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Abstract For the further study of acoustic emission characteristics of rock breaking under double shear loading condition，this paper will use independent developed coal rock double shear test device and PCT–2 acoustic emission system to explore the sandstone?s acoustic emission characteristics with the increase of water content. The results show that under different rates of water content the changes of the shear stress are same with the time trend. The time reaching the peak decreased when the rate of water content increased. Under the double shear loading，sandstone Hit rate-time curve and accumulative Hit number-time curve can be divided into three stages，the Hit rate peak lags behind the peak value of the shear stress and the extreme points of Hit rate increased when the rate of water content heightened. Under the double shear loading，the internal micro crack initiated and expended when the shear stress is at the 1/2 of the shear strength. At that time the sandstone is in the steady micro rupture development stage and the expending mode of the internal micro crack is mainly around the crystal and the rupture. The extension of internal micro cracks was mainly around the crystals and the last small passed through them.
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2015, Vol. 34 
