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Abstract A series of direct shear tests were carried out to study the effect of stress history on shear behavior of interface between clay and concrete. The clay-concrete interfaces of different roughnesses(sawtooth height of 0，1 and 2 cm，respectively) were loaded to an initial normal stress，then unloaded to a normal stress before shearing according to the schemes of loading and unloading. Results are presented for interface shear behavior in forms of shear stress-shear strain curves，vertical strain-shear strain curves and shear strength parameters. Results show that the shape of shear stress-shear strain curves is hyperbolic；and no strain-softening phenomenon was observed in the tests. Higher initial normal stresses offer higher shear stress with the same horizontal displacement. The strength of interface still obeys the Mohr-Coulomb criterion；and the internal friction angle and cohesion can be obtained by fitting lineally. The effective parameters of friction and cohesion are employed to reflect interface strength normalized by the strength parameters of clay. The higher applied initial normal stress offers the lower effective parameter of friction. But the higher effective parameter of cohesion is received for higher applied initial normal stress. The dilation was observed during the process of shearing the interfaces of different roughnesses；the rougher interface offers the higher dilative displacement. Meanwhile，the effect of stress history on dilation law of interface is obvious. For the interface without experiencing normally unloading，it first exhibits a short contraction behavior before dilatation，while directly exhibits dilation for the interface experienced normally unloading. The more significant dilation was found for the higher initial normal stress.
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Received: 01 April 2011
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2011, Vol. 30 
