循环荷载下桩网复合地基受力变形模型试验研究

Model test of stress and deformation characteristics of pile-net composite foundation under cyclic loading

采用缩尺比例为1∶10的桩网复合地基模型,对循环荷载下软土地区桩网复合地基的受力变形特性进行试验研究。通过试验分析了循环荷载幅值、频率以及土工格栅层数对循环荷载下软土地区中桩网复合地基受力变形特性的影响,并结合曲线拟合方法探讨循环荷载下桩网复合地基中桩基的桩端阻力、桩侧总摩阻力与沉降变化之间的关系。研究结果表明:桩网复合地基沉降在循环荷载作用初期时发展速率较快,增加荷载幅值和频率会增大沉降,而上层格栅的加入能减小沉降。循环荷载下桩身轴力随桩深的增加先增大后减小,桩网复合地基桩身轴力随循环荷载幅值、频率和土工格栅层数的增大而增加。桩端阻力会随着地基沉降的发展而增大,桩侧总摩阻力则随着地基沉降的发展逐渐减小,不同荷载幅值、频率及土工格栅层数下桩网复合地基中的桩端阻力与桩侧总摩阻力随沉降的变化规律可分别用幂函数和多项式函数描述。研究结果可为软土地区高速公路设计与施工提供一定依据。

Based on a series of pile-net composite foundation models at a reduced scale of 1∶10, the stress and deformation characteristics of pile-net composite foundation in soft soil areas under cyclic loading were investigated. The influence of the cycle loading amplitude, frequency and number of geogrid layers on the stress and deformation characteristics of pile-net composite foundation under cyclic loading were analyzed. The relationship among pile end resistance, total pile side friction resistance and settlement changes in pile-net composite foundation under cyclic loading was further discussed by using curve fitting method. The results show that the settlement of pile-net composite foundation develops rapidly in the first stage of cyclic loading. The foundation settlement increases with the increase of the loading amplitude and frequency while decreases with the introduction of the upper geogrid. The axial force of the pile firstly increases and then decreases with the deepening of the pile under cyclic loading. The axial force of the pile-net composite foundation increases with the increase of load amplitude, frequency and number of geogrid layers. The pile end resistance increases while the total pile side friction resistance gradually decreases with the development of foundation settlement. The variations of pile end resistance and total pile side friction resistance in pile-net composite foundation with foundation settlement under different load amplitudes, load frequencies and geogrid layer numbers can be described by power function and polynomial function respectively. The research results are expected to provide a basis for the design and construction of expressways in soft soil areas.