STUDY OF DEFORMATION PROPERTIES OF JOINTED SPECIMENS UNDER UNLOADING CONDITIONS
XIA Caichu1，2，LI Hongzhe1，2，3，LIU Sheng1，2
(1. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China；2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China；3. Beijing Zhongjiao Qiaoyu Technology Co.，Ltd.，Beijing 100176，China)
Abstract：A series of triaxial tests on intact and jointed granite specimens under loading and unloading conditions are conducted，and the results reveal that：(1) in the axial loading and unloading tests，unloading stress-strain curves of intact specimen are almost the same as loading curves，while curves of jointed specimens show distinct difference；(2) deformation properties of jointed specimens show sharp difference under two unloading paths. To reveal the test results and deformation behavior of jointed specimen in theory，numerical model for jointed specimens under different stress paths is formed and methods to determine joint deformation parameters are proposed. Taking account of the difference in constitutive model of jointed rock specimens under loading and unloading conditions respectively，numerical analysis agrees with the test results，which shows that the model can be applied to the description of the deformation behaviors of jointed specimens under unloading conditions. The result can also be used to reveal unloading deformation characteristics of rock mass containing a set of joints.
