双层地基中倾斜偏心荷载下基桩非线性模型试验研究

引入初始地基比例系数、初始地基系数、水平位移特征值，导出一种新型双曲线型p-y曲线，并给出了参数经验选取参考值范围。在上层粘土下层砂土地基中进行了2组模型桩试验，含2根水平加载的钢桩和6根倾斜偏心荷载下的木桩。试验表明，水平荷载、竖向荷载和偏心弯矩荷载下柔性木质模型桩非线性特征显著。按双曲线型p-y曲线计算的模型桩地面处和桩顶水平位移与实测值吻合良好，验证了双曲线型p-y曲线。水平位移特征值增大时，桩身位移将减小，桩身最大剪力将增大，桩身最大弯矩将减小，桩侧最大土压力将增大。双层地基中，下层砂土位移特征值变化对试桩受力影响极小，从简化计算参数和应用角度出发，实际应用时可将下层砂土水平位移特征取值与上层粘土的相同。

Nonlinear behavior of pilesunder inclined and eccentric loads indouble layered soils by model test

A new hyperbolic p-y curve was derived to generally simulate then onlinearity of piles in layered soils, and the new p-y curve was presented containing parameters such as the initial ratio of elastic foundation coefficient, the initial elastic foundation coefficient,characteristic value of lateral displacementfor soils, and etc.. Model test of six timber piles and two steel piles in two groups settled in layer soils with upper clay and lower sand were done. The calculated lateral displacements of model piles both at the top and at the ground are consistent with the test values by p-y curve method, and the new hyperbolic p-y curve is verified. While the characteristic value of lateral displacement for layered soils increases, the displacement and the maximum bending moment of the pile decrease, the maximum shear and the maximum soil pressure around the pile increase. The variety of characteristic value of lateral displacement for the lower sand has extremely small effect on mechanical property of the pile, then the characteristic value of lateral displacement for lower soils can be defined as the same as that of the top soil during engineering application.