干湿交替对地基岩体变形影响及模量损伤

Effects of wetting-drying cycles on deformation and modulus reduction of on foundation rock

为明确开挖地基岩体所处环境湿度干湿交替作用对其力学特性损伤劣化作用,设置4种工况8组方案共24试样,探究了泥质粉砂岩在此因素下的变形规律及模量损伤程度。结果表明,与开挖初始状态相比,当环境湿度干湿循环变化时,泥质粉砂岩受荷变形显著增大,且其塑性变形比例增大,变形模量及永久变形模量显著降低。泥质粉砂岩岩体模量受干湿循环作用损伤劣化的程度,取决于不同应力状态塑性变形增量大小,其塑性变形增量与干湿循环次数符合对数变化规律。将岩体塑性变形增量作为干湿循环作用下岩体力学性质损伤变量,当采用刚性承压板法测定岩体模量时,建议将损伤变量、变形模量与永久变形模量相结合来评价环境湿度干湿作用对红层地基岩体模量损伤规律。

To understand the effects of dry wetting cycles of environment humidity during the excavation of the foundation rock on the damage and deterioration of its mechanical properties, a total of 24 specimens in 8 groups under 4 conditions were tested to e-valuate the deformation and modulus reduction of argillaceous sandstone. Test results showed that, when environmental humidity changes in dry and wet cycles, the deformation under loading for shaly siltstone was significantly increased. The plastic deforma-tion ratio was also increased, while deformation modulus and permanent deformation modulus was significantly decreased. The rock mass modulus of shaly siltstone was affected by dry and wet cycles and the degree of deterioration was dependent on the in-crement of plastic deformation increment under different stress states. The plastic deformation increment followed the logarithm of the number of dry and wet cycles. The increment of plastic deformation of rock mass was regarded as the damage variable of rock mechanics properties under dry and wet cycles. When the rock mass modulus was measured by the rigid compression plate method, the damage variable, deformation modulus and permanent deformation modulus were proposed for the evaluation of the damage law of the rock mass modulus under the influence of the environmental humidity and the wetting and drying action