高层建筑桩箱基础共同作用现场测试分析

In-situ test and analysis of interaction between tall building and pile-box foundation

通过一高层建筑桩箱基础原位测试,阐述了箱基底板钢筋应力变化特征、基础变形和沉降规律、箱底土压力分布规律及桩-土荷载分担比例。测试结果表明,箱基底板钢筋应力仅为设计强度的8%;基础沉降量为理论计算值的20%;基础纵向弯曲值仅为0.319‰,设计时可只考虑局部弯曲而不考虑整体弯曲;箱基底板土分担了11%的荷载,土压力没有得到充分发挥,建议增大桩距来实现这一目的,从而降低工程造价。

Based on the in-situ test of pile-box foundation for a tall building, variation charateristics of box foundation, including steel stress of base slab, deformation and settlement of foundation, earth pressure under box, and load sharing ratio between pile and box, etc. are described. The results indicate that the steel stress of base slab is only 8% of its design strength; and settlement of foundation is only 20% of the theoretical calculaed value. Overall flexure value of foundation is only 0.319 ‰; so local flexure is main influence factor on base slab. Soil can only share 11% of the load above and the contact pressure is very small comparing with its resistance capacity. In order to improve earth pressure under box and reduce construction cost, enlarging interals of piles is an effective way.