Study On Bearing Characteristics Of CFG Pile Composite Foundation Based On Field Test Statistics

CFG pile composite foundation has been widely used as a building foundation treatment technology.However,the theoretical research speed of this technology is still lower than that of practice,and the study of basic theoretical system is not complete.The design and application of composite foundation have strong locality,which makes the regional experience coefficient especially important.It can be found that the value of bearing capacity coefficient of single pile and that of soil between piles have a strong correlation with regional experience in the process of calculating the bearing capacity of CFG pile composite foundation.Although China’s standard stipulated the value range of relevant regional experience coefficient,the value varies greatly due to the wide territory of China.Therefore,it is necessary to study how to select regional experience coefficient reasonably.In this study,combined with the project under construction,the field load test of CFG pile composite foundation with representative stratum in Jiyuan,Henan province was carried out.The variation characteristics of soil bearing stress between piles under different stress states are summarized according to the statistics and analysis of load detection data of CFG pile composite foundation.Then some suggestions on the value range of soil bearing capacity coefficient between piles are put forward,which provides a reference for the design and construction of CFG piles in this area.The main research contents of this study and its research results are as follows.(1)The problem that bearing capacity of composite foundation and single pile can not meet the design requirements was put forward according to the field load test of CFG pilecomposite foundation of four projects with representative stratum in Jiyuan.The geotechnical data,design calculation and construction of these four fours were analyzed.The analysis results showed that the main reason that the bearing capacity of CFG pile composite foundation does not meet the design requirements was that the bearing capacity of single pile was artificially overestimated,which leaded to the insufficient bearing capacity of soil between piles.(2)It was found that the actual bearing capacity of soil between CFG pile composite foundations was different from the theoretical calculation according to the test analysis of the bearing capacity of typical engineering field.The regional recommended value of soil bearing capacity coefficient between CFG pile composite foundations in Jiyuan was obtanined through the statistical analysis of the test data in the engineering field.(3)The technical requirements and improvement measures of design,construction and monitoring of CFG piles in different regional areas of Jinanwere put forward according to the analysis and theoretical research of typical project monitoring data.