Title page for ETD etd-06192009-113231


Type of Document Master's Thesis
Author Chakraborty, Sukanta
Author's Email Address schakr3@lsu.edu
URN etd-06192009-113231
Title Numerical Modeling for Long Term Performance of Soil-Bentonite Cut-Off Walls in Unsaturated Soil Zone
Degree Master of Science in Civil Engineering (M.S.C.E.)
Department Civil & Environmental Engineering
Advisory Committee
Advisor Name Title
Radhey Sharma Committee Chair
Murad Yusuf Abu-Farsakh Committee Member
Zhi Qiang Deng Committee Member
Keywords
  • Performance of Soil-Bentonite Cut-Off Walls
  • Numerical Modeling
Date of Defense 2009-06-09
Availability unrestricted
Abstract
ABSTRACT

The construction practices of containment walls are extremely important in this competitive economic market, but development is limited. Unsaturated zone is an integral part of the geotechnical problems, as it affects on any kind of soils structures. The unsaturated zone plays significant role in many aspects of water flow and contaminant transport, including containment system such as: cut-off walls, infiltration, soil moisture storage, evaporation, plant water uptake, ground water recharge, erosion, and runoff.

This research focuses on the hydraulic sustainability and performance of soil-bentonite cutoff walls (Britton et al, 2004) models showing hydraulic behavior of barrier walls. The cutoff wall are designed and constructed to stop contaminated flow which causes contamination nearby useful fields permit excavation dewatering, and reduce seepage beneath and through dams. Evans et al. (1995) proposed that there is a lack of information about the in situ performance of vertical soil-bentonite cutoff wall technology. The effectiveness of these cutoff walls depends on the hydraulic conductivity of the soil-bentonite slurry, ksb. There are several methods available to measure the hydraulic conductivity of soil-bentonite, but there is uncertainty of getting true representative data for hydraulic conductivity that is happening in in-situ cut-off wall.

Among the various analytical and numerical models to predict water and or solute transfer process, Richardís equation and Fickian-based convection-dispersion equation for solute transport are most popular models. Hydraulic conductivity through cut-off wall is modeled in this research with idealized initial boundary conditions and feed them to HYRUS software to obtain different results, such as: soil water characteristics, suction profile with depth, volumetric water contents etc. Here this is an effort to do something one of the cheapest cut-off walls that can be designed instead of constructing heavy construction. The cut-off can be constructed with soil-bentonite slurry which can resist contaminant transport from particular place for a time of interests. There are some researchers (Brooks and Corey, 1964, van Genuchten, 1980, Vogel and Cislerova, 1988, Kosugi, 1995, Durner, 1994) who came up with good models on hydraulic properties of soil and HYDRUS is based on those models.

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