Road structure – process – or apparatus – Process – In situ treatment of earth or roadway
Patent
1985-06-24
1988-02-02
Leppink, James A.
Road structure, process, or apparatus
Process
In situ treatment of earth or roadway
404102, 404133, E01C 736
Patent
active
047226358
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of compacting soil in which a vibration mass bearing on the ground is caused to vibrate by means of a vibration source.
Such a method is known. The invention has for its object to compact the soil in a shorter time, to a greater extent and/or by lower driving energy of the vibration source. This is achieved by applying one or more characteristics defined in the claims.
The invention furthermore provides a device described in the claims for carrying out the method according to the invention.
Experiments have shown that as compared to fall weights the soil can be worked to the same extent of compaction within a shorter time or better compacted within the same time.
The invention will be described more fully hereinafter with reference to a drawing.
The drawing shows schematically in
FIGS. 1 to 5, 12, 16, 17, 18 individually different devices embodying the invention for carrying out various kinds of the method in accordance with the invention.
FIG. 6 the device of FIG. 5 in a different working position,
FIG. 7 a diagram of the kinds of dynamic power,
FIGS. 8 to 10 different directing means usable in the device embodying the invention,
FIG. 11 a mass spring system of soil during compaction,
FIGS. 13, 14 and 15 vibration diagrams.
The device 1 of FIG. 1 for compacting soil 2 comprises a vibration mass m.sub.1 bearing on the soil 2 to be compacted, to which a vibration source 4 is fastened by means of bolts 3. This vibration source 4 comprises a vibration aggregate having an eccentric mass known per se m.sub.ex consisting of two eccentric weights 7 turning in opposite senses 6 about axes 5 and being driven through a driving gear 8 by a hydraulic motor 9. The motor 9 is fed through hoses 30 by a pump aggregate 31. The centrifugal force F of the eccentric mass m.sub.ex is, at the maximum rate of the eccentric mass m.sub.ex higher than the overall weight G of the vibration mass m.sub.1. As a result the vibration mass gets each time free of the soil so that each time an impact is applied to the soil 2, which has a strong compacting effect on the soil 2.
The device 1 of FIG. 2 is distinguished from that of FIG. 1 in that the vibration mass m.sub.1 is provided with fastening means, for example, tapped holes with matching bolts 3 for fastening thereto an additional mass m.sub.2. The mass m.sub.1 or m.sub.2 respectively is chosen so that it is not allowed the soil 2 to require a dynamic power D from the vibration device 1 which this vibration device 1 cannot supply.
The foregoing will be elucidated with reference to formulae ##EQU1## wherein represent: F the centrifugal force or the maximum of the alternation in the vibration force of the eccentric weights 7, frequently has a constant value with a given vibration source 4, the vibration and
When the soil 2 is worked by the device 1 embodying the invention, a schematic mass spring system as shown in FIG. 11 is produced. The vibration mass m.sub.1 moves along with the soil mass m.sub.g1, which may be considered to be coupled herewith. The soil mass m.sub.g1 is elastic and damped with respect to a second soil mass m.sub.g2 and this second soil mass m.sub.g2, in turn, is elastically supported and damped with respect to the soil 40.
In reality distinction should be made between various kinds of dynamic power indicated in FIG. 7, i.e.
The angle q is a measure for the generated damping. The idle power D.sub.b is equal to the apparent power D.sub.s when there is no damping, that is to say, when the angle q is 90.degree.. The idle power D.sub.b supplied by the vibration device 1 is invariably at an angle of 90.degree. to the working power D.sub.2. With a decrease of the angle q and hence with an increase of the damping of the soil the dynamic working power D.sub.w to be supplied by the vibration device 1 is raised so that there is a risk that the number of revolutions n of the vibration source 4 should drop below its maximum, as a result of which the working power D.sub.w further decreases. In order to avoid this the vibration mass m.sub.1 is var
REFERENCES:
patent: 3909148 (1975-09-01), Vural et al.
patent: 4382715 (1983-05-01), Vural et al.
Ballast-Nedam Groep N.V.
Leppink James A.
Neuder William P.
Snyder John P.
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