Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia:

V. V. Chervov, Head of Mining Mechanization Laboratory, Doctor of Engineering Sciences, chervov@misd.ru
I. V. Tishchenko, Senior Researcher, Candidate of Engineering Sciences
A. V. Chervov, Leading Engineer

Many special construction operations need pneumatic percussion machines. The feasibility of increasing the penetration rate in driving of rods in soil is assessed via physical modeling. The promising nature of high-frequency pulse load generators in rock fracture at the ensured threshold value of the unit impact energy is justified. The best approach to this effect is the valve-aided air distribution implemented in pneumatic hammers of variable impact capacity. Such air distribution system uses a ring-shaped elastic valve at the compressed air exhaust from the back stroke chamber. The stable operation conditions of the ring-shaped rubber valve are determined within a wide range of impact frequency adjustment. The authors have experimentally determined the elastic valve temperature versus impact frequency, the influence of the angular orientation of the ring-shaped elastic valve cross-section on the air tightness of the back stroke chamber, as well as the values of radial and axial crumpling of the elastic valve with increasing radial gap between the piston and the device housing. The studies into pipe driving by a compound generator composed of two coaxial tandem impact facilities are analyzed. The increased impact on the pipe by the united percussive facilities at the unit blow energy higher than the threshold value ensures higher penetration rate of the pipe owing to the improved bottomhole interaction. Duty harmonization of two percussive facilities by means of frequency synchronization ensures reliable and stable operation of the compound generator. The capabilities of the machine were tested using a prototype model with smooth variation of impact frequency in a vertical channel in soil. The article describes the designs of the pneumatic hammer prototypes with smooth blow frequency variation and with mechanical synchronization of two impact bodies placed in the common housing and having the joint air distribution system.

1. Ballay F., Frey H., Hein S., Herrmann A., Kuhn V. und andere. Bautechnik : Fachkunde für Maurer, Maurerinnen, Beton- und Stahlbetonbauer, Beton- und Stahlbetonbauerinnen, Zimmerer, Zimmerinnen und Bauzeichner, Bauzeichnerinnen. 17., überarbeitete Auflage. Wuppertal : Verlag Europa-Lehrmittel, Nourney, Vollmer GmbH & Co. KG, 2018. 539 s.
2. Hongfang Lu, Matthews J., Iseley T. How does trenchless technology make pipeline cons truction greener? A comprehensive carbon footprint and energy consumption analysis. Journal of Cleaner Production. 2020. Vol. 261. 121215. DOI: 10.1016/j.jclepro.2020.121215
3. Sterling R. L. Developments and research directions in pipe jack ing and microtunneling. Underground Space. 2020. Vol. 5, Iss. 1. pp. 1–19.
4. Zaneldin E., Khatib O. A., Ahmed W. Investigating the use of no-dig technologies for underground utilities in developing countries. Innovative Infrastructure Solutions. 2020. Vol. 5, Iss. 1. 17. DOI: 10.1007/s41062-020-0265-5
5. Gurkov K. S., Klimashenko V. V., Kostylev A. D., Plavskikh V. D., Rusin E. P. et al. Pneumatic punching machines. Novosibirsk : Izdatelstvo IGD SO RAN, 1990. 217 p.
6. Tsytovich N. A. Mechanics of soils: Full course : tutorial. Moscow : URSS, 2020. 640 p.
7. Bauman V. A., Bykhovskiy I. I. Vibrating machines and processes in construction : tutorial. Moscow : Vysshaya shkola, 1977. 255 p.
8. Chervov V. V., Chervov A. V., Tishchenko I. V. Impact Device. Patent RF, No. 2691238. Applied: 20.07.2018. Published: 11.06.2019. Bulletin No. 17.
9. Anurev V. I. Reference book of designer-mechanical engineer. 5^th enlarged and revised edition. Moscow : Mashinostroenie, 1979. Vol. 1. 728 p.
10. Tishchenko I. V., Chervov V. V., Gorelov A. I. Effect of additional vibration exciter and coupled vibropercussion units on penetration rate of pipe in soil. Journal of Mining Science. 2013. Vol. 49, Iss. 3. pp. 450–458.
11. Chervov V. V., Smolyanitskiy B. N., Trubitsin V. V. et al. Impact Device. Patent RF, No. 2462575. Applied: 29.04.2011. Published: 27.09.2012. Bulletin No. 27.
12. Verstov V. V., Gaydo A. N. Study the effectiveness of the steel sheet pile driving in dense soil by different mechanisms. Mekhanizatsiya stroitelstva. 2013. No. 2(824). pp. 44–49.
13. Tishchenko I. V. Pneumatic hammer with increased impact frequency. Vestnik Kuzbasskogo gosudarstvennogo tekhnicheskogo universiteta. 2014. No. 3(103). pp. 12–17.
14. Vanag Yu. V. Application of pneumatic machines in conditions of a confined technological space. Fundamentalnye i prikladnye voprosy gornykh nauk. 2021. Vol. 8, No. 2. pp. 178–183.
15. Tishchenko I. V., Chervov V. V. Principles of Designing Air-Driven Hammer with Decoupled Piston for Driving Rods in Soil. Journal of Mining Science. 2018. Vol. 54, Iss. 6. pp. 949–958.
16. Ajibose O. K., Wiercigroch M., Pavlovskaia Е. Е., Akisanya A. R., Károlyi G. Drifting Impact Oscillator With a New Model of the Progression Phase. Journal of Applied Mechanics. 2012. Vol. 79, Iss. 6. 061007. DOI: 10.1115/1.4006379
17. Pavlovskaia E., Hendry D. C., Wiercigroch M. Modelling of high frequency vibro-impact drilling. International Journal of Mechanical Sciences. 2015. Vol. 91. pp. 110–119.