US2342243A - Construction of piles, caissons, and the like in situ - Google Patents

Description

E. A. BRIZAY Feb. 22, 1944.

CONSTRUCTION OF FILES, CAISSONS, AND THE LIKE IN SITU Filed Feb. 10, 1941 3 Sheets-Sheet l E. A. BRIZAY 2,342,243 CONSTRUCTION OF PILES, CAISSONS, AND THE LIKE IN SIT U Filed Feb. 10, 1941 s Sheets-Sheet 2 Feb. 22, 1944.

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- CONSTRUCTION OF FILES, CAISSONS, AND THE LIKE IN SITU Filed F eb 10. 1941 s Sheets-Sheet s Patented Feb. 22, 1944 UNITED CONSTRUCTION OF PILES, CAISSONS, AND THE LIKE IN SITU Emile Alexandre Brizay, Singapore, Straits Settlements; vested in the Alien Property Custodian Application February 10, 1941, Serial No. 378,299 In Great Britain January 9, 1940 Claims.

This invention relates to the construction of piles, caissons and the like in situ, and comprises a method of driving into the ground a plurality of tubes arranged end to end in superposed relation, and apparatus therefor, and also improvements in the driven pile or the like. Although the invention will be described with reference to the construction of piles, it is to be understood that a caisson comprising a plurality of superposed sections could be constructed in a similar manner, and where reference is made herein to piles, the term is to be understood to include and to refer also to such caissons or the like where the context permits.

Heretofore it has been proposed to drive solid piles substantially continuously without impact by providing an anchorage carrying upwardly extending tie members supporting pressure-exerting means above the head of the pile or a length thereof to be driven.

When a pile or the like comprising a plurality of superposed tubes is driven by pressure-exerting means, the problem of keeping tubes in substantial alinement during the driving operation arises, and an important object of the present invention is to ensure such alinement, and to prevent the vertical row of tubes from being defiected during the driving operation. Another object is to reduce the cost of driving piles of the type referred to above.

According to the present invention, a method of driving into the ground a hollow casing comprising a plurality of tubes arranged end to end in superposed relation constituting a hollow pile or the casing of a solid pile, is characterised by applying to the uppermost tube of the casing a pressure of a magnitude sufiicient to overcome the resistance to penetration by the lower end f t e casin and also the skin friction acting on the outside of the casing, and retaining the tubes in substantial alinement one with another during the driving operation by means of a mandrel that extends downwards with radial play from the uppermost tube to a situation at or adjacent to the bottom of the casing without itself transmitting any driving force to the tubes. In this way comparatively light and thin concrete tubes, which need not be reinforced, or tubes of other materials, such as earthenware or asbestos, can be used, because at no time are they subjected to shock such as occurs owing to the impact of a heavy monkey, because the tubes are subjected only to a pressure which can be applied to the upper part of the casing by hydraulic or mechanical means, as by a hydraulic or mechanical jack, or by a static load, such as a kentledge or by a combination of such means and a static load. By suitably arranging gauges, the load on the casing due to the pressure can be determined at any time throughout the driving operation.

Preferably, the pressure of an upper tube is applied to the upper end of the next lower tube through a washer of plastic or yielding material, e. g., rubber, for the purpose of avoiding point contact between the two adjacent ends of the tubes and consequent liability to fracture, and to ensure that the pressure shall be distributed substantially evenly over the end of the lower tube.

The adjacent ends of the tubes may be centered during the driving operation by centering means, such as metal rings, surrounding the joints between two adjacent tubes, and a joint washer as described above may be prevented by the centering means from being extruded radially outwards from a joint which may be of stepped formation.

The radial space between the mandrel and casing is preferably such that, during the driving operation, each plastic washer between two adjacent tube-ends is extruded radially inwards against the mandrel.

Conveniently, the pressure is applied to the casing by means of a pressure plate provided with means, such as a washer of plastic or yielding material, for distributing the pressure substantially evenly over the top end of the casing.

When desired, a shoe may be provided at the bottom of the casing for facilitating the driving operation, and it may be driven into the ground while the mandrel is relieved from driving pressure, in which case the driving force on the shoe may be transmitted by a driving member that is movable in the mandrel. This driving member may be a monkey arranged to impart hammer blows directly to the shoe, or, alternatively, it may be a thrust member, preferably of tubular formation, arranged to apply a driving pressure to the shoe independently of that imparted to the casing.

When carrying the improved method into practice, it will be appreciated that if concrete tubes are employed, it is important that they shall be of high quality and capable of withstanding a severe crushing test, so as to give a wide margin of safety between the crushing load and the load which it is necessary to impose on them to force them into the ground. Such concrete tubes may be made of any convenient length, for example between three feet and ten feet, e. g. about six feet.

The invention also provides apparatus for driving a pile by a method as described above, which apparatus comprises a pressure plate seated, or to be seated on the top of the casing, and. pressure-exerting means, such as hydraulic or mechanical means with or without a static load. for

exerting on the pressure plate a pressure to be imparted to the casing for pressing it into the ground, in combination with a mandrel that extends or is to extend downwards with radial play from the uppermost tube to near the bottom of the casing for retaining the tubes in substantial alinement during the driving operation.

When the pile has a shoe at its lower end, the apparatus may also comprise a driving means operative, or arranged to be operative within the casing for driving the shoe independently of the casing into the ground.

This driving means may comprise a rigid driving member that extends, or is arranged to extend within the casing to the shoe to thrust the latter into the ground under the action of pressure acting on the upper portion of the driving member.

In some cases a second pressure plate may be seated, or arranged to be seated on the top of the driving member, and the pressure-exerting means may be arranged to exert on it a pressure to be imparted to the shoe.

When a shoe is used during the driving operation it may be arranged telescopically in relation to the mandrel or the casing, and packing means may be arranged between the shoe and the telescopic part associated with it.

Other features of the invention relate to means for tying the shoe temporarily to the pile-head, and to a buoyant reservoir for use as a counterweight when driving piles in water, and to improved hollow or solid driven piles, as described hereinafter.

One construction of pile-driving apparatus for carrying into practice the improved method of driving iles, caissons and the like, and modifications thereof are diagrammatically illustrated by way of example in the accompanying drawings, wherein:

Figure 1 is an elevation, partly in vertical section, showing one form of pile-driving apparatus according to the invention, and illustrating the pile during the sinking operation, and

Figure 2 is a detail sectional view, on a scale 1 larger than that of Figure 1, showing a joint between the adjacent ends of tubes forming the pile;

Figures 3, 4 and 5 are similar detail views showing modified forms of joints;

Figure 6 is an elevation, partly in section, showing another form of pile-driving apparatus, comprising a monkey and a shoe driven thereby;

Figure 7 is a like view showing another form comprising two mandrels whereof one is arranged to drive a telescopic shoe which is shown adjacent the lower end of the pile casing, and

Figure 8 is a detail view showing the shoe spaced downwards away from the pile casing;

Figure 9 is a detail sectional view showing another arrangement of a telescopic shoe;

Figure 10 is a detail sectional view showing a grab within the pile casing;

Figure 11 is an elevation, partly in section, showing part of a modified form of pile-driving apparatus according to the invention;

.Figure 12 is a perspective view showing part of another form, and

Figure 13 is an elevation showing a modified 'form of ballast for use when driving piles under water.

Like reference characters designate like parts throughout the several views.

' Referring first to Figures 1 and 2, a plurality of concrete tubes 29 are arranged vertically end to end and may form, when driven, either a hollow casing constituting a hollow pile, or the casing of a solid pile. These tubes have between their adjacent externally-tapered ends joints comprising a washer 22 and an external metal ring M, and they rest at the bottom on an ex- P 34, for the purpose-s described hereinafter.

A plate 36, preferably of steel, has a circular opening 38 and rests on the top of the top tube 20, a joint washer 40 being provided between the latter and the plate 36. A mandrel 42 extends downwards with radial play through the tubes 2!] and forms with the latter an annular space 44; during the driving operation this mandrel has its upper end extending through the opening 38 in the plate 36. Each of the washers 22, 32 and 40 is composed of plastic or yielding material, e. g. rubber.

Hydraulic means for pressing the plate 36 down on the pile casing may comprise a plurality of hydraulic jacks. As illustrated, each of these jacks comprises a vertical hydraulic-cylinder 46 that is anchored below by a rod 48 to'ballast 50 on the ground, and contains a plunger 52, whereof its rod 54 extends upwardly through the plate 36, to which it may be connected in any convenient manner. As shown, the upper end of the rod is screwthreaded and carries a nut 55.

When the hydraulic means is in operation, the jacks pull down the pressure plate and pressure is distributed evenly by means of the washer 40 on the top end face of the top tube. The tubes are prevented from collapsing or deflecting from the vertical any substantial amount by the mandrel which is seated on the top reduced end of the shoe. During the pressing operation, the joint washers tend to be extruded across the space 44 between the tubes and the mandrel, thereby centering the tubes and holding the mandrel in position. Conveniently, the radial width of this space 44 may be about to inch. At the same time, the metal rings 24 and 34 ensure that only a very small quantity of the jointing material will be extruded outwards. These joint washers have the advantage of permitting the pressure to be transmitted from one tube to the next without damaging their ends, and at the same time taking up any small inequalities or irregularities at the ends of the tubes. The jointing material has the further advantage of permitting the hollow pile or shell to deflect a permissible amount as a whole, although individual tubes are kept substantially straight and true, and at the same time transmit the full load from one tube to the next without damage to the ends of the tubes even though the ends of adjacent tubes may not lie exactly in two parallel planes. If such deflection occurs, a lateral thrust will be exerted and transmitted by a joint washer to the mandrel, but as the mandrel has great rigidity it will absorb such lateral thrust without allowing undue deflection of the entire casing which might cause damage to the ends of the tubes, and in this way the casing or pile can be kept straight and true within reasonable limits for very considerable depths and under heavy load.

It will be appreciated that. the mandrel is completely free in the centre of the. tubes except for the relatively slight gripping action exerted on it by the joint washers which centre it in the tubes; further, the mandrel is not loaded at any time by the hydraulic means, and does not transmit the driving pressure in any way whatsoever, its sole purpose being to ensure that the tubes shall be kept true and concentric one above another, and to resist any tendency of the easing to be materially deflected; consequently, a relatively light mandrel can be. used.

In some cases, when a joint between two adjacent tube ends is stepped, a metal ring such as 24 surrounding the joint may be dispensed with. Figures 3 and 4 show examples of such stepped joints, the upper and lower steps 58, 68 of the joint in Figure 3 between tube sections Zila being substantially equal in width, while in the joint between tube sections 20b shown in Figure 4 the upper step 62 is narrower than the lower step 64 that is situated nearer the centre of the tube.

Alternatively, the adjacent tube ends may be straight, as shown at 66 in Figure 5, in which case no washer 22 need be used in the joint when the tubes 200 are made perfectly and when the piles are to be erected under exceptionally easy conditions.

After the casing has been driven to a set the mandrel 42 will be removed, and if a solid pile is required the casing will be filled with any convenient material, such as inundated sand, or concrete, either reinforced or not.

In the example described above with reference to Figures 1 and 2, the hydraulic means exerts on the casing a pressure of a magnitude suflicient to overcome not only the reaction due to the shoe 28 entering the ground, but also the reaction due to skin friction on the outside of the casing. If desired, a static load, such as lead blocks, may be placed on the plate 35 for overcoming the skin friction.

In some cases, the pressure applied to the plate 36 may serve for driving the casing into the ground, while the shoe may be driven independently of the casing by a heavy weight, hereinafter referred to as a monkey, actuated within the mandrel by a winch or other means outside the same. Figure 6 shows such an arrangement, in

which a shoe B8 driven independently of the casing by a monkey I0, is slidable in the bottom end of the mandrel 42c, and has an upper external flange l2 and a lower external detachable flange M spaced apart vertically, between which flanges extends an internal flange IE on the bottom end of the mandrel. If desired, rubber rings 18 may be permanently fixed to the monkey for guiding it in the centre of the mandrel during the hammering operation, and serving also for cushioning laterally directed shocks on the mandrel, in order to obviate slow deformation of the mandrel due to repeated shocks at approximately the same situation. The concrete tubes 29 may be formed and interconnected substantially as .1

shown in Fig. 1 and a cast-iron or steel ring 80 may be provided on the bottom end of the lowest tube 2% at the time of its manufacture. A wire rope 82 may connect the monkey 'H] to a friction winch or other operating means, not shown, for operating the monkey. The bottom of the shoe 68 may be made of hardened steel for crushing or breaking boulders or other obstructions and may be of chisel shape. The driving pressure on the casing in this arrangement has only to overcome the skin friction, and the resistance to penetration offered by the lower end of the bottom tube 29, while penetration of the shoe B8 is obtained by hammering. When used, as described, the monkey delivers blows on a member of a negligible weight and can be of light weight as compared with monkeys generally used for hammering piles on their head. Furthermore the fact that the blows are delivered at the right spot, close to the obstruction, assures a high degree of efficiency.

Such a shoe can be removed with the mandrel through the casing, whereupon a grab, such as that shown at 84 in Figure 10, can be lowered down the casing for obtaining samples of the stratum on which the pile has finally come to rest. If desired, a shoe constructed as described hereinafter with reference to Figures 7 and 8, or Figure 9, may be driven in a like manner.

Figures 7 and 8 show a modified construction of improved pile-driving apparatus, in which two concentric tubular members 42b, 86 are provided in the casing, the outer member 42h constituting a mandrel as described above, and the inner member 86 constituting a thrust member for driving a shoe 88 having an upwardly extending external steel sleeve 9B fitting as closely as practicable over the lower end portion of the bottom tube 29 of the casing. Two pressure plates 36a, 92, each actuated by pressure means, such as hydraulic means described above, are arranged seated respectively on the top of the casing, and on the top of the inner tubular member 86 which is seated on the shoe 88. When driving a pile with this apparatus, the casing will be driven as described above with reference to Figures 1 and 2 without impact, i. e. solely by pressure until it penetrates the ground no further, or until the load developed on it is equal or nearly equal to the total reaction oifered by the ballast or counterweight 50. The driving action on the casing will then be stopped, and pressure will be applied to the plate 92, so that the shoe 88 will receive the full load transmitted by it and, if a solid bottom was not previously obtained, the shoe will sink further and be separated from the bottom of the casing, as shown inFigure 8. The driving action on the inner member will then be stopped, and driving pressure will again be applied to the plate 360, to the casing, when the bottom end of the latter will again be seated on the shoe 88, as shown in Figure 7. The same operations will be repeated until a satisfactory set has been obtained.

if the driving of the pile is to be executed under difficult conditions, and if perfect centering of the telescopic shoe is desirable in order to avoid chances of breaking the lowest tube 20, one or preferably two rubber rings 94 may be placed between the tube 2!! and the sleeve 90, as shown in Figure 9. When the shoe penetrates the ground either by pressure or by hammering, the rubber rings 94 will roll downwards; when pressure is exerted on the tube 20 to cause it to seat again on the shoe, the rubber rings 94 will then roll upwards. It is clear that, during this action. the depth of relative penetration of the shoe 88 with regard to the lowest tube 20 will be such that the top rubber ring 94 will not leave the top of the sleeve 9Q. These rubber rings 94 have also the great advantage of preventing water from entering the shoe.

The bearing capacity of a hollow casing constituting a hollow pile or the casing of a solid.

pile driven as described above, is equal to the combined reactions of (1) the skin friction exerted on the outside of the casing and (2) resistance to penetration of the point or bottom end of the casing. As both these reactions can be determined, the weight of the counterweight or ballast can be reduced to a minimum, and true information is furnished on the bearing capacity of the completed pile.

Referring to Figure 10, if no shoe is provided at the bottom of the casing, a grab 84 lowered into the mandrel 42a may be operated at the point of the pile to remove obstructions and thereby reduce the pressure required to drive the pile, and also to obtain information about the strata in which the work is being executed.

Referring to Figure 11, provision may be made, as by making perforations 86 in the lower portion of the shoe 68a, for jetting the bottom end of the pile in certain kinds of ground. When operating in this manner, a pipe $8 affixed fluidtight by packing M to the top of the mandrel 42a may supply water under pressure to the shoe, which has lateral flanges 1211, Ma as described above, a fluid-tight joint being preferably formed between the bottom end of the mandrel and the shoe, as by means of a rubber washer N82, or other convenient packing means, applied to the internal flange 16a at the bottom of the mandrel.

Figure 12 shows a shoe H24 provided with three 1 holes I06 spaced equally apart around the sleeve 90a to receive means for attaching ties to the shoe. When starting the driving operation a hook Hi8, preferably of relatively soft metal, is

fixed into each hole Hi5, and attachment means used for driving it has been removed, an annular plate ill! will be placed on the top of the upper tube 2%, providing a flange on the latter, and then each tie H0 will be fastened to the flange as by a nut-equipped hooked fastener H4 or other convenient attachment means. of this operation is temporarily to keep the pileshoe and the pile-head equidistant, as it sometimes happens-due to the buoyancy of the soil that the pile or a part of it has a tendency to float upwards after being driven. ments, e. g. of steel, will then be placed inside the tubes 20 and the core will be concreted. When the concrete core has set, a sufficient pull is exerted on the ties l Ill in order to extract them. To facilitate this operation, each hook lflll is preferably made of material of smaller diameter than the tie l lil, and will break or straighten owing to the pull on it. These hooks 1% will generally be unrecoverable, but the ties H0 can be used repeatedly. If desired, some rupturable or otherwise detachable attachment means may be used with the ties in place of the hooks lfit.

The improved method of pile driving enables a pile to be sunk or driven in water, in which event, as shown in Figure 13, barges I H5 or other reservoirs may be used as counterweights, in which water can be filled to make them heavier without preventing them from floating. Hydraulic jacks comprising cylinders 46, as described The object Reinforceabove, may thenbe anchored to the barges, and can exert a downward pull on the top of the easing. When the casing has penetrated into the ground a predetermined distance, one or more additional tubes 20 may be added to lengthen it as, required, whereupon the driving operation may be repeated until a satisfactory set is ob tained.

It may be added that the invention is suitable for underpinning works, in which case casings of a shorter length may be used, say 1 foot to 3 feet, and also mandrels made of a series of short lengths preferably equal to the adopted length of tubes. In this case no counterweight is needed as the reaction can be obtained from the structure to be underpinned.

Various modifications may be made in the details of construction described above without departing from the invention. For example, the mandrels 42, 42a, 421), which may be of any convenient length, may be made in sections screwed together. Further, in some cases, the washers transmitting pressure may be made of a composition containing asbestos fibre, china clay and a very small quantity of rubber.

I claim:

1. The combination with a hollow casing comprising a; plurality of tubes arranged end to end in superposed relation, and a shoe at the lower end of the casing, of a pressure plate seated on the top of the uppermost tube, pressure-exerting means arranged to exert on the pressure plate a pressure to be imparted to the casing for forcing it solely by pressure into the ground, a mandrel that extends downwards with radial play from the uppermost tube into the bottom tube for retaining the tubes in substantially vertical alinement during the driving operation, and driving means operative within the mandrel for driving the shoe independently of the casing into the ground.

2. A combination of parts as set forth in claim 1, wherein said driving means comprises a rigid driving member that extends downwards from the uppermost tube to the shoe for thrusting the latter into the ground solely under the action of pressure acting on the upper portion of the driving member.

3. The combination with a hollow casing comprising a plurality of tubes arranged end to end in superposed relation, and a shoe at the lower end of the casing, of a mandrel that extends downwards with radial play from the uppermost tube into the bottom tube for retaining the tubes in substantial alinement during the driving operation, a rigid driving member that extends downwards in the mandrel from a situation above the top of the uppermost tube and mandrel, two pressure plates whereof one is seated on the top of the uppermost tube, and the second is seated on the top of said rigid driving member, and pressure-exerting means arranged to exert pressure on said pressure plates for driving the casing and the shoe solely by pressure into the ground while the mandrel is relieved from drivmg pressure.

4. A combination of parts as set forth in claim 1, wherein the shoe and mandrel are arranged telescopically one slidable in the other.

5. A combination of parts as set forth in claim 1, wherein the shoe and lowest tube are arranged telescopically one slidable in the other.

EMILE ALEXAN DRE BRIZAY.

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