US2452196A - Method of stabilizing roadbeds - Google Patents

Description

Oct. 26, 1948. J. KELLEY METHOD 0F STABIIIZING ROADBEDS Filed NOV. 8, 1945 Patented Uci. 26, 1948 METHOD F STABILIZING RUADBEDS William J. Kelley, Chicago, Ill.

Application November 8, 1945, Serial No. 627,323

2 Claims.

This invention relates to an improved method of stabilizing a road bed and more particularly to railway road beds where the subgrade of track is of clay.

Most of the road beds of United States railroads rest on a clay bearing surface which is basin-like in cross-section, to receive ballast which is usually made of crushed stone, gravel, cinders or the like. The ties are laid on crushed stone and steel rails are spiked to the ties. The pounding of the wheels of the trains running over the steel rails exerts a strong downward pressure and from time to time it is necessary to raise the ties and pack ballast beneath the ties.

Although the clay subgrade has ample bearing power to sustain the heaviest trafiic loads without considerable compression, it is found that the top face of the clay gradually becomes basinshaped in cross-section, with a pronounced depression beneath each rail, From these depressions the side walls extend upwardly and outwardly to the shoulder of the road bed. A clay surface is very slippery when wet, and even when special precautions are taken to providegood drainage of the road bed the clay surface is wet and slippery a great deal of the time.

I have found that the bottom-most portion of the ballast and the top-most portion of the clay subgrade commingle to form a plastic mass which, under pressure from the load on the rails, is gradually extruded laterally because it slides rather readily along the surface of the clay subgrade. This extruding action causes the ballast and clay mixture gradually to work outward and frequently upward to the toe of the ballast section. The ties, of course, keep sinking, and careful maintenance is required to keep the track level and firm.

In laying new track, it is desirable to have the surface of the clay furrowed longitudinally and to arrange for good drainage, so that the clay will be kept as dry as possible. However, clay does not yield up water readily, and a slippery surface is restored by each rain or thaw.

As most of the railway road beds in the United States are not constructed to avoid the extruding action described above, the primary object of my invention is to provide a way of stabilizing existing road beds, without having the necessity of removing the track and ballast to break up the smooth contour of the clay.

Another object -of the invention is to provide a method 0f treating road bed by means of equipment which is carried on the track supported by the road bed being treated.

or in) The results of practice of the method is illustrated on the accompanying drawing, which is a transverse sectional view of a railway road bed.

In the embodiment illustrated, the subgrade l is formed of clay or similar material and its upper face has depressions 2 and forms a basinlike pocket for the ballast 3. The usual ties 4 rest on the ballast and support steel rails 5, which are secured in position by spikes 6.

In order to reduce the extruding action of the ballast sliding over the surface of the subgrade, a ychannel-like trench or groove 'l is formed in the subgrade a little beyond the ends of the ties 4. These trenches should be within the bearing area of the ties. It has been found that the bearing area extends outwardly at an angle of labout one-half to one, that is, for each foot of depth the bearing area is extended laterally about six inches, as indicated by the angle between the lines 8 of the drawing. By having the channellike trenches within the bearing area, the downward component of force tends to pack the ballast into the trenches, and a rough surface is provided at the top of the trenches, which resists the sliding or extruding elfect of the ballast over the surface of the ballast-basin.y

It is preferred to have the trenches 'l substantially continuous, `but some interruptions are usually necessary to permit signal wires, conduits, and the like, to reach the track on the road bed. As indicated in the drawing, it is preferred that the trenches extending through the subgrade have a width substantially equal to the thickness of an ordinary wooden cross tie 4, and the trench should extend through the subgrade from at least six to ten inches.

The trenches may be formed in existing road beds a, number of ways, for example, by a digging machine carried by a car on the track above the section being treated. Another way is to drive a pointed false pile into the subgrade and then withdraw the pile and allow the space which it occupied to be lled with ballast. After the trenches have been formed, by either method, it is usually necessary to add additional ballast above the trench, to restore the contour of the road bed.

The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, for some modifications will be obvious to those skilled in the art.

I claim:

1. The method of stabilizing a railway road bed, while under traffic conditions, having ties 2. The method of stabilizing an existing ral- Way road bed having ties resting on ballast in a basin-like subgrade, comprising: displacing some of the ballast and forming a deep, substantially l continuous, channel-like trench through the outwardly and upwardly inclined face of the subgrade beyond the ends of the ties but within the bearing area of said ties; filling the trench with ballast; and adding sufficient ballast above said trench to restore the level of the road bed.

WILLIAM J. KELLEY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 679,867 Smith Aug. 6, 1901 1,355,833 Howe Oct. 19, 1920 5 FOREIGN PATENTS Number Country Date 6,278 England Mar. 13, 1911

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