditional controlled blasting, not only to achieve the expected crushing, compaction, loosening and cutting and other blasting effects, but also the scope of blasting damage, the direction of the collapse of buildings, broken blocks of the throwing distance and the shape of the pile as well as blasting seismic waves, air shock waves, noise and crushed material dispersal and other hazards are controlled within the prescribed limits to achieve the effect of blasting and blasting hazards of the double control.

Compared with the traditional control of blasting, fine blasting in quantitative blasting research, blasting design, explosive blast energy release and blasting process control, quantitative evaluation of blasting effects, etc., have put forward higher requirements.

Fine blasting pay more attention to the use of explosion mechanics, rock dynamics, structural mechanics, mechanics of materials and engineering blasting and other related disciplines of the latest research results and make full use of the rapid development of computer technology, quantitative blasting design and calculation of theories, methods and experimental means, optimization of blasting programs and parameters, blasting and harmful effects of the control.

Fine blasting focuses on the mechanical properties of the blasting medium, blasting conditions and engineering requirements, relying on excellent performance of blasting equipment and advanced and reliable detonation technology, supplemented by careful construction and strict management, to achieve the release of explosive blast energy, media fragmentation, throwing and accumulation of precision control of the process.

Fine blasting is not limited to traditional controlled blasting, the concept applies to soil and rock, demolition and special blasting and other aspects of engineering blasting, it can be seen, fine blasting is not a blasting method, but the concept of a wide range of meanings.

(C) the composition of the fine blasting system

According to the Yangtze River Academy of Sciences in a number of large-scale national hydropower projects in the practice of blasting, fine blasting should include the following parts: (1) accurate numerical blasting technology research; (2) quantitative engineering blasting design; (3) high precision and high reliability of blasting equipment selection; (4) refinement of the blasting construction technology; (5) Refined construction management methods; (6) quantitative evaluation of blasting effect and so on. The core is quantitative and refined.

(1) Precise numerical blasting technology research

With the continuous progress in the field of basic theoretical research of explosion mechanics, rock dynamics, engineering mechanics and engineering blasting technology, with the help of the leaping development of computer technology, blasting test and measurement technology, it is possible to make quantitative blasting technology research. Based on the basic theories of kinematics and structural mechanics, numerical methods such as FEM, DDA, AEM and LS-DYNA have been used to make more accurate prediction and simulation of urban demolition blasting, soil and rock blasting, explosive processing, etc., and the analysis, comparison and research of different blasting programs can be realized without the help of solid models. In addition, the use of high-speed photography and its three-dimensional numerical analysis system, has been able to implement numerical monitoring of the whole process of blasting, can quantitatively analyze the movement process and movement law of each broken block.

In terms of earth-rock blasting, the following purposes can already be achieved: (1) simulation of crack generation and development in the process of blasting action; (2) prediction of the composition of the blasting block and the morphology of the bursting pile; (3) evaluation of the blasting effect and optimization of the parameters; and (4) simulation and reproduction of the blasting process.

(2) quantitative engineering blasting design

Quantitative blasting research and analysis makes quantitative blasting design possible. A complete engineering blasting design includes the comparison and selection of blasting programs, blasting parameters, the determination of the form of gun-hole arrangement, detonation network design.

Quantitative blasting program, including excavation, excavation zoning, excavation step height, detonation mode, blasting scale, etc., through the numerical optimization analysis, given in a quantitative manner.

Quantitative blasting parameter selection: the main blasting hole blasting parameters include explosive unit consumption, row spacing between the holes, density coefficient, hole diameter, explosives diameter, hole plugging length; pre-cracking hole blasting parameters mainly include line charge density, hole spacing, plugging length, etc., in addition to the construction of pre-cracking parameters. In the determination of blasting parameters, with the help of current numerical analysis and experimental means, has basically got rid of the traditional mode of determination based on experience in the past, accurate quantitative selection has become a reality.

Precision of the detonation network: the traditional detonation system, the design method has been quantitative, but due to the error of the detonation equipment, both electric and non-electric detonation, in practice, it is difficult to meet the requirements of refinement. In recent years, the maturity of high-precision non-electric initiation system and digital detonator detonation system, only to make the precise design of the detonation network possible, high-precision non-electric initiation system and digital detonator detonation system can be achieved to achieve precise milliseconds of detonation accuracy.

(3) high-precision and highly reliable blasting equipment selection

High-precision non-electric detonators and digital detonators have been successfully developed in the control of the structural collapse process, improve the effect of rock fragmentation, to achieve the control of throwing accumulation and reduce the vibration effect of blasting, basically realizing the precise control of the blasting process. In addition, to adapt to different lithology and blasting conditions of high-performance and performance-adjustable explosives, detonating cord with different bursting speeds, making the release of explosive energy, the use of explosives and the control of the transformation process has become possible. For example, the emergence of performance-adjustable explosives, explosives and rock impedance to truly realize the impedance of matching the conditions created by the explosives can greatly improve the utilization of energy; the success of the development of low detonation velocity detonating cord, greatly reducing the marble and other stone mining in the blasting damage, which can improve the rate of mining and utilization of stone, can effectively save resources.

These advances in blasting equipment, strengthening the control of the blasting process, so that in the construction to achieve the requirements of refinement possible.

(4) refinement of blasting construction technology

Construction mechanization and automation level increases for the fine blasting construction provides technical support, especially with the 3S technology (RS, GIS, GPS) as a representative of information technology in the application of blasting projects, blasting projects, measuring and placing, drilling accuracy, charging plugging, and other processes to greatly increase the degree of refinement. Construction machinery and construction technology to meet the requirements of fine blasting, from the construction level for the fine blasting to provide technical protection. For example, large foreign mines use submerged drilling rigs or tusk drilling equipment, carrying GPS systems, can realize the automatic positioning of the drill; relying on the drilling rig equipped with measurement and control systems, can be realized in the drilling process of hole direction and inclination of the automatic adjustment and control. Another example is in the hydropower project excavation and blasting, through the drilling rig modification, increase the limit plate, add the righting device, according to the characteristics of lithology customized diameter of the drill pipe and other technical means, to achieve to meet the requirements of fine blasting technology construction equipment.

Construction process control, hydropower system summarized the "blasting design and approval → excavation area leveling → clear surface → measurement and alignment → hole laying → technical briefing → set up insertion, drilling rig in place, fixed → drilling → clearing → drilling quality inspection → drilling protection → charging → network connection → network inspection → detonation → slag → slope cleanup → excavation of slope Measurement and testing → blasting effect analysis → next cycle" process flow, effective control of construction quality, for the final realization of the blasting process of fine control plays an important role.

(5) refined construction management methods

To realize the precise control of the blasting process, inseparable from the refined construction management methods. Construction management methods include the establishment of rules and regulations and the development of quality control standards, quality control standards, including blasting vibration control standards, acoustic wave velocity attenuation rate standards, the retained surface of the over-underdigging and leveling and residual hole rate requirements

Pre-implementation preparations: including from the organization, technology, resources, progress, environmental protection, and other aspects of the management of the overall arrangements. The establishment of the appropriate organizational structure, a clear division of their respective responsibilities, the preparation of management methods to meet the requirements of fine blasting.

Construction process control: strictly in accordance with the design of the construction, set up a full-time engineering blasting supervision to monitor the establishment and operation of the quality management system, check the site construction quality control procedures, links, quality control methods in place, analysis of construction quality control problems, and in the organization and management, technical and technological improvements in the proposed specific measures and quality control requirements. For example, water conservancy and hydropower projects are being implemented "a gun a summary", "a ladder section of a pre-acceptance", "a dam section of an acceptance", the ladder dam section of the lessons learned in a timely manner to summarize, in order to guide the improvement of the next ladder section of the construction. Guidance to improve the construction of the next ladder section. Strictly implement the "three" (fixed people, fixed machines, fixed holes), "three certificates" (permit to drill, permit to charge, permit to explode), "three calibration drill" (0.2m, 1.0m, 2.0m) and other systems during the construction process, including the "three" (0.2m, 1.0m, 1.0m, 2.0m). (0.2m, 1.0m, 2.0m) and other systems and other construction process management techniques, are well implemented the concept of fine blasting.

(6) fine numerical evaluation of blasting effect

Blasting effect evaluation includes numerical monitoring of blasting vibration, numerical testing of the depth of rock blasting relaxation, leveling and overdigging detection, drilling TV testing and other numerical detection means. Numerical monitoring of blasting vibration: for example, the international advanced level of the Canadian MiniMate Plus vibration measurement system and the domestic EXP 3850 blasting vibration test system can provide timely and effective numerical analysis of blasting vibration. Wuhan Rocksea's RS-ST01C integrated digital ultrasonic instrument realizes timely detection of the depth of retained rock relaxation layer before and after blasting. The RS-DTV digital color drilling TV camera system produced by Wuhan Rocksea can numerically analyze the internal quality of the retained rock body. In addition, the residual hole rate, flatness and over and under excavation detection..., provide quantitative indicators to evaluate the blasting effect.