Method for determining the compaction state of substrate

Patent metadata

Field	Value
Publication number	US-10435852-B2
Application number	US-201615366303-A
Country	US
Kind code	B2
Filing date	Dec 1, 2016
Priority date	Dec 2, 2015
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A method for determining the compaction state of a subgrade to be compacted using a roller compactor comprising at least one compactor drum having an oscillation-inducing arrangement and rotatable about a drum axis of rotation comprising the following steps: during at least one period of oscillating movement of the compactor drum, repeatedly determining the acceleration of the compactor drum in an first direction, representing a first acceleration value; in association with each first acceleration value, determining an acceleration of the compactor drum in a second direction representing a second acceleration value in order to provide acceleration value pairs, each consisting of a first acceleration value and a second associated acceleration value; and for at least one oscillation period, defining a compaction state value representing the compaction state of the subgrade based upon the period of oscillation determined for said acceleration value pairs.

First claim

The invention claimed is:

1. A method for determining the compaction state of a subgrade to be compacted using a roller compactor comprising at least one compactor drum rotatable about a drum axis of rotation, wherein one of the at least one compactor drum of the roller compactor is associated with an oscillation-inducing arrangement for inducing an oscillating rotation in said compactor drum in order to generate an oscillating torque on the drum axis of rotation, wherein the method comprises the following step:
a) during at least one period of oscillating movement of the compactor drum, repeatedly determining the acceleration of the compactor drum in a horizontal direction, representing a first acceleration value,
b) in association with each first acceleration value, determining an acceleration of the compactor drum in a vertical direction representing a second acceleration value in order to provide acceleration value pairs, each consisting of one of the first acceleration values and the associated second acceleration value, and
c) for at least one period of oscillation, defining a compaction state value representing the compaction state of the subgrade based upon the period of oscillation determined for said acceleration value pairs,
wherein step c) for determining the compaction state value comprises determining the area of an acceleration value pair curve defined by consecutive plots of acceleration value pairs on a graph of acceleration values during one period of oscillation, wherein the acceleration value graph is defined by a first graph axis associated with the first acceleration values and a second graph axis associated with the second acceleration values.

2. The method according to claim 1 , wherein, regarding step c), an acceleration value pair vibration is defined based upon a sequence of acceleration value pairs along the first graph axis.

3. The method according to claim 2 , wherein acceleration value pairs from a first group of acceleration value pairs and a second group of acceleration value pairs are assigned in such a way that the acceleration value pairs from the first group of acceleration value pairs generally form the upper end of the acceleration value pair vibration and the acceleration value pairs from the second group of acceleration value pairs generally form the lower end of the acceleration value pair vibration.

4. The method according to claim 3 , wherein, regarding step c), an upper envelope is determined based upon the first group of acceleration value pairs, and a lower envelope is determined based upon the second group of acceleration value pairs.

5. The method according to claim 4 , wherein, regarding step c), the area value is generally defined as being the area bordered by the upper envelope and the lower envelope.

6. The method according to claim 1 , wherein during a rolling motion of the roller compactor, a depression forms beneath said compactor drum, wherein the depression is restricted toward a direction of travel and opposite to the direction of travel through accumulations of material.

7. The method according to claim 6 , wherein the said compactor drum oscillates back and forth within the depression and, during each period of oscillation, the compactor drum is moved once up and once down by each of the accumulations of material.

8. The method according to claim 7 , wherein a depth of the depression and an amount of the accumulations of materials gradually decreases by the oscillating rotation in said compactor drum causing the acceleration of the compactor drum in a horizontal direction to increase.

9. The method according to claim 8 , wherein a frequency of the second acceleration value is double a frequency of the first acceleration value during each period of oscillation.

Assignees

• Hamm Ag

Inventors

• Pistrol Johannes
• Kopf Fritz
• Völkel Werner
• Villwock Sebastian

Classifications

• G01N9/00

  Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity · CPC title

• E01C19/288 Primary

  adapted for monitoring characteristics of the material being compacted, e.g. indicating resonant frequency, measuring degree of compaction, by measuring values, detectable on the roller; using detected values to control operation of the roller, e.g. automatic adjustment of vibration responsive to such measurements · CPC title

• E01C19/286

  Vibration or impact-imparting means; Arrangement, mounting or adjustment thereof; Construction or mounting of the rolling elements, transmission or drive thereto, e.g. to vibrator mounted inside the roll (E01C19/287 and E01C19/288 take precedence) · CPC title

• G01N3/32

  by applying repeated or pulsating forces · CPC title