Monitoring While Drilling Shafts In Florida Limestone

The focus of this research is the assessment rock strength in real time during drilled shaft installations. This is achieved through measurements of specific energy which requires five drilling parameters to be continuously monitored and recorded during shaft construction. In a recent investigation conducted by the Florida Department of Transportation, real time measurements of specific energy were used to assess both the quality and length of rock sockets. It was found that the specific energy required to excavate a shaft was directly correlated to the compressive, tensile, and shear strength of the drilled rock. Furthermore, the specific energy obtained from monitoring clearly defined the spatial variability, both horizontally and vertically, within each socketed rock mass. Based on these findings, a new method of estimating shaft capacity was developed in terms of specific energy that can be used as a quality control measure for every drilled shaft installed on a site.