Numeric simulation analysis of load-settlement relation of pile in layer foundation

Considering the level distribution of soil layers, the soils surrounding pile are simulated with level finite layer elements. Supposing that the vertical deformation of the soil elements surrounding pile varies in the form of exponent function with radial distance, and considering the nonlinear constitutive relation of stress and strain, the stiffness matrix is established. The mechanics behavior of the pile—soil interface is simulated with a nonlinear interface element. This method can truly express the behavior of the pile-soil system. The load-settlement relation Q-S curves of two big diameter prototype piles on bearing test are analyzed, and satisfying results are obtained. This method is reasonable in theory and feasible in engineering.

桩侧注浆抗拔桩的试验研究与工程应用

为研究桩侧注浆抗拔桩的性能,结合上海白玉兰广场工程开展了9组桩侧注浆抗拔桩现场足尺试验,其中3组试桩采用了双套管技术,将工程桩桩顶标高以上桩身与土体隔离开,以使试桩与工程桩的实际受荷状态更接近。基于试桩结果,首先比较了常规和采用双套管两种试桩荷载位移曲线的差异;其次研究了注浆后桩侧摩阻力的发挥及与规范推荐值的比较;采用指数函数拟合本次试验结果并预测试桩抗拔极限承载力。背景工程最终采用了桩侧后注浆抗拔桩,相比于常规等截面桩大幅提高承载力,并节约混凝土用量和减少泥浆排放量,具有较好的经济及环保效益。

基于单桩静荷载试验的群桩沉降预测研究

通过单桩静荷载试验的Q–s曲线推算各级荷载下土体的等效弹性模量,建立单桩桩顶位移与等效弹性模量的函数关系,利用Mindlin位移解计算群桩相互作用,并引入一个修正弹性理论误差的经验公式来计算群桩的沉降。计算群桩沉降时认为土的等效弹性模量与单桩在相应沉降量下反演出的土体等效模量相等,以此将弹性理论的方法推广到塑性阶段。最后通过一个实例验证本文算法的可行性。