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[SCG63-12] Frictional strength of montmorillonite gouge: Effects of orientation and adsorbed water
Keywords:Double shear test, Dependence of normal stress, Hydration, Drying temperature, Clay minerals
Previously reported frictional coefficient of montmorillonite vary widely from 0.04 to 0.8 . Here we measured the shear stress of montmorillonite gouges at dry condition. The degree of orientation and the presence of adsorbed water were precisely controlled to reveal these effects on the frictional properties of montmorillonite.
The thermal analysis (TG-DTA) was conducted before the shear measurements to confirm the presence of adsorbed water as a function of drying temperature. Shear experiments were performed at the normal stress from 5 to 40 MPa. The effect of adsorbed water strongly depends on the degree of orientation. Highly orientated montmorillonite gouges show high shear stress and strong normal stress dependence compared to the gouges of low orientation. This implies the cohesion force acting between montmorillonite basal planes at dry condition and/or the increased real area of contact have a large effect on the frictional properties of highly orientated montmorillonite gouges.
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