US2663152A - Pile-driving - Google Patents

Description

| hilhil L. HART FILE-DRIVING Filed Feb. 12, 1952 Dec. 22, 1953 INVENTOR. BY L/NTo/v HART 40144! 7 1% AOfi/VEVS.

Patented Dec. 22, 1 953 FILE-DRIVING Linton Hart, Birmingham, Mich., assignor to Raymond Concrete Pile Company, New York, N. Y., a corporation of New Jersey Application February '12, 1952, Serial No. 271,171

5 Claims. (01. 61-53) This invention relates to a novel method for driving piles or pile shells and the like in locations close to existing structures, other piles,

walls, embankments and the like, which are liableto be seriously displaced or otherwise disturbed and damaged by the pile driving'operations;

If a group of piles are driven into certain types of clay formations (such by way of typical examples as occur in the citiesof Detroit, Michigan, and West Hartford, Connecticut) at locations adjacent to buildings, or other structures supported by the clay, a peculiar eifect will arise in that the clay displaced by the piles will exert enough outward and upward pressure on the adjacent areas, even to cause parts of multistory buildings nearby quite promptly to rise as much as a foot or more for example, causing great damage thereto. the clay formations, similar problems arise when numerous piles are driven adjacent other groups of piles, walls, sewer pipes, embankments or the like which are caused to be displaced and are seriously damaged and all of which will herein be referred to as adjacent structures.

On the other hand, if piles, pile shells or the like are placed in previously excavated holes in such clay of a diameter loosely to receive the pile or shell, the chances are that there will be suiiicient spaces or loosened areas remaining around the shell into which the surrounding areas of clay will tend to migrate, to thereby allow adjacent parts of such buildings or structures to sink, generally after the elapse of some time, but to a degree sufficient to cause serious damage to the structures.

Despite much thought and effort over along period, heretofore no reliable, dependable and satisfactory solution of this serious problem of thus damaging adjacent structures has been found, except by resorting to the expensive expedient of shoring such structures or their foundations or in one way or another substanr tially isolating the effects of the pile driving from the foundations. However, according to the present invention it has been found that if holes are first drilled in the clay to receive the piles, pile shells and the like, and if such holes are made of a sizesmaller by a predetermined amount (as hereinafterexplained') than the piles or pile shells to be placedtherein, then thelat ter may be easily driven into place down to the desired solid bearing without danger-of damaging the adjacent structures, even under conditions heretofore considered most diflicult to over-- come Due to such pressures in The reasons why this problem may be solved in this dependable and relatively simple way as well as more specific objects, features and advantages of the invention will appear from the detailed description given below, taken in connection with the accompanying drawing which ilustrates somewhat schematically, certain examples of the invention.

It has been found that when driving piles into clay formations such as above referred to, the effect which causes rising or undesirable movement of adjacent structures away from the piles, takes "place quite promptly and as soon as the heaving effect on the earth reaches the region of the structures, and thus marks may be placed on adjacent structures to be viewed through surveying instruments for promptly determining as the pile driving Work proceeds, whether the structures are rising or being displaced to such an extent as to cause damage thereto. On the other hand the opposite effect where the clay migrates toward or into vacant spaces about the piles, may take several weeks or months to result in the sinking displacement of parts of the adjacent buildings to a damaging degree. Thus it appears that the clay between the piles and the adjacent structures does not act in either direction with equal speed and, if conditions during the placing of the piles are such that this latter effect can take place, the possibilities of its doing so may not be known or detectable until after the pile-driving work is completed and the causes which brought about the damage are practically irremediable.

As above indicated the method of the present invention involves first drilling a hole into the clay of dimensions corresponding to the pile or shell which is to be introduced, except that the cross section of the hole, or at least the volume of the soft clay or like material removed, may be, by a predetermined amount, less than the volume of the corresponding parts of the pile to be inserted. This difference in volume or cross section in a typical case, for example, may be about 10%, although it may vary considerably up to 15 or 20% or down to a substantially smaller percentage, as may be determined by trial, and depending on the proximity of the adjacent structures, the character of the earth and the pile dimensions as further explained below.

Such holes may readily be drilled to the desired dimensions by conventional well-known types of rotary wet drilling apparatus similar. to that used for oil well drilling and the holes are allowed to remain filled with Water and slurry which flows up from the lower end of the drill during the drilling operations. slurry remaining in the hole resists flow of the adjacent clay into the cavity, until the piling or shell is driven in place therein.

The piles or pile shells are placed in the Wet drilled holes and are driven down to a solid bearing by the use of conventional types of pile drivers, the water and slurry being thereby displaced. Since the piles or pile shells are larger than the holes, or are tightly embraced therein, there will be, during the driving, adequate embracing eiiect on the pile or pile shell to hold it securely in proper position or alignment during driving and thereafter, but since the amount of earth displaced is greatly reduced as compared with the usual pile driving conditions, the placing of the piles or pile shells can be accomplished much more safely and quickly. In the cases of stepped or tapered piles or shells, same will settle into corresponding stepped or tapered cavities to the greater part of their lengths before the pile driving hammer has to be used. The Water and slurry is especially easily displaced without undue washing away of the clay walls of the hole if the holes are stepped or tapered.

With the preferred procedure of the invention, the percentage by which the volume of the piles or pile shells exceeds that of the holes as drilled is made just enough so as to cause incipient rising of the adjacent building or other structure supported on the clay as the piles are driven. As above pointed out, this incipient rising of the adjacent structures can be promptly determined by the use of markings thereon and with instruments and this insures that the driving action has caused some positive migration of the clay outwardly from the piles. It also is surprisingly effective in insuring that conditions in the clay will not be left such that there will be any danger of migration of the clay toward the driven piles to such a degree as to later cause sinking of the adjacent structures after the piles have been driven. Thus, the provision of holes just small enough to insure that the driving of the piles therein causes the adjacent structures to start to rise provides an expedient enabling the structures to be dependably checked while the driving work is proceeding and offers a positive way of promptly detecting whether or not conditions in the inaccessible areas down in the earth are such that the buildings might sink several weeks or more later and at a time after the contractor has taken has equipment away from the job and when any economical remedy for the condition might be impossible or the damage might be undetected promptly enough to prevent serious progress of the damage.

It should be here noted that the usual types of city buildings, including those made with structural steel or of reinforced concrete, may in parts thereof be raised or lowered slightly without causing any substantial cracks in the plastering or concrete or other damage. Thus in carrying out the invention so as to cause parts of the buildings to start to rise slightly, it will not be liable to cause any damage. On the other hand, if parts of such buildings are either caused to rise or permitted to sink substantially as compared with other parts, cracks and other damage generally start, and if the vertical movement is very substantial, the floor surfaces may, of course, become inclined noticeably and to a prohibitive degree, or elevator shafts and the guides therein or door casings may be so disturbed as to require same to be, repositioned. In some cases, even. the

Such water and 4 l sinking eifect occurring in buildings several weeks after pile shells or caissons have been carefully installed by former methods, has been so serious as to involve large damage claims.

While it would naturally be assumed that the ideal procedure would be to excavate a hole of substantially exactly the same dimensions as the pile or shell to be received therein so that the surrounding clay would, after the pile or shell is in place, have no opportunity to migrate in any direction from its normal condition, yet in practice in the usual case such a procedure would not solve the problem and in no case would it make possible any way of dependably detecting whether, after the job is completed, conditions might remain such that the adjacent structures would sink at a later time because of disturbances around the piles during the driving thereof. Also if the hole is excavated by a wet drilling method, portions of the hole may become irregularly oversized by reason of the wobble of the drillstem and because of channeling of the water and slurry from the lower end of the drill upwardly along the walls of the hole. Thus almost inevitably there may be places or regions around the holes where during the drilling they may be made too large or the earth or clay may be channeled to a degree such that if it is attempted to make the hole of the same size as the pile, there would be some migration of the clay inwardly toward the pile after it is in place. And since on the usual job quite a large number of piles of relatively large dimensions have to be driven, the cumulative effects may become quite substantial.

In carrying out the method according to the invention, the proper size of the holes may be determined well within the required limits of accuracy in the following way. Several or a quite small number of the piles at a given distance from the adjacent structure may be driven in place in holes of dimensions determined by previous experience with comparable conditions. For example, these first piles may be driven in holes 5% smaller than the piles and while the effect on the adjacent building is carefully watched. If no observable tendency for the building to rise occurs, then subsequent pile holes at approximately the same distance from the building are made enough smaller so that as the piles are driven therein the building will start to rise slightly by an observable amount, depending on the kind of building, and for example one-quarter of an inch in a typical case. On the other hand, if the first pile driven, or piles driven later, cause an objectionable rising of the building, then, of course, the holes for subsequently driven piles at approximately the same distance from the building are somewhat enlarged, but to a degree only such that there will still be some observable rise but less and less tendency for the building to rise as the later piles are placed. Due allowance may readily be made for the distance between the building and the piles. Of course, those nearest the building will cause the greatest amount of disturbance to the building foundations.

In the event the adjacent structure which is to be protected against disturbance is for example, a large concrete sewer or other underground passage or conduit, either an area may be excavated to expose a small area of its surface for observation or a rod or the like may be driven into contact with such surface and kept in such contact and observationsthereon may be made I as to whether it rises or falls (or is otherwise displaced) in the manner similar to the observation made on the buildingsduring the progress of the pile driving work. Preferably in case such conduits or the like are quite deep, observations should be made not only as to whether they rise or fall-vertically, but'also as to whether they tend to move outwardly from the area of the pile driving work. i

The invention is particularly advantageous for use with pile shells of the type formed of corrugated sheet metal in that it not only insures that the adjacent structures will be prevented from being unduly disturbed by reason of the outward pressure effects, such as are caused by driving any form of pile in place, but also the method greatly reduces displacement of earth by the piles and consequently the inward pressure against such pile shells as compared with the conditions which occur when such shells are driven without any previously driven hole therefor and hence it is not necessary that the shells used be as strong or of Such thick sheet metal as ordinarily required Still there will be sufficient pressure and friction during and after the driving along the walls of the shell to insure that it will remain inproperly aligned position during the driving and properly in place on its bearing after driving.- Some common forms of pile shells are made in sections, each succeeding lower section being of a smaller diameter and such sections are commonlydriven by a core member therein so shaped that the driving impacts will be .applied to rings attached to the lower ends of the 7 sections whereby in effect each section is pulled into the earth by impacts applied to its lower end. The length of such sections may be limited by reason of the fact that, if they are too long as ordinarily driven, the pulling forces from the impacts will tear them apart. But with the present invention the required pulling forces are greatly diminished and hence, if desired, the sections may be made considerably longer than heretofore.

Since with the method of the invention the total displacement of earth by the piles and the total driving force on the piles and the number of impacts may be greatly reduced as compared with ordinary pile driving methods, the consequent agitation of the clay and jarring effect on adjacent structures will be greatly diminished,

thus reducing the liability of damage to such structures from repeated or prolonged jarring.

In some locations where piles are driven, peculiar sand formations exist which, upon being sub jected to powerful jarring forces during the driving of a large number of piles, will tend to settle.

These sand formations may in some cases have been so deposited naturally that they will settle by becoming more compact upon being powerfully jarred, and other such formations apparently occur by reason of water having been drained from the sand leaving it in a condition whereby it similarly settles upon heavy jarring. Yet since such jarring may be minimized by following the procedure of, this invention, the disturbance of adjacent structures from that cause is also minimized.

The procedure of the invention is particularly advantageous where it is desired to prevent one group of piles from being displaced upwardly in clay formations upon the driving of adjacent piles. This difiiculty sometimes arises when a number of piles or the like have been driven and concrete foundation portions have been poured in or upon same supposedly at the desired permanent level and then, when additional adjacent pilesare driven, such foundation portion will rise to a prohibitive degree at a time when the correction of the defect will be difficult and expensive.

The accompanying drawing indicates, somewhat schematically, typical examples of conditions under which the method of the invention is well adapted to be used. Here a solid stratum in the earth is indicated at E suitable to provide a bearing on or into which the lower ends of piles may be driven. A stratum of soft clay or the like such as above mentioned is indicated at H and on which is superposed a surface layer l2. The outlines of a building structure are indicated at [3 having a foundation portion l4 supported in any of the variousknown ways on the clay. An underground sewer pipe or conduit is indicated at l5 lodged in part within the clay. Under these conditions if a tall or heavy structure is to be built in this region, piles will have to be driven to properly support the same, and these should preferably be driven down through the clay to the solid bearing. On the drawing one of the drilled holes is indicated at 18, filled with water or slurry and of dimensions, as above explained, slightly smaller by a predetermined amount than the pile to be received therein and ready to receive a stepped type corrugated sheet metal sectional pile shell, the same as indicated at H, the shell I! being one which has been driven into a previously drilled hole such as at l6 and at the same time has displaced the water and slurry. The shell H is preferably watertight, its lower end being closed by a plate l8, so that the Water and slurry is displaced from the hole up along the outside walls of the shell as the latter is put in place. As indicated at [9, the shell is filled with concrete after the driving core is removed.

Another one of the corrugated sheet metal pile shells is indicated at 20 in the process of being driven into a hole 2| of slightly smaller diameter,-

the internal stepped driving core being indicated at 22.

While only two pile shells are indicated in the drawing, atthe usual construction job, of course, a great many will be driven at closely adjacent points so that the accumulative displacement effects in the adjacent earth give rise to the difficulties overcome by the procedure of the invention.

A surveying instrument is indicated at 23 on the drawings for'observing a marker as at 24 in the manner above explained, or for observing a small monument as at 25 located on a levee or embankment of a river, the displacement of which is to be avoided by the invention. At the same time a vertical rod 25 may be driven in the unrestrained portion of the embankment and this rod may also be observed with instruments to detect displacements which might otherwise cause damage to the embankment during the pile driving work. For similar purposes a rod 2'! may be driven down and kept in contact with the conduit I5 and similar observations may be made on such rod. The instrument 23 should, of course, as readily will be understood by surveyors, either be located far enough away (for example to the front or rear of the plane shown in the drawing) so that its elevation will not be disturbed by the driving of piles, or when each observation is made by the instrument, its height should be checked and corrected with respect to some fixed point not subject to disturbance by the pile driving activities.

It will be understood that, as compared with of explanation, various 7 the other parts in the drawing, the piles are, for clearness, shown considerably enlarged. It will generally be found convenient, in drilling the holes, to mount the drill rig along with and on one side of the guideways or leads of the pile driving hammer so that after a hole has been drilled, the pile driver rig merely has to be turned slightly about its usual pivotal axis to bring the leads accurately and promptly into proper position for driving a pile or pile shell in alignment with the drilled hole.

Although certain particular embodiments of the invention are herein disclosed for purposes further modifications thereof, after study of this specification, will be apparent to those in the art to which the invention pertains. Reference should accordingly be had to the appended claims in determining the scope of the invention.

What is claimed and desired to be secured by Letters Patent is:

l. In the driving of piles and the like into the earth, in the vicinity of structures subject to damage due to displacement during the driving work. of the earth supporting the structures, the

method which comprises: excavating holes each smaller by a predetermined amount than the piles or the like to be received therein; determining said amount as being such that when the piles are driven into the holes, such an adjacent structure will be caused to start to rise only slightly by an observable amount, but insufficient to damage the structure; then driving the piles into place in said holes; and observing the structure to detect that it has thus started to rise.

2. In the driving of piles and the like into formations of clay, in the vicinity of structures subject to damage due to displacement of the clay during the driving work, the method which comprises: wet drilling holes of generally the same shape as the piles or the like to be received therein but of cross-sectional dimensions which are smaller by a percentage determined as sufficient so that when the piles or the like are driven into said holes, such an adjacent structure will be caused to start to rise only slightly by an observable amount insuificient to damage same; allowing the holes upon drilling to remain sub stantially filled with water and slurry until the piles or the like are driven therein; then driving the piles or the lilze into place; and observing the structure to detect that it has thus started to rise.

3. In the driving of corrugated sheet metal shell types of piles made substantially watertight with closed lower ends, the method which comprises: drilling a hole of a size to permit the pile shell to be tightly embraced therein, by the use of a rotary drill flooded with water; allowing the hole to remain filled with water and slurry until the pile shell is placed therein; then placing the pile shell in position thereby displacing the water and slurry from the hole; driving the pile shell to firm bearing; and finally filling the shell with concrete.

4. In the driving of piles and the like into clay formations in the vicinity of structures subject to damage due to displacement of the clay during the driving work, the method which com prises: drilling holes for a small number of piles, each hole being smaller than the pile to be received therein by a percentage such that when the piles are driven into said holes, such an adjacent structure will be displaced only slightly by an observable amount, but insufficient to damage same; driving such small number or piles into place in said holes; observing the adjacent structure to detect whether it has thus started to rise; estimating on the basis of such observation whether the holes for the remaining piles to be driven should diller a greater or lesser percentage from the piles to be received therein in order to cause said structure to be further displaced only by amounts insufficient to damage same when the latter piles are driven; drilling the holes for the latter piles accordin to the latter estimates; and driving the piles into place therein and then observing the structure to detect whether it is still only slightly displaced by an observable amount.

5. in the driving or" stepped pile shells formed of corrugated sheet metal sections into formations such that adjacent structures supported by the formation are subject to displacement and damage during the driving work, the method which comprises wet drilling a hole of substantially the same shape as the pile shell to be received therein and of a size such that the pile shell when placed therein will be tightly ernbraced by. the walls of the hole; allowing the water and slurry from the drilling operation to remain in the hole pending placing the pile shell therein; then placing the pile shell in the hole; and driving same down to a firm bearing by impacts internally applied to the lower ends of the shell whereby the sections are in effect pulled into the hole and the water and slurry is displaced thereby.

LINTON HART.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,954,094 Newman Apr. 10, 1934.- 2,G89,04l Smith Aug. 3, 1937

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