Document Type

Thesis

Date of Award

12-31-1988

Degree Name

Master of Science in Civil Engineering - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

John R. Schuring

Second Advisor

Paul C. Chan

Third Advisor

Dorairaja Raghu

Abstract

A laboratory study was conducted to investigate the flow and mass transport of a conservative tracer in the unsaturated phase. For this purpose, a relatively "large-scale" cylindrical column(12 in. O.D. x 4 feet long) was fabricated and equipped with tensiometer and psychrometer sensors.

The soil used in the study was a New Jersey based silty sand compacted to an average dry density of 93 lb/ft3. The soil was permeated with a 0.5 M NaCl solution infiltrated at the top of the column using a perforated spiral tube assembly. The permeant was applied at a constant rate of approximately 1 ml/min. for a period of 6 hours each day. The total duration of the experiment was 112 days at which time the solution front reached the bottom of the column.

The measured hydraulic conductivity varied non-linearly from 7x10-11 to 6x10-7 cm/sec. for the range of volumetric moisture content from 4% to 15%. Characteristic curves were developed for the soil-solute combination including Ψ vs θ, Ψ vs Κ, and θ vs Κ. The measured soil-water diffusivity varied from 7x10-9 to 7x10-6 cm2/sec. for the range of volumetric moisture content from about 2.7% to 16.7%. A curve was also developed for the specific moisture capacity of the soil. The experimental results are summarized both in curve form and equation form.

The data obtained from the study will be used to calibrate and verify a mathematical model presently under development. Suggestions are made for future studies.

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