刚性桩桩网复合地基桩顶段桩间土附加应力分析

摘要

结合铁路CFG桩复合地基现场试验,进行桩网复合地基桩顶段桩间土附加应力分析.试验表明,在路堤填土荷载作用下,桩顶段桩间土压力仪在一定深度范围内有所增加,并且桩间土附加应力随深度迅速衰减,而桩顶段桩身轴力随深度增大,采用轴对称圆柱坐标系,针对有无桩帽的刚性桩复合地基,选取单桩处理面积范围内土体进行桩土相互作用分析,得出刚性桩复合地基桩顶段桩间土附加应力的计算方法.分析结果表明,在桩间土内部的剪切力和桩与土间摩擦力的作用下,桩和桩间土所承担的荷载在桩顶段重新分配,使桩间土所承担的荷载减小,而桩身所承担的荷载增加.桩土间黏聚力和摩擦角越大,桩间土中附加应力衰减的速度越快.计算值与数值模拟及现场实测结果的对比表明,计算方法可靠.%Combining with the field test of CFG pile-net composite foundation, the additional soil stres's of upper soil between piles was analyzed. The test shows that the soil stress of upper soil is just increased in a certain range of depth, while the additional soil stress decreases quickly with depth and the axial force of upper pile increases with depth. Using axially symmetric cylindrical coordinate, for rigid-pile composite foundation without pile cap, the pile-soil interaction in the treatment area of single pile is analyzed, and a calculation method of additional stress in the upper soil of pile-net composite foundation is created. The results show that, under the action of the shearing force in the soil and friction among pile and soil, the load supported by pile and soil is redistributed. The load supported by soil is decreased and the load supported by pile is increased. The larger the cohesion and friction angle of soil is, the faster the decay rate of the additional stress of soil will be. By comparing the calculation value with the result of numerical simulation and field test, it shows that the calculation method proposed in this paper is reliable.