An Experimental and Numerical Study on Creep Behavior of Soil Nail Walls in High Plasticity Clays
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The use of soil nails for earth retaining structures have increased tremendously. Since soil nail walls are now considered as permanent structures there is a need to study and characterize creep behavior of soil nail walls. FWHA restricts the construction of soil nail walls in high plasticity soils. This is because it is thought that clays with high plasticity fines show creep tendencies which will adversely affect the stability of the retaining wall in the long term. This thesis presents the results from laboratory testing on remolded high plasticity clays from Beaumont, Texas. Direct shear tests were conducted to understand the variation in strength with water content. Consolidated undrained tests were done to obtain undrained parameters of clay. Unconsolidated undrained and consolidated drained tests were also conducted to understand the drained behavior and variation of strength with depth. Creep tests on samples with two different saturations was conducted to understand the viscous behavior of clay under different saturation conditions. The deformation and stresses in nails of an actual soil nail wall constructed in Beaumont was monitored during construction and one year after construction. Numerical modelling of this wall using FLAC-3D was done with input parameters obtained from laboratory testing. A failure that occurred during construction because of over excavation was simulated. The creep behavior was modelled using Burger model. The stability of the retaining wall for a period of 75 years was predicted using this model. Field experience and results from numerical modelling and lab tests recommend that creep behavior of soil nail walls in high plasticity soils need not be necessarily considered in the design.
Kamath, Abhijith Chandrakaran (2016). An Experimental and Numerical Study on Creep Behavior of Soil Nail Walls in High Plasticity Clays. Master's thesis, Texas A & M University. Available electronically from