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为研究卸荷条件下裂隙岩体的蠕变特性,以通过对砂岩切割并充填水泥砂浆制备的裂隙试样为对象,开展了恒轴压分级卸围压三轴卸荷蠕变试验。试验结果表明:试件在破坏时对应应力差最小的是缓缓和陡缓裂隙组合岩体,其次为陡陡裂隙组合岩体和完整试样;从变形特点来看,相同应力状态下,瞬时应变与蠕应变从大到小的顺序依次均为缓缓、陡缓、陡陡裂隙组合岩体和完整岩石。采用元件模型对各试件不含加速蠕变阶段的变形进行的拟合显示,可采用同一形式的本构模型对裂隙岩体和完整试样进行描述。根据这一结论提出了基于Lemaitre应变等效原理和Sidoroff能量等价原理的裂隙岩体损伤蠕变模型,并与室内试验结果进行了对比与分析。该模型可通过完整岩石蠕变模型参数推导裂隙岩体蠕变模型参数,从而建立了完整岩石与裂隙岩体间的关系。
In order to study the creep characteristics of fractured rock mass under unloading condition, the uniaxial unloading creep test of constant axial pressure classification and unloading confining pressure was carried out through the crack specimen prepared by sandstone cutting and filling with cement mortar. The experimental results show that the rock masses with gentle and steep cracks combined with the lowest stress difference are the rock masses with the steep and steep cracks followed by the intact rock samples and the intact samples. According to the deformation characteristics, under the same stress state, the instantaneous strain The order of creep strain from creep to creep is slow, steep and steep, and the complete rock is composed of steep and fractured rock. Fitting the deformation of the specimens without accelerating creep stage using the component model shows that the same form of constitutive model can be used to describe the fractured rock mass and the complete specimen. According to this conclusion, the damage creep model of fractured rock mass based on Lemaitre strain equivalent principle and Sidoroff energy equivalence principle is proposed and compared with the laboratory test results. The model can derive the parameter of creep rock model through the parameters of intact rock creep model, and establish the relationship between complete rock and fractured rock mass.