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饱和砂土中振动孔压波动特性的研究是建立瞬态孔隙水压力模型的基础。为了研究振动孔压的波动特性,对细粒含量为0%,5.0%,13.5%的饱和南京细砂试样,分别施加频率为0.5,1.0,5.0 Hz的正弦波荷载,进行了局部排水条件下的应力控制循环三轴试验。定量分析试验得到:①当正弦波荷载频率为0.5 Hz,渗透系数为1.35×10-3 cm/s(细粒含量0%)时,振动孔压的波动反应超前轴向应变反应的相位角接近于90°,而与轴向应变率反应同步。②随着正弦波荷载频率的增大或渗透系数的减小,振动孔压的波动反应超前轴向应变反应的相位角逐渐减小,滞后于轴向应变率反应的相位角逐渐增大。基于饱和固液两相介质理论,建立了适用于任意排水边界条件的振动孔压方程。该方程不仅能解释不排水条件下振动孔压波动反应与轴向应变反应同步的现象,也能解释局部排水条件下振动孔压波动反应超前轴向应变的现象。
The study on the characteristics of vibration pore pressure fluctuation in saturated sand is the basis for establishing transient pore water pressure model. In order to study the fluctuation characteristics of the vibration pore pressure, the saturated Nanjing fine sand samples with the fine content of 0%, 5.0% and 13.5% were respectively subjected to the sine wave loads of 0.5, 1.0 and 5.0 Hz, and the local drainage conditions Under the stress control cycle triaxial test. The results of quantitative analysis show that: ① When the sine wave load frequency is 0.5 Hz and the permeability coefficient is 1.35 × 10-3 cm / s (the content of fine particles is 0%), the phase angle of the precessional axial strain reaction At 90 °, while synchronizing with the axial strain rate reaction. ② With the increase of the sine wave load frequency or the decrease of the permeability coefficient, the phase angle of the precessional axial strain reaction of the fluctuating response of the vibration pore pressure gradually decreases, and the phase angle lagging behind the axial strain rate reaction gradually increases. Based on the theory of saturated solid-liquid two-phase medium, a vibration pore pressure equation suitable for arbitrary drainage boundary conditions is established. The equation can not only explain the phenomenon of vibration and pore pressure fluctuations synchronized with the axial strain response under undrained conditions, but also explain the phenomenon of the axial strain of the vibration and pore pressure fluctuations under local drainage conditions.