US3894401A - Sand fill compaction system - Google Patents

Abstract

A system for effecting underwater compaction of submerged sand. The system utilizes a towboat that drags a vibratory compactor slowly over the sea floor as dredged sandy material is deposited. The travel route and speed of the towboat and compactor are coordinated with the dredge discharge rate and discharge location whereby the compactor completes one pass over the entire fill area for each predetermined increment of fill depth.

Description

United States Patent Johnson 1 1 July 15, 1975 [54] SAND FILL COMPACTION SYSTEM 3,336,848 8/1967 Moir .1 404/114 3,371,586 3/1968 Nikolaev et a1 404/113 X 1 1 lflvemori CWT-10111150", Long Beach Cahf- 3.614916 10/1971 Benson 404/133 I B h 3,664,142 5 1972 Jansz 61/72.4 [73] Asslgnee Long Beach Long edc 3.838933 10/1974 Lehman et a1. 404/114 [22] led J ly 1974 Primary Examiner-Dennis L. Taylor [21] AppL NO: 486,178 Attorney, Agent, or Firm-Fu1wider, Patton, Rieber,

Lee & Utecht [52] 1.1.5. Cl 61/724; 61/63 57 S R T i lt ild l f- IIIIIIIII 7 2 A system for effecting underwater compaction of sub- 4 A merged sand. The system utilizes a towboat that drags a vibratory compactor slowly over the sea floor as dredged sandy material is deposited. The travel route [56] References Cited and speed of the towboat and compactor are coordi- UNITED STATES PATENTS nated with the dredge discharge rate and discharge 10- ],380379 6/1921 Heltzel 404/113 cation whereby the compactor completes one pass 153321660 1935 y over the entire fill area for each predetermined incre- 2646,729 7/1953 Godenir ment of n depth. 3.008.388 11/1961 Nare v. 3,292.512 12/1966 Schaperclaus 404/113 11 Claims, 7 Drawing Figures wamwwm SHEET SAND FILL COMPACTION SYSTEM BACKGROUND OF THE INVENTION 1, Field of the Invention The present invention relates generally to dredging and more particularly, to a system for densifying sand fill during a dredging operation.

2. Description of the Prior Art Applicant is aware of the following US. patents directed to the use of a vibrating mechanism for densifying underwater soil:

Degen US. Pat. 3,195,314 Degen US Pat. 3,309,887 Malan US. Pat. 3,413,902 Hanot US. Pat. 3,488,963 Jansz US. Pat. 3,664,l42

SUMMARY OF THE INVENTION The reclamation of submerged coastal land is often accomplished by placing fill material, generally sand, on the site by means of a hydraulic dredge. The initial portion of the sand is necessarily placed below water level where it remains permanently saturated and relatively loose. The land fill thus produced may, under static conditions, be quite stable and capable of carrying normal structural loads. If subjected to the vibrations of a moderate to strong earthquake, however, the loose, saturated material below ground water level may become quick or liquefy. In this condition it may slide or flow horizontally or settle vertically, and may temporarily lose most or all of its load-carrying ability. This hazard can be reduced by adequate compaction of the submerged dredge material. Under existing practice such compaction, if required, takes place after filling has been completed. This is often accomplished by using a vibratory probe, by driving displacement piles, by adding a temporary superimposed load, or by a combination of these procedures. Each of these procedures are time-consuming, costly, and must usually be limited to those portions of a fill area under or immediately adjacent to a proposed major structure. The remainder of the fill area, and the structure resting there-upon, as well as the occupants thereof, are vulnerable to the aforementiond effects of earthquake-induced ground liquefaction.

It is a major object of the present invention to provide a system for effecting underwater compaction of submerged soil so as to construct strong, dense, earthquake-resistant dredged land fills economically and practically. The basic arrangement of such system consists of towing a vibratory compactor slowly over the sea floor as the dredged sandy material is being deposited. The travel route and speed of the towboat and compactor are coordinated with the dredge filling rate and discharge location such that the compactor completes one pass over the entire fill for each predetermined increment of fill depth.

A further object of the present invention is to provide a system of the aforedescribed nature wherein the compactor utilizes a plurality of vibrator plate units flexibly attached to a frame which is in turn connected to a towboat by a cable. The flexibility of attachment permits the vibrator units to adjust individually to unevenness of the fill surface.

An additional object of the present invention is to provide a system of the aforedescribed nature wherein each vibrator plate unit is apertured to reduce the damping effect of the water surrounding the plate.

Yet a further object of the present invention is to provide a system of the aforedescribed nature wherein each vibrator plate is provided with a heavy weight and resilient means are interposed between the weight and the vibrator plate to minimize the vibration damping effect of the weight.

These and other objects and advantages of the present invention will become apparent from the following detailed description, when taken in conjunction with the appended drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view showing a preferred form of soil compaction system embodying the present invention;

FIG. 2 is a top plan view taken in enlarged scale on lines 22 of FIG. 1 and showing a vibratory compactor utilized in said system;

FIG. 3 is a vertical sectional view taken on line 3-3 of FIG. 2;

FIG. 4 is a perspective view in further enlarged scale showing an individual vibrator plate unit embodying the present invention;

FIG. 5 is a top plan view of the vibrator plate unit shown in FIG. 4;

FIG. 6 is a front elevational view of the vibrator plate unit of FIGS. 4 and 5; and

FIG. 7 is a vertical sectional view taken in yet further enlarged scale along line '77 of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a preferred system embodying the present invention includes an underwater vibratory compactor C connected to propulsion means such as a towboat T by a cable 10 so as to be towed along the bed 12 of a body of water 16 such as an ocean, lake or river upon which a thin layer of loose fill material, such as sand 18, has been deposited. The movement of the towboat T and the underwater compactor C are from left-to-right with respect to FIG. I. Vibration is applied to the till sand 18 by means of the underwater compactor C so as to effect densification of such sand as the compactor unit C moves forwardly thereover.

More particularly, the underwater compactor C includes a horizontal, elongated cross-frame, generally designated 20, formed at its front end with a yoke 22 that receives the lower end of cable 10. Frame 20 is transverse to the direction of travel of compactor C and supports a plurality (such as four) of like vibrator plate units, generally designated 24, 26, 28 and 30. Each vibrator plate unit includes a plate defined by plurality of like spaced-apart flat bars 34 which are parallel and extend longitudinally in the direction of travel of the compactor C. As indicated in FIGS. 1, 3 and 4, the front portion of bars 34 are angled upwardly to facilitate their sliding movement over bed 12. The spacing between the bars 34 define apertures that reduce the damping effect of the water 16 surrounding the compactor unit as such bars are vibrated by means of vibrators 40. The spacing should not be so great, however, that sand fill l8 flows upwardly between the bars 34 during forward Compactor movement. Bars 34 trail from transverse front angle elements 36, to which such bars are rigidly affixed as by welding.

Vibrators 40 are of like, conventional construction utilizing rotating weights which are operated either pneumatically or hydraulically through suitable supply and return conduits 50. Conduits 50 extend from a manifold 5B. of frame 20. Manifold Si connects to supply and return hoses 53 attached to a suitable power source (not shown) on towboat T. A suitable type of vibrator is marketed by Koehring, Dart Division of Denver, Colorado.

One of the vibrators may be provided for each of the vibrator plates 24, 26, 28 and 30. To this end, a pair of transversely extending crosspieces 6d and 66 are rigidly affixed to the upper surface of the rear portion of the bars 34, as by welding. One of the vibrators 40 is secured to the midportion of each pair of the crosspieces 64 and 66 by a pair of conventional clamps 68. Preferably, each vibrator 40 is mounted in such a way that the rotary motion of its eccentric weight (not shown) imparts not only a downward vibratory force on the fill sand 18 through bars 34, but also a horizontal component which assists in effecting forward travel of the vibratory compactor.

In order that a maximum downward compactive force may be applied to the sand fill 18, a box-like heavy weight 70 is mounted upon each of the vibrator plates. Thus, a pair of brackets 72, '74 and 76, 78 are affixed to each crosspiece a4 and 66, respectively, for attachment to the corners of weight 70. It is preferable that a pad of resilient material 89 of generally cylindrical configuration be interposed between each corner of the weight '70 and the brackets 72, 7 i and 76, 78 so as to reduce the vibration damping effect of the weight relative to its vibrator plate unit. Such pads are of like construction and one of such pads and its attachment to its respective bracket 78 and one corner of weight 80 is shown in detail in FlG. '7.

It should be particularly noted that the individual vibrator plates 24-, 26, 28 and 30 are moveable vertically relative to crossframe 2t and relative to one another. In this regard, each of the aforementioned front angle elements 36 are provided with a pair of forwardly extending struts 86 and 38 that are pivotally attached to the rear of cross-frame 20. This arrangement permits the vibrator plates to freely selectively automatically adjust to any uneveness of the bed 12 as the compactor unit C moves forwardly thereover.

In the operation of the aforedescribed apparatus, the towboat T is provided with a crane 9% to raise and lower Compactor C relative to the bed 12. With compactor C resting on bed 12 and the vibrators i-ll actuated, towboat T pulls such unit forwardly at a desired rate of speed that is Coordinated with the rate sand fill 18 is deposited and along a path located in the general area upon which such fill is being deposited. The towing speed should be comparatively slow, with a speed of between about one-half to one knot having proven satisfactory. A faster towing rate may be utilized, however, depending upon the number of compactors C employed, the weight thereof, and the vibratory frequency employed. In this regard it will be understood that a plurality of rows of compactors C may be utilized if de sirable.

As the Compactor C moves over sand fill 18, the latter will be effectively compacted by the rapidly vibrating bars 34. The number of passes made with the compactor C will depend upon the increment depth of fill employed, with the compactor unit generally completing one pass for each predetermined increment of fill. Towboat T should be navigated so as to systematically cover the entire fill area, as by means of electronic tracking, laser guidance or visual targets in a manner well-known in the art. At the completion of the compacting operation the fill area will be effectively compacted so as to resist any tendency to liquefy or settle significantly as during an earthquake.

Various modifications and changes may be made with respect to the foregoing detailed description without departing from the spirit of the present invention.

I claim:

1. Compactor apparatus moveable over a submerged soil bed for effecting underwater compaction of the upper layer of such soil, said apparatus comprising:

a frame attachable to propulsion means that moves said frame forwardly over the soil to be compacted;

vibrator plate means connected to said frame, the underside of said plate means resting upon the soil to be compacted; and

vibrator means operatively connected to said plate means to vibrate said plate means and thereby compact said soil as said plate means is moved forwardly thereover.

2. Apparatus as set forth in claim 1 wherein said plate means are apertured to reduce the damping effect of the water surrounding said plate means.

3. Apparatus as set forth in claim 1 wherein said plate means comprise a plurality of transversely aligned plate units affixed to said frame so as to be independently, vertically rnoveable for individual adjustment to the contour of said bed as said plate means move thereover.

4. Apparatus as set forth in claim ll wherein said plate means carry a heavy weight and resilient means are interposed between said weight and the vibrator means for such plate means to reduce the vibration damping effect of said weight.

5. Apparatus as set forth in claim 2 wherein said plate means comprise a plurality of transversely aligned plate units affixed to said frame so as to be independently vertically moveable for individual adjustment to the contour of said bed as said plate means move thereover.

6. Apparatus as set forth in claim 2 wherein said plate means carry a heavy weight and resilient means are interposed between said weight and the vibrator means for such plate means to reduce the vibration damping effect of said weight.

'7. Apparatus as set forth in claim 5 wherein said plate means carry a heavy weight and resilient means are interposed between said weight and the vibrator means for such plate means to reduce the vibration damping effect of said weight.

8. Compactor apparatus moveable over a submerged soil bed for effecting underwater compaction of the upper layer of such soil, said apparatus comprising:

a frame attachable to propulsion means that moves said frame forwardly over the soil to be compacted, said frame extending transversely to the direction in which it is moved;

a plurality of transversely aligned apertured vibrator plates trailing from said frame and pivotally con- 10. Apparatus as set forth in claim 8 wherein each of said plates carry a heavy weight and resilient means are interposed between each vibrator plate and its weight to reduce the vibration damping effect of said weight.

11. Apparatus as set forth in claim 9 wherein each of said plates carry a heavy weight and resilient means are interposed between each vibrator plate and its weight to reduce the vibration damping effect of said weight.

Claims (11)

1. Compactor apparatus moveable over a submerged soil bed for effecting underwater compaction of the upper layer of such soil, said apparatus comprising: a frame attachable to propulsion means that moves said frame forwardly over the soil to be compacted; vibrator plate means connected to said frame, the underside of said plate means resting upon the soil to be compacted; and vibrator means operatively connected to said plate means to vibrate said plate means and thereby compact said soil as said plate means is moved forwardly thereover.

2. Apparatus as set forth in claim 1 wherein said plate means are apertured to reduce the damping effect of the water surrounding said plate means.

3. Apparatus as set forth in claim 1 wherein said plate means comprise a plurality of transversely aligned plate units affixed to said frame so as to be independently, vertically moveable for individual adjustment to the contour of said bed as said plate means move thereover.

4. Apparatus as set forth in claim 1 wherein said plate means carry a heavy weight and resilient means are interposed between said weight and the vibrator means for such plate means to reduce the vibration damping effect of said weight.

5. Apparatus as set forth in claim 2 wherein said plate means comprise a plurality of transversely aligned plate units affixed to said frame so as to be independently vertically moveable for individual adjustment to the contour of said bed as said plate means move thereover.

6. Apparatus as set forth in claim 2 wherein said plate means carry a heavy weight and resilient means are interposed between said weight and the vibrator means for such plate means to reduce the vibration damping effect of said weight.

7. Apparatus as set forth in claim 5 wherein said plate means carry a heavy weight and resilient means are interposed between said weight and the vibrator means for such plate means to reduce the vibration damping effect of said weight.

8. Compactor apparatus moveable over a submerged soil bed for effecting underwater compaction of the upper layer of such soil, said apparatus comprising: a frame attachable to propulsion means that moves said frame forwardly over the soil to be compacted, said frame extending transversely to the direction in which it is moved; a plurality of transversely aligned apertured vibrator plates trailing from said frame and pivotally connected thereto for individual vertical movement relative to said frame and to one another; and a vibrator carried by each of said vibrator plates to vibrate said plates and thereby compact said soil as said frame is moved thereover.

9. Apparatus as set forth in claim 8 wherein said vibrator plates are defined by a plurality of parallel longitudinally extending, spaced-apart bars having their front portion angled upwardly.

10. Apparatus as set forth in claim 8 wherein each of said plates carry a heavy weight and resilient means are interposed between each vibrator plate and its weight to reduce the vibration damping effect of said weight.

11. Apparatus as set forth in claim 9 wherein each of said plates carry a heavy weight and resilient means are interposed between each vibrator plate and its weight to reduce the vibration damping effect of said weight.

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