Reply to Discussion on 'Empirical methods for determining shaft bearing capacity of semi-deep foundations socketed in rocks'

摘要

Semi-deep foundations socketed in rocks are considered to be a viable option for the foundations in the presence of heavy loads imposed by high-rise buildings and special structures, due to the low settlement and high bearing capacity. In this study, the unconfined compressive strength(UCS) and rock mass cuttability index(RMCI) have been applied to investigating the shaft bearing capacity. For this purpose, a comprehensive database of 178 full-scale load tests is compiled by adding a data set(n = 72)collected by Arioglu et al.(2007) to the data set(n = 106) presented in Rezazadeh and Eslami(2017).Using the database, the applicability and accuracy of the existing empirical methods are evaluated and new relations are derived between the shaft bearing capacity and UCS/RMCI. Moreover, a general equation in case of unknown rock types is proposed and it is verified by another set of data(series 3 in Rezazadeh and Eslami(2017)). Since rock-socketed shafts are supported by rock mass(not intact rock),a reduction factor for the compressive strength is suggested and verified in which the effect of discontinuities is considered using the modified UCS, based upon RMR and RQD to consider the effect of the rock mass properties.