Method for calculating target value of continuous compaction index based on Bootstrap method

The effective control of compaction quality of the filling body is essential to ensure the service life and operation safety of infrastructures such as roads, dams and airports. With the wide application of the continuous compaction control technology, it is important to determine the reasonable target value of continuous compaction index to guarantee the compaction quality. A novel method for calculating the target value of compaction index based on the Bootstrap method is proposed. Compared with the traditional methods based on the empirical formula along with a limited number of test data, the proposed method statistically establishes a regression model confidence band with the confidence level of (1-α)100% based on the empirical formula, and then determines the target value of compaction index by selecting the upper confidence limit. Finally, the proposed method is verified through the existing field test data of foundation compaction projects from literatures. The results show that the target value calculated by the proposed method has a higher reliability compared to that by the empirical formula. Besides, the errors of compaction index caused by the uncertainty due to the limitation of samples can be amended by the proposed method, and the amendment value increases as the correlation of the test data decrease, which ensures the reliability of the control standard of compaction quality. In addition, compared with that of the confidence interval given in the literatures, the width of the confidence interval obtained by the proposed method is narrower, hence the over-estimation can be avoided, indicating that the proposed method is of significance in both the current engineering design and the prospective application.