A Prediction Method Of Soft Foundation Settlement Considering Anomaly And Newness-oldness Degree Influence Boundedness Of Measured Data

A reasonable settlement prediction method is an important basis for the safety performance evaluation and reinforcement scheme decision of foundation or subgrade.Because the settlement deformation of the foundation or roadbed soil is always dominated by infiltration,consolidation and secondary consolidation settlement,and it takes a long time to complete,that is,the soft soil foundation or roadbed after completion will continue to produce settlement,which has a significant time effect.And the time series data of these measured data contain the change rule of settlement development.Therefore,it is of great importance to explore a more reasonable prediction method of post-construction settlement on soft foundation,to improve the accuracy of prediction,and to predict the future development of settlement from the existing field measured data,and it has important theoretical and engineering values.Therefore,this paper will introduce the freshness function and statistical principle to the newness-oldness degree of measured settlement data,and improve the theory and method of settlement prediction of soft foundation on the basis of the study of the existing settlement combination model prediction method.Firstly,an analytical model of freshness function is proposed to measure the newness-oldness degree of measured settlement data by considering the features of newness-oldness degree and boundedness of its influence degree of measured settlement data,it can also reflect the time distance between the measured and predicted point,measured error and boundedness of newness-oldness as well as its influence degree of the measured data on the settlement prediction.From this calculation,a more reasonable single settlement prediction model can be obtained.Secondly,considering the possible man-made factors or improper operation and measurement methods of monitoring equipment,resulting in the anomaly or untruthfulness of the measured settlement data,if these measured data are not processed but directly participate in the settlement prediction of soft soil foundation or roadbed,It will inevitably lead to unreasonable or even fallacious results of settlement prediction.Therefore,based on statistical theory,a disposal method of measured data sample is developed which can exclude the unreasonable settlement prediction caused by some abnormal measured data.Then,using the above-mentioned model and method,a new method for combined prediction of foundation or subgrade settlement is put forward,which can reflect the influence of abnormality of measured settlement data,degree of their oldness and newness and boundedness of its influence degree on settlement prediction of foundation or subgrade.This method is obviously more reasonable and feasible than the old method in predicting the settlement of soft soil or roadbed.Finally,the measured data of two engineering examples are selected,and their calculation and analysis are carried out,the rationality and superiority of the prediction model and method for foundation or roadbed can be verified by comparing the prediction and measurement results of this method with those of the existing similar methods.