基于能量法柔性桩复合地基的沉降计算

Settlement calculation of composite foundation with flexible piles by energy method

为精确计算柔性桩复合地基沉降,对基于能量法的沉降计算方法进行研究。首先,以荷载传递法为基础,假设桩侧摩阻力与桩土相对位移满足弹塑性关系,推导出桩体及桩间土的能量方程,建立柔性桩复合地基的系统总势能表达式,基于最小势能原理获得桩土的荷载分担值;然后,采用修正剑桥模型计算桩间土的压缩量,同时引入柔性桩应力应变特性曲线计算桩体压缩量,其与下卧层压缩量之和即为复合地基沉降量。最后,利用该方法对室内试验和既有案例进行建模与计算。研究结果表明:复合地基沉降量计算值与实测值相吻合,验证了该计算方法的正确性。

In order to accurately calculate the settlement of the flexible piles composite foundation, the settlement calculation based on energy method was carried out. Firstly, on the basis of the load transfer method, the energy equation of soil and pile was derived and the expression of the total potential energy of the composite foundation was established based on the hypothesis that the relationship between the friction and the relative displacement conforms with that of the relationship between elastic and plastic. The load-sharing ratio of pile-soil was obtained based on the principle of the minimum potential energy. Then, the modified Cam-clay model was used to calculate the compression of the soil around the pile, and the stress-strain curve of the flexible piles was introduced to calculate the compression of piles, either of which constitutes the settlement of composite foundation along with the compression of underlying stratum. Finally, the method was verified by the indoor experiment and the existing cases. The results show that the calculated settlement of the composite foundation agrees with the measured results, which verifies the correctness of the proposed method.