To predict the settlement of turfy soil subgrade with the method of traditional non-equal interval models, there are a few shortages such as cumbersome calculation and low accuracy for short-term forecast Especially when there is a slope mutation point in the subsidence curve, it is difficult to meet the prediction accuracy requirements. For the above shortcomings, average step length conversion is used for non-equal interval sequence to obtain quasi-equal interval sequence; the improved quasi-equal interval QGM(1,1) forecasting models are obtained by amending the original settlement data with the method of linear interpolation; and the subsidence curve is divided into two parts to carry out the prediction at the slope mutation point. As is illustrated in the examples, when the improved quasi-equal interval QGM(1,1) models are used to predict turfy soil subgrade settlement, the average errors between predicted and measured values are 2. 99% and 0. 25% respectively, far less than the results obtained by means of traditional non-equal interval models. The quasi-equal interval QGM(1,1) model with pretty high accuracy for short-term prediction can serve as a reliable reference to settlement control in project.%利用传统非等时距模型预测草炭土路基沉降时,存在计算繁琐、中短期预报精度低等缺点,尤其是当沉降曲线存在斜率突变点时,采用该模型很难达到预测精度的要求.针对以上不足,对非等时距时间序列进行平均步长换算,得到准等时距序列,利用线性插值法对原始沉降数据进行修正,得到改进后的准等时距QGM(1,1)预测模型,并将沉降曲线在斜率突变点处分成两部分进行分段预测.实例计算表明:采用改进后的准等时距QGM(1,1)模型预测草炭土路基沉降,两段的预测值平均误差分别为2.99％和0.25％,均远远小于传统非等时距模型,且具有很高的中短期预测精度,可以为工程沉降控制提供可靠参考.
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