Semester of Graduation

Fall 2018

Degree

Master of Science in Civil Engineering (MSCE)

Department

Department of Civil and Environmental Engineering

Document Type

Thesis

Abstract

Geotechnical characterization has an important role in engineering geology as well as in implementation of any project. There are several variables and uncertainties involved in characterizing a project site. Four different sources of uncertainties represent the characterization of geotechnical variability, which include spatial variability, measurement error, statistical error and model bias. Spatial variability is expressed in terms of the mean, variance, and scale of fluctuation. Several statistical techniques such as the Gauge R & R, which includes X-Bar/R and ANOVA, and the Second Moment can be applied to compute site variability in terms of the coefficient of variations. Measurement error is evaluated using data extracted from several laboratory tests. Statistical error and model bias arise when a correlation model is selected to interpret specific data. To measure site variability in this research, tests were conducted using different devices in the box and at the field. Analyses were conducted using the Gauge R & R and Second Moment (SM), and variability is expressed in terms of standard deviations and coefficient of variations (COVs). While comparing variability from the box and the field tests, it is apparent that the COVs from the second moment are smaller than the COVs from the ANOVA method. Similarly, operator related variations show comparatively low values of the COVs than those generated from location/specimen related variability. Besides, analyses of variability from the box test indicate lower bound of coefficient of variations than the field tests. The under-constructed sections tested at LA highway exhibited higher values of COVs compared with the constructed sections at the Accelerated Loading Facility (ALF). In the case of laboratory tests, specimen related variability renders higher COVs than the operator related variability. The inclusion of variabilities into the practical applications, such as bearing capacity of shallow foundation and settlement analysis, showed reduction in the probability of failure and reduction in the magnitude of settlement, respectively.

Date

8-21-2018

Committee Chair

Abu-Farsakh, Murad

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