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WłodzimierzAndrzejBednarek
continuousweldedrailtrack.Itscourseisshownschematicallybythe
continuouslineinFig.2.Thisnon-uniformityisadditionallyincreasedbythe
influenceofcontinuousweldedrailtrackcreepundertraffic,whichcauses
unfavourablechangesinthetemperaturelayoutt
P[3].AdashedlineinFig.2
denotes,ontheotherhand,theanalyticaldistributionofthermalforceNt0.For
thedistributionofN
t0inthecentralpartofCD
(
N
t0
=
const
.wehaveu=0
)
(confinedlengthofCWRtrack).Ontheotherhandu≠0(2ndorderparabola)
occursoverthe-socalled-moving(breathing)endsoflengthl
r
,whereN
t0
is
oflineardistribution(for
r
=,Fig.4a).Thecomputed(trapezoidal)
r
g
distributionofN
t
0
inFig.2thuscorrespondstothecaseofthebehaviourofa
straight,CWRtrackatauniformtemperatureincreaseoveritsentirelength,for
tp=const.[2,3].
2.CHARACTERISTICSOFBALLASTLONGITUDINAL
RESISTANCEINTHERAILWAYTRACK
Thecharacteristicsoflongitudinaltrackresistanceobtainedempiricallyon
thebasisoftheinfluenceofrailwayworks(e.g.railwaytamping)areshownin
Fig.3[4,8].
Inordertosimplifythetrackstabilityproblem,thereal,non-linear
characteristicoflongitudinalresistanceismostoftenreplacedbylinearmodels
(F
r
r=r
g
r
a)
g
u
r
r=ku
k=tg
1
b)
.
1
u
r
r=k
r=r
u
g
1
g
.
u,u<u
c)
u>u
r
g
g
g
u
r
r
0
r=r+ku
0
d)
1
k
.
1
=tg
u
r
r
0
r=r+ku,u<u
r=r
0
g
u
g
,u>u
e)
1
.
g
r
g
u
g
r
r=au
.
f)
b
u
Fig.4.Modelsoflongitudinalresistanceoftheballast
3.LONGITUDINALDISPLACEMENTSTATEINCWRTRACK
DUETOLOCALRAILTEMPERATURECHANGES
Arisingforces∆Noverthelengthofthetrack,duetolocaltemperature
differences(shownschematicallyinFig.2),causelocal,zonedhorizontal
