US3596577A - Apparatus for soil stabilization - Google Patents

Abstract

The method and apparatus for soil stabilization wherein the soil to be stabilized is first shaved and the shavings rubbed against the resultant soil face while at the same time applying a liquid stabilizing additive. The apparatus employed includes a driven reel having shaving and rubbing elements thereof which continuously, as the reel is rotated and moved over the ground, first shave the sol to provide a soil face, then pulverize the shavings and rub the shavings against the soil face as a liquid stabilizing additive is sprayed onto the pulverized soil so as to be mixed therewith as the reel rotates.

Description

' United States Patent [72] Inventor Donald A. Cbennells l3 Iroquois Bay, St. Boniface 6, Manitoba,

Canada 2 l] A li No. 780.472 [22] Filed Dec. 2, 1968 [4S] Patented Aug. 3, 1971 [54] APPARATUS FOR SOIL STABILIZATION 4 Claims, 5 Drawing Figs.

52] us. Cl 94/40, 37/24 [51] lnt.Cl EOlc 19/02 [50] FieldofSearcb 37/38,2l, 24. 189; 94/40, 39, 44

[56] References Cited UNITED STATES PATENTS 678,277 7/1901 Poore 37/24 X 2,152,264 3/1939 Loft 94/50X 2,368,331 l/l945 Seaman 94/40 2,397,782 4/1946 Flynn 94/40 3,224,347 l2/l965 Seaman 94/40 3,292,510 l2/l966 Chennells .l 94/40 Primary Examiner-Jacob L. Nackenoff Attorney-Lyle G. Trorey ABSTRACT: The method and apparatus for soil stabilization wherein the soil to be stabilized is first shaved and the shavings rubbed against the resultant soil face while at the same time applying a liquid stabilizing additive. The apparatus employed includes a driven reel having shaving and rubbing elements thereof which continuously, as the reel is rotated and moved over the ground, first shave the sol to provide a soil face, then pulverize the shavings and rub the shavings against the soil face as a liquid stabilizing additive is sprayed onto the pulverized soil so as to be mixed therewith as the reel rotates.

PATENTEU AUG 312m SHEET 1 OF 3 Dona M A. Chunnvlls 4/?rtor Lyle G. Trorcy,

Agent PATENTl-Zmuc sun SHEET 2 BF 3 1d A. Che'nnells,

v ntor y Lyle G. Trorey,

Agent PATENIED AUG 3BR 3.596577 III 55 Donald A. Chennells, Inventor Lyle Trorey,

Agent APPARATUS son SOIL STABILIZATION BACKGROUND OF THE INVENTION The invention relates to a method of stabilizing heavy clay soils, particularly of a type known as gumbo" prevalent in the central plains of North America, and found in many other parts of the world. As well, the invention relates to apparatus by means of which the method is carried out.

In Miscellaneous Paper No. 3-122 Report No. 6 dated May 1961, published by US. Army Engineer Waterways Experiment Station, Corps of Engineers, Vicksburg, Mississippi, U.S.A., the following is found at page vii. ...No single item of mixing equipment currently exists that is capable of efficient mixing of wet, plastic, clay soils." The Paper further states, at page 1 paragraph 2, ...Existing mixing equipment and techniques for incorporating a stabilizing ingredient in a soil are quite adequate for use with certain favorable soil types and under conditions of favorable soil moisture contents. However, severe deficiencies in mixing capabilities have been observed in situations where the soil type and moisture content are not ideal. The mixing problems are particularly acute in the case of fine-grain clay soils, which can become extremely cohesive and sticky at moderate to high water content. Since the stabilization of unstable, wet clays is one of the major objectives of the military soil stabilization research program, it is imperative that suitable mixing principle sand equipment be available for these specific stabilization situations" Accordingly, it is authoritatively stated above that no single item of mixing equipment existed in 1961 capable of efficient mixing of wet, plastic, clay soils. To the best of my knowledge and belief, this situation has persisted until now, Dec. 1967.

The problem, as set forth in Paper No. 3-122 above is well.

known, and many inventors have directed their attention towards effecting solutions. US. Pat. No. 2,865,268 issued to Adryl W. Gardner in 1958 for use in the construction of roads, airfields, parking areas, etc., where it is desired to pulverize and blend the road-building building materials and intimately to mix them with a liquid stabilizer or binder to provide a structure having a longer life and greater load-bearing capacity. This invention is designed to produce more effective mixing of liquid stabilizer with pulverized soils and aggregates, and thereby reduce the number of passes required to effect an intimate mixture of the clay, and to provide effective stabilization of the road-building materials. This apparatus uses a rotor driven in such a direction as to cause the bottom thereof to move in the same direction as the mixer, and by flowing a layer of the liquid stabilizer over the top of the pickup blade.

U.S. Pat. No. 2,885,934, issued in 1959 to Harold L. Gardner, is also to a traveling-plant mixer for effecting in place mixing of soil and aggregates with a suitable stabilizing agent and, more particularly, it relates to a mixing machine embodying a new improved device for completely disbursing the stabilizing material throughout the soil the aggregate being treated, and for thoroughly mixing it therewith.

These ingenious machines, and associated techniques, are effective and adequate for use in certain favorable circumstances as set forth in Paper No. 3-122 ibid. The opinion of experts of the US. Army Corp. of Engineers as set forth in the Paper above has been given, and from this it is evident that these machines and techniques cannot effectively be used for stabilization of heavy wet clays such as those to which the present invention is directed.

British Pat. No. 1,040,098 sealed in I964, and US. and Canadian patents generally corresponding thereto, have issued to me. These patents are directed to improvements in devices for stabilizing gumbo for surfaces of roads and the like. Information as to the state of the art as it existed in 1964 as known to me is set forth in this patent at lines -46.

My existing patents above are to apparatus which can pulverize gumbo or clay in situ and, at the same time, inject and mix the necessary stabilizing materials. This invention teaches a rotating reel havinga plurality of spaced parallel transverse bars extending between peripheral edges of discs secured to a rotating shaft. Spaced, downwardly depending, shoes extend below the reel lower run and assist in breaking up the material, together with leading shoes disposed forward of the rotating reel and making initial contact with the undisturbed surface thus breaking it in advance of the rotating reels. Pulverization is effected first by initial breaking accomplished by the leading shoes, and by further breaking by the downwardly depending shoes first aforesaid, together with cutter bars of the rotating reel, suitable means being provided to inject a stabilizing material into the pulverized clay.

SUMMARY OF THE INVENTION Method l have now discovered that improved results are obtainable by a method having steps of a. shaving a first thin portion off a soil face, the shaving being typically a hundredth of an inch in thickness,

b. pulverizing the thin portion by mixing or beating,

c. concurrently with both steps above injecting stabilizing material on the shavedface and on the pulverized material,

d. then shaving a second thin portion off the face shaved in step (a) above,

e. while continuing the pulverizing and concurrent injection,

f. and repetition of the steps aforesaid, so that the additive is continuouslybeing forced on a-shaved face, being rubbed and smeared thereon, while the rubbed and smeared shavings are being pulverized by mixing and beating so that intimated mixture of pulverized particles and additives is attained.

Prior breaking-up of the surface is not required, and would in fact prevent formation of a suitable face. The pulverization attained is such that subsequent plowlike actions is not required.

' In this way, the pulverization is finer than heretofore, and moreover is carried out with less expenditure of power. In this connection the USCE Paper above states that (page 1 at paragraph 3)'among many primary basic requirements are, that the equipment should be self-powered and light enough to travel and moreover on weak soils, and should be able to perform the mixing operation in a single pass. Consequently, the reduction in power resulting from the use of my method herein has marked effect upon reduction of weight of the apparatus and, accordingly, makes it easier to attain the basic requirement of a light self-powered unit. As well, the apparatus to effect my method above is able to perform the mixing operation in a single pass.

Apparatus to Effect the Method The apparatus which I use to carry out the method above has an independently driven rotating reel including transverse shaver bars, and does not require either initial or subsequent breaking of the soil by means of shoes or other plowlike members. Shaver bars of a reel according to the present invention work cutting downwards against a face which suitably can be 6 inches below the undisturbed surface, that is to say a bottom run of the reel extends about 6 inches below the unbroken surface continuously shaving about a hundredth of an inch. The apparatus is inoperative to accomplish the method if the reel be oppositely rotated.

With a 6-inch cutting depth, a 24-inch diameter reel gives a 12-inch central, or hub, portion which is about a minimum adequately to provide for a drive sprocket. Shaving thickness determines speed of travel for given r.p.m. of the reel and number of shaver bars, which parameters are discussed later in this disclosure.

As is well known, there are many different additives that can be used, the choice of a particular additive being determined by the particular soil which is to be stabilized. While much research has been carried out to determine the optimum additive, and the optimum amount of the additive per cubic foot of material, research on these aspects of soil stabilization is continuing. However, the present state of that part of the art is sufiiciently advanced that effective stabilization can now be carried out provided that the pulverization is adequate. The matter of the particular additives, and the proportion thereof,

I is not herein further discussed as not being directly relevant to a central concept of the present invention.

It is well known to those skilled in the art that a main difficulty mitigating against successful stabilization of soils of the subject kind is difi'iculty, approaching near impossibility, of causing a liquid additive adequately to permeate such soils. This is a main reason why previous pulverization methods and apparatus have failed to achieve the objectives set forth by the U.S.C.E., nor is the difficulty overcome by using additives other than liquids, since pulverization finer than hitherto attained in a single pass is required. MOreover, the smearing, rubbing and forcing of the additive according to the method above has not heretofore been provided in any prior apparatus known to me.

Notwithstanding that parameters of forward speed, number of blades and peripheral speed of the blades have properly been established, of necessity such parameters will be optimum only for a particular soil condition-which particular conditions may or may not actually be encountered on a specific site. Soil conditions vary not only with geographical location of a site, but within a site or even in a single pass on that site. The variation may result from change in the nature of the soil, or of moisture content, or of both--and as well from other variations the nature of which does not appear clearly to be understood.

Thus, when soil conditions change, for example while actually making a pass, that change can be, and often is, such as to overload the machine.

Overload Protection An operator experienced in the use of such equipment will learn to perceive overloading before it has increased harmfully. That is, he can learn to perceive this if the increase in load is gradual, but he cannot himself always react sufficiently quickly, taking into consideration also the time taken for the machine itself to react to such remedial action as he may take-such as for instance lifting the reel-effectively to prevent overloading.

Overloading at the least will result in impaired performance and increased wear, and may result in serious damage. Notwithstanding the operator might be experienced it would be advantageous to provide visual signal to indicate imminent overloading. Should a soil condition change resulting in such overloading occur quickly,because of the reaction time of the operator, and because the machine itself requires time to respond to such corrective action as may be taken by the operator, it is of further advantage to provide automatic means responding more quickly than the reaction times aforesaid to reduce the overloading. I have found that such overloading is preceded by an increase in vibration. Accordingly, I provide a vibration sensor of a known kind suitably mounted, and constructed and arranged to activate the visual signal means aforesaid upon a moderate increase over normal vibration. When this occurs more quickly than the time taken by the operator to respond to the signal and to take such action as he may deem necessary, with the increasing beyond the increase aforesaid, the sensor activates mechanism constructed and arranged rapidly to swing the reel to a disengaged position. The mechanism hereinafter disclosed effects such reel disengagement in about a tenth of a second. Consequently if vibration commences to build up rapidly, the reel is automatically raised and overloading avoided.

As well as from overloading as above, the sensor will react if for instance a largish stone-such as occasionally is encountered in gumbo clays-is struck. When this happens, the reel will rapidly lift as explained. Although damage can result notwithstanding, the value of the quick lifting in reducing damage, which in these circumstances would be likely otherwise to result, is apparent.

I BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF FIGURE 1 FIG. 1 illustrates a self-propelled carrier 10 adapted to move over the ground in the direction as illustrated by the arrow 12. A shaving and pulverizing reel 14 is mounted, in a known conventional manner, on the carrier 10 for controlled vertical movement from a digging position 14.1 below the ground surface as illustrated in solid lines to an elevated position 14.2 as illustrated in broken lines. The reel is mounted for rotation about a horizontal transverse axis so that with the reel in its digging position 14.1 it engages and digs the said to be stabilized forming a shaved face 16. A spray bar 18 is mounted on the carrier ahead of the reel 14 for directing a spray of liquid stabilizing additive towards the reel and face 16. The liquid additive is normally carried in a tank 21 mounted on the carrier and is forced by pump, not shown, through conduits 22 connected to the spray bar 18. Engine 23 mounted on the carrier is operatively connected, in a known manner, to the liquid pump and is also connected by a chain sprocket drive means 23.1 to the reel 14 for rotating the latter.

DESCRIPTION OF FIGURES 2 AND 3" FIG. 2 shows the reel l4 16 inches in outside diameter and 4 feet wide in a test rig. The reel is secured to a reel shaft 25 mounted between supports 25.1 and driven by the engine 23. In the reel shown in FIG. 2, enddiscs 28 are welded to the shaft 25, as are intermediate spaced discs 29, as here shown four in number and spaced a foot apart. A plurality of spaced bars 31 are provided secured to outer peripheries of the discs.

FIG. 3 is a section of an experimental 28-inch reel a foot wide, designated l4-B, shown set up in a similar test rig. Chain and sprocket drive means 231 are seen operatively connected to the engine, not shown in this, figure. It will be noted that peripheral spacing and number of bars 31-B differ from FIG. 2.

DESCRIPTION OF FIGURE 4 FIG. 4 is a diagram illustrating orientation of a transverse shaving bar 31. This bar is rectangular in section, having an advance sidewall 32 inclined at an angle 1 to a radius 33 as shown, direction of rotation being as before, and as indicated by the arrow 15. I is suitably ten to 15, so that an outer sidewall 34 is correspondingly inclined to a cut face portion 16.1. As here illustrated the thickness of a shaving being cut by the rotating shaver bar 31 is designated T. As before stated, T is of the order of a hundredth of an inch, and here is shown much exaggerated.

Having reference to the angle 1 and having reference to the shaver bar 31, I have found that a rectangular bar so disposed is effective, and has obvious advantages in that such a bar is easily fabricated. It is clear that a bar having rectangular section need not be used, for a shaving or planing action can be accomplished, as is well known in the art, by elements having shapes other than rectangular-for instance a modified chisel shape. As well-cutting edges of the bars can be provided with a plurality of toothed members, as taught in my patents above. Also, the shaver bars themselves can be in a helical arrangement, after the fashion of a reel of a common lawn mower.

It is essential to the invention that, whatever kind of shaver bar is being used, the parameters aforesaid be such that the thickness of the shaving is small-namely about one one-hundredth of an inch. I have found that shaving of one-eightieth inch (one and one'quarter one-hundredths of an inch) gives satisfactory results with a forward speed of about 18 feet per minute. It is apparent from the general disclosure herein that the concept of thin shaving with simultaneous smearing and rubbing of the additive is new, and that in consequence it is difficult, based upon present experience, to indicate with precision limits which are optimum in relation to particular soil conditions which, as explained, may vary materially even upon the same site.

I have however obtained data which indicate that a range of thickness varying from slightly over a hundredth of an inch to about a third of that thickness will give satisfactory results in a variety of gumbos. From the simple mathematics involved it is apparent that a particular thickness of shaving can be accomplished at a slow forward speed and a slow peripheral speed, and that the same thickness can be accomplished at increased forward speed and increased peripheral speed. l have obtained satisfactory results with forward speeds varying from 18 feet per minute to 6 feet per minute, with shaving thicknesses within the range aforesaid.

As an example, with a reel drive in 1,500 r.p.m. and having l2 shaver bars, a bar comes in contact with the undisturbed surface 18,000 times a minute resulting in the shaved face 16. With a forward speed of 18 feet per minute, thickness of the shavings off the face is l/l000 foot a l/80 inch, i.e. about one and one quarter hundredths of an inch. With the speed reduced to 6 feet per minute, the thickness reduces to about 1/240 inch.

DESCRIPTION OF FIGURE 5 In FIG. 5, a reel swinging means assembly is designated generally by the numeral 40. The assembly has double-acting pneumatic cylinder 42 connected by air lines indicated generally by the numeral 43, obtaining a supply of air under pressure in tanks 44 supplied by a compressor 45 feeding tank supply lines 46. A four way manually operated valve 47 is controllable by an operator seated in a driving seat 48, the seat being shown in FIG. 1 only. By means of the four-way valve 47, piston rods 49 may be extended or retracted in unison, the said piston rods being operatively connected by means adapted to swing the reel from the full line position 14.1 FIG. 1, to the broken line position 14.2, or intermediately.

A vibration sensor 51 is electrically connected to each of two solenoid valves 52 through suitable electrical lines 53. A second line 54 extends to a visual warning signal 55 see now FIG. 1, in plain view of a driver on the seat 48. When vibration valve 47. Should the operator not take necessary action in' response to the signal, or if he is unable to take such action or actions quickly enough, if overloading continues to increase by a further determinate amount over the level at which the signal 55 is actuated, lined 53 are energized so activating the solenoid valves 52.

The sensor can also trigger the valve when shock occurs, for instance if a blade encounters a boulder. These valves are of a normally closed type constructed and arranged to open almost instantaneously upon being energized so that, when the solenoid energizing higher vibration level is reached, the piston rods 49 move quickly to swing the reel to the broken line position 14.2 FIG. 1. While there are several possibilities, the solenoid valves can be such that once the solenoid has been energized to open them, they remain open until manually closed. The sensor 41 is mounted in a suitable position, for instance on a supporting arm (not shown) of the reel shaft.

The solenoid valves are of a common type obtainable through ordinary trade sources, as is the vibration sensor. METHOD, with reference to FIG. 4. I

While the face 16 has been formed by successive cuts of the blade, consider the cut being made in FIG. 4 as the first cut aforesaid, In some soils :1 slice may result, in other soils and/or with different moisture content, fragmentation will occur during the stroke, producing chips or even small particles. These slices or fragments are urged downwards of the face by the bar 31, and mixed or beaten by this and succeeding bars. Note that with a 12 bar reel driven at 1,500 rpm, an adjacent blade passes a particular pace position one three-hundredths of a second after the first blade.

1 [15 9x 27i15f999] Concurrently additive spray 19 is impinging as seen, so that it is carried by the rotating blades to be injected to the pulverized material by contact and centrifugal force. As well, the additive is similarly urged against the shaved face being rubbed or smeared thereon by the nest blade-and to an extent by the first blade. Additionally or alternatively additive may be sprayed radially outwards as indicated at 19.1.

What is taking place is an action analogous to cutting shortening into a flour as practiced by bakers-the flour" here being the pulverized material, the spatula the bars, the bowl side against which the shortening is smeared and intimately mixed with the flour, the face 16.

The additive may be liquidor may for instance be cement. In either case the action is, in substance, as above described.

It will be appreciated that, during rotation of the reel soil will tend to be thrown tangentially therefrom. In order to avoid this and to obtain proper pulverizing and mixing of the soil a sheet metal hood 60, (see FIG. 1) is extended from the carrier over the reel. The hood is of conventional design normally employed in rotary tillers and the like consequently further description is deemed unnecessary.

This hood 60 is provided with resilient inner lining 61 which can be rubber, sprayed thereon. Dampeoil shavings, which would otherwise stick to base metal and form lumps, will rebound from the inner lining back into reel to be further mixed and pulverized.

The present invention is thus seen materially to reduce the problem of adequate pulverization of clay and gumbo soils, and to provide a method and apparatus for pulverizing as aforesaid, and for intimate mixing of the pulverized material with either a liquid or solid additive to the extent required for adequate stabilization, materially reducing previous difficulties in stabilizing soils substantially impermeable to known usual additives.

1 claim:

1. Apparatus for soil stabilization including:

a. a carrier arranged for movement over soil to be stabilized,

b. a reel mounted on the carrier for rotation about an axis of rotation transverse to direction of movement of the carric. the reel having a plurality of circumferentially spacedapart bars extending the length of the reel parallel to the axis of rotation,

d. each bar being square in cross section so as to present flat sidewalls extending from straight transverse corner edges,

e. each bar being angularly disposed so as to present an advance sidewallinclined forward from an outer corner edge at an angle between 10 and 15 to a radius line between the axis of rotation of the reel and the outer comer edge so that the outer corner edge serves as a cutting edge for shaving a face of the soil and the advance sidewall rubs soil shavings against the face,

f. power-lifting means for lifting and lowering the reel relative to the surface of the ground,

g. a sensor for sensing vibrations in the reel,

h. and means, activated by the sensor when the vibrations reach a predetermined value, for causing the power-liftthe reel and a resilient inner lining on the hood to reduce tendency of shavings thrown outward by the reel to adhere to the hood.

4. Apparatus as claimed in claim 1 wherein the inner lining is formed of rubber applied in liquid form to the hood.

Claims (3)

1. 2. Apparatus as claimed in claim 1 wherein the reel includes a driven axle, and supporting discs nonrotatably mounted on the axle in axially spaced-apart relationship for supporting the bars.
2. 3. Apparatus as claimed in claim 1 including a hood over the reel and a resilient inner lining on the hood to reduce tendency of shavings thrown outward by the reel to adhere to the hood.
3. 4. Apparatus as claimed in claim 1 wherein the inner lining is formed of rubber applied in liquid form to the hood.

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