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Abstract On the view of energy，energy absorption and release of the deformation and damage process of sandstone are studied under cyclic loading of pore water pressure. The results show that plastic-loop is divided into four stages during a single cycle；and energy absorption and release is also divided into four stages. In loading，energy absorption per unit volume and energy release per unit volume decrease and gradually tend to stabilization with the increase number of cycles and the greater lower limit of pore water pressure，the greater energy absorption per unit volume and energy release per unit volume are. Axial effective stress of demarcation points of energy absorption and release increases with the increase number of cycles. In unloading，energy release per unit volume decrease with the increase number of cycles；while energy absorption per unit volume increase with the increase number of cycles and the greater lower limit of pore water pressure，the smaller energy absorption per unit volume is. Axial effective stress of demarcation points decreases with the increase number of cycles. Plastic energy per unit volume decreases with the increase number of cycles which means that the deformation and damage of rock decreases under a single cycle of rock pore water pressure. At the early stage of the loop，the greater lower limit of pore water pressure is，the smaller plastic energy per unit volume is.
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Received: 23 July 2010
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2011, Vol. 30 
