US2015030392A1PendingUtilityA1
Method and apparatus for determining stiffness of a roadway
Est. expiryApr 6, 2032(~5.7 yrs left)· nominal 20-yr term from priority
E01C 19/28E01C 19/23E01C 19/288
32
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Cited by
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0
Claims
Abstract
An apparatus for the compaction of roadway materials includes a compaction analyzer for calculating stiffness during construction of the roadway. The apparatus generates a dynamic modulus for each layer of a roadway which can be used to calculate the overall effective modulus. A method for determining stiffness includes generating a dynamic modulus for each layer and calculating the overall effective modulus using the modulus of each layer.
Claims
exact text as granted — not AI-modified1 . A method of compacting a multi-layer roadway section with a roller having a compaction analyzer operably associated therewith comprising:
entering initial input parameters of the first layer of the roadway section into the compaction analyzer; making a plurality of passes with the roller over the first layer of a portion of the roadway section; applying a vibratory energy to the first layer of the portion of the roadway section with the roller as it moves thereover; repeatedly gathering responsive vibration signals of the roller as it moves over the first layer portion of the roadway section; generating, with the compaction analyzer, estimated dynamic modulus signals representative of estimated moduli based upon the responsive vibration signals of the roller and the initial input parameters entered into the compaction analyzer; measuring the dynamic modulus of the first layer of the roadway section at a plurality of locations on the portion of the roadway section; comparing the measured modulus with the estimated modulus at the plurality of locations to determine the difference between the measured and the estimated moduli; adjusting selected ones of the initial input parameters to the analyzer based on the difference between the determined modulus and the estimated modulus so that an adjusted modulus output signal generated by the compaction analyzer will more closely approximate an actual modulus of the roadway section than does the estimated modulus signal; and rolling the remainder of the roadway section until the compaction analyzer with the adjusted input parameters generates a desired adjusted output modulus signal.
2 . The method of claim 1 , wherein the initial input parameters include mix characteristics of roadway material, an estimated minimum modulus (M ld ) and an estimated maximum modulus (M T ) for the first layer.
3 . The method of claim 1 , wherein (M ld ) is the modulus at a specified lay-down density and M T is the modulus a target density achieved in a mix specification for the roadway material used in the first layer.
4 . The method of claim 3 , further comprising:
identifying the responsive vibration signals with the highest power, the lowest power, and equally spaced power levels therebetween; and designating specified minimum, maximum and equally spaced compaction levels as corresponding to the responsive vibration signals with the highest, lowest, and equally spaced powers; delivering the compaction levels to an analyzer module of the compaction analyzer; and generating the estimated modulus (M est ) of the first layer portion of the roadway section in real time with the formula M est =M ld +k in *(C l )+off in , where k in is an initial slope parameter that is an initial input parameter, off in is an estimated offset from the minimum estimated modulus and is also an initial offset parameter, and C l is the compaction level delivered to the analyzer module.
5 . The method of claim 4 , wherein the adjusting step comprises adjusting the initial slope and offset parameters, so that the compaction analyzer will generate an adjusted density (M adj ) with the formula
M adj =M ld +k adj (C l )+offset adj , where k adj and off adj are the adjusted slope and offset parameters respectively.
6 . The method of claim 4 wherein the power of a given responsive vibration signal is calculated using the equation
p
=
∑
i
=
1
n
[
S
i
*
(
f
i
)
2
10
6
]
where f i represents a plurality of frequencies contained in the given responsive vibration signal and S i is the square of the amplitude of the frequencies.
7 . The method of claim 6 wherein the initial slope parameter k in is represented by the equation k in =M T −M ld /n cl −1 where n cl is the total number of compaction levels, and wherein the estimated initial offset is zero.
8 . The method of claim 7 , wherein the adjusting step comprises adjusting the initial slope and offset parameters, and generating an adjusted density (M adj ) with the formula
M adj =M+k adj (C l )+offset adj , where k adj and off adj are the adjusted slope and offset parameters respectively.
9 . The method of claim 8 , wherein the adjusted offset is calculated using the equation
off
adj
=
1
n
∑
i
=
1
n
(
M
meas
i
-
M
est
i
)
where n is the number of the plurality of locations at which density is measured, M est is the estimated modulus at the plurality of locations, M meas is the measured modulus at the plurality of locations and the adjusted slope is calculated using the equation
k
adj
=
∑
i
=
1
n
[
M
meas
i
-
M
ld
-
off
adj
)
x
C
l
i
]
∑
i
=
1
n
(
C
l
i
)
2
10 . A method of compacting, comprising performing the steps of claims 1 through 5 on each additional layer of the portion of the roadway section to determine M adj for each layer of the roadway section.
11 . The method of claim 10 further comprising determining an overall effective modulus E eff based on the M adj for each layer of the roadway section.
12 . The method of claim 11 , where the roadway is a three layer roadway section, and E eff is determined using the equation
E
effective
=
(
C
2
(
C
1
h
1
EL
1
3
+
h
2
EL
2
3
)
+
h
3
EL
3
3
h
1
+
h
2
+
h
3
)
3
where EL 1 , EL 2 and EL 3 are the dynamic modulus for layers L1, L2 and L3, respectively, and h 1 , h 2 and h 3 are the thickness of the respective layers and are correction factors.
13 . A method of determining the stiffness of a multi layer roadway comprising:
(a) making a plurality of passes with a roller over the first layer of the roadway section; (b) applying a vibratory energy to the first layer of the portion of the roadway section with the roller; (c) generating, with a compaction analyzer operably associated with the roller, estimated modulus signals based upon the responsive vibration signals of the roller; (d) independently determining the dynamic modulus at a plurality of locations on the first layer; (e) adjusting selected ones of input parameters for the compaction analyzer based on the differences between the estimated modulus and the independently determined modulus at the plurality of locations to arrive at an adjusted modulus that more closely approximates the actual modulus than the estimated modulus; (f) performing steps (a)-(e) for each layer of the roadway section; and (g) calculating an overall modulus E eff using the adjusted modulus M adj for each layer of the roadway.
14 . The method of claim 13 wherein the independently determining step comprises:
determining the modulus at the plurality of locations with a falling weight deflectometer.
15 . The method of claim 14 wherein the roadway is a three layer roadway, and E eff is calculated with the following equation
E
effective
=
(
C
2
(
C
1
h
1
EL
1
3
+
h
2
EL
2
3
)
+
h
3
EL
3
3
h
1
+
h
2
+
h
3
)
3
where EL 1 , EL 2 and EL 3 are the dynamic modulus for layers L1, L2 and L3, respectively, and h 1 , h 2 and h 3 are the thickness of the respective layers and C 1 and C 2 are correction factors.
16 . The method of claim 15 , wherein the initial input parameters include mix characteristics of roadway material, an estimated minimum modulus (M ld ) and an estimated maximum modulus (M T ) for the first layer.
17 . The method of claim 16 , wherein (M ld ) is the modulus specified lay-down density and M T is the modulus a target density achieved in a mix specification for the roadway material.
18 . The method of claim 17 , further comprising:
identifying the responsive vibration signals with the highest power, the lowest power, and equally spaced power levels therebetween; and designating specified minimum, maximum and equally spaced compaction levels as corresponding to the responsive vibration signals with the highest, lowest, and equally spaced powers; delivering the compaction levels to an analyzer module of the compaction analyzer; and generating the estimated modulus (M est ) of the first layer portion of the roadway section in real time with the formula M est =M ld +k in *(C l )+off in , where k in is an initial slope parameter that is an initial input parameter, off in is an estimated offset from the minimum estimated modulus and is also an initial offset parameter, and C l is the compaction level delivered to the analyzer module.
19 . The method of claim 18 , wherein the adjusting step comprises adjusting the initial slope and offset parameters, so that the compaction analyzer will generate an adjusted density (M adj ) with the formula
M adj =M ld +k adj *(C l )+offset adj , where k adj and off adj are the adjusted slope and offset parameters respectively.
20 . The method of claim 13 , wherein the independently determining step comprises:
cutting cores from the plurality of locations, measuring the density of the cores; and finding the modulus that corresponds to the measured density based on master curves for the mix used for each layer respectively.
21 . The method of claim 13 , wherein the independently determining step comprises using known empirical models for the mixes to determine the modulus.
22 . A method of determining the stiffness of a roadway comprising:
compacting the asphalt mix to be used for each layer of the roadway to obtain a plurality of laboratory specimens of a plurality of densities for each layer; determining a laydown modulus M ld and a target modulus M T that correspond to the laydown and target densities of the specimens for each layer; using the laydown modulus and the target modulus of each layer to calculate a modulus of each roadway layer; and calculating an overall effective modulus for the roadway using the modulus of each layer.
23 . The method of claim 22 wherein the using step comprises:
making a plurality of passes with a roller having a compaction analyzer operably associate therewith over each layer of a portion of the roadway section beginning with the first layer;
applying a vibratory energy to each layer of the portion of the roadway section with the roller as it moves thereover;
repeatedly gathering responsive vibration signals of the roller as it moves over each layer portion of the roadway section;
calculating an estimated modulus M est of each layer of the roadway section with the formula M est =M ld +k in (C 1 )+off in at a plurality of locations on each layer, where an initial slope parameter k in is (M T −M ld )/(n CL −1) and an initial input parameter, off in is an estimated offset from the minimum estimated modulus and is also an initial offset parameter, C l is the compaction level delivered to the analyzer module and n CL is the number of compaction levels;
measuring the dynamic modulus of each layer of the roadway section at the plurality of locations on the portion of the roadway section;
comparing the measured modulus with the estimated modulus at the plurality of locations to determine the difference between the measured and the estimated moduli; and
adjusting selected ones of the initial input parameters to the analyzer based on the difference between the determined modulus and the estimated modulus so that an adjusted modulus output signal generated by the compaction analyzer will more closely approximate an actual modulus of the roadway section than does the estimated modulus signal, the adjusting step comprising adjusting the initial slope and offset parameters, so that the compaction analyzer will generate an adjusted density (M adj ) with the formula
M adj =M ld +k adj (C l )+offset adj , where k adj and off adj are the adjusted slope and offset parameters respectively.
24 . The method of claim 23 , wherein the road is a three-layer road, and wherein the overall modulus for the road is calculated using the equation:
E
effective
=
(
C
2
(
C
1
h
1
EL
1
3
+
h
2
EL
2
3
)
+
h
3
EL
3
3
h
1
+
h
2
+
h
3
)
3
where EL 1 , EL 2 and EL 3 are the dynamic modulus for layers L1, L2 and L3, respectively, and h 1 , h 2 and h 3 are the thickness of the respective layers and C 1 and C 2 are correction factors.
25 . The method of claim 23 , the determining step comprising:
creating master curves to represent the relationship between the density of the specimens and the modulus of the specimens for each layer; and locating M ld and the M T on the master curves.
26 . The method of claim 23 , wherein the measuring step comprises using an FWD to find the modulus at the plurality of locations.
27 . A method of compacting a multi-layer road comprising:
determining a modulus at a plurality of locations on each layer; and calculating an overall effective modulus for the roadway using the modulus for each of the layers.
28 . The method of claim 27 , wherein the roadway is a three-layer roadway and the modulus is calculated using the equation:
E
effective
=
(
C
2
(
C
1
h
1
EL
1
3
+
h
2
EL
2
3
)
+
h
3
EL
3
3
h
1
+
h
2
+
h
3
)
3
where EL 1 , EL 2 and EL 3 are the dynamic modulus for layers L1, L2 and L3, respectively, and h 1 , h 2 and h 3 are the thickness of the respective layers and C 1 and C 2 are correction factors.
29 . The method of claim 26 , the determining step comprising:
making a plurality of passes with a roller having a compaction analyzer over each layer of a portion of the roadway section; applying a vibratory energy to each layer of the portion of the roadway section with the roller as it moves thereover; repeatedly gathering responsive vibration signals of the roller as it moves over the first layer portion of the roadway section; generating, with the compaction analyzer, estimated dynamic modulus signals representative of estimated moduli based upon the responsive vibration signals of the roller and the initial input parameters entered into the compaction analyzer; measuring the dynamic modulus of the first layer of the roadway section at a plurality of locations on the portion of the roadway section; comparing the measured modulus with the estimated modulus at the plurality of locations to determine the difference between the measured and the estimated moduli; adjusting selected ones of the initial input parameters to the analyzer based on the difference between the determined modulus and the estimated modulus so that an adjusted modulus output signal generated by the compaction analyzer will more closely approximate an actual modulus of the roadway section than does the estimated modulus signal.
30 . The method of claim 27 , further comprising rolling the remainder of each layer of the roadway section until the compaction analyzer with the adjusted input parameters generates a desired adjusted output modulus signal.Join the waitlist — get patent alerts
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