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自从2008年汶川地震以来,对于饱和砂砾土液化问题的研究一直是岩土工程界与地震工程领域关注的热点。本文基于振动台试验,通过输入不同的台面波形,对饱和砂土和砂砾土侧向动力响应特性进行对比分析研究。以试验成果为基础,对桩基在饱和砂土与砂砾土两种不同液化土中侧向动力响应特性的异同也进行了初步探讨。研究结果表明:饱和砂砾土具有与饱和砂土类似的液化现象和特点,随着振动输入,饱和砂土孔压先逐渐升高然后又逐渐降低至低水平,而饱和砂砾土在初期迅速升高,而随后的残余孔压没有明显减低并一直保持较高水平至振动结束;饱和砂土土表加速度衰减速度要明显快于饱和砂砾土,在降低时刻上饱和砂砾土明显滞后于饱和砂土,说明饱和砂砾土较饱和砂土具有较强的抗液化能力;正弦波输入下饱和砂土中承台加速度随着孔压升高先增大后减小然后又缓慢升高,而饱和砂砾土中承台加速度仅经历了先升后降的简单过程,饱和砂土中桩头加速度在振动初期的放大倍数要低于砂砾土,而在振动输入后期,饱和砂土桩头加速度要比饱和砂砾土中放大效果明显,承台位移响应时程则表现出极为相似的规律,地震波输入下的反应与正弦波略有不同。
Since the Wenchuan earthquake in 2008, the research on liquefaction of saturated gravel soil has been a focus of attention in geotechnical engineering and seismic engineering. Based on the shaking table test, the lateral dynamic response characteristics of saturated sand and gravel soil are compared and analyzed by inputting different table waveforms. Based on the experimental results, the similarities and differences of lateral dynamic response of pile foundations in two different liquefiable soils of saturated sand and gravel soil were also discussed. The results show that saturated gravel soil has liquefaction phenomenon and characteristics similar to that of saturated sands. With the input of vibration, the pore pressure of saturated sands gradually increases first and then gradually decreases to a lower level, while saturated gravel soil increases rapidly in the early stage , While the residual pore pressure did not decrease significantly and remained at a high level until the vibration was completed. The acceleration attenuation of saturated sand soil was obviously faster than that of saturated gravel soil. Saturated gravel soil obviously lagged behind saturated sand at the reducing time, It shows that saturated gravel soil has stronger anti-liquefaction ability than saturated sands. The acceleration of bearing platform in saturated sands increases with the increase of pore pressure and then decreases and then increases slowly. However, in the saturated gravel soil, Acceleration only experienced a simple process of first rising and then lowering. The acceleration of pile head in saturated sand was lower than that of gravel soil in the early stage of vibration, while in late stage of vibration input, the acceleration of pile head in saturated sand was larger than that in saturated gravel The effect is obvious. The displacement response time history of the caps shows very similar laws. The response of the seismic wave input is slightly different from the sine wave.