Study on settlement characteristics of composite foundation of Shenzhen-Zhongshan link immersed tube tunnel
The Shenzhen-Zhongshan Link is the first super project in China to use underwater deep cement mixing pile to treat the foundation of immersed tunnel on a large scale,and it has the characteristics of large gravel cushion thickness and high replacement rate of deep cement mixing piles.At present,there are few relevant studies.In order to study the settlement deformation law of thick cushion and deep cement mixing pile composite foundation with high replacement rate,on the basis of the field load plate test results,the gravel cushion,composite foundation and completely weathered rock at the pile end were considered as a joint action system.Assuming that the displacement mode of pile and soil at the pile soil interface is not synchronous,and the displacement mode of soil between piles at the same depth is not coordinated,and considering that the stress and deformation of each part of the system are continuous at the interface,the formulas for calculating the pile-soil stress ratio and settlement of composite foundation were derivedthrough the analysis of typical elements.Finally,the results were compared with the field load plate test results andtraditional method.The results show that the error between the settlement calculated by this method and the measured settlement is less than 8%,the calculation accuracy is better than the traditional method,and the change trend of settlement with load is basically the same,indicating that the method in this paper can better reflect the settlement characteristics of composite foundation of immersed tube tunnel.The error between the pile-soil stress ratio calculated by this method and the measured pile-soil stress ratio is within-7%,which can be considered as reliable.
immersed tube tunnelcomposite foundationsettlement calculationanalytical methodload transfer
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