Studies On Selecting Methods For Ground Improvement And Analyzing Reliability Of Ground Settlement

The treatment of soft foundation has gained a lot of efforts, but how to improve the ground suitably and effectively is still unsolved. In this dissertation, the selection of the method and the prediction of the ground settlement in Qingdao Qianwan have been discussed.Using random field theory, the correlation distances of 7 geotechnical parameters have been obtained and conclusions have been made hereunder: the correlation distance of each GP has increased differently after improvement in three foundation cases, but the sequences which arranged from large to small according to the change of correlation distance in three cases is totally same.AHP is an analytic estimation method in system engineering, through setting up a hierarchy model and calculating the relative weightiness or the order of relative excellence of the lowest hierarchy to the highest hierarchy in the model, the sequence of factors in lowest level can be obtained. In this paper the highest level is made up of the treatment methods which should be determined by engineers or designers, and the lowest hierarchy is made up of 7 GPs. If the sequence from AHP is same to the sequence from random field theory, then the treatment method must be suitable.Using the K-S test method, the GPs' probability distributions have been obtained. Further, the parameters' value of every distribution has been optimized by using the Extended Bayes method. Based on the probability analyses of GPs, the reliability of ground settlement has been discussed. Based on the geometric definition of reliability index β and one-dimensional Terzaghi consolidation theory, the simplified formula of β has been deduced and the settlements of 6 time points under 5% failure probability can be calculated. Comparing with the factual settlement of D74 in case B, it can be found the prediction settlement which considering the change of Cv coincides with factual settlement well.