Experimental study on depth correction factor k₂ for characteristic value of bearing capacity of weakly cemented sandstone foundation

To explore the rationality of depth correction value of the weakly cemented sandstone and the correction coefficient, relying on the north anchorage of large block foundation of the Yangtze River bridge in Longtan of Nanjing, the plate loading tests on deep and shallow rock of the bearing layer of weakly cemented sand stone 25 m in depth are carried out to obtain the characteristic values of bearing capacity of the foundation before and after depth correction. The depth correction rules are investigated. The results show that the correction coefficient k_2t for the shallow loading tests is 3.3, and the correction coefficient k_2c for the standard method is 8.0. Under conservative consideration, the method for obtaining the uncorrected characteristic values of bearing capacity is not distinguished, and k₂ is uniformly 3.3. After the depth correction, the bearing capacity of foundation is greatly improved, which indicates that it is necessary to revise the bearing capacity of weakly cemented sandstone in this project. Compared with the valuing rules of k₂ of soil foundation in the existing code, the values of k_2t and k_2c of weakly cemented sandstone in this study are conservative, so it may provide a reference for the projects under similar geological conditions.