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Abstract In order to study the strength degradation law of surrounding rock in fractured zone of deep roadway，the loading-unloading tests on intact sandy mudstone samples were implemented according to the stress path simulating the changing law of stress in fractured zone of roadway by applying the MTS815 servo-controlled rock mechanics testing machine. The initial damaged rock samples for different broken levels were obtained and their triaxial strength characters under varying confining pressures were tested with single block method. The strength degradation ratio and volume expansion ratio DV were applied as damage valuables at unloading point；and the function relationships between peak strength，strength parameters of initial damaged rock samples and ，DV were established. The study results indicate that the peak strength，cohesion and internal friction angle decrease greatly with the increasing broken level in exponential degradation law.
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Received: 04 November 2011
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2012, Vol. 31 
