US3774718A

US3774718A - In-situ acoustic sediment probe

Info

Publication number: US3774718A
Application number: US00257022A
Authority: US
Inventors: Y Igarashi; J Campbell; R Allman
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1972-05-25
Filing date: 1972-05-25
Publication date: 1973-11-27
Anticipated expiration: 1990-11-27

Abstract

An in-situ acoustic sediment probe which includes a barrel having a bottom cutting edge. An acoustic transducer is mounted on the barrel and means are mounted within the barrel for removing sediment adjacent to the cutting edge as the barrel penetrates the sediment. The sediment removing means may include an open-ended tube concentrically mounted within the barrel so as to provide an annular water passage between the barrel and the tube. The tube has a bottom end which is spaced above the bottom cutting edge of the barrel so that upon forcing water through the water passage the water will jet into the barrel space below the tube, remove sediment, and displace the sediment upwardly through the tube. In this manner, the sediment adjacent to the transducer will remain substantially undisturbed so that more accurate acoustic data can be obtained with the probe.

Description

[ Nov. 27, 1973 ABSTRACT paced above the bottom cutting and displace be. In this manill re- Primary Examiner-Benjamin A. Borchelt Assistant ExaminerJ. V. Doramus AttorneyRichard S. Sciascia et al.

An in-situ acoustic sediment probe which includes a barrel having a bottom cutting edge. An acoustic transducer is mounted on the barrel and means are mounted within the barrel for removing sediment adjacent to the cutting edge as the barrel penetrates the sediment. The sediment removing means may include an open-ended tube concentrically mounted within the barrel so as to provide an annular water passage between the barrel and the tube. The tube has a bottom end which is s edge of the barrel so that upon forcing water through the water passage the water will jet into the barrel space below the tube, remove sediment,

the sediment upwardly through the tu ner, the sediment adjacent to the transducer w main substantially undisturbed so that more accurate acoustic data can be obtained with the probe.

10 Claims, 3 Drawing Figures lN-SITU ACOUSTIC SEDIMENT PROBE [75] Inventors: Yoshiya Igarashi, Altadena; James R. Campbell, Arcadia; Richard L. Allman, La Canada, all of Calif.

The United States of America as 70 05 wno I. 059 f 7735 A e 2 v. 3 Z 0 m flfim A 5 7 C %7 6 1 "1 D 5 8 2 M a 15 m tm NH m 0 you 3 "C7 b.m 2 7 "P h 7 u" .I. a m N W t 5 W 2 u m 2 m m m A v. ""0 a m 3 RN M 2 m o. 5 N 1.. LM/ C 1 d l d8 e p s .1 n P ma F A U IF 1 1] 2 .l 2 00 2 2 5 [73] Assignee:

[56] References Cited UNITED STATES PATENTS 3,186,502 6/1965 Rademacher......................... 3,376,922 4/1968 Leonhardt PAIENIEDHuvzv 197s 3,774,718

SHEET 2 BF 2 1 IN-SITU ACOUSTIC SEDIMENT PROBE 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 The present invention relates to an in-situ acoustic sediment probe which can be driven into sediment with substantially no disturbance of the sediment adjacent to its exterior wall.

Ocean-bottom sediment can be classified according to its acoustic properties by inserting a pair of spaced probes within the sediment. One probe transmits an acoustic signal and the other probe receives the signal. These signals are then compared to determine the speed and attenuation of sound within the particular sediment in question.

A prior method of obtaining acoustic data of ocean sediment consisting of driving solid cylinder acoustic probes with conical points into the sediment. This type of configuration disturbed the sediment surrounding the probe since the conical point deflected the sediment laterally upon penetration. This disturbance resulted in erroneous data. Further, in marine sediments with a high sand content, measurements at desired depths were often impossible because of the resistance to penetration of a solid probe.

SUMMARY OF THE INVENTION The present invention provides an acoustic sediment probe which can be easily inserted into marine sediment with substantially no disturbance of the sediment adjacent to the exterior wall of the probe. This has been accomplished by providing a barrel which has a bottom cutting edge, a transducer mounted on the barrel, and means mounted within the barrel for removing sediment adjacent to the inside cutting edge as the barrel penetrates the sediment. The sediment-removing means may include an open ended tube concentrically mounted within the barrel so as to provide an annular passage between the barrel and the tube. The tube has a bottom end which is spaced above the bottom cutting edge of the barrel so that upon forcing water through the water passage the water will get into the barrel space below the tube, remove sediment therefrom, and displace the sediment upwardly through the tube. In this manner, a sediment core with substantially the same diameter as the barrel is removed as the barrel penetrates the ocean bottom. Sediment adjacent to the barrel is left substantially undisturbed so that sediment sound speed and attenuation can be measured under true in-situ conditions.

OBJECTS OF THE INVENTION An object of the present invention is to provide an in-situ acoustic sediment probe which can be inserted into soil or sediment with substantially no disturbance thereof.

Another object is to provide an in-situ sedimentprobe which can be easily inserted into sandy sediment and enable collection of accurate acoustic data.

A further object is to provide a method of enabling a more accurate determination of the acoustic properties of a material.

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 FIG. 1 is a vertical ocean view of the sediment probes mounted on a work vehicle which is tethered to a surface ship.

FIG. 2 is a longitudinal vertical cross-section view of the sediment probe.

FIG. 3 is an isometric view of a pair of laterally spaced probes mounted on a horizontal member which is removed from'the work vehicle to illustrate various details.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings there is shown in FIG. 1 a submerged work vehicle 10 which istethered to a surface ship 12 by a cable 14 for desired movements and work functions within the water. A pair of the present acoustic probes l6 and 18 may be mounted in a laterally spaced relationship on the work vehicle 10 by a horizontal member .20. The probe 16 may be adapted for transmitting acoustic signals and the probe 18 may be adapted for receiving these signals. When the work vehicle is lowered so that the

probes

16 and 18 are allowed to penetrate the ocean bottom this acoustic transmission will enable a determination of sound velocity and attenuation characteristics of the sediment. The work vehicle 10 is merely atypical platform for the probes l6 and 18, and it should be understood that other platforms, such as independently operating submarine vehicles, or even divers, could place the probes into position.

In FIG. 2 there is shown an illustrative embodiment of the present acoustic sediment probe 16 or 18.This probe includes a barrel assembly 22 which has a bottom cutting edge 24. A transducer 26, for either transmitting or receiving acoustic signals, is mounted on the barrel assembly 22. It is important that when the probe penetrates the ocean bottom that the sediment surrounding the transducer 26 be substantially undisturbed. In this manner, the acoustic data obtained will more nearly indicate the true characteristics of the sediment in question. This has been accomplished by providing the probe with means in the barrel assembly 22 for removing sediment adjacent the inside of the cutting edge 24 as the barrel penetrates the ocean bottom.

The sediment removing means may include an open ended sediment discharge tube 28 which is concentrically mounted within the barrel assembly 22 so as to provide an annular water passage 30 between the barrel 22 and the tube 28. The tube 28 has a bottom end 32 which is spaced above the bottom cutting edge 24 so as to provide a sediment removing chamber 34 therebetween.

The barrel 22 may include a tube 36 and a cutting head 38 which is mounted to the tube 36 by any simple means such as bolts 40. These bolts 40 may extend inwardly beyond the tube 36 so as to concentrically position the bottom end of the sediment discharge tube 28 within the barrel assembly 22. The cutting head 38 may have a top end 42 which radially extends from the barrel tube 36. An elastomeric jacket 44, such as polyethylene, may be mounted about the barrel tube 36 above and substantially coextensive with the exterior surface of the cutting head 38. In this manner the probe 22 has a smooth exterior surface along its entire length. The transducer 26 may be embedded in the elastomeric jacket 44 along with its connecting wire 46.

As illustrated in FIG. 2 the top end of the barrel assembly 22 may be closed by a plate 48. The tube 28 may extend through this plate 48 and be open at its top for the discharge of sediment as will be described in more detail hereinbelow. The plate 48 also serves as a means for positioning the top end of the sediment discharge tube 28 within the barrel assembly 22. The wire 46 may exit the plate 48 through a plug 50 and the plate 48 may be provided with a fitting 52 for introducing water under pressure into the annular water passage 30.

It is desirable that water exiting the bottom of the water passage 30 and entering the sediment removing chamber 34 efficiently remove the sediment therefrom so that there is a minimum of disturbance to the sediment surrounding the exterior of the probe. This function can be enhanced by providing the bottom of the tube 28 with a flare 54 so that the water will jet outwardly in the sediment removing chamber 34. This jetting action can be optimized by providing the inside surface of the barrel cutting head 38 with a first rapidly diverging portion 56 and then a more gradual diverging portion 58 in the sediment removing chamber 34. This uniquely configured cutting head causes inward deflection of the sediment and almost no outward deflection so as to produce minimum disturbance to the sediment adjacent to the exterior of the barrel assembly 22. The annular jet of water from the water passage 30 cuts out the sediment along the thin cross section of the cutting head 38 and circulates the mixture of water and sediment upwardly into the tube 28.

In FIG. 3 the work vehicle, the member 20 has been shown removed so that various details can be described more fully. The top plates 48 of the

probes

16 and 18 may be mounted to the bottom side of the member 20 with the sediment discharge tubes 28 and the water fittings 52 extending therethrough. A pump 60 may be mounted on the top of the member 20 and the water fittings 52 may be joined thereto by water hoses 62. In this manner the pump 60 will be capable of pumping water through the hoses 62 into the annular water passages 30 (see FIG. 2) of the

probes

16 and 18. A pressure-limiting device (not shown) may be included either internal to or external to the pump. Also there may be mounted on the member 20 an electronics relay box 64 for relaying the transmitted and received acoustic signals from and to the surface ship. The wires 46 from the transducers 26 of the probes l6 and 18 extend through the member 20 and are connected to this relay box 64. Accordingly, the transmitted acoustic signals of 16 are received by the probe 18 and these received signals provide the data which enables classifying the sediment of the ocean bottom.

OPERATION OF THE INVENTION The pump 60 is on so that further lowering of the work vehicle causes the

probes

16 and 18 to easily penetrate the ocean bottom. During penetration water is pumped through the water passages 30 into the sediment removing chambers 34. This action loosens the sediment and forms a water sediment mixture which is forced upwardly within the sediment discharge tubes 28 and finally discharged through the tops thereof. After the probes l6 and 18 have been penetrated within the ocean bottom to a desired depth acoustic signals are transmitted from the probe 16 and received by the probe 18. It can readily be understood that the sediment between the probes has been substantially undisturbed since all sediment represented by the penetrated volumes of the probes 16 has been removed.

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.

We claim:

1. An in-situ acoustic sediment probe comprising:

a barrel assembly having a bottom cutting edge;

a transducer mounted on the barrel assembly outside the inner surface thereof;

means mounted within the barrel assembly for removing sediment adjacent the inside cutting edge and discharging the sediment through the barrel assembly as the barrel penetrates the sediment,

whereby sediment adjacent the exterior of the barrel assembly is substantially undisturbed for acoustic transmission.

2. A probe as claimed in claim 1 wherein the sediment removing means includes:

an open ended tube concentrically mounted within the barrel assembly so as to provide an annular water passage between the barrel assembly and the tube; and

said tube having a bottom end which is spaced above the bottom cutting edge of the barrel assembly whereby upon forcing water through the water passage the water will jet into the barrel space below the tube, remove sediment, and displace the sediment upwardly through said tube.

3. A probe as claimed in claim 2 including:

the bottom end of the tube being flared so that water leaving the water passage will jet outwardly in the barrel space below the tube.

4. A probe as claimed in claim 3 including:

the inside surface of the barrel assembly below the tube first rapidly diverging and then gradually diverging to the bottom cutting edge of the barrel assembly. 5. A probe as claimed in claim 2 including: said barrel assembly comprising:

a tube;

a cutting head concentrically mounted to the barrel tube and having a top end which radially extends from the barrel tube;

an elastomeric jacket mounted about the barrel tube and substantially coextensive with the exterior surface of the cutting head; and

said transducer being imbedded in the elastomeric jacket.

6. A probe as claimed in claim 2 including:

means closing the top end of the barrel assembly; and

the closing means having a water inlet which opens into the water passage between the barrel assembly and the tube.

7. A probe as claimed in claim 6 including:

said barrel assembly comprises:

a tube;

a cutting head concentrically mounted to the barrel tube and having a top end which radially extends from the tube;

an elastomeric jacket mounted about the barrel tube and substantially coextensive with the interior surface of the cutting head; and

said transducer being imbedded in the elastomeric jacket.

Claims

1. An in-situ acoustic sediment probe comprising: a barrel assembly having a bottom cutting edge; a transducer mounted on the barrel assembly outside the inner surface thereof; means mounted within the barrel assembly for removing sediment adjacent the inside cutting edge and discharging the sediment through the barrel assembly as the barrel penetrates the sediment, whereby sediment adjacent the exterior of the barrel assembly is substantially undisturbed for acoustic transmission.

2. A probe as claimed in claim 1 wherein the sediment removing means includes: an open ended tube concentrically mounted within the barrel assembly so as to provide an annular water passage between the barrel assembly and the tube; and said tube having a bottom end which is spaced above the bottom cutting edge of the barrel assembly whereby upon forcing water through the water passage the water will jet into the barrel space below the tube, remove sediment, and displace the sediment upwardly through said tube.

3. A probe as claimed in claim 2 including: the bottom end of the tube being flared so that water leaving the water passage will jet outwardly in the barrel space below the tube.

4. A probe as claimed in claim 3 including: the inside surface of the barrel assembly below the tube first rapidly diverging and then gradually diverging to the bottom cutting edge of the barrel assembly.

5. A probe as claimed in claim 2 including: said barrel assembly comprising: a tube; a cutting head concentrically mounted to the barrel tube and having a top end which radially extends from the barrel tube; an elastomeric jacket mounted about the barrel tube and substantially coextensive with the exterior surface of the cutting head; and said transducer being imbedded in the elastomeric jacket.

6. A probe as claimed in claim 2 including: means closing the top end of the barrel assembly; and the closing means having a water inlet which opens into the water passage between the barrel assembly and the tube.

7. A probe as claimed in claim 6 including: said tube extending through the top closed end of the barrel assembly.

8. A probe as claimed in claim 7 including: the bottom end of the tube being flared so that water leaving the water passage will jet outwardly in the barrel space below the tube.

9. A probe as claimed in claim 8 including: the inside surface of the barrel assembly below the tube first rapidly diverging and then gradually diverging to the bottom cutting edge of the barrel assembly.

10. A probe as claimed in claim 9 wherein: said barrel assembly comprises: a tube; a cutting head concentrically mounted to the barrel tube and having a top end which radially extends from the tube; an elastomeric jacket mounted about the barrel tube and substantially coextensive with the interior surface of the cutting head; and said transducer being imbedded in the elastomeric jacket.