大面积分级堆载预压工况下软土地基的沉降预测分析

准确预测软土地基的沉降是保障软土地基工程安全的重要前提。文章首先通过理论分析将预测单级荷载作用下地基沉降的指数曲线法模型（简称单级模型）拓展为预测多级荷载作用下地基沉降的指数曲线法模型（简称多级模型），其次收集了某机场分级堆载预压联合排水板处理软土地基的沉降观测数据。最后对比分析了最小一乘法（least absolute deviation method，LADM）和目前广泛采用的最小二乘法（ordinary least square method，OLSM）拟合单级模型和多级模型对软土地基后期沉降的预测效果。研究结果表明：相对于OLSM，LADM拟合单级模型或多级模型时不仅能更好地反映拟合段沉降监测数据的变化规律，还能更精确地预测单级荷载或多级荷载作用下软土地基后期的沉降，并且预测误差也更加稳定。基于OLSM拟合时，相对于单级模型，多级模型预测地基后期沉降误差的稳定性较高。此外，相对于基于LADM和传统广泛采用的OLSM拟合单级模型对软土地基后期沉降进行预测的方法，文章所提出的基于LADM拟合多级模型对软土地基后期沉降进行预测的方法不仅能真实反映实际分级加载工况下软土地基沉降发展的全过程，还能更精确地预测软土地基后期的沉降，并且预测误差也更加稳定。

Accurately predicting the settlement of soft soil foundation is an important premise to ensure the safety of soft soil foundation engineering. Firstly, through theoretical analysis, the exponential curve method for predicting foundation settlement under single-stage load (single-stage model) is extended to the exponential curve method for predicting foundation settlement under multi-stage load (multi-stage model). Secondly, the settlement observation data of soft soil foundation treated by staged surcharge preloading combined with drainage board in an airport are collected. Finally, the prediction effects of least absolute deviation method (LADM) and ordinary least square method (OLSM) fitting single-stage model and multi-stage model on the later settlement of soft soil foundation are compared and analyzed. The results show that compared with OLSM, LADM fitting single-stage model or multi-stage model can not only better reflect the change law of settlement monitoring data in the fitting section, but also more accurately predict the later settlement of soft soil foundation under single-stage load or multi-stage load, and the prediction error is more stable. When fitting based on OLSM, compared with the single-stage model, the stability of error of multi-stage model in predicting the later settlement of foundation is higher. In addition, compared with the method of predicting