长短桩复合地基应力与沉降分析

利用三维有限元对长短桩复合地基进行对比分析,给出全长桩、全短桩、长短桩、无垫层、天然地基5种方案下的桩身应力与土体附加应力分布,并探讨垫层模量和厚度对承台沉降的影响和对应力的调节作用。研究结果表明:复合地基能有效减少天然地基沉降和改善浅层土的应力状态,复合地基中桩身应力与土体附加应力按刚度分配,桩侧土应力与桩身应力表现出互补的特性。而垫层使桩与桩、桩与土之间应力分配趋于合理,垫层模量对承台沉降影响显著;随着垫层模量增加,长桩桩顶应力增加,短桩桩顶应力和桩身应力及土体表面应力降低;随着垫层厚度的增加,变化趋势则相反。

Analysis of stress and settlement of long-short-pile composite foundation

The distribution pattern of axial stress of long pile and short pile and additional soil stress of whole-long-pile composite foundation,whole-short-pile composite foundation,the long-short-pile composite foundation,without cushion composite foundation and natural foundation were obtained by using 3D FEM.The influence of support dais and the stress adjustment by the modulus and thickness of the cushion on the settlement was discussed.The results show that by the use of the long-short-pile composite foundation,the settlement of natural foundation can be reduced effectively and the shallow soil stress state can be improved.The axial stress of long pile and short pile and additional soil stress are distributed according to their stiffness,and the additional soil stress along the pile is complementary to the axial stress of the pile.The cushion makes the stress distribution pattern between piles and soils reasonably.The modulus of cushion affects the settlement of support dais notably.With the increase of the modulus,the top stress of long pile increases,the axial stress of short pile and the surface soil stress decrease.When the thickness of cushion increases,they will change conversely.