用单桩沉降估算群桩沉降的计算方法

Calculation Method of Pile Group Settlement Based on Single Pile Settlement

由于群桩沉降计算时参数的选取不易把握,而单桩沉降较易得到,找到一种用单桩沉降来代替群桩沉降的方法无疑会使得问题变得简单。单桩沉降由桩身压缩和桩端沉降组成。采用桩身线弹性的假定计算单桩桩身压缩,利用分层总和法计算单桩桩端沉降。同时在群桩沉降计算时考虑桩身压缩对沉降的贡献,并用承台下的平均附加应力乘以桩端荷载传递系数后作为桩端的附加应力。根据单桩和群桩沉降计算时的异同,提出了一种用单桩的沉降估算群桩沉降的方法,使得在群桩沉降计算时,参数选取较为容易,且计算较为简单。最后介绍了该方法在桥梁工程桩基础沉降计算中的应用。

The selection of parameter of single pile settlement can be obtained more easily than the one of pile group. That means, if single pile settlement can be used to estimate pile group settlement, the problem will be easier. The settlement of single pile consists of compressive deformation of pile stem and settlement of pile tip. The compressive deformation of pile stem is calculated by adopting hypothesis of linear-elasticity and settlement of single pile tip is calculated by layerwise summation method. Furthermore, in the process of calculating pile group settlement, the method pays attention to the contribution made by compressive deformation of pile stem. Meanwhile, additional stress of pile tip is obtained by multiplying average stress under platform and coefficient of load transfer. According to similarities and differences of the method of calculating settlement between single pile and pile group, it shows a new way of calculation, which is single pile settlement estimates pile group settlement. This method can makes it easier choose parameter and do calculation. The last part of this paper introduces the application of the new way in calculating the pile foundation settlement of bridge project.