US3521415A - Sand column support - Google Patents

Description

July 21, 1 970 K. o. VARTIA SAND COLUMN SUPPORT Original Filed Aug. 12, 1964 AAA ' 1N VENTOR.

United States Patent 3,521,415 SAND COLUMN SUPPORT Karl 0. Vartia, 5214 Grover Ave., Austin, Tex. 78756 Original application Aug. 12, 1964, Ser. No. 389,139, now Patent No. 3,382,627, dated May 14, 1968. Divided and this application Mar. 19, 1968, Ser. No. 749,224 Int. Cl. B66b 29/18; E04g 21/00 US. Cl. 52--126 1 Claim ABSTRACT OF THE DISCLOSURE The invention comprises a supporting arrangement for heavy concrete slabs and the like, to be used in conjunction with a lifting means, whereby a slab can be fabricated at ground level or on a previously placed slab and then be held at any intermediate level during the process of being raised to a final elevated position. The supporting arrangement utilizes the characteristics of dry sand or equivalent cohesionless granular material which will flow relatively freely under the action of gravity on slopes exceeding its angle of repose but which will develop a high passive resistance to load when confined or partially confined in such a way that its angle of repose is not exceeded.

This is a division of application Ser. No. 389,139 filed Aug. 12, 1964, now patent No. 3,382,627 issued May 14, 1968, for Sand Column Support.

The invention has particular application when used in conjunction with inflatable balloons as the lifting means. Such a lifting means is disclosed in my Pat. No. 2,749,- 592. Because of the low pressures that can be used with balloons having relatively large contact area with a slab supported thereby, the balloons can be made of inexpensive fabrics, and the blowers used to inflate them can be low cost centrifugal blowers on the order of household vacuum cleaners.

However, the balllons do not provide a safe intermediate support since excessive loss of air would permit the load to descend, perhaps at a damaging rate. My present invention overcomes this problem by the arrangement further described herein, which in general terms, simply provides a confined space defined in part by a surface integrally connected with the part being lifted and then provides means for feeding sand or its equivalent into the confined space as it becomes larger through the raising of the part being lifted. Should lifting cease and a retrograde movement begin, the passive resistance of the sand quickly rises to a value suflicient to carry the load independently of the lifting means.

The confined space, other than the portion attached to the part being lifted, is usually a hole in the foundation. However, for special cases, an alternate arrangement may be preferred in which the confined space is provided above the slab being lifted. For a more particular description of the invention reference is made to the attached drawings in which,

FIG. 1 is an elevation showing a general type or method of construction in which my present invention is used, with ballons as a lifting means,

FIG. 2 is an enlarged cross-section through one of the posts and parts of the foundation shown in FIG. 1,

FIG. 3 is an elevation of an alternative lifting means for use with supporting posts such as in FIGS. 1 and 2,

FIG. 4 is a cross-section of an alternate arrangement for a supporting post,

FIG. 5 is an alternate arrangement for supplying sand to downwardly projecting posts as in FIGS. 1 and 2 and FIG. 6 is an alternate form of the post of FIG. 1.

Referring now to FIG. 1, a slab 1 to which are rigidly attached posts 2 is being lifted by inflation of balloons 3. The posts 2 project down into holes preformed in the foundation 4. As shown in FIG. 2, the posts 2 are hollow steel pipes provided at their lower ends with flanges 5 having a diameter approaching that of the holes 6 in the foundation 4. The posts would have been placed in the holes prior to the fabrication of slab 1, with the upper ends of the posts being suitably anchored and embedded in the slab to enable them to carry the weight of the slab as supporting columns. The steel pipes are filled with sand 7 which also fills the holes in the foundation up to the level of the flanges '5. If the slab -1, with the attached posts 2, is caused to rise, sand flows from the pipes into the holes to maintain contact with the undersides of the flanges 5. The sand supply is replenished as necessary through the open top ends of the pipes. Whenever the support of the lifting means is Withdrawn for any reason, the weight of the slab 1 is transferred through posts 2 to the flanges 5 and thence to the sand 7. After the slab has been raised to the required final position any of several procedures may be followed. For instance, load hearing walls may be constructed or installed at the perimeter of the slab and the load transferred thereto by appropriate wedging. The sand could then be removed by vacuum from the posts and from beneath the flanges 5, and the posts or portions thereof could then be removed for reuse elsewhere. Or the lower ends of the posts could be anchored to the foundation to remain as permanent supports. Such anchorage could include a temporary transfer of the load to an alternate support while sand is removed from the post and hole, with the hole then being filled with concrete to encase and support the post and its portion of the Weight of the slab 1. Or the sand could be left in place and impregnated with chemicals that would convert it into an unmovable support. Should it be undesirable to provide holes the full depth of the required lift, shorter posts 2 may be installed in shallower holes 6 and the lift procedure carried out to the extent possible. The load at each support point may then be relieved, all or part of the sand removed and an additional length of post installed. Alternatively, the hole 6 might be extended upwardly at this time by extending the casing.

FIG. 3 illustrates the use of hydraulic jacks 8 in place of balloons 3 as a lifting means. Preferably the slab 1 would have been fabricated upon a deflated balloon as disclosed in my Pat. No. 2,749,592 and then lifted a short distance by inflation of the balloon. As before, sand from the pipe column 2 would fill the hole beneath the flanges 5, permitting the initial lift to be stopped as soon as required clearance for the jacks had been obtained. The jacks could then be mounted on the pipe columns either by solidly bolted clamps or by pivoted yokes which would cause sharp edges on the jack assembly to wedge into the pipe when hydraulic pressure is applied to the jack. The moveable head of the jack would engage the foundation to lift the pipe a short distance out of the hole. Since, as with the balloon lifting means, sand from the pipe would fill the hole beneath the flange 5, the hydraulic jack can be unloaded at any time and repositioned to continue the lift. It should be noted at this point that there exists a significant distinction between the lift afforded by a large balloon and that ,by separate hydraulic jacks. This difference calls for slightly different procedure in the lifting process to insure adequate control. Whereas the large balloon in contact with the underside of the slab provides inherent balancing for the slab, separate hydraulic jacks connected to a common pressure source would not. If there is tilting of the slab on the balloon, support is automatically withdrawn on the rising side and added on the opposite side. Unless the balloon is improperly placed, the slab comes into equilibrium within tolerable limits of tilt. With hydraulic jacks on a common line, however,

the lifting force at opposite sides does not vary with the tilt to thus control the tilt. Consequently it is necessary to have valving in the hydraulic lines to control the lift. However, with the sand follow-up support it is not necessary to provide the individual precise control of lift at each jack point that is characteristic of the usual structural jacking procedures. Instead it is only necessary to provide valving that will permit closing the lines to two or more jacks on a straight line at one edge of the structure and to apply pressure from a common line to the remaining jacks until permissible tilt about the non-lifting support points has been reached. Pressure is then relieved at the jacks on the high edge and applied to the other jacks to first level the slab and then tilt it the maximum permissible amount in the other direction. This procedure is repeated until final position is attained.

FIG. 4 illustrates an inverted supporting arrangement for use where it is impracticable to provide holes beneath the slab to house the posts and to serve as the containers for the supporting column of sand. In this case posts 9 rest on or may be rigidly anchored in foundation 4. The posts 9 are closed at the top and have at their upper ends suitable packing 10 to provide a sand-tight fit with an outer casing 11. This outer casing is placed over post 9 to rest upon the foundation 4 while slab 1 is fabricated about it. Outer casing -11 is provided with suitable anchorage so that its embedment in slab 1 will be sutficiently firm to permit the slab load to be transferred to the casing at later stages in the process. The casing 11 preferably has near its upper end a constriction 12. Sand is placed in the upper end of the casing prior to lifting the slab and flows past the constriction to fill the casing down to the top of post 9. Should lifting be interrupted and retrograde movement begin, the constriction prevents the sand from being pushed upwardly out of the casing and the slab load is then carried through the post 9 to the foundation 4. The constriction would be unnecessary if a sufficient length of sand-filled casing 11 were provided above the top of the post 9 to initiate by means of friction on the inside surface the internal arching that wedges the sand in the casing.

FIG. substitutes a solid post 14 for the hollow post of FIGS. 1 and 2 and shows a separate tube 15 for conveying sand into hole 6 and thence underneath the solid end of post 14. Either the slab to be raised or the side of the hole in the foundation could have a hole for initial entry of sand while the slab is still in contact with the foundation. After raising has begun the tube 15 could be entered directly into the hole 6 and would be fixed to the post 14 or otherwise maintained in a proper functional position with respect to the bearing area at its lower end. The sizes of both the post and the hole and the load to be carried by the post enter into the determination of proper position. The depth to which the lower end of the post can safely be buried in the loose sand is influenced by the clearance between the post and the side of the hole. If the depth of burial were to become excessive with respect to clearance the sand could become packed between the sides of the post and the sides of the hole sufficiently to seriously interfere with the desired free upward movement of the post. If the depth of burial be insuificient, the sand will not How into position beneath the bearing area of post 14 with sutficient firmness to quickly build up support against retrograde movement. However, the considerations just noted allow a sufilcient range of satisfactory functioning that, as an instance, with a slender post and a correspondingly light structure, plus a somewhat oversize hole, the hole could be completely filled initially with loose sand, with no addition being required to make up for the volume of the withdrawn post until final stages of lifting. Still further, where the hole is thus filled initially, instead of using dry sand to insure its free-flowing quality, the sand may be completely saturated to obtain the same action. However, there is then an increased possibility that inadvertent vibration of the structure might prematurely pack the sand about the post to prevent its withdrawal. As insurance against such a happening, the post might be wrapped in a thin plastic sheath. Such a sheath is very slippery when wet and would permit easy withdrawal of the post. The sheath would remain in the sand and collapse beneath the post under the pressure of the sand to permit the latter to come into supporting position.

FIG. 6 merely illustrates an alternate form of post which would function similarly to the post 2 and flange 5 of FIG. 2. In this case the post 16 substantially fills the hole and has an inner passageway 17 and lower bearing surface 18.

My invention is readily adapted to multi-story building construction. The raised slab needs only to be provided with suitable holes in which casings may be installed, to become the foundation 4 for fabricating an additional slab. The holes and casings would preferably be located in close proximity to the supporting points for the previously raised slab to enable vertical continuity of support from the posts of the uppermost slab through the sandfilled casing to the supporting structure of the lower slab or slabs.

Also the combination of inner and outer casings movable with respect to each other and provided with arrangements such as in FIGS. 4 or 6 for feeding sand into a confined space defined in part by each could be applied to individual adjustable shores for general use in construction. Such shores could be either wedged or jacked into supporting position after being extended to approximately the required length and manipulated to cause sand to fill the confined space.

I claim:

1. An extensible structure support comprising an outer casing attached to a structure to be supported and projecting upwardly therefrom, said outer casing having an open top end and a constriction in the upper portion, a post within said outer casing projecting downwardly to a supporting foundation and having an upper end closely fitting the inner surface of said outer casing below the level of said constriction, and a supply of sand or equivalent granular material filling the space defined by said outer casing and said internal constriction, whereby load from said outer casing is enabled to be transmitted in turn to said internal constriction, thence to the filling of sand, thence to said post and thence into the foundation.

References Cited UNITED STATES PATENTS 2,510,688 6/1950 Evans 248354 2,555,359 6/1951 Montague 61-52 2,741,910 4/ 1956 Thornley 52l22 FOREIGN PATENTS 315,414 1930 Great Britain. 1,277,405 1961 France.

JOHN E. MURTAGH, Primary Examiner U.S. Cl. X.R. 248334

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