刚性桩复合地基沉降计算的简化方法

既简便又具有较好精度的刚性桩复合地基沉降计算方法仍是工程实践中迫切需要而又有待于解决的问题，文中提出了一个解决的简化方法。在刚性桩复合地基中，由于桩间土荷载水平不高，将桩间土荷载-沉降曲线近似为线性。当桩的荷载水平不高时，对桩的沉降可按线性考虑，线性关系可按线弹性方程计算得到。若桩可能进入非线性甚至塑性，则假设桩的荷载-沉降曲线满足双曲线规律，可较好地考虑桩的非线性沉降过程。通过计算单桩承载力特征值下的沉降，然后通过双曲线方程特点得到桩的非线性沉降方程。对于有单桩静载试验的情况，提出直接利用单桩试验曲线建立单桩的双曲线方程。最后依据共同作用时桩和桩间土的变形协调条件和静力平衡方程，即可计算其实际基础下复合地基的沉降，从而得到一个刚性桩复合地基沉降计算的简化方法。工程实例表明，简化是方法既简便又具有较好的精度，可为工程实践提供一个有效实用的计算方法。

A simplified method for calculating settlement of rigid pile composite foundation

To find a simple and precise method for rigid pile composite foundation is still an urgent problem which is not resolved as yet. A simplified method for calculating its settlement is proposed. The settlement of soil between piles was assumed linear due to the bearing capacity of soil between piles play a little in rigid-pile composite foundation. When the load level of pile is not high, the settlement of pile can be considered linear. If the pile may enter nonlinear even plastic, the load-settlement curve of pile is deemed to satisfy hyperbolic law; thus the nonlinear process of pile can be well considered. According to the mathematic property of hyperbolic equation, the nonlinear load-settlement equation can be deduced by the settlement under the characteristic values of bearing capacity of single pile. For the composite foundation with loading test, the hyperbolic equation of pile can be established by directly using the test curve. Based on the deformation coordination between soil and piles and the static equilibrium equation, the actual foundation settlement can be calculated. On the whole, it is a simplified method for calculating settlement of rigid piles composite foundation. By case studies this method is demonstrated to be not only simple but also be precise and can provide an effective and practical calculation method for engineering practice.