For other parts of the book, visit Vibro-Engineering and the Technology of Piling and Boring Work.
This is a reasonable summary at the time it was written (1987) as far as it goes. Already, however, the dominance of the Japanese was waning (one Russian trade representatives told me that the Japanese weren’t very good students, which may explain much of their problem.)
The whole story of the Bodine resonant driver is a complicated one, complicated as much by Albert Bodine as anything else. More effect on the industry took place with the products of American manufacturers in the 1970’s, which were given some mention. Their statement that “The design of vibration exciters of foreign machines is basically similar to domestic ones” isn’t quite there; the French had already made some advances which were picked up by the Americans and the Japanese.
Our meeting with the Russians in 1988 didn’t evidence much familiarity with Vulcan on their part, but given the situation of the time that was understandable.
The beginning of the development of foreign pile vibration technology dates back to 1958. This was facilitated by the experience of the USSR, summarized in a report at the IV International Congress on Soil Mechanics and Foundation Engineering, held in London (D. D. Barkan, 1957).
Currently, the total number of vibratory hammers used abroad reaches approximately 15 thousand pieces. In Western European countries alone, about 3 thousand vibrators are used, with the help of which sheet pile walls and lintels are erected in hydraulic engineering, construction and metro construction. Vibrators are successfully used in the countries of Asia, Africa, America. More than 20 companies are engaged in the production of vibration equipment abroad.
The main parameters of vibratory drivers are in the ranges: static mass moment of unbalances 0.6-1000 kg-m, oscillation frequency 4.3-50 Hz, driving force 10-3000 kN, power 3.7-200 kW, weight 150-20000 kg. The vast majority of foreign vibrators for driving and extracting sheet piles, pipes, metal profiles are high-frequency. The only exceptions are some modifications of vibratory pile drivers from Japan and the Netherlands.
In the last of these countries, vibrators are being developed with the following parameters: power 20-280 kW, driving force 250-2400 kN, frequency 8.0-50 Hz. With their help, about 80% of all pile work is carried out in the Netherlands, and not only flat profiles are immersed, but also massive piles of large cross section, which is due to the soil conditions of the country.
The design of vibration exciters of foreign machines is basically similar to domestic ones.
Among the foreign manufacturers of vibratory pile drivers, Japan is the largest, supplying its products to the USA, France, Germany, Switzerland, Italy, England, Czechoslovakia, Hungary, Brazil, India, Iraq, Indonesia, etc. In the European socialist countries, Poland is a major manufacturer of pile vibrotechnics.
Romania manufactures four standard sizes of 1.7-28 kW vibrators designed for driving small piles, flat profiles and pipes. For immersion of reinforced concrete shells with a diameter of 1.2 m and a length of 30 m, a 190 kW vibratory hammer has been developed in Romania. This machine allows stepwise regulation of the static moment of the mass of unbalances in the range of 72.261 kg-m and a frequency of 6.4-12.8 Hz.
In 1962, the Bodine system vibrators began to be used in the United States, which are distinguished by an increased (sound) range of vibration frequencies up to 140 Hz. The oscillation frequency of these vibrators is maintained at the level of the natural frequency of the longitudinal oscillations of the submerged elements. Periodic elongation and shortening of the submerged element cause its corresponding transverse deformations, which leads to a discontinuity in the contact of the lateral surface of the element with the ground and a sharp decrease in the forces of lateral resistance.
The first experiments showed that the sonic vibratory driver provides high speeds of immersion and extraction of steel elements – up to 10-15 m/min; it was successfully used in the 60’s at a number of facilities in the United States. After acquiring a license, the use of these machines began in 1971-1973. in England. In 1983, the production of sonic vibratory drivers began in Canada.
The electric motors of Japanese vibrators are asynchronous, squirrel-cage, with a housing of increased strength, vibration-resistant, with special insulation. The electrical characteristics of the electric motors take into account the mode of operation of the vibrator. In Germany, the USA and France, they have mastered the drive of vibratory drivers with the help of hydraulic motors, which makes it possible to control the oscillation frequency and significantly improves the starting characteristics of vibratory drivers.
In addition to gears, which are used to transmit torque from the drive motor to the eccentric shafts, Japanese firms use V-belt transmission with special high-strength belts that have an increased wedge effect.
Almost all foreign firms produce vibratory hammers with hydraulic caps, sometimes with a lever system (Figure 54c), which ensures the effective transfer of forces from the hydraulic cylinder to the rams. If necessary, several caps are used, installed around the circle of the pipe or pile-shell.
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