## 4 Analysis of Test Results
### Horizontal Displacement of Existing Line Foundation Slope Toe  
Figure 6 shows the load changes for the newly built subgrade during the test phase. Later displacements and stress changes corresponded to this loading date. The test results for the inclinometer tube showed that the excavation stage of the foundation pit was affected by the unloading of the soil, and the foundation soil of the existing road base moved out, but the surface data were greatly disturbed by the construction, so a horizontal soil-strain gauge was used to test the horizontal displacement of the foundation slope of the existing line foot. The horizontal displacement of the existing line foundation slope toe and the displacement curve are shown in Figure 7. It can be seen that the displacement change rule at this point was that the deformation developed most rapidly in the excavation stage of the foundation pit, and a slight rebound occurred during the raft-pouring period. We believe that the raft had a strengthening effect on the existing subgrade slope. The displacement development was relatively gentle, and there was a significant increase again after the preload was unloaded. Figure 5: Horizontal displacement time curves for deep foundation soil. Figure 6: Timeline of new subgrade filling. Considering the horizontal displacement of the fixed end of the element during construction, the test result was equivalent to the relative displacement of the soil within the length of the element (40 cm). By combining it with the finite-element estimation, the actual displacement of the existing line foundation slope toe [17] was calculated, and the calculation results are as follows: Figure 8 shows the horizontal displacement of the excavated slope toe node and the node at a horizontal distance of 0.5 m from the slope toe. The finite-element calculation showed that the excavation and unloading of the slope toe had obvious camber displacement, which occurred with the simulated raft and roadbed filling. The displacement was suppressed, or there was even retraction. The distance between the node at the slope toe of the finite-element model and the node at a distance of 0.5 m was regarded as the test range of the soil-strain gauge; the displacement difference, H\({}_{2}\), between the two points was counted, and the ratio of the measured result, H\({}_{1}\) (0.5 m-deep soil-strain gauge test data), to the calculated result, H\({}_{2}\), was used as the conversion coefficient, a. Owing to the large difference in the rates of change in displacement in different stages, the conversion coefficient, a, was divided into three distinct stages, as shown in Figure 9. The distribution of the conversion coefficient, a, was obtained as follows:  
\[\text{a}\ =\left\{ \begin{array}{ll}\ \in[0.08,\ 0.27],\ \text{average value a}_{1}=0.16,\ (2009-6-18 \ \text{to}\ 2009-8-18)\\ \ \in[0.47,\ 0.93],\ \text{average value a}_{2}=0.57,\ (2009-8-18 \ \text{to}\ 2009-10-25)\\ \ \in[1.18,\ 1.49],\ \text{average value a}_{3}=1.46,\ (2009-10-25 \ \text{to}\ 2010-2-18)\\ \end{array} \right. \tag{1}\]  
Figure 8: Finite-element slope toe horizontal displacement. Figure 7: Change curves for relative horizontal displacement. During the excavation stage of the subgrade and foundation pit (from June to August 2009), the conversion factor was calculated to be \(0.08\leq\) a \(\leq\) 0.27, and the mean value was a\({}_{1}\) = 0.16. When rafts were laid for new roadbeds and the roadbeds were preloaded (August to October 2009), the calculated conversion factor was \(0.47\leq\) a \(\leq\) 0.93, and the average was a\({}_{2}\) = 0.57. In the preloading and unloading stage (October 2009 to February 2010), the conversion factor was calculated to be \(1.18\leq\) a \(\leq\) 1.49, and the mean value was a\({}_{3}\) = 1.46. Based on this conversion factor, the finite-element calculation results were revised.