US3621805A - Embedment anchor - Google Patents

Abstract

AN ANCHOR OF THE EMBEDMENT TYPE HAVING AN ELONGATE STAFF AND AN ARTICULATED SOIL PENETRATING TIP BEARING RADIALLY ARRANGED FLUKES. DURING SOIL PENETRATION, THE FLUKES ARE DISPOSED EDGEWISE TO INSURE MINIMUM RESISTANCE TO SOIL PENETRATION. AFTER FULL PENETRATION A SHORT UPWARD PULL ON THE STAFF ROTATES THE ARTICULATED TIP TO A POSITION WITH THE FLUKES DISPOSED CROSS WISE TO GAIN MAXIMUM PURCHASE ON THE SOIL. IT MAY BE EMBEDDED EITHER BY FREE FALL IMPACT OR BY VIBRATION.

Description

1971 J. E. SMITH 3,621,805

EMBEDMENT ANCHOR Filed Feb. 2, 1970 4 Sheets-Sheet l INVENTOR. JASPER E SM/TH ATTORNEY Nov. 23, 1971 Filed Feb. 2, 1970 J. E. SMITH EMBEDMENT ANCHOR 4 Sheets-Sheet 2 Nov. 23, 1971 J. E. SMITH 3,621,805

EMBEDMENT ANCHOR Filed Feb. 2, 1970 4 Sheets-Sheet S Nov. 23, 1971 Filed Feb. 2. 1970 J. E. SMITH 3,621,805

EMBEDMENT ANCHOR 4 Sheets-She0t 4 Fig.9

\ II A k I Q .o 'N z United States Patent 01 lice 3,621,805 EMBEDMENT ANCHOR Jasper E. Smith, Ventura, Calif., assignor t the United States of America as represented by the Secretary of the Navy Filed Feb. 2, 1970, Ser. No. 7,725 Int. Cl. B63b 21/40 US. Cl. 114-208 R 4 Claims ABSTRACT OF THE DISCLOSURE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION (1) Field of the invention There is currently great demand for anchor arrangements adapted to mooring large objects at sea such as work platforms, cranes, derricks, oil drilling rig platforms, etc., and particularly for an anchor arrangement for mooring at great depths and having great resistance to vertical uplift forces.

(2) Description of the prior art The prior art is replete with examples of anchors using dead weights or which are embedded into the sea bottom by lateral dragging to develop horizontal pull resistance. In many anchoring situations resistance to uplift forces is a prime consideration and anchors relying upon horizontal dragging to insure embedment generally provide minimum resistance to uplift forces. Embedrnent of an anchor by lateral drag is ordinarily impractical at depths exceeding 500 feet.

SUMMARY OF THE INVENTION The present invention provides an embedment anchor which affords low penetration resistance during embedment but may be manipulated or keyed to provide maximum holding power without requiring substantial vertical movement of the anchor staff in order to set the anchor flukes. It includes a central elongate anchor staff, an articulated fluke assembly mounted on the lower end of the staff and a bail or anchor cable payout container at the upper end of the staff. Suitable stabilizing surfaces insure vertical orientation of the anchor during free fall descent to the sea bottom and a fluke tripping and setting means enables the fluke assembly to be rotated into maximum uplift force resistance position after its deepest soil penetration. It is also adapted to be embedded by vibration.

STATEMENT OF THE OBJECTS OF THE INVENTION It is an object of the present invention to provide an embedment type anchor which exhibits minimum resistance to soil penetration but may readily be keyed without Patented Nov. 23, 1971 significant loss of penetration to a soil engaging position exhibiting maximum resistance to anchor extraction.

A further object of the present invention is to provide an embedment anchor readily adapted to free-fall embedment in sea bottom compositions of relatively low penetration resistance.

A further object of the present invention is to provide an embedment anchor adapted to be driven into the soil 'by vibrations of certain amplitude and frequency through the incorporation therewith of a suitably powered vibratory mechanism which introduces rapid sinking movement of the fluke end of the anchor into the soil.

A further object is to provide a soil penetrating fluke assembly which exhibits a minimum resistance to soil penetration and which is retained in secure alignment with the anchor staff during such penetration but may thereafter be keyed to a position which provides maximum resistance to uplift forces.

A further object is to provide the streamlined anchor assembly which will fall straight and true through the water without excursion, is compact, easy to fabricate from readily available materials, inexpensive and simple in function and having an optimum hydrodynamic shape.

Other objects, advantages and novel features of the invention will become apparent from. the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings in detail wherein like reference characters designate like parts throughout the several views:

FIG. 1 is a diagrammatic representation of an anchor embodying the concept of the present invention shown after release from a surface vessel and during its vertical descent to sea bottom.

FIG. 2 is a similar representative showing of such embodiment after maximum soil penetration has been achieved.

FIG. 3 is a change position view of the device of FIG. 2 wherein upward tension has been applied to the anchor cable and showing the fluke stabilizing assembly partially rotated toward its maximum holding position.

FIG. 4 is a similar view showing the fluke assembly in its maximum holding position.

FIG. 5 is a view of the illustration of FIG. 4 taken from the right hand side to show the manner in which the flukes resist uplift forces.

FIG. 6 is a greatly enlarged side elevational view of the soil penetrating fluke assembly in its descent position wherein it offers minimum resistance to soil penetration.

FIG. 7 is a change position view of the fluke assembly of FIG. 6 showing the fluke member rotated to its maximum uplift force resisting position.

FIG. 8 is an enlarged detailed elevational view of the fluke locking detent and trip assembly employed to hold sembly into the ocean bottom.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail the general operation of the device is best depicted in FIGS. 1

through wherein a surface vessel having a crane 12 is shown suspending an anchor cable 14 over the side of the vessel. At the end of the anchor cable is illustrated an elongate sea bottom penetrating embodiment anchor including a fluke assembly 16, an intermediate anchor staff portion 18 and an anchor cable pay out bail portion 20.

As shown, the foregoing anchor portions are generally oriented in axial alignment and are usually disposed perpendicular to the ocean floor. Because of the relative configurations of the parts they exhibit a minimum resistance to anchor descent through the sea water so that a maximum speed of descent and hence a maximum degree of soil penetration is thereby achieved. Stabilization of the entire assembly during descent is assisted by a stabilizer ring 22 which is preferably shroud-like in nature and is spaced from the upper portion of the anchor bail 24 by means of radially extending fins 26 located at intervals between the web of the stabilizer ring 22 and the outside surface of the bail 24.

In order to avoid erratic movement through the water during descent and to minimize kinks, twists and hockles in cable 14 suitable swivels may be provided therein. These enables the cable to pay out of bail 24 without kinking or snarling. It is impractical at great depths to permit the anchor to draw the cable behind it. Such practice would build up momentum. forces in the cable causing it to pile up around the anchor after emhedment with consequent possibility of fouling. Therefore the cable is normally stored within pay out container 24 in coil fashion and is dispensed therefrom during anchor descent as additional cable length is required. For great depths two or more pay out containers may be mounted in tandem, such arrangement being quite effective in eliminating water resistance and insuring anti-fouling deployment of the cable.

As illustrated in FIG. 2 a free-fall anchor, upon striking the sea bottom, penetrates until the lowermost tip of the anchor staff is buried to the maximum possible extent. Thereafter, to rotate the fiukes from their minimum soil penetration resistance position to a position oriented at approximately 90 thereto, which is the position at Which maximum uplift resistance is achieved, a relatively short upward force, as depicted by the arrow in FIG. 3, is applied. This withdraws the anchor staff 18 a slight distance and, through the action of suitable articulated linkage bars the fluke assembly is rotated as shown in FIG. 3 until its axis is at about 90 to vertical and the flukes exhibit maximum uplift force resistance characteristics. Such rotated position is shown in FIGS. 4 and 5, wherein FIG. 5 particularly shows the broad fluke surfaces 30-32 which exhibit maximum purchase on the ambient soil.

Details of the fluke assembly are shown in FIGS. 6 and 7 wherein sturdy rounded fluke plates 30 and 32 are depicted radiating from a medial point of contact with a central fluke plate 34. The fluke plates are strengthened by a reinforcement bar or gusset strap 36 one being located on each side of plate 34. A similar one 38 interconnects fluke plates 30 and 32 to prevent collapse during high stress situations.

A pressure pad 40 may be welded or otherwise suitably secured near the center of the fluke assembly and may be cup shaped to better receive the lower end 42 of the anchor stalf assembly 44 which will be discussed in detail hereafter.

In order to permit articulate movement of the fluke assembly from its attitude of minimum. soil penetration resistance to its position of maximum resistance to fluke withdrawal the end 42 of staff 44 is provided with a bifurcated fitting 46 which by pin 48 is joined to the inner end of linkage bar 50. The outer end of such bar receives an outer link pin 52 journaled in a short coupling link 54 the opposite end of which is journaled to the tip of fluke 34 by means of a fluke link pin 56. This fluke link pin may be reinforced at its point of juncture by passage through the gusset strap 36.

The details of the fluke assembly retaining and release latch mechanism are shown in FIGS. 8 and 9. In those views the staff 44 is shown provided with pairs of spaced weldments 58 projecting from the Wall of staff 44 and located immediately below elongate openings 60-61 extending through the wall of said staff. Each of the weldments 58 has a short pivot pin 62 provided immediately adjacent the hexagonal head thereof with threads 64 which engage with corresponding threads in lateral aligned openings 66 in each weldment. A smooth tip portion 68 on each pin forms a journal for one end of a toggle latch member 70 comprising narrow fiat cheeks 72 spaced apart throughout most of their length but interconnected by a broad cam surface 74.

Through the slot formed between spaced cheeks 72 extends the tongue portion 76 of a toggle link 78, said link having a transverse pin 80 passing through its upper end. The tips of cheeks 72 have a notch 86 which receives pin 80. Said pin may be in the form of a threaded nut and bolt member. The toggle link is affixed to the end of guy wire 82 by a suitable ring fastener 84.

As best shown in FIG. 9 there are at least two toggle latch members 70 each including a notch 86 which normally receives transverse pin 80 so as to apply tension to toggle links 78 and retain guy wires 82 snugly in place to hold the emhedment fluke assembly 16 in the assembled position shown in FIGS. 1 and 2. As best shown in FIG. 6 the pressure pad 40 may be provided with ears 88 which are apertured to receive a clevice 89 on the lower end of guy wire 82. When tension is applied thereto, such wires hold the pressure pad and related portions of the emhedment fluke assembly in the aforesaid aligned relationship.

Provision is made to trip the toggle latches 70 and swing them to the dotted line change position illustrated in FIG. 9 when it is desired to release tension on the guy wires 82. Upon this movement it will be apparent that pin 80 together with tongue 76 and link 78 are thrown outwardly and clear by the outward movement of the latch mechanism. This frees the guy wires and allows the emhedment fluke assembly to rotate in the manner which will now be described. As best shown in FIG. 6 the em.- bedment fluke assembly is normally retained in place with the lower end 42 located in cup 40 and the linkage 50 extends laterally substantially perpendicular to the axis of the anchor staff.

After the emhedment fluke assembly has penetrated the soil to its greatest extent the application of a vertical pulling force upon anchor cable 14 causes the now released emhedment fluke assembly 16 to rotate in the fashion demonstrated in FIG. 3 to a new position shown in FIG. 4 where partial fluke 34 extends upwardly as shown in FIGS. 4, 5 and 7. This release is affected when initial application of strain to anchor cable 14 causes tripping slug 90, fastened to the lower end of cable 14 by tapered enlargement 92 (FIG. 9), to move upwardly along with the cable. It first strikes shear pins 94 which, being frangible, readily break and allow continued upward movement of the tripping slug until the upper face 96 thereof strikes against the lower face 98 of limiter block 100 which is securely welded at its periphery to the inside wall of the anchor staff 44. It will be noted that near the upper end of the tripping slug it has been peripherally recessed to provide a re-entrant groove 102 into which the cam portion 74 of the toggle latch 70 is normally received. This peripheral groove 102 is annular in form and provides a ring like depending wall 104 which, in the position shown in FIG. 9, normally covers a portion of the upper end of rectangular openings 60-61 and hence serves as an obstruction or keeper to prevent outward movement of the tips of toggle latches 70 to the guy wire release position.

After upward movement of the anchor cable 14 has lifted the tripping slug 90 upwardly sufficiently to sever shear pins 94 the keeper portion 104 of the tripping slug uncovers the upper portion of rectangular openings 60-61 and allows the tip 74 of toggle latches 70 to swing therethrough. Since the toggle latch pivot is almost in line with the pull of tongue 76 on shackle 78 a force is required in order to initiate outward movement of toggle latch. This is provided by the cammed surface 106 near the neck of the tripping slug which surface strikes similarly cammed surface 108 on the inside surface of toggle latch 70. Continued upward movement of the tripping slug 90 forcefully ejects the toggle latches through openings 60-61.

By the foregoing arrangement a secure and positive means is provided to retain the embedment fluke assembly in place on the end of staff 44 until the moment when its release is desired so that it may rotate into the position of FIGS. 4, and 7 to provide maximum soil engagement.

Though the description has so far been primarily directed toward an anchor of the free falling variety it will be apparent that the embedment fluke assembly and its tripping mechanism may readily be employed in anchor constructions utilizing other means of embedment. Thus in FIG. 10 is illustrated an embodiment whereby an elongate anchor of the type heretofore described may be supported by any suitable framework arrangement such as the tripod base 110 shown and the anchor shaft may be forced into the sea bottom soil by any suitable power means. As illustrated in FIG. 10 such power means may comprise a vibrating unit 112 with power for operation being either self-contained or being delivered from the surface vessel in any known fashion. The device of the present invention, presenting low resistance to soil penetration is particularly adapted to vibration or similar anchor insertion means and all of the foregoing advantages of deep insertion, easy seating or keying without material loss of insertion depth and substantial holding power are still retained irrespective of the means of anchor insertion.

The embedment anchor of the present invention is found to be particularly effective at depths in excess of 500 feet and descending as deep as 20,000 feet, and, Without requiring the application of dragging movement in order to cause embedment, provides a penetration sufficient to develop a resistance to uplift in excess of 7 to 1 and approaching to 1. With an anchor of the present design a holding power to weight ratio about 2 /2 to 1 has been achieved and with a linkage bar of 13 /2" length the fiu-kes have successfully been keyed to the open position with vertical withdrawal movements of the staff between 4 and 11 inches. Furthermore at penetration depths from 42 to 122 inches the holding capacity varied by 5.7 kips to 16.7 kips and the holding power to weight ratio varied from4to 1 to 11 to 1.

During descent a velocity of fall estimated at 18 feet per second was achieved and fluke penetration of 34 inches was obtained.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A fluke assembly for an anchor of the type which is directly embedded into the soil, said assembly insuring low opposition to penetration into the soil and exerting high resistance to extraction from the soil, said assembly comprising:

a plurality of substantially fiat plates of relatively narrow edge profile, said plates being rigidly joined to one another along a line essentially coinciding with the direction of soil penetration and with each plate being angularly disposed, in a plane normal to said junction line, with respect to each remaining plate of said plurality, the rigid interrelationship of said plates creating an integral member movable as a unit;

means normally supporting said plates with their narrow edge profiles presented to the soil surface, whereby soil penetration may be achieved with a minimum resistance; and

means for bodily moving said plates as a unit to re-orient them with their said junction line transverse to the direction of soil penetration to thereby increase the resistance of at least some of said plates to withdrawal movement from said soil;

the bodily movement of said plates being accompl'shed with minimum withdrawal movement of said supporting means.

2. An embedment anchor comprising:

an elongate shank having an anchor cable secured to its upper end and a fluke assembly located at its lower end;

said fluke assembly comprising at least two rigidly interconnected plate members presenting a slim profile when viewed along the line of interconnection;

means supporting said plate members on the lower end of said shank with the slim profile marginal edge of each plate directed downwardly whereby the fluke assembly may be embedded into the sea bottom with a minimum of effort; and

means for rotating said plates as a unit to a crosswise position so that their line of interconnection lies at an angle of to its original position;

whereby said fluke assembly exerts a maximum resistance to extraction from the sea bottom.

3. The anchor of claim 2 wherein the fluke assembly is retained on the lower end of the shank by releasable securing means; and

means releasing said securing means upon the application of the initial lift force to said anchor cable.

4. An embedment type anchor adapted to ready penetration to holding depth and designed to move into maximum holding position upon slight uplift movement of the anchor assembly comprising:

an elongate shank member having provision at its upper end for securement to the end of an anchor cable;

a fluke assembly mounted on the lower end of said shank and movable from a minimum resistance posi tion for greatest anchor embedment to a maximum resistance position of greatest holding strength;

said fluke assembly including a laterally directed linkage bar presenting a narrow profile to the soil being penetrated; and

means linking said bar both to said shank member and also to said fluke assembly at a point remote from the shank,

whereby initial upward movement of said shank moves said fluke assembly to its maximum resistance position of greatest holding strength.

References Cited UNITED STATES PATENTS 3,207,115 9/1965 Anderson 114206.1 3,187,705 6/1965 Costello et a1. l14206 1,086,053 2/1914 Howell 114-208 MILTON BUCHLER, Primary Examiner F. K. YEE, Assistant Examiner US. Cl. X.R. 52l64

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