Date of Graduation

5-2013

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Degree Level

Graduate

Department

Civil Engineering

Advisor/Mentor

Coffman, Richard A.

Committee Member

Dennis, Norman D. Jr.

Second Committee Member

Soerens, Thomas S.

Keywords

Applied sciences; Civil engineering; Hydraulic conductivity; Soil mechanics; Two stage borhole

Abstract

Historic methods (the time lag approach, the velocity approach, and the Z-t approach), utilized to reduce two stage borehole test data, were evaluated. Two of the historic methods provided viable results and were used for this research project. Additionally, these two methods are recommended for reducing two stage borehole test data in the future.

Flexible wall permeameter and soil index laboratory testing were conducted on the soil used to construct three environmentally controlled compacted clay liners (test pads) to develop a zone of acceptance (placement window). Using the results from the laboratory testing, two acceptance criterions were evaluated, while one criterion was used for construction purposes and is recommended. Two stage borehole testing was conducted in Test Pads 1 and 2, while sealed double ring infiltrometer testing was conducted in Test Pad 3. After in-situ hydraulic conductivity testing was completed for Test Pads 1 and 2, Shelby tube and hand carved samples were obtained and laboratory testing was performed on the samples. Time domain reflectometry probes and tensiometers were used to monitor the movement of the wetting front during testing conducted in Test Pad 3.

Hydraulic conductivity results obtained from each testing method were compared. The laboratory obtained hydraulic conductivity values from testing conducted on Shelby tube samples were compared to laboratory hydraulic conductivity values obtained from testing conducted on hand carved samples. The laboratory hydraulic conductivity values obtained from testing conducted on Shelby tube and hand carved samples were compared to field hydraulic conductivity values obtained from two stage borehole hydraulic conductivity testing. The field hydraulic conductivity values obtained from two stage borehole hydraulic conductivity testing were compared to field hydraulic conductivity values obtained from sealed double ring infiltrometer hydraulic conductivity testing.

Collection of soil specimens using Shelby tubes causes the soil to compress and thereby changes the soil parameters (unit weight and hydraulic conductivity). Results of this research project indicate that comparable hydraulic conductivities within half an order of magnitude can be obtained from two stage borehole and sealed double ring infiltrometer field testing and laboratory testing conducted on hand carved and Shelby tube flexible wall samples.

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