Title page for ETD etd-11112009-113914


Type of Document Master's Thesis
Author Pokhrel, Dev Raj
Author's Email Address dpokhr1@lsu.edu,devrajpokhrel@hotmail.com
URN etd-11112009-113914
Title Hydro-Mechanical Behavior of Unsaturated Soil Subjected to Drying
Degree Master of Science in Civil Engineering (M.S.C.E.)
Department Civil & Environmental Engineering
Advisory Committee
Advisor Name Title
Sharma, Radhey S. Committee Chair
Deng, Zhi-Qiang Committee Co-Chair
Abu-Farsakh, Murad Committee Member
Keywords
  • soil water characteristic curve
  • hydraulic conductivity
  • matric suction
  • Unsaturated soils
  • soil stiffness
  • water content
Date of Defense 2009-08-06
Availability unrestricted
Abstract
The literature of unsaturated soils in terms of hydraulic and mechanical behavior is reviewed. The hydro- mechanical behavior of unsaturated soil was studied using experimental investigation and numerical simulation of 1D and 2D modeling in HYDRUS software. Low plasticity silty clay (CL) and sand bentonite mixed soil SB (5% and 2% bentonite) specimens were investigated. Soil water characteristics curve (SWCC) tests were carried out in CL sample along with shear wave velocity measurement test using bender element (BE). The influence of moisture variation on specimens was investigated to see its impact on suction and on stiffness of soil. Similarly, the influence of suction on stiffness of soil and influence of density on stiffness of soil were also observed separately. To see the influence of moisture variation on suction (SWCC) and the influence of moisture variation on soil hydraulic properties (specially, hydraulic conductivity), finite element modeling was prepared representing 1D and 2D simulation using HYDRUS software. The results from the experimental investigation were compared with the results from the HYDRUS simulation. From the research, it is concluded that if the moisture content of the soil is decreased, both suction and stiffness modulus of soil is found to be increased. With the decreased moisture content, the initial increasing rate of suction was found higher than the rate of increase of stiffness modulus of the specimen. It was also observed that further decreasing the moisture content to a certain level, stiffness of soil is found to be increased with higher rate than the rate of change of suction.

The available models for prediction of soil water characteristics curve (SWCC) based on grain size distribution and index properties proposed by various researchers were also examined. Recommendations are proposed for future work.

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