# Assessment of the Bearing Capacity of Bridge Foundation on Rock Masses
## 4 Results and Discussion
### The Influence of the Self-Weight on Bearing Capacity  
Once the difference between the analytical and the numerical results of the bearing capacity is defined as in Section 4.1 for the weightless rock mass, the next step would be to study the influence of the self-weight on the bearing capacity by the numerical method since this analysis allows understanding the influence of foundation width. With the results of the bearing capacity considering weightless rock mass (\(P_{hWL}\)) and the bearing capacity with the self-weight (\(P_{hSW}\)) deduced from the FDM, the correction coefficient was developed due to the self-weight of the rock mass (\"weight factor\", \(W_{F}\)). It should be noted that \(P_{hFDM}\) presented in Section 4.1 is defined as \(P_{hWL}\) in this section, 4.2, to identify the self-weight cases and follow the abbreviations. The influence of four variable parameters (\(m_{i}\), \(UCS\), \(GSI\), and \(B\)) in the correlation of the results between \(P_{hSW}\) and \(P_{hWL}\) were also analyzed to develop the correction coefficient. Figure 12 shows that the four parameters that were analyzed affect the correlation between the results obtained with the hypothesis of the weightless rock mass and considering the self-weight of the material, with the influence of the \(GSI\) and the \(UCS\) being the most influential parameters. In Figure 12c,d, a clear decrease in the dispersion range is observed with the increase of \(UCS\) and \(GSI\). It must be emphasized that for \(GSI=10\) the variation between the results reaches almost 400%, while for \(GSI=50\) was close to 80% and for greater values of \(GSI=85\) this variation dropped to less than 20% (Figure 12d). Regarding the influence of \(m_{i}\) (Figure 12a), in general, the tendency is that the higher the value of \(m_{i}\), the smaller the dispersion between results (\(P_{hSW}\) and \(P_{hWL}\)). While Figure 12b shows the increase in the value of dispersion between results (\(P_{hSW}\) and \(P_{hWL}\)) with the increase of the value of \(B\), as the foundation width is directly related to self-weight of the rock mass (greater widths of the foundation on the ground imply more rock mass affected, therefore, greater failure wedge and also more influence of its weight). These variations in the results clearly show the need to incorporate the influence of the foundation width in the calculation of the bearing capacity. From Figure 12, it can be concluded that \(m_{i}\) and \(B\) affect the dispersion of the results mainly in combination with other parameters, in particular with low values of \(GSI\). In cases where the range between \(P_{hSW}\) and \(P_{hWL}\) exceeded 60% when associated with \(GSI=10\), the dispersion range was very dependent on the values of \(m_{i}\) and \(B\). Regarding _UCS_, it can be observed in Figure 12c that variation was much greater between cases with low _UCS_ (5 and 10 MPa), than among those with higher _UCS_ (50 and 100 MPa). In other words, as the value of the _UCS_ increased, less dispersion was observed, and this decrease occurred exponentially. Figure 13 shows that the most influential parameter was the _GSI_. For higher _GSI_ values (_GSI_ = 85), the dispersion was smaller than 10%. However, a lower value of the _GSI_ implies a greater influence of other parameters, for example, in cases with _GSI_ = 10 all the studied parameters influenced the relation \(P_{hSW}\)/\(P_{hWL}\). In turn, Figure 14 shows that the bearing capacity lower than 2.5 MPa was the most conditioned by the consideration of the self-weight of the material, with the difference in the values at least doubled. For the bearing capacities in the range between 2.5 and 25 MPa the influence of the self-weight was very variable, increasing between 1 and 2 times. Additionally, for the values of the bearing capacity greater than 25 MPa little influence of the self-weight of the material was observed, decreasing the difference for greater values of the bearing capacity; lower or around 20%.