Modeling of a subsurface barrier formation by a gelling liquid-colloidal silica /
Mathematical models are developed to simulate the formation of subsurface gel barrier by injecting colloidal silica solution, an aqueous suspension of colloidal silica particles. The mathematical model consists of a flow model and Multi-phase, multi-component mass transport equations. A phase equati...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1999.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://search.proquest.com/docview/304563921?accountid=7082 |
| Summary: | Mathematical models are developed to simulate the formation of subsurface gel barrier by injecting colloidal silica solution, an aqueous suspension of colloidal silica particles. The mathematical model consists of a flow model and Multi-phase, multi-component mass transport equations. A phase equation is introduced to describe the substantial mass transfer between phases and corresponding phase volume changes. A simple reaction model is proposed to represent the gelling reaction and the viscosity rise of colloidal silica solution. By the time-normalized viscosity curve and the relation model, the gel mixture viscosity is determined from the gel phase volumetric fraction in the gel mixture. Gel mixture volumetric contents in an unsaturated zone are obtained by scaling the known water retention curve by gel mixture surface tensions. The dependency of the surface tension on the viscosity is observed in the laboratory test. A fully implicit, finite difference method is employed to solve the governing equations. For multi-dimensional models the alternating direction implicit scheme is used. To solve the nonlinearities in governing equations, the modified Picard iteration and Picard iteration is employed for the flow equation and mass transport equations, respectively. In Chapter II, a mathematical model is developed to describe one-dimensional flow of colloidal silica solution in an unsaturated porous medium. The proposed numerical model is evaluated by comparing the measured equivalent hydraulic conductivities of the gel-treated soil columns to the model predictions. Sensitivity analysis is performed for the governing factors. The horizontal gel barrier system via multiple horizontal injection wells and the one via multiple vertical injection wells are simulated in Chapter III and IV, respectively. The effects of design parameters such as soil and medium properties are evaluated. The emplacement of a gel barrier in a saturated porous medium is investigated in Chapter V. The one-dimensional barrier system and the three-dimensional vertical gel barrier system via multiple vertical injection wells are simulated. The modeling performed in this research shows that the gel barrier technology is applicable to the field situation. This study will provide a guideline for future laboratory and/or field work. |
|---|---|
| Item Description: | Vita. "Major Subject: Civil Engineering". |
| Physical Description: | xv, 263 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 259-262). |