US2167500A - Ditch cutting device - Google Patents

Description

July 25, 1939- R. D ORNFELD Er AL, 2,167,500

DITGH CUTTING DEVICE Filed Jan.'2l, 1958 :kk/f

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Patented July 25, 1939 UNITED STATES PATENT OFFICE DITCH CUTTING DEVICE Application January 21, 1938, serial No. 186,060 In Germany October 22, 1936 4 Claims.

Our invention relates to the production of ditches, trenches and galleries under and above ground. It is an object of our invention to provide a device adapted for use in the production of such ditches, trenches or galleries in compressible soil without resorting to digging or excavating by means of shovels, dredges or the like.

According to this invention the ditches, trenches or galleries are produced in a manner similar to that employed when driving piles into the ground under he-avy pressure. It is wellknown that any kind of soil, excepting rocky soil, can be condensed or compacted by pressure, as is evidenced by the possibility of driving piles into soil of any descriptionv save only rocky ground. We have found that by employing methods similar to those used in pile driving, we are enabled to produce galleries, ditches and trenches in any kind oi non-rocky ground including sand, gravel, marl and loam.

In the drawing affixed to this specification and forming part thereof a device embodying our invention is illustrated diagrammatically by way of example.

In the drawing- Fig. 1 is a vertical longitudinal section on the line A-B in Fig. 3, while Fig. 2 is a cross-section on the line C-D in Fig. 1 and Fig. 3 a plan view, partly in longitudinal section.

Referring to the drawing, the device here shown consists of three main parts, viz., a propelling wedge a, a block of cylinders l2 and laterally arranged pressure plates c.

rlhe wedge a is connected by means of connecting pieces lc, formed with ball-shaped ends, with pistons e arranged for axial reciprocation in horizontally superposed cylinders y extending in the longitudinal direction of the gallery or trench to be produced, these cylinders g being arranged in pairs, as shown more particularly in Fig. 2. Between two pairs of superposed cylinders and extending at right angles thereto are arranged horizontally positioned cylinders h enclosing pistons d which are connected by means of connecting pieces k with the pressure plates c, which are arranged to the rear of the propelling wedge a in such manner as to be accommodated in the cavity produced by the wedge.

The cylinders g and h are here shown at fr as being rigidly iixed te each other by welding and forming together the block of cylinders b.

p is a pressure pump and q is an electro-motor driving it. The pump is arranged to force a pressure fluid, for instance water, through a pipe 0 into all the cylinders g and h.

j is a bottom plate fixed to the bottom 'It of the propelling wedge and supporting the cylinder block b, which may slide thereon, relative movement being facilitated by the insertion of a lubricant or of rollers i or the like.

In the operation of this device, if it is lowered into a hollow in the ground produced by digging or in some other suitable way, pressure liquid is forced into the cylinders y yand h and since the pistons d carrying the pressure plates c meet with the least resistance, these pistons are rst forced to the outside until the pressure plates have applied themselves against the side walls of the cavity. When this has taken place, the liquid pressure in the cylinders will rise until the longitudinal pistons e start forcing the propelling wedge a through the ground against the resistance offered by the soil. pelled, the wedge acts towards condensing and compacting the soil laterally of and above and below the wedge. Since the pressure acting on the plates c rises in the same proportion as the pressure acting on the wedge a, the plates c are forced against the side walls of the cavity with great force. If now the size and number of plates c and of the pistons d acting on them is chosen correspondingly, the pressure exerted by the plates c on the side walls will become such that the friction generated between the plates c and the side walls easily balances the back pressure exerted by the longitudinally propelled pistons e. The friction coeflicient between the plates c and the side walls of the cavity will amount to about 0.4-0.6 and consequently the entire supercial area of the lateral pistons d should be about the double of the entire area of the longitudinally active pistons e.

I'fhe superficial area of the pressure plates c should be so chosen that the specific pressure between these plates and the lateral walls of the cavity is smaller th-an the specific pressure between the propelling wedge a and the soil, in order that the Wedge and not the pressure plates c will enter the ground.

If now the wedge a. has been forced a certain distance into the ground, the cylinders y and h are connected with the sucking side of the pump p, whereby the pistons are drawn back into the cylinders. Here again the pistons d carrying the pressure plates c will be the first to recede, since they are not required to overcome any resistance. Only after these pistons have returned into their initial inner position, the vac- In being thus prouum in the cylinders will rise and the pistons e, instead of being drawn into their cylinders, will pull the entire block of cylinders forward, since the Wedge is anchored in the ground.

Owing to the provision of the ground plate f and the antifriction means such as a lubricant or rollers z' inserted between this plate and the block of cylinders the friction between the block and the plate f will always be lower than the friction between the plate f and the soil. Apart there-- from the bottom plate n and the top plate m of the propelling wedge are also retained by friction in the cavity made by the wedge.

The ecienoy of the device is a surprisingly great one. Corresponding to conditions prevailing in pile driving it may be assumed that in the case of middle heavy soils the propelling wedge is forced into the ground when the pressure acting on its front surface attains 20-40 kilograms per square centimetre, and this without taking into account that with the Wedge far more favorable conditions prevail than with the pile, which must overcome, besides the front resistance, also very high frictional forces arising at the long cylindrical surface. Assuming a frontal surface of 1.2 square metres and a specific pressure of 40 kilograms per square centimetre, a force of 480,000 kilograms is required to force the wedge into the ground. If the hydraulic pump is driven by a H. P. motor, 7500 metreekilograms per second are available. Assuming the eiciency to be 11:08, there then results a speed of propulsion 0.8-7500 V-m-QOIZ metre per second which amounts to a propulsion of 43.2 metres per hour. Assuming further the pulling up of the cylinder block tol require the same time as the propulsion of the wedge (which assumption is in reality altogether too unfavorable) there results a total propulsion of 518.4 metres per day of 24 hours. Thus a very high efficiency is reached even in soils, in which a considerably higher specific pressure is required.

The new device thus appears to be particularly suitable for the construction of sewers at considerable depth below ground, which can now be done without any digging. It is also very suitable for a quick noiseless production of mining galleries and of connections between different stations.

Obviously the same or a similar device may also prove useful in the production of ditches and trenches, and in this case the advantage is obtained that the grass cover is not destroyed and no soil visibly ejected. The strongly condensed and compacted side walls of these trenches are far more resistive against the influence of the weather than the walls of trenches produced by digging.

We Wish it to be understood that we do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

We claim:

1. A device for the driving of galleries and trenches in compressible soil comprising in combination, a wedge having a greatest cross-section substantially equal to the cross-section of the gallery or trench to be driven, a body to the rear of said wedge, pressure plates guided on the outside of said body and means forming part of said body for propelling said wedge so as to force it into the soil and for expanding said plates in a direction transversely to the direction of propulsion so as to force same against the walls of the trench or gallery and to provide an abutment for said wedge.

2. The device of claim l, in which the body to the rear of the wedge comprises hydraulic cylinders and pistons for propelling the wedge and for expanding the pressure plates, means being provided to the rear of said body for forcing a pressiue fluid into said cylinders.

3. The device of claim 1, in which the body to the rear of the wedge comprises hydraulic cylinders and pistons for propelling the wedge and for expanding the pressure plates, means being provided to the rear of said body for forcing a pressure fluid into said cylinders, the total effective surface area of the expanding piston being about twice that of the propelling piston.

4. The device of claim 1 in combination with a bottom plate connected with the wedge forming a support for the body to slide on.

REINHOLD DORNFELD. KONRAD HAAGE.

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