Method and a device for ascertaining the degree of compaction of a bed of material with a vibratory compacting device

A system for measuring the degree of compaction achieved in a bed of material by a vibratory compaction device comprising:

• means for vibrating the compaction device against the bed of material to be compacted;
• transducer means for generating a characteristic signal of the vibratory motion of the compacting device against said material, said characteristic vibratory motion signal having a fundamental frequency and a plurality of harmonic frequencies;
• first filter means for filtering said fundamental frequency from said characteristic frequency to obtain a fundamental amplitude signal;
• means for measuring the amplitude of said fundamental amplitude signal;
• second filter means for filtering at least one harmonic frequency component from said characteristic signal to obtain a harmonic frequency signal;
• means for measuring the amplitude of said harmonic frequency signal;
• and
• means for comparing the amplitudes of said fundamental and harmonic frequency signals to generate a signal representative of the degree of material compaction of said material.

A method for measuring the degree of compaction achieved in a bed of material by a vibratory roller of a compaction device comprising steps of:

• vibrating the vibratory roller of the compaction device such that said vibratory roller vibrates against the bed of material to be compacted to generate a characteristic signal of the vibratory motion of the vibratory roller against said material, said characteristic vibratory motion signal having a fundamental frequency and a plurality of harmonic frequencies;
• measuring the amplitude of said characteristic vibratory motion signal at said fundamental frequency;
• measuring the amplitude of said characteristic vibratory motion signal for at least the second harmonic of said fundamental frequency;
• and
• comparing the measured amplitudes of said fundamental frequency and said at least second harmonic frequency to ascertain the degree of compaction of said bed of material.

A system for measuring the degree of compaction achieved in a bed of material by a vibratory compaction device comprising:

• roller means;
• means for vibrating said roller means for compaction device against the bed of material to be compacted;
• transducer means for generating a characteristic signal of the vibratory motion of said roller means of the compacting device against said material, said characteristic vibratory motion signal having a fundamental frequency and a plurality of harmonic frequencies;
• first filter means for filtering said fundamental frequency from said characteristic frequency to obtain a fundamental amplitude signal;
• means for measuring the amplitude of said fundamental amplitude signal;
• second filter means for filtering at least one harmonic frequency component from said characteristic signal to obtain a harmonic frequency signal;
• means for measuring the amplitude of said harmonic frequency signal;
• and
• means for comparing the amplitudes of said fundamental and harmonic frequency signals to generate a signal representative of the degree of material compaction of said material.