黏土中防沉板—桩复合基础地震反应特性研究

Study on seismic response characteristics of mudmat-pile composite foundation in clay

为了研究海底防沉板—桩复合基础在地震荷载作用下的动力反应特性,以我国南海深水工程实例为研究对象,利用Flac;有限差分仿真软件建立了计算模型,土体采用Mohr-Coulomb本构模型,模型底部输入EL Centro地震波,对不同桩长的复合基础进行分析计算。在该特定工程背景下,研究结果表明:随着桩长的增加,防沉板顶部加速度放大系数呈减小趋势;地震荷载下,复合基础发生震陷,沉降量在地震波加速度峰值过后趋于稳定;当桩长为6 m时,复合基础的水平振动程度和震陷量最小;由于桩基础把震动能量传输到深部土层中,复合基础周围土体的加速度响应值小于远场土体。在动力时域内,防沉板与桩连接处弯矩最大,需要在此处增设加固装置。

In order to study the dynamic response characteristics of submarine mudmat-pile composite foundation under seismic load, taking a deepwater project in the South China Sea as the research object, a calculation model was established by using Flac;finite difference simulation software. The Mohr-Coulomb constitutive model was adopted for soil, and EL Centro seismic wave was input at the bottom of the model. The composite foundation with different pile lengths was analyzed and calculated. With this particular engineering background, the results show that the acceleration amplification coefficient of the top of the mudmat decreases with the increase of the pile length. Under the seismic load, the composite foundation subsided, and the subsidence tends to be stable after the peak of seismic acceleration. When the pile length is 6 m, the horizontal vibration degree and seismic subsidence of composite foundation are the minimum. Because the pile foundation transmits the vibration energy to the deep soil, the acceleration response value of the soil around the composite foundation is less than that of the soil in the far field. In the dynamic time domain, the bending moment of the joint between the mudmat and the pile is the largest, so it is necessary to add reinforcement device here.