贮灰场子坝粉煤灰动力特性试验研究
Experimental Study of Dynamic Characteristicsof Fly Ash in Ash Storage Dams

贮灰场子坝冲填粉煤灰的动力特性是评估挡灰坝在地震作用下动力稳定性的关键因素。为探究冲填粉煤灰的动力变形和强度特性，利用液压控制振动三轴试验仪测试饱和沉积灰和冲填灰两类试样在偏压固结条件下的动应力—动应变关系、动强度、阻尼比和动孔隙水压力。结果表明：试样骨干曲线均表现出应变硬化特征，可近似描述为双曲线型关系。此外，循环振次增大导致试样动强度降低，且主要与动黏聚力降低有关，受内摩擦角影响较小。双对数坐标轴下，量纲处理后的阻尼比与动剪切模量近似呈线性关系，且与围压关系不显著。不同围压下动孔压水平随破坏振次增大仅在较窄范围内变化，为简便计算，可忽略围压和循环振次对动孔压水平的影响。据此，可采用Finn公式描述偏压固结下粉煤灰试样的动孔隙水压力特征。
The dynamic behavior of filling fly ash in ash storage dams is critical for evaluating the dynamic stability of ash retention dams under seismic action. In order to investigate the dynamic deformation and strength characteristics of filling fly ash, the dynamic stress-strain relationship, dynamic strength, damping ratio, and dynamic pore pressure of two types of specimens, i.e., saturated sedimentary ash and flushing ash, were tested by a hydraulic control dynamic triaxial apparatus under conditions of anisotropic consolidation. Results showed that the backbone curves of specimens showed a strain-hardening tendency, which can be an approximate hyperbolic relationship. In addition, the increase in vibration cycles will cause a decrease in dynamic sample strength, and is mainly related to the decrease in the dynamic cohesion rather than the internal friction angle. In the double logarithmic axis, the damping ratio after dimensionless treatment showed a linear relationship with the dynamic shear modulus, but was not closely related to the confining pressure. Under differing confining pressures, the dynamic pore water pressure changed only in a narrow range with increasing vibration cycles. For convenience of calculation, the influence of confining pressure and vibration cycle on the dynamic pore pressure can be neglected. Accordingly, the Finn formula can be used to describe the dynamic pore water pressure of fly ash specimens under anisotropic consolidation.