Development of a program for the determination of in-situ unit weight of soils from cone penetrometer data and soil properties

Keywords

Soil penetration test; Soils -- Density

Abstract

The determination of in-situ or "in place" unit weight of soils is mainly conducted throughout the industry today by the use of a nuclear density machine. One major limitation of the nuclear density machine falls within its ability to only obtain soil densities for the surficial exposed soils of up to one or two feet below land surface (BLS). Utilizing today's practices, the determination of the in-situ dry density of soils at depth is very limited. Based on a recent study, an indirect method of determining the in-situ dry density of sandy soils at depth was achieved through an extensive iterative calculation process using correlations between Cone Penetrometer Test (CPT) data and soil properties. These correlations are developed in large calibration chambers; the results thereof are only applicable to primarily sandy soils. This thesis focuses on creating a facilitated method for estimating the in-situ dry density of sandy soil from CPT and soil property data for several projects conducted by the Florida Department of Transportation (FDOT) over a ten year period; and validating this method and correlation used within, with respect to its applicability to soils engmeenng. A correlation for calculating the in-situ density is identified based on the soil types encountered within the data supplied from the FDOT. A discussion of this correlation between the laboratory and field tests such as the CPT and Dilatometer Test, and the in-

situ dry density is pres~nted. A method is developed to correlate the results of CPT tests to the in-situ dry density of sandy soils through relative density and the uniformity coefficient obtained from grain size distribution. This methodology was accomplished by the creation of a fully functional windows based program, CPT2Density. Laboratory testing such as sieve analyses, specific gravity and standard proctor tests, and field-testing· using nuclear density and speedy moisture tests, cone penetrometer tests, and dilatometer soundings, have been used to evaluate the soil densities for test locations within seven FDOT projects. Dry densities from the program compared well with the dry densities obtained from the Nuclear Density Tests with an average deviation of only 3.5 percent. Nuclear Density Tests used to obtain in-situ dry densities were also compared with dry densities obtained from Dilatometer Soundings. The dry densities from the Dilatometer were found in most cases to over-estimate the dry densities obtained from the nuclear methods. It is the opinion of the author that CPT2Density is not entirely practical for every projects soil profile, but it should give a realistic estimate for the in-situ dry density of sandy soils commonly used by the FDOT for construction fill material. This program should be considered a viable alternative when there is currently very few methods of determining the in-situ dry density for soils at depth. For every day use, by adopting proper assumptions based on the knowledge of local soils and engineering experience, this program can be expected to yield good results for clean, normally consolidated, moderately compressible, quartz sand.

Notes

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Graduation Date

2003

Advisor

Chopra, Manoj B.

Degree

Master of Science (M.S.)

College

College of Engineering

Department

Civil and Environmental Engineering

Degree Program

Civil Engineering

Format

PDF

Pages

211 p.

Language

English

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Identifier

DP0029126

Subjects

Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic

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