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Abstract The stress relaxation test of saturated silty mudstone under triaxial compression is carried out on the RLJW–2000 rock microcomputer-controlled rheology servo test system by step loading method. Based on the test results，the stress relaxation of silty mudstone is divided into three stages；and the variation laws of stress relaxation rate，radial strain，volumetric strain and relaxation modulus with time are investigated under different strain levels. Moreover，the variation law of stress-strain tautochrone is analyzed. The triaxial stress relaxation properties of silty mudstone is systematically revealed，which provide the fundamental materials for the establishment of silty sandstone?s relaxation models. Burgers model is selected to describe the stress relaxation properties of silty mudstone. Based on the LM-NLSF method，the model parameters under different strain levels are obtained. Comparing testing curves with theoretical curves，it is shown that Burgers model is suitable to describe the stress relaxation properties of silty mudstone；and the obtained parameters have certain practical value.
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Received: 18 November 2010
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2011, Vol. 30 
