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Rapid and reliable technique for determining unit weight and porosity of deep-sea sediments
Marine Geology - Elsevier Publishing Company, Amsterdam - Printed in The Netherlands
RAPID
AND
RELIABLE
TECHNIQUE
FOR
DETERMINING
UNIT
WEIGHT AND POROSITY OF DEEP-SEA SEDIMENTS RICHARD H. BENNETT AND DOUGLAS N. LAMBERT National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratories, Marine Geology and Geophysics Laboratory, Miami, Fla. (U.S.A.}
(Received March 10, 1971) ABSTRACT
BENNETT,R. H. and LAMBERT,D. N., 1971. Rapid and reliable technique for determining unit weight and porosity of deep-sea sediments. Marine Geol., 11: 201-207. A rapid and reliable technique is explained for determining unit weight and porosity of deep-sea sediment from water content and average grain density measurements. Comparisons are made between this method and the standard tube method (volumetric), with 77 samples. The correlation coefficient is found to be 0.994 with a standard deviation between the methods of 4- 0.01 g/cmL The two techniques used to determine porosity are found to have a correlation coefficient of 0.998 with a standard deviation of 0.42~. A nomographic chart is shown which permits rapid determination of unit weight using water content and average grain density.
INTRODUCTION Unit weight o f submarine sediments, also referred to as wet bulk density or saturated unit weight, is a function o f the grain specific gravity and water content. By definition, unit weight is the weight per unit o f volume regardless of the degree o f saturation (A.S.T.M., 1967). However, submarine sediments, especially deep-sea sediments, are usually totally saturated. A c o m m o n technique for measuring unit weight is by inserting a tube o f k n o w n volume into a sediment mass, such as a core, extracting the tube and sediment and determining the sediment weight. This gives a measure of the mass in grams per unit o f volume. Difficulty in eliminating small voids between the cylinder wall and the sample as well as the influence o f gases which m a y be present in the interstitial water due to the change f r o m high hydrostatic pressure to atmospheric pressure could affect the unit weight as measured in the laboratory. In an undisturbed sediment sample the relative proportions o f water to solids are not destroyed and at 100 ~ saturation, unit weight is at a maximum. BENNETT et al. (1970) consider ___ 1 ~o o f the observed value to be a reasonable estimate o f the reproducibility o f the tube method. Porosity (n), defined as the ratio o f the volume o f the voids to the total volume o f the sediment mass, is usually c o m p u t e d from unit weight, average grain Marine Geol., 11(1971) 201-207
202
R. H. BENNETT AND D. N. LAMBERT
density, water content and an assumed interstitial water density. It is sometimes determined from the void ratio by the relationship n = e/(l + e). Void ratio (e) is defined as the ratio of the volume of the voids to the volume of the solids. The purpose of this study is to describe a rapid and reliable technique for determining unit weight and porosity of deep-sea sediment with an evaluation of the method using various sediment types. Carbonate content of the sediments ranged from less than 10~ to greater than 98~, and textures ranged from less than 1 ~ to greater than 66 ~ sand-size particles. TECHNIQUESAND BASICPRINCIPLES An advantage of the technique employed here for determining unit weight and porosity is that raw data from water content and grain density measurements are used. These data are frequently studied by the marine geologist and ocean engineer concerned with mass physical properties of submarine sediments and are usually numerous and readily available from laboratory reports. Water content measurements are determined from approximately 10--20 g samples of sediment taken from the center of a core. The sample is immediately weighed and dried for about 24 h at 110 °C and then reweighed to determine water loss. Average grain density is usually found by volumetric displacement of distilled water by the solids in a calibrated flask (LAMBE,1951). From these three measurements, weight of dry solids, weight of water driven off during drying, and the average grain density, the unit weight (~) can be easily determined by the following relationships:
wtt
~--Wd+Ww Dg
-
w,o~ W.+ WwO~
(~)
where Wt = Ww + Wo; Ww = weight of the water = approximately the volume of water; Wd = weight of dry solids including salts; Dg = average grain density. The total weight (Wt) of the sample taken for water content determination is equal to the weight of the water lost during oven drying (Ww) plus the weight of the dry solids (Wa). For practical purposes Ww is equivalent to the volume of water in the cgs system. The weight of the solids divided by the average grain density (Wd/Dg) is the volume of the dry solids. The weight of the dry solids contains the weight of the salt. However, this increase in the volume of the solids, due to the presence of salts, closely approximates the slight deficit in the volume of the water (Ww) owing to the dissolved salts in the interstitial water. Therefore, by definition, the unit weight of the sample is equal to the total weight divided by the total volume. Similar expressions may be equated with eq.1 in text books on soil mechanics such as TERZAOHIand PECK (1967), SCOTT (1963) and Wu (1966) and Marine GeoL, 11(1971) 201-207
UNIT WEIGHTAND POROSITYOF DEEP-SEASEDIMENTS
203
are usually intended to show the relationships among density, porosity, and void ratio for a given sediment mass. Porosity (n), expressed in percent, is the ratio of the volume of the voids to the total volume of the sediment mass and can be determined by the relationship: n-
Vw + Vss
w~ Dg
x 100
(2)
+Ww
Vs~is the volume of the salts in solution. Again, Vwis equal to the volume of the water and approximately equal to the weight of the water in grams. If Vs~ is neglected or considered negligible the equation then becomes: n-
w.
× 100
(3)
--+Ww Dg Vss is very close to 1.2 ~ of Vw for concentrations of dissolved salts of 35~o. RELIABILITY As a measure of the reliability of the above technique expressed by eq. 1, 77 unit weight measurements were determined using this method and compared with unit weight determinations using the tube method. In addition, porosity was determined using eq.3 from the same raw data used to obtain unit weight. These values were compared with porosities calculated from unit weight measurements determined by the tube method, average grain density and water content values with no corrections for salt content. Correlation coefficients were determined for unit weight and porosity. A linear correlation coefficient of + 0.994 was found between the two unit weight techniques with 67 700 of all measured values failing within 0 . 0 1 g/cm 3 of each other. A linear correlation coefficient of +0.998 was found between the two porosity methods with 67 ~ of all measured values falling within 4-0.42 700 of each other. The significance of these data shows that for all practical purposes, the correlation between the techniques is nearly perfect and that either method for determining unit weight and porosity is as good as the other. RELATIONSHIPS The effect of large differences in drying temperatures has been found to be not as critical as might be expected. Using eq.l and data from LAMBE (1951), differences in drying temperatures from 90°C to 190°C increase the unit weight measurement by only 0.002--0.004 g/cm 3. Porosity values determined by eq.3 however, show differences ranging between 1 ~ and 3 ~ when drying temperature varies from 90°C to 190°C. Usually consistent techniques and control of ternMarine GeoL, 11(1971) 201-207
204
R. H. BENNETT AND D. N. LAMBERT
perature within reasonable limits are well within the means of most soils laboratories. Examination of eq.1 reveals that large changes in average grain density are necessary to appreciably affect the unit weight measurement. Clearly, the higher the water content the less average grain density variation influences those determinations. For example, with a water content of 50 ~ an increase in average grain density from 2.75 to 2.80 increases the unit weight from 1.736 to 1.750. However, at a water content of 100K a change in the grain density of 0.05 changes the unit weight by only 0.007 g/cm 3. The other parameters Wt, Ww and Wd depend upon the accuracy of the balance which is usually well within the reproducibility of the technique described here. Due to the above relationships, difficulty in determining unit weight and porosity of relatively clean sands by the proposed method might be encountered because such sediments are usually characterized by low water contents. Obtaining a true water content for this sediment type may be difficult. However, accurate unit weight and porosity values of a relatively clean sand are also difficult to obtain with the tube method because of possible loss of pore water in inserting the tube into the sediment and its subsequent handling. DISCUSSION
Several advantages of the technique expressed in eq.1 for determining unit weight are apparent. If gas is present it does not affect the measurement, and values of unit weight for 100 %osaturation at a given water content are obtained. This is considered by the authors to be a closer approximation of the actual unit weight, in situ, than values obtained by the tube method (volumetric), especially for sediment that includes gas. In addition, unit weight and porosity can be determined for relatively thin stratified sediment with a minimum amount of material and for small irregularly shaped pieces of cohesive sediment not amenable to the tube method. Volumetric errors introduced in the tube method include error resulting in the incomplete filling of the tube with sediment and inaccurate measurement of the radius of the tube (any error in the radius is squared). Unit weight and porosity, using the relationships of eq.1 and 3, are determined from measured parameters which consequently avoids the use of any assumed values such as the density of interstitial water and average grain density. However, relatively large variations in the average grain density are required to appreciably influence the unit weight determination by eq.1. Large changes in the drying temperatures such as 90°-190°C usually have small affects on the unit weight determination; however, porosity by eq.3 is more responsive to these temperature differences. Control of temperature is important when porosity values are critical and comparable to within 1 ~ of the observed values. Fig.1 was constructed using eq.1 with a range of average grain density Marine GeoL, 1! (1971) 201-207
,,.j
2.70
<
z
1.10
~soo~
1.20
3~
1.30
2oo
L40
~
~ ?.50
~
.
WATER CONTENT I~)
~
~.... ~_.~_~, ~ 1.70
UNIT WEIGHT
1.60
gs go 85 80 7s 70 6s
6o
~
. 1.80
ss
_
50
~ 1.90
4s
Fig.1. Nomographic chart for determining unit weight from grain density and water content.
1.70 ~ 1.00
1.80
Lgo
2-l
2.10
2.20
2.30
2.$0
~2.6o
z
2.80
2,90
3.00
3.10
3.20
3.30
40
2.00
35
25
2,10
2.20
2.30
(BENNEI"I AND LAMBERT, |971)
30
>-
~rJ
©
© r~
@
206
R. H. BENNETT AND D. N. LAMBERT
values from 1.70 to 3.19 and a number of selected weights of dry solids (Wd) and water (Ww). This homographic chart shows average grain density plotted against unit weight with isolines for water content (used here as Ww/Wa × I00) ranging between 25 ~ and 600 ~. Clearly, the relationship is non-linear and the isolines (delineating water content) would ultimately converge at a value of 1.00. The relationships among porosity, unit weight, and grain density have been clearly depicted by R1CHARDS (1962). The advantage of this chart is that, given values of average grain density and water content, values for unit weight can be readily determined. The chart covers values for average grain density and water content most commonly found in submarine sediments (KELLER and BENNETT, 1970). Detailed tables for determining unit weight from water content and average grain density have been compiled and will form the bulk of a N.O.A.A. Technical Memorandum (BENNETT and LAMBERT,in preparation). In deep-sea sediments, unit weight as measured in the laboratory, may be lower than in situ unit weight owing to the increase in the density of interstitial water at high hydrostatic pressures. This effect has been shown by HAMILTON(1969) to be significant, especially for deep-sea sediments with high porosities (75 ~-85 ~o). At these porosities, such as in the deep Central Pacific (5,000 m), the increase in unit weight can be 0.02 g/cm 3. Sediments high in organic carbon content may significantlyinfluence measurement of average grain density, therefore caution should be exercised when dealing with such materials. ACKNOWLEDGEMENTS
The authors express their sincere appreciation to Drs. George H. Keller, Edwin L. Hamilton, Peter A. Rona, Louis W. Butler and Adrian F. Richards for their critical review of the manuscript. Many thanks are due to Paul J. Grim and Alan Herman for their competent computer programming of the homographic chart and statistical parameters. The helpful discussions with John W. van Landingham are appreciated. REFERENCES AMERICAN SOCIETYFOR TESTING MATERIALS, 1967. 1967 Book of A.S.T.M. Standards, Part lI. A.S.T.M., Philadelphia, Pa., pp. 285-302. BENNETT, R. H., LAMBERT,D. N. and GRIM, P. J., in preparation. Tables for determining unit weight of deep-sea sediments using water content and average grain density. Natl. Oceanic Atmospheric Admin., Tech. Mere., ERL TM-AOML. BENNETT, R. H., KELLER, G. H. arid BUSBY, R. F., 1970. Mass property variability in three closely spaced deep-sea sediment cores. J. Sediment. Petrol., 40: 1038-1043. HAMILTON, E. L., 1969. Sound velocity, elasticity, and related properties of marine sediments, North Pacific III. Prediction of in situ properties. Naval Undersea Res., Develop. Center, N U C TP: 145 pp.
Marine Geol., 11(1971) 201-207
UNIT WEIGHT AND POROSITY OF DEEP-SEA SEDIMENTS
207
KELLER, G. H. and BENNETT,R. H., 1970. Variations in the mass physical properties of selected submarine sediments. Marine Geol., 9: 215-223. LAMBE, Z. W., 1951. Soil Testing for Engineers. Wiley, New York, N.Y., 165 pp. RICHARDS, A. F., 1962. Investigations of deep-sea sediment cores, II. Mass physical properties. U.S. Navy Hydrograph. Office, Tech. Rept., TR-106:146 pp. SCOTT, R. F., 1963. Principles of Soil Mechanics. Addison-Wesley, Reading, Mass., 550 pp. TERZAGHI, K. and PECK, R., 1967. Soil Mechanics in Engineering Practice. Wiley, New York, N.Y., 2nd ed., 729 pp. Wu, T. H., 1966. Soil Mechanics. Allyn and Bacon, Boston, Mass., 431 pp.
Marine Geol., 11( 1971) 201-207
RAPID
AND
RELIABLE
TECHNIQUE
FOR
DETERMINING
UNIT
WEIGHT AND POROSITY OF DEEP-SEA SEDIMENTS RICHARD H. BENNETT AND DOUGLAS N. LAMBERT National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Meteorological Laboratories, Marine Geology and Geophysics Laboratory, Miami, Fla. (U.S.A.}
(Received March 10, 1971) ABSTRACT
BENNETT,R. H. and LAMBERT,D. N., 1971. Rapid and reliable technique for determining unit weight and porosity of deep-sea sediments. Marine Geol., 11: 201-207. A rapid and reliable technique is explained for determining unit weight and porosity of deep-sea sediment from water content and average grain density measurements. Comparisons are made between this method and the standard tube method (volumetric), with 77 samples. The correlation coefficient is found to be 0.994 with a standard deviation between the methods of 4- 0.01 g/cmL The two techniques used to determine porosity are found to have a correlation coefficient of 0.998 with a standard deviation of 0.42~. A nomographic chart is shown which permits rapid determination of unit weight using water content and average grain density.
INTRODUCTION Unit weight o f submarine sediments, also referred to as wet bulk density or saturated unit weight, is a function o f the grain specific gravity and water content. By definition, unit weight is the weight per unit o f volume regardless of the degree o f saturation (A.S.T.M., 1967). However, submarine sediments, especially deep-sea sediments, are usually totally saturated. A c o m m o n technique for measuring unit weight is by inserting a tube o f k n o w n volume into a sediment mass, such as a core, extracting the tube and sediment and determining the sediment weight. This gives a measure of the mass in grams per unit o f volume. Difficulty in eliminating small voids between the cylinder wall and the sample as well as the influence o f gases which m a y be present in the interstitial water due to the change f r o m high hydrostatic pressure to atmospheric pressure could affect the unit weight as measured in the laboratory. In an undisturbed sediment sample the relative proportions o f water to solids are not destroyed and at 100 ~ saturation, unit weight is at a maximum. BENNETT et al. (1970) consider ___ 1 ~o o f the observed value to be a reasonable estimate o f the reproducibility o f the tube method. Porosity (n), defined as the ratio o f the volume o f the voids to the total volume o f the sediment mass, is usually c o m p u t e d from unit weight, average grain Marine Geol., 11(1971) 201-207
202
R. H. BENNETT AND D. N. LAMBERT
density, water content and an assumed interstitial water density. It is sometimes determined from the void ratio by the relationship n = e/(l + e). Void ratio (e) is defined as the ratio of the volume of the voids to the volume of the solids. The purpose of this study is to describe a rapid and reliable technique for determining unit weight and porosity of deep-sea sediment with an evaluation of the method using various sediment types. Carbonate content of the sediments ranged from less than 10~ to greater than 98~, and textures ranged from less than 1 ~ to greater than 66 ~ sand-size particles. TECHNIQUESAND BASICPRINCIPLES An advantage of the technique employed here for determining unit weight and porosity is that raw data from water content and grain density measurements are used. These data are frequently studied by the marine geologist and ocean engineer concerned with mass physical properties of submarine sediments and are usually numerous and readily available from laboratory reports. Water content measurements are determined from approximately 10--20 g samples of sediment taken from the center of a core. The sample is immediately weighed and dried for about 24 h at 110 °C and then reweighed to determine water loss. Average grain density is usually found by volumetric displacement of distilled water by the solids in a calibrated flask (LAMBE,1951). From these three measurements, weight of dry solids, weight of water driven off during drying, and the average grain density, the unit weight (~) can be easily determined by the following relationships:
wtt
~--Wd+Ww Dg
-
w,o~ W.+ WwO~
(~)
where Wt = Ww + Wo; Ww = weight of the water = approximately the volume of water; Wd = weight of dry solids including salts; Dg = average grain density. The total weight (Wt) of the sample taken for water content determination is equal to the weight of the water lost during oven drying (Ww) plus the weight of the dry solids (Wa). For practical purposes Ww is equivalent to the volume of water in the cgs system. The weight of the solids divided by the average grain density (Wd/Dg) is the volume of the dry solids. The weight of the dry solids contains the weight of the salt. However, this increase in the volume of the solids, due to the presence of salts, closely approximates the slight deficit in the volume of the water (Ww) owing to the dissolved salts in the interstitial water. Therefore, by definition, the unit weight of the sample is equal to the total weight divided by the total volume. Similar expressions may be equated with eq.1 in text books on soil mechanics such as TERZAOHIand PECK (1967), SCOTT (1963) and Wu (1966) and Marine GeoL, 11(1971) 201-207
UNIT WEIGHTAND POROSITYOF DEEP-SEASEDIMENTS
203
are usually intended to show the relationships among density, porosity, and void ratio for a given sediment mass. Porosity (n), expressed in percent, is the ratio of the volume of the voids to the total volume of the sediment mass and can be determined by the relationship: n-
Vw + Vss
w~ Dg
x 100
(2)
+Ww
Vs~is the volume of the salts in solution. Again, Vwis equal to the volume of the water and approximately equal to the weight of the water in grams. If Vs~ is neglected or considered negligible the equation then becomes: n-
w.
× 100
(3)
--+Ww Dg Vss is very close to 1.2 ~ of Vw for concentrations of dissolved salts of 35~o. RELIABILITY As a measure of the reliability of the above technique expressed by eq. 1, 77 unit weight measurements were determined using this method and compared with unit weight determinations using the tube method. In addition, porosity was determined using eq.3 from the same raw data used to obtain unit weight. These values were compared with porosities calculated from unit weight measurements determined by the tube method, average grain density and water content values with no corrections for salt content. Correlation coefficients were determined for unit weight and porosity. A linear correlation coefficient of + 0.994 was found between the two unit weight techniques with 67 700 of all measured values failing within 0 . 0 1 g/cm 3 of each other. A linear correlation coefficient of +0.998 was found between the two porosity methods with 67 ~ of all measured values falling within 4-0.42 700 of each other. The significance of these data shows that for all practical purposes, the correlation between the techniques is nearly perfect and that either method for determining unit weight and porosity is as good as the other. RELATIONSHIPS The effect of large differences in drying temperatures has been found to be not as critical as might be expected. Using eq.l and data from LAMBE (1951), differences in drying temperatures from 90°C to 190°C increase the unit weight measurement by only 0.002--0.004 g/cm 3. Porosity values determined by eq.3 however, show differences ranging between 1 ~ and 3 ~ when drying temperature varies from 90°C to 190°C. Usually consistent techniques and control of ternMarine GeoL, 11(1971) 201-207
204
R. H. BENNETT AND D. N. LAMBERT
perature within reasonable limits are well within the means of most soils laboratories. Examination of eq.1 reveals that large changes in average grain density are necessary to appreciably affect the unit weight measurement. Clearly, the higher the water content the less average grain density variation influences those determinations. For example, with a water content of 50 ~ an increase in average grain density from 2.75 to 2.80 increases the unit weight from 1.736 to 1.750. However, at a water content of 100K a change in the grain density of 0.05 changes the unit weight by only 0.007 g/cm 3. The other parameters Wt, Ww and Wd depend upon the accuracy of the balance which is usually well within the reproducibility of the technique described here. Due to the above relationships, difficulty in determining unit weight and porosity of relatively clean sands by the proposed method might be encountered because such sediments are usually characterized by low water contents. Obtaining a true water content for this sediment type may be difficult. However, accurate unit weight and porosity values of a relatively clean sand are also difficult to obtain with the tube method because of possible loss of pore water in inserting the tube into the sediment and its subsequent handling. DISCUSSION
Several advantages of the technique expressed in eq.1 for determining unit weight are apparent. If gas is present it does not affect the measurement, and values of unit weight for 100 %osaturation at a given water content are obtained. This is considered by the authors to be a closer approximation of the actual unit weight, in situ, than values obtained by the tube method (volumetric), especially for sediment that includes gas. In addition, unit weight and porosity can be determined for relatively thin stratified sediment with a minimum amount of material and for small irregularly shaped pieces of cohesive sediment not amenable to the tube method. Volumetric errors introduced in the tube method include error resulting in the incomplete filling of the tube with sediment and inaccurate measurement of the radius of the tube (any error in the radius is squared). Unit weight and porosity, using the relationships of eq.1 and 3, are determined from measured parameters which consequently avoids the use of any assumed values such as the density of interstitial water and average grain density. However, relatively large variations in the average grain density are required to appreciably influence the unit weight determination by eq.1. Large changes in the drying temperatures such as 90°-190°C usually have small affects on the unit weight determination; however, porosity by eq.3 is more responsive to these temperature differences. Control of temperature is important when porosity values are critical and comparable to within 1 ~ of the observed values. Fig.1 was constructed using eq.1 with a range of average grain density Marine GeoL, 1! (1971) 201-207
,,.j
2.70
<
z
1.10
~soo~
1.20
3~
1.30
2oo
L40
~
~ ?.50
~
.
WATER CONTENT I~)
~
~.... ~_.~_~, ~ 1.70
UNIT WEIGHT
1.60
gs go 85 80 7s 70 6s
6o
~
. 1.80
ss
_
50
~ 1.90
4s
Fig.1. Nomographic chart for determining unit weight from grain density and water content.
1.70 ~ 1.00
1.80
Lgo
2-l
2.10
2.20
2.30
2.$0
~2.6o
z
2.80
2,90
3.00
3.10
3.20
3.30
40
2.00
35
25
2,10
2.20
2.30
(BENNEI"I AND LAMBERT, |971)
30
>-
~rJ
©
© r~
@
206
R. H. BENNETT AND D. N. LAMBERT
values from 1.70 to 3.19 and a number of selected weights of dry solids (Wd) and water (Ww). This homographic chart shows average grain density plotted against unit weight with isolines for water content (used here as Ww/Wa × I00) ranging between 25 ~ and 600 ~. Clearly, the relationship is non-linear and the isolines (delineating water content) would ultimately converge at a value of 1.00. The relationships among porosity, unit weight, and grain density have been clearly depicted by R1CHARDS (1962). The advantage of this chart is that, given values of average grain density and water content, values for unit weight can be readily determined. The chart covers values for average grain density and water content most commonly found in submarine sediments (KELLER and BENNETT, 1970). Detailed tables for determining unit weight from water content and average grain density have been compiled and will form the bulk of a N.O.A.A. Technical Memorandum (BENNETT and LAMBERT,in preparation). In deep-sea sediments, unit weight as measured in the laboratory, may be lower than in situ unit weight owing to the increase in the density of interstitial water at high hydrostatic pressures. This effect has been shown by HAMILTON(1969) to be significant, especially for deep-sea sediments with high porosities (75 ~-85 ~o). At these porosities, such as in the deep Central Pacific (5,000 m), the increase in unit weight can be 0.02 g/cm 3. Sediments high in organic carbon content may significantlyinfluence measurement of average grain density, therefore caution should be exercised when dealing with such materials. ACKNOWLEDGEMENTS
The authors express their sincere appreciation to Drs. George H. Keller, Edwin L. Hamilton, Peter A. Rona, Louis W. Butler and Adrian F. Richards for their critical review of the manuscript. Many thanks are due to Paul J. Grim and Alan Herman for their competent computer programming of the homographic chart and statistical parameters. The helpful discussions with John W. van Landingham are appreciated. REFERENCES AMERICAN SOCIETYFOR TESTING MATERIALS, 1967. 1967 Book of A.S.T.M. Standards, Part lI. A.S.T.M., Philadelphia, Pa., pp. 285-302. BENNETT, R. H., LAMBERT,D. N. and GRIM, P. J., in preparation. Tables for determining unit weight of deep-sea sediments using water content and average grain density. Natl. Oceanic Atmospheric Admin., Tech. Mere., ERL TM-AOML. BENNETT, R. H., KELLER, G. H. arid BUSBY, R. F., 1970. Mass property variability in three closely spaced deep-sea sediment cores. J. Sediment. Petrol., 40: 1038-1043. HAMILTON, E. L., 1969. Sound velocity, elasticity, and related properties of marine sediments, North Pacific III. Prediction of in situ properties. Naval Undersea Res., Develop. Center, N U C TP: 145 pp.
Marine Geol., 11(1971) 201-207
UNIT WEIGHT AND POROSITY OF DEEP-SEA SEDIMENTS
207
KELLER, G. H. and BENNETT,R. H., 1970. Variations in the mass physical properties of selected submarine sediments. Marine Geol., 9: 215-223. LAMBE, Z. W., 1951. Soil Testing for Engineers. Wiley, New York, N.Y., 165 pp. RICHARDS, A. F., 1962. Investigations of deep-sea sediment cores, II. Mass physical properties. U.S. Navy Hydrograph. Office, Tech. Rept., TR-106:146 pp. SCOTT, R. F., 1963. Principles of Soil Mechanics. Addison-Wesley, Reading, Mass., 550 pp. TERZAGHI, K. and PECK, R., 1967. Soil Mechanics in Engineering Practice. Wiley, New York, N.Y., 2nd ed., 729 pp. Wu, T. H., 1966. Soil Mechanics. Allyn and Bacon, Boston, Mass., 431 pp.
Marine Geol., 11( 1971) 201-207