海上大直径钢管桩打桩过程中桩周土强度弱化研究

Study on the weakening of soil resistance around large diameter steel pipe pile during pile driving

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明:土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。

In the process of large diameter steel pile driving in the sea,the soil around the pile is disturbed and the soil strength weakens significantly.It is of great significance to accurately grasp the law of soil strength weakening around the pile to ensure the safe and efficient completion of the project.In order to study the weakening law of soil strength,the ring shear test was carried out to simulate the disturbance of pile driving on the soil around the pile,and the variation law of soil strength with shear rate was tested.The fitting formula describing the weakening law of soil strength was established and introduced into the pile driving analysis software.The results show that the strength reduction degree of soil is not only related to the properties of soil itself,but also affected by the buried depth and shear rate of soil.The deeper the buried depth,the lower the strength reduction degree of soil,the higher the shear rate,and the higher the strength reduction of soil.In the pile driving analysis,the linear reduction method recommended in this paper can be used to simulate the reduction law of soil strength at different depths.