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Ion distribution, moisture content and density of soil columns measured with gamma radiation
ABSTRACTS
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investigation of the moisture-density-strength relationships of the subgrade soils and base course materials, and examination of degradation due to laboratory and field methods of compaction. (U.S. Gov. Res. Dev. Rep., August 1967, PB 174876.) 102. E. T. Selig and W. B. Truesdale. Soil compaction study, Volume II. Field test apparatus and procedures. Res. Inst., Chicago. 150 pp. (April 1967). The report is Volume II of a study on compacted soils. The volume discusses the scope of the field tests and the basis for the plans. The apparatus and procedures for measuring the soil properties are described in detail. These include a penetrometer, bearing plate, CBR fixture, seismograph, portable backscatter nuclear gage and nuclear Road Logger. The pertinent characteristics of the commercial compaction equipment used in the study are given. The method of processing the data is outlined and then illustrated in detail by a sample set of field data sheets and a set of computer output showing the processed data. (U.S. Gov. Res. Dev. Rep., August 1967, PB-174877.) 103. E. T. Selig, W. B. Truesdale and D. Hampton. Soil compaction study, Volume III. Analysis of field tests of subgrade soils. Res. Inst., Chicago. 165 pp. (April 1967). The report is Volume III of a study on compacted soils and contains the results of the study. Properties of the field compacted soils were found to be similar to those compacted in the laboratory. W i t h i n the range of test conditions moisture content was found to be the most significant field variable, with soil type next in order of importance. The compactor type, level of compactive effort and thickness of lift also influenced the results in many cases. Strength properties continued to increase at sixteen coverages for most test conditions. Both density and strength decreased with an increase in lift thickness. The magnitude of field variability was such that individual measurements would appear inadequate for compaction control. (U.S. Gov. Res. Dev. Rep., August 1967, PB-174878.) 104. J. Shalhevet and B. Yaron. Ion distribution, moisture content and density of soil columns measured with gamma radiation. Proc. Soil Sci. Soc. Am. 31, 153-156 (1967). Cobalt-60 hexacyano complex anion was used as a model for the non-destructive measurement of anion distribution in soil columns. The ,~, activity of the tracer was measured along uniformly packed columns through several wetting and drying cycles. Moisture content and density of the soil were measured simultaneously by the y-attenuation method, corrected for the variation of bulk density with moisture content. (Authors' summary.) 105. K. Szechy. Influence of the shape of continuous footing base on the bearing capacity and the pressure distribution. V D I Zeitschri/t, 109 (8), 339-344 (March 1967). Paper describes a series of model tests, performed with concrete foundation models (10 x 25 or 2 0 x 12-5 cm) laid in the natural soils, to examine the influence of the shape (in cross section) of the foundation base on the bearing capacity of this foundation. Conclusions of these tests are that in a cohesionless soil a footing with a concave base has a bigger bearing capacity, and a footing with a convex base has a smaller one than the bearing capacity of a footing of the same dimensions but with a flat base. The differences fluctuate between 2% and 20% for smaller models laid in pure sand, and between 22% and 30,% for bigger models laid in gravelly sand. The limit settlement of a foundation with a concave base is smaller than that of foundations with other shapes. Other series of model tests are described, concerning the distribution of pressures in soilmass situated beneath the foundations of different shapes. These tests, being the elasto-optical ones, lead to conclusions that the shape of footing base also has a significant influence on the pressure distribution in the subgrade, e.g., a convex foundation exerts less pressure on the layer situated immediately beneath its base than a flat one does. Reviewer believes the paper discusses an engineering problem which has not been investigated until now and some general rules mastering the phenomena involved. (Appl. Mech. Rev., 1968.) 106. D. Taylor and M. Kansara. A theory of the nuclear dcnsimeter. Soil Sci. 104, 25 34 (1967). A theory is outlined and on it are based proposals for obtaining the best performance from the instrument. (Soil and Fertilizers, 1967.) 107. Kuei-wn Tsai. Strength response parameters of natural soil surfaces and their application to the landing problem of aircraft. Princeton Univ. 85 pp. (January 1967). A suitable rheological model is found to represent the soil deformations under impact loads. The parameters of the model are evaluated from the deceleration history curves of
69
investigation of the moisture-density-strength relationships of the subgrade soils and base course materials, and examination of degradation due to laboratory and field methods of compaction. (U.S. Gov. Res. Dev. Rep., August 1967, PB 174876.) 102. E. T. Selig and W. B. Truesdale. Soil compaction study, Volume II. Field test apparatus and procedures. Res. Inst., Chicago. 150 pp. (April 1967). The report is Volume II of a study on compacted soils. The volume discusses the scope of the field tests and the basis for the plans. The apparatus and procedures for measuring the soil properties are described in detail. These include a penetrometer, bearing plate, CBR fixture, seismograph, portable backscatter nuclear gage and nuclear Road Logger. The pertinent characteristics of the commercial compaction equipment used in the study are given. The method of processing the data is outlined and then illustrated in detail by a sample set of field data sheets and a set of computer output showing the processed data. (U.S. Gov. Res. Dev. Rep., August 1967, PB-174877.) 103. E. T. Selig, W. B. Truesdale and D. Hampton. Soil compaction study, Volume III. Analysis of field tests of subgrade soils. Res. Inst., Chicago. 165 pp. (April 1967). The report is Volume III of a study on compacted soils and contains the results of the study. Properties of the field compacted soils were found to be similar to those compacted in the laboratory. W i t h i n the range of test conditions moisture content was found to be the most significant field variable, with soil type next in order of importance. The compactor type, level of compactive effort and thickness of lift also influenced the results in many cases. Strength properties continued to increase at sixteen coverages for most test conditions. Both density and strength decreased with an increase in lift thickness. The magnitude of field variability was such that individual measurements would appear inadequate for compaction control. (U.S. Gov. Res. Dev. Rep., August 1967, PB-174878.) 104. J. Shalhevet and B. Yaron. Ion distribution, moisture content and density of soil columns measured with gamma radiation. Proc. Soil Sci. Soc. Am. 31, 153-156 (1967). Cobalt-60 hexacyano complex anion was used as a model for the non-destructive measurement of anion distribution in soil columns. The ,~, activity of the tracer was measured along uniformly packed columns through several wetting and drying cycles. Moisture content and density of the soil were measured simultaneously by the y-attenuation method, corrected for the variation of bulk density with moisture content. (Authors' summary.) 105. K. Szechy. Influence of the shape of continuous footing base on the bearing capacity and the pressure distribution. V D I Zeitschri/t, 109 (8), 339-344 (March 1967). Paper describes a series of model tests, performed with concrete foundation models (10 x 25 or 2 0 x 12-5 cm) laid in the natural soils, to examine the influence of the shape (in cross section) of the foundation base on the bearing capacity of this foundation. Conclusions of these tests are that in a cohesionless soil a footing with a concave base has a bigger bearing capacity, and a footing with a convex base has a smaller one than the bearing capacity of a footing of the same dimensions but with a flat base. The differences fluctuate between 2% and 20% for smaller models laid in pure sand, and between 22% and 30,% for bigger models laid in gravelly sand. The limit settlement of a foundation with a concave base is smaller than that of foundations with other shapes. Other series of model tests are described, concerning the distribution of pressures in soilmass situated beneath the foundations of different shapes. These tests, being the elasto-optical ones, lead to conclusions that the shape of footing base also has a significant influence on the pressure distribution in the subgrade, e.g., a convex foundation exerts less pressure on the layer situated immediately beneath its base than a flat one does. Reviewer believes the paper discusses an engineering problem which has not been investigated until now and some general rules mastering the phenomena involved. (Appl. Mech. Rev., 1968.) 106. D. Taylor and M. Kansara. A theory of the nuclear dcnsimeter. Soil Sci. 104, 25 34 (1967). A theory is outlined and on it are based proposals for obtaining the best performance from the instrument. (Soil and Fertilizers, 1967.) 107. Kuei-wn Tsai. Strength response parameters of natural soil surfaces and their application to the landing problem of aircraft. Princeton Univ. 85 pp. (January 1967). A suitable rheological model is found to represent the soil deformations under impact loads. The parameters of the model are evaluated from the deceleration history curves of