地基土沉降对复合地基工作性状的影响

Influence of ground subsidence on working behavior of composite foundation

采用数值分析方法,考虑桩-土-褥垫层的共同作用,对复合地基在地基土沉降前后的沉降、桩侧摩阻力和桩身轴向应力等工作性状进行了研究.结果表明:与常规条件下相比,在相同上部荷载作用下,地下水位下降使基础和桩顶的沉降增加,桩身轴向应力增大,桩-土应力比提高,上部荷载的增大会加剧这些现象.随着降水造成的地基土沉降增加,加固桩体中负摩阻力的影响逐渐增大,中性点位置下移,负摩阻力引起的下拉力增大,桩侧摩阻力发挥更加充分.

Considering the pile-soil-cushion interaction,the working behaviors of composite foundation fore and after ground subsidence,such as the displacement of soil and reinforced piles,skin friction distribution of pile and pile axial stress are studied by finite element method.The results show that,compared with conventional conditions,the settlement of foundation,including soil and reinforced pile increases,axial stress in pile enhances,pile-soil stress ratio improves while groundwater level lowering in the same applied load.Increase of load acted on the foundation would promote the above-mentioned phenomena.In reinforced piles,the influences of negative skin friction increase gradually,neutral point moves down,down drag caused by negative skin friction increases,skin friction along the piles develops more fully along with the increase of the ground subsidence caused by groundwater level lowering.