含节理岩石试件的卸荷变形特性研究

STUDY OF DEFORMATION PROPERTIES OF JOINTED SPECIMENS UNDER UNLOADING CONDITIONS

开展含节理岩石试件在主应力差卸载路径下的变形特性试验,试验发现:(1)恒定σ3减小σ1卸载主应力差过程中,完整岩石卸载变形曲线与加载变形曲线基本重合,但节理试件加卸载变形曲线表现出较大差异,且卸载后试件轴向和环向均出现较大残余应变;(2)按照2种不同路径卸载主应力差时,含节理试件变形特征存在很大差异。为从理论上研究含节理试件变形特征并解释上述试验现象,建立节理加卸载本构模型,并提出确定模型参数的方法。研究表明:用节理面加载与卸载变形特征的差异,从理论和试验结果两方面能很好地解释含节理岩石试件加卸载变形特性的差异以及在不同卸荷应力路径下的变形差异。研究成果可以反映含单组节理岩体的加卸载变形特性。

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.