U.S. patent number 3,878,987 [Application Number 05/331,357] was granted by the patent office on 1975-04-22 for railway track structure.
This patent grant is currently assigned to Japanese National Railways. Invention is credited to Hankichi Uzuka.
United States Patent |
3,878,987 |
Uzuka |
April 22, 1975 |
RAILWAY TRACK STRUCTURE
Abstract
An improved track structure which can hold the progress track
irregularities under high-speed, high axle load and high-density
train operation to a minimum, with the settling of conventional
ballasted track structures due to the ballast being minimized. In
the improved track structure, large panel sleepers or reinforced
concrete including prestressed concrete or of steel are placed on
the bottom ballast previously fully rolled to flatness with the
gaps filled in with smaller crushed stones; the top-ballast is
spread and rolled around the sleepers; rails are laid and fastened
over the sleepers; the rail top is lifted to a specified height; a
quick-hardening material is injected into the space between the
base of the sleepers and the top surface of the bottom ballast to
form an elastic hardened layer; a waterproof coat made of a
quick-hardening waterproofing material is provided on the surface
of the top ballast; and a gutter to drain the rainwater from the
ballast is provided along the sides of ballast.
Inventors: |
Uzuka; Hankichi (Tokyo,
JA) |
Assignee: |
Japanese National Railways
(Tokyo, JA)
|
Family
ID: |
11848356 |
Appl.
No.: |
05/331,357 |
Filed: |
February 12, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Feb 10, 1972 [JA] |
|
|
47-13980 |
|
Current U.S.
Class: |
238/2; 104/11;
404/75; 238/283; 405/270 |
Current CPC
Class: |
E01B
3/40 (20130101); E01B 3/38 (20130101); E01B
1/008 (20130101); E01B 1/001 (20130101); E01B
2204/07 (20130101); E01B 2204/03 (20130101) |
Current International
Class: |
E01B
3/00 (20060101); E01B 3/40 (20060101); E01B
3/38 (20060101); E01B 1/00 (20060101); E01b
001/00 () |
Field of
Search: |
;238/283,1-9 ;104/10,11
;404/17,75,82 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Bertsch; Richard A.
Attorney, Agent or Firm: Armstrong, Nikaido & Wegner
Claims
What is claimed is:
1. A railway track structure comprising a bottom ballast having a
relatively flat upper surface, at least one large panel sleeper
disposed over said bottom ballast; top ballast disposed around said
large panel sleeper; a quick-hardening material injected between
the base of said large panel sleeper and the adjacent upper surface
of said bottom ballast and a waerproof layer of a quick-hardening
waterproofing material provided on the upper surface of said top
ballast.
2. A railway track structure of claim 1 wherein gutters with at
least one through hole in the wall adjoining the ballast are
provided along the longitudinal sides of the ballast.
3. A railway track structure of claim 1 wherein the waterproof
layer is provided with a drainage gradient.
4. A railway track structure of claim 1 wherein crushed stones of a
size smaller than that of the bottom ballast are disposed on the
upper surface of the bottom ballast thereby controlling the depth
of the injected material into the ballast.
5. A railway track structure of claim 1 wherein the injected,
quick-hardening material is of a thermoplastic nature which fills
adjacent voids in the ballast.
6. A railway track structure of claim 5 wherein the injected
quick-hardening material is asphalt.
7. A railway track structure of claim 5 wherein the injected
quick-hardening material is a synthetic resin.
8. A railway track structure of claim 5 wherein the injected quick
- hardening material is a mixture of asphalt and synthetic
resin.
9. A railway track structure of claim 1, wherein the ballast around
the large panel sleeper is consolidated with the injected material,
thereby increasing the ballast resistance.
10. A railway track structure of claim 1 wherein said large panel
sleeper is reinforced concrete.
11. The railway track structure of claim 1 wherein said large panel
is steel.
12. A method for making a railway track structure comprising
rolling bottom ballast to substantial flatness placing at least one
large panel sleeper on said bottom ballast; spreading and rolling
top ballast around said large panel sleeper; lifting said large
panel sleeper; injecting a quick-hardening injection material into
the space created between the base of said large panel sleeper and
the surface of said bottom ballast beneath said large panel sleeper
and coating with a waterproof layer of a quick-hardening
waterproofing material the exposed top surface of said top
ballast
13. A method of claim 12 wherein gutters with at least one through
hole in the wall adjoining the ballast are provided along the
longitudinal sides of the ballast.
14. A method of claim 12 wherein the waterproof layer formed on the
top surface of said top ballast is provided with a drainage
gradient.
15. A method of claim 12 wherein crushed stones of a size smaller
than that of said bottom ballast are spread on the rolled surface
of said bottom ballast prior to placing said large panel sleeper
thereby controlling the injected depth of the material into the
ballast.
16. A method of claim 12 wherein said quick-hardening injection
material is of a thermoplastic nature and is injected in a hot
molten state and allowed to cool and harden whereby an extensive
solid mass is formed with the voids in the ballast filled up.
17. A method of claim 12 wherein the ballast around said large
panel sleeper is consolidated with said injection material, thereby
increasing the ballast resistance.
Description
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of the ballasted
track structure. The present invention provides particularly an
improved track structure which can hold the progress of track
irregularities under high-speed, high axle load and high-density
train operation to a minimum, with the settling of the conventional
ballasted track structure due to the ballast being minimized.
The commonly used railway track structure is a so-called
"ballasted" track structure, wherein cross-ties are continuously
laid on ballast, with rails fastened to the cross-ties by means of
a rail-fastening device. Thus structure has been primarily designed
for facilitating the correction of track irregularities caused by
ballast settling under train load. In one of the known repair
procedure, the ballast is vibrationally compacted by means of
tie-tampers, etc. The width of the cross-ties is commonly set at
20-30 cm and the tie-to-tie distance set at least at 20 cm. These
values have been chosen to permit effective work with the
tie-tamper, etc. It is desirable, however, as mentioned hereinafter
that, if possible, the width of the ties be increased to give a
greater base and width. Meanwhile, it has been revealed that the
vibrational compaction by tie-tampers or the like itself
contributes to the settling of ballast.
In his basic survey before development of a track structure with
minimum settling, the present inventor found the items listed in
Table 1 to be the factors causing rail deflections in the ballast
track structure of the prior art.
TABLE 1
__________________________________________________________________________
Site of Description of Cause Deflection Phenomena
__________________________________________________________________________
Sleeper Cutting of rail into Compressive failure of sleeper, wood
under wood rail Wear of P.C. tie bottom Insufficiency of contact
area with
__________________________________________________________________________
ballast Ballast Ballast pumping Dust from concrete tie and from
ballast turned into mud after rainfall and cause mud-pumping under
the train road. Sinking of ballast into Combination of three
factors; bad bed, roadbed and mud-pumping rainwater penetration and
ballast ("ballast pocket) pressure. Loss of gap between ballast Gap
created between stones as result of stones due to compaction
ballast maintenance work Pulverization of ballast Ballast
maintenance work; pulverization and mud-pumping in ballast due to
acceleration of ballast vibration; and invasion of rainwater.
"Sifting" of ballast Increased acceleration of ballast vibra- tions
(due to train speed up)
__________________________________________________________________________
Road bed Settling due to compaction Insufficiency of fillings;
Insufficiency of rolling work
__________________________________________________________________________
Natural Settling due to compression Poor geology ground
__________________________________________________________________________
Among the settling-causing factors enumerated above, the cutting of
rail into wood is a phenomenon peculiar to the wooden sleepers and
never occurs in P. C. ties. Meanwhile the compression settling of
roadbed or natural ground is attributable to poor geology or a
fresh roadbed. On elevated track, in tunnels or roadbeds, which
have been in service under track for 20-30 years, the degree of
such settling has been negligible. The conventional ballasted track
structure, however, is inherently not free from the factors listed
in Table 1, i.e., the factors other than those mentioned above.
In addition to the above-mentioned ballasted track structure,
recently a "ballastless" slab track structure has been proposed as
an improvement. This proposal is fundamentally different from the
ballasted one in that an elastic deformation of the track in the
former absorbs energy of train and an artificial correction of
track is not needed. But, if in this structure the heavy train load
is to be borne through elastic deformation alone, special
installation will be required for spreading the load and providing
elastic elements. Thus, it would particularly be difficult to
realize such a stucture through a short-term work on lines with
ballasted track in existence.
SUMMARY OF THE INVENTION
In view of the disadvantages of these conventional track structures
for railways, an object of the present invention is to provide an
improved ballasted track structure which is free from the major
factors causing rail deflection inherent in the conventional
ballasted track structure and the attendant maintenance practice,
and which can minimize the progress of track irregularities under
high-speed, high axle load and high-density train operation.
Another object of the present invention is to provide an improved
ballasted track structure in which large panel sleepers with
increased dimensions consistent with workability are placed on the
elastic hardened layer formed in the ballast, thereby the flat area
and weight being utilized to spread the train load and mitigate
vibration.
A further object is to fill the gap between the base of the sleeper
and the bottom ballast and a part of the ballast adjacent to the
sleeper with a quick hardening injection material, thereby
mitigating an excessive ballast vibration.
An additional object is to coat the top ballast surface with a
waterproof layer to prevent the rainwater from invading the ballast
or roadbed, thereby averting a rail deflection as far as
possible.
Still another object of the present invention is to provide an
improved ballasted track structure which can be installed easily
and with few materials and within limited train intervals by using
a quick hardening material and which permits train operation
immediately after installation.
The problems of the prior art are solved by the present invention
which provides for a railway track structure comprising a bottom
ballast having a relatively flat upper surface; at least one large
panel sleeper of reinforced concrete including prestressed concrete
or steel disposed over said bottom ballast; top ballast disposed
around said large panel sleeper; a quick-hardening material
injected between the base of said large panel sleeper and the
adjacent upper surface of said bottom ballast and a waterproof
layer of a quick-hardening waterproofing material provided on the
upper surface of said top ballast. Preferably, gutters with at
least one through hole in the wall adjoining the ballast are
provided along the longitudinal sides of the ballast.
Advantageously, the waterproof layer is provided with a drainage
gradient. Crushed stones most suitably of a size smaller than that
of the bottom ballast are disposed on the upper surface of the
bottom ballast thereby controlling the depth of the injected
material into the ballast. Preferably, the injected,
quick-hardening material is of a thermoplastic nature, such as
asphalt, synthetic resin or combinations thereof, which fills
adjacent voids in the ballast. Most preferably, the ballast around
the large panel sleeper is consolidated with the injected material,
thereby increasing the ballast resistance.
The present invention further relates to a method for making a
railway track structure comprising rolling bottom ballast to
substantial flatness; placing at least one large panel sleeper of
reinforced concrete including prestressed concrete or steel on said
bottom ballast; spreading and rolling top ballast around said large
panel sleeper, lifting said large panel sleeper; injecting a
quick-hardening injection material into the space created between
the base of said large panel sleeper and the surface of said bottom
ballast beneath said large panel sleeper and coating with a
waterproof layer of a quick-hardening waterproofing material the
exposed top surface of said top ballast. Preferably, gutters with
at least one through hole in the wall adjoining the ballast are
provided along the longitudinal sides of the ballast.
Advantageously, the waterproof layer formed on the top surface of
said top ballast is provided with a drainage gradient. Most
suitably, crushed stones of a size smaller than that of said bottom
ballast are spread on the rolled surface of said bottom ballast
prior to placing said large panel sleeper thereby controlling the
injected depth of the material into the ballast. Preferably,
quick-hardening injection material is of a thermoplastic nature,
such as asphalt, synthetic resin or mixtures thereof, and is
injected in a hot molten state and allowed to cool and harden
whereby an extensive solid mass is formed with the voids in the
ballast filled up. Most preferably, the ballast around said large
panel sleeper is consolidated with said injection material, thereby
increasing the ballast resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features and advantages of the present
invention will become more readily apparent from the following
detailed description taken in conjunction with the drawings
wherein:
FIG. 1 (a) is a plan view of an embodiment of the present
invention.
FIG. 1 (b) is a sectional view along the line 1b -- 1b of FIG. 1
(a).
FIG. 1 (c) is a sectional view along the line 1c -- 1c of FIG. 1
(a)
FIG. 1 (d) is a sectional view, corresponding to FIG. 1 (c), of
another embodiment of the present invention.
FIG. 1 (e) is a plan view illustrating a third embodiment of the
present invention.
FIG. 2 (a) is a plan view illustrating a fourth embodiment of the
present invention.
FIG. 2 (b) is a sectional view along the line 2b -- 2b of FIG. 2
(a).
DETAILED DESCRIPTION
Referring to FIGS. 1 (a) - 1 (c), bottom ballast 3 has been
elaborately rolled on a roadbed 8, with smaller crushed stones 32
filling the gaps therebetween. The height of the bottom ballast is
usually set at about 15.about.25 cm. At a specified portion of the
thus-formed ballast, usually at the center following the
longitudinal axis of the ballast, are continuously placed, with a
specified interval, large panel sleepers 2 and 2' of the same size
in two rows. The opposite sleepers 2 and 2', constituting the two
rows, are arranged parallel with a specified spacing, ballast being
spread and rolled around the sleepers to form top ballast 33. The
height of the top ballast 33 is usually set at about 15.about.25
cm. Range of sizes of stones constituting top and bottom ballasts
is usually 10.about.75 mm. Each large panel sleeper can be a
prestressed concrete member with a profile as illustrated in FIGS.
1 (a) - 1 (c) or a steel member of the prior art with a -cross
section as illustrated by numeral 21 in FIG. 1 (d). The prestressed
concrete sleepers 2 and 2' illustrated in FIGS. 1 (a) - (c) are
approximately rectangular cubes, each with the top surfaces of the
two end portions thereof in the axial direction of ballast being
formed as downward -- inclined surfaces 24 (FIG. 1 (b)) at a
certain angle and recess 31 being provided at the mid-point of the
bottom surface. The large panel sleeper, however, can be a simple
rectangular cube. Rails 1 are laid over these two rows of large
panel sleepers and fixed thereto by rail-fastening devices 7 of the
prior art provided at equal intervals in the longitudinal direction
of the large panel sleepers.
In FIG. 1 (a) which illustrates the dimensions and layout of large
panel sleepers and rail-fastening devices, the width W.sub.1 of the
large panel sleepers 2 and 2' can be set at, e.g., 95 cm for the
narrow track gauge 1,067 mm and, say, 130 cm for the standard track
gauge of 1,430 mm; while the length L.sub.1 can be set regardless
of the track gauge, at from about 50 cm to 300 cm. To accomplish
the purpose of the present invention, however, the value of L.sub.1
is preferably over 50 cm. Desirable preferred values of the
tie-to-tie distances g.sub.1, W.sub.2 can be as follows; g.sub.1 =
10 cm; W.sub.2 = 18 cm for the narrow gauge and about 20 cm for the
standard gauge. The reason for selection of these values are as
follows: The value W.sub.1 has been selected to make it possible to
apply the track structure of the present invention to an existing
track in a limited time without dismantling the rails especially on
so-called long-rail sections. The value of W.sub.1 being set
smaller than rail-to-rail distance RD permits easy insertion of a
large panel sleeper between the rails and accordingly, the
placement of the large panel sleepers in the position indicated in
FIG. 1 (a) - (e) can be made easily. The value of L.sub.1 depends
on the spacing of the rail -- fastening devices 7, the number of
such devices to be provided on one large panel sleeper and
tie-to-tie distance g.sub.1. Regardless, both design and handling
restrictions make the value of over 50 cm desirable. Tie-to-tie
distance g.sub.1, for reasons of ballast resistance and working, is
preferably about 10 cm. W.sub.2 is automatically set from the
relation between W.sub.1 and the track gauge. Two large panel
sleepers laid in opposition to each other in the longitudinal
direction of the ballast, when the ballast resistance is not large
enough, may be linked together by say, turn buckle 23 of the prior
art as illustrated in FIG. 1 (a), 1 (c) and 1 (d), thereby
supplementing the ballast resistance.
FIGS. 2 (a) and 2 (b) illustrated another embodiment of a large
panel sleeper. In this case, large panel sleeper 22 can again be of
reinforced concrete including prestressed concrete or of a -shaped
steel as in the embodiments of FIGS. 1 (a) - 1 (e). However, large
panel sleepers 22 are provided only in a single row with both rails
being laid on the single row. An example of the desirable
dimensions of a large panel sleeper in this embodiment, is as
follows: L.sub.2 = 73 cm; W.sub.3 = 200 cm for the narrow gauge and
240 cm for the standard gauge; g.sub.2 = about 10 cm. For the same
reason as stated previously with respect to W.sub.1 in FIGS. 1 (a)
- (c), it is desirable that L.sub.2 be set smaller than the
distance between the oppositely laid rails. When 12 rail-fastening
devices are provided at equal spacing for every 10 m. of rail, the
above condition will be brought about.
For all of the above embodiments elastic hardened layer 6 made of a
quick-hardening injection material is formed in the space between
the base of large panel sleepers 2, 2' 21 and 22 and the surface of
the bottom ballast beneath said large panel sleepers. The injection
material can be a 1 : 1 mixture, heated and molten, of a straight
asphalt (penetration less than 10) and bronze asphalt (penetration
10 - 20) or an asphalt mixed with a small amount of a substance
which is thermoplastic at low temperatures such as polyethylene.
This injection material is injected into the large panel sleeper
through injection holes 25. The injection material is necessarily
heated before injection to improve fluidity to thereby fill up
voids in the ballast. After passing through the voids in the
ballast, the hot injection material goes also into the adjacent
ballast. After cooling and hardening, the material consolidates the
adjacent portion of the ballast into integral ballast cohesion 61.
When cohesion takes place to the desired depth, it is possible to
minimize vibrational deflection of ballast in the track structure
of the invention. For accomplishment of this purpose, it is
desirable to form different depths of the cohesion, depending on
the site of the track structure. If the site is on a stable
roadbed, cohesion 61 should extend through the total depth to the
bottom of the bottom ballast 3. When the site is on an elevated
track, where the rail expansion and contraction due to the
temperature variation takes place separately from that of the
bridge, it is desirable that the depth of cohesion 61 be set
smaller than the ballast thicknes so that the rail and bridge may
be mutually insulated at ballast layer. The depth of ballast
cohesion 61 depends on the type of the injection material, the
heating temperature for injection and particle size of ballast
including smaller crushed stones 32. In an experiment conducted by
the inventor, when said asphalt preparation was injected in a hot
state at 170.degree.C into a ballast of small crushed stones 32, 5
- 30 mm in diameter spread at 0.05 m.sup.3 / m.sup.2 over bottom
ballast 3 of stones 10 - 75 mm in diameter, cohesion 61 could be
made to a uniform depth of about 10 cm.
The vibrational acceleration of ballast differs depending on the
train speed. According to the result of practically measuring a
train running at over 200 km/hr., 25 cm thick ballast having a 10
cm thick top ballast developed 1 g in the top ballast and in the
bottom ballast developed less than 1 g. Thus, it is learned that
cohesion of the ballast to at least 10 cm from the top can
effectively prevent the ballast deflection. It is known, meanwhile,
that the depth of ballast cohesion is practically governed by
spread amount of small crushed stones 32 and preferable range of
thickness of small crushed stone layer is 1.about.4 cm.
Quick hardening injection material penetrates not only downwardly
into the lower portion of bottom ballast 3, but also, sideways
reaching a height of several cm. above the top surface of the
bottom ballast, causing a cohesion of the ballast. Consequently,
the ballast resistance to the sleeper (resistance to longitudinal
and transverse displacement of the sleeper in the horizontal
direction) can be increased. If necessary, an additional amount of
the injection material may be spread over the ballast provided
around the large panel sleeper, thereby creating a wider area of
ballast cohesion 61. On the surface of the ballast except the area
on which said large panel sleeper is laid there is provided
waterproof layer 4 made of a quick-hardening waterproofing
material. As the waterproofing material for this purpose a
quick-hardening waterproofing material of prior art such as cutback
asphalt or filler bitumen may be employed. When waterproof layer 4
is constituted as an inclined surface with a progressively
decreasing height toward both sides of the center of the sleeper in
the axial direction of the ballast, a good drainage effect is
obtained.
Meanwhile, along both sides of the ballast, gutters 5 with a
U-shaped section are installed with the walls of gutters 5
contacting the ballast including more than one throughhole 51, to
permit the egress of rainwater from the ballast.
The track structure of this invention can be executed, for
instance, in accordance with the following procedure.
In the case of a line of conventional track structure, the
conventional cross-ties are first dismantled by a method of the
prior art. Next a pair of the ballast is removed, thereafter the
ballast is elaborately rolled to flatness by a roller of prior art,
for instance, Vibroplate B PN 1,000, for form bottom ballast 3 of,
e.g., 15.about.25 cm high. In this case, the finishing accuracy of
the surface roughness of bottom ballast 3 may be, say, 1 cm. If
necessary, on the surface of the bottom ballast, smaller crushed
stones, of, say, 5 - 20 mm diameter may be spread at a rate of 0.05
m.sup.3 / m.sup.2 to fill existing gaps. A large panel sleeper (2
and 2', 21 or 22) is then disposed on bottom ballast 3, with the
positional adjustment made by a method of the prior art. Ballast is
then spread around the large panel sleepers and rolled by, for
intance, a hand capacitor of the prior art to form top ballast
layer 33 of 15.about. 25 cm high. Thereafter, rails 1 are fastened
with rail-fastening devices 7 of the prior art to the large panel
sleeper. A track skeleton thus-composed of a plurality of large
panel sleeper groups with a definite length of rails fastened
thereto is lifted to a specified height by a jack of the prior art;
and after fine lateral adjustment and adjustment of alignment and
cross-level, is held in the lifted position. The standard amount of
lift is about 20 mm on the average and the tolerance of the
adjustments of alignment and cross-level is preferably less than 5
mm.
The space created, as the result of the track skeleton being
lifted, between the base of the large panel sleepers 2.about.22 and
the surface of the bottom ballast is filled with a quick-hardening
material injected through through-hole 25 bored in the large panel
sleeper 2.about.22, thereby forming an elastic hardened layer 6. As
the quick-hardening material, for instance a 1 : 1 mixture, heated
and molten, of a straight asphalt (penetration less than 10) and a
bronze asphalt (penetration 10 - 20) is injected at about
170.degree. - 180.degree.C, the quick-hardening material may be
spread also around the large panel sleeper. Meanwhile it is
desirable that for instance a lime solution be preliminarily spread
as a mold - releasing agent over the base and sides of the sleeper
and on the inside of the through-hole 25 for injection. A wire
stopper-removing provided at the through-hole 25 is also
useful.
When the temperature of the injected material drops, say, below
50.degree.C, the lifted sleeper is lowered by removal of the jack,
and, consequently, rails 1 are set into position. Next, the ballast
surface except the area where the large panel sleepers lie is paved
with a quick-hardening waterproofing material with a drainage
gradient, thereby forming waterproof layer 4. Waterproof layer 4 is
desirably 30 - 40 mm thick with a drainage gradient desirably of
2/100 - 3/100. Thereafter, again using a method in the prior art
the alignment and cross-level are adjusted by means of
rail-fastening devices 7 of the prior art and then the rails are
prefectly fastened.
On both sides of the ballast are installed gutters 5 with a
U-shaped cross section.
In the case of a fresh roadbed, ballast is spread and elaborately
rolled to flatness to a specified height, to form the bottom
ballast 3.
Thereafter the procedure as described above relating to a line of
conventional track structure is followed. The same procedures as
above are followed, whether it is the case, as illustrated in FIGS.
1 (a) - (e), of large panel sleepers being arranged in two rows, or
the case, as illustrated in FIGS. 2 (a) - (b), of sleepers being
arranged in a single row.
Through successive applications of the above procedures, a track
structure of any desired length according to the present invention
can be constructed.
In the track structure of the present invention, fine adjustments
for track irregularities can be done with a method of prior art by
means of rail-fastening devices 7, while a heavy settling of the
track can be corrected by lifting the track skeleton to a definite
height by means of a jack or the like and then injecting through
injection hole 25 a quick-hardening material.
EXPERIMENT
To confirm the beneficial effects of the present invention, the
following tests were carried out to yield the indicated
results:
1. Test conditions
Ballast was spread and elaborately rolled to flatness to form a
bottom ballast 15.about.25 cm high. The ballast was then filled
with small crushed stones of 5 - 20 mm in diameter in an amount of
0.04 m.sup.3 .about.0.06 m.sup.3 / m.sup.2 with thereon large panel
prestressed-concrete sleepers, as illustrated in FIGS. 1 (a) - (c)
(2 m. long .times. 0.6 m. wide .times. 0.2 m. thick) were arranged.
In this case, the thickness of small crushed stones layer was
1.about.4 cm. Rails were laid and fastened thereon. Thereafter,
ballast was spread and rolled around the large panel sleepers to
form top ballast 15.about.25 cm high, and the track skeleton thus
formed with lifted by a jack of the prior art. Thereupon, a 1 : 1
mixture, preliminarily heated and molton, of a straight asphalt
(penetration less than 10) and a bronze (penetration 10 - 20) was
amply poured through the injection hole 25 at a temperature of
170.degree. - 180.degree.C. After the temperature of the injected
mixture dropped below 50.degree.C, the lifted large panel sleepers
were lowered through removal of the jack and the surface of top
ballast 33 was paved with a quick-hardening waterproof material
like cutback asphalt.
Using a cyclic vibration tester of the prior art, i.e., Vibrogir,
the rate of track settling and the longitudinal and traverse
resistance of the invented track structure and the traditional P.C.
sleeper-crushed stone ballast were measured.
2. Test results
(a) Measured results of track settling are as follows:
Initial settling Secondary Settling .gamma.(mm) rate .beta.
(mm/10,000 cycles) ______________________________________
Traditional PC sleeper crushed stone ballast 45 0.10 Track
structure of present invention 8.5 0.02
______________________________________
Note:
1. Effect of rainwater was not investigated in the present
test.
2. In the traditional P.C. sleeper-crushed stone ballast initial
settling occurs every time maintenance is executed using a multiple
tie-tamper, but in the track structure of the present invention the
initial settling occurs only once.
b. Results of ballast resistance measurements are as follows:
Longitudinal Transverse resistance .gamma. t/m resistance g t/m
______________________________________ Traditional about 1.0 about
1.0 P.C sleeper crushed stone ballast Track struc- about 3.0 about
2.0 ture of pre- sent invention
______________________________________
From the test data it is apparent with the track structure of the
present invention that:
1. The train load-bearing area of large panel sleepers is more than
2.5 times as wide as that of the traditional PC sleeper and,
correspondingly, the ballast pressure can be reduced.
2. The large panel sleeper used in the present invention is about
three times as heavy as the traditional P.C. sleeper. The large
panel sleeper and an elastic hardened layer formed thereunder work
together as an integral supporting mass that can as a whole absorb
train vibration.
3. Since there is established a plane contact between large panel
sleeper and ballast through the injection material, there is no
likelihood of mutual breaking and settling.
4. Since the part of ballast where the vibrational acceleration
exceeds 1 g has been consolidated with the injection material, no
vibrational deflection can take place.
5. Since the ballast surface is waterproofed, settling of ballast
or roadbed caused by mud-pumping due to rainwater can be minimized,
the resistance to the horizontal displacement of track can be
increased, and the aggravation of track irregularities under high
speed, high axle load and high-density train load can be
minimized.
6. In the present invention, unlike the conventional ballasted
track structure, is not intended for repairs to be made through
vibrational compaction by means of a tie-tamper or the like.
Accordingly, there can be no repetition of the initial deflection
nor any pulverization of ballast by a tie-tamper.
7. Further, since a quick-hardening material is employed to form an
elastic hardened layer and waterproof layer, the track structure of
this invention can be installed even during short train intervals
and the train operation can be resumed immediately after
installation.
Thus this track structure is found economically advantageous in
applications to the lines already in existence, since it saves
manpower in track maintenance. Even in conjunction with a new line,
it would be particularly effective where the compression settling
of the roadbed is negligible or when the site is elevated or in a
tunnel.
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