Aiming at the defect of the traditional grey linear regression combination model for requiring raw data sequence to be monotone increasing,the method of generating series model on raw data with secondary accumulation and absolute value method are presented.Taking the radical displacement of a measuring point of Xiaowan arch dam for an example,two improved methods are used to fit and predict.Compared with the measured value,the results show that the generating series model on raw data with the absolute value method has higher precision,and is closer to the measure value.

With the hydropower resources continue to develop,the dam sites with good geological condition had been used;so,the trend of dam building on the thick overburden becomes increasingly obvious.The thick overburden has the characteristics of loose structure,strong permeability,uneven lithological,so as to make projects to exhibit problems of lower bearing capacity of foundation,serious uneven settlement,seepage flow instability.The authors use the finite element software SDAS to model and calculate a project example on the thick overburden,and analyze the stress-strain calculation results,so as to provide a favorable evidence for engineering application.

In the Middle Route of the South-to-North Water Transfers Project,cement is used to modify the engineering characteristics of expansive soil,and the quality of the stabilized expansive soil depends on the cement content,therefore it is important to ensure the accuracy of detecting the cement content.EDTA(Ethylene Diamine Tetra Acetic Acid Disodium Salt) titration method is used to detect the cement content;however,age effects occur using this method.In this paper,expansive soil samples obtained from Nanyang area were mixed with different cement contents and then titrated using the EDTA method after they were stored for different time periods,which can help understand the age effects of the stabilized soil on the EDTA titration in detecting the cement content.The problems and solutions of using the EDTA titration method in detecting the cement content of the stabilized expansive soil in the Middle Route of the South-to-North Water Diversion Project were discussed.The experiment results showed that the effective calcium content decreases significantly and the detected cement content using the EDTA titration method may be lower than the actual value when the storage time is longer than 2h and the cement content is not less than 4%.In this case,the standard curve of EDTA consumption with time or the decay curve of the effective calcium content should be used to correct the detected value to ensure the accuracy of the conclusions.