## 5 Recognition and Validation of Inadequate Grouting Section
### Single Hole Grouting Quantity Analysis  
According to the above analysis of grouting record, the right lane of D3K279 + 898, D3K279 + 905.5, D3K279 + 925.5 and left lane of D3K279 + 938 are selected to make further study. Figure 13 shows the grouting volume of single hole, 11 grouting holes are designed for the grouting engineering. As shown in Figure 13a, in the D3K279 + 898 section, the grouting volume of No. 4 grouting hole (28.95 m\({}^{3}\) SAC slurry) is much more than that of No. 1-No. 3 grouting holes, and the grouting volume of No.8 is also large than that of No. 9-No. 11 grouting hole. It is indicated that the grouting hole at the side of the section is not grouted enough. The end pressure of the No. 1 grouting hole is 2.1 MPa, which is larger than the pressure at the end of another grouting hole. It is indicated that the grouting hole on the side of this section cannot produce an effective slurry stop curtain to seal the reinforcement region, and the erosion of slurry is serious. The grouting effect should be estimated by a direct method such as coring observation.  
Figure 13b shows the single grouting volume of the right lane of D3K279 + 905.5 section. The grouting volume of No. 1 and No. 10 are 40.87 m\({}^{3}\) and 22.37 m\({}^{3}\), respectively, are larger than the adjacent grouting hole. Generally, the grouting volume of the side grouting hole is larger than that of the central grouting hole, but the end pressure is contrary to the conclusion of the grouting volume. The end pressures of No. 6 and No. 7 are 1.7 MPa and 1.8 MPa, respectively, which are larger than the other grouting holes. However, the  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Grouting** & **Drill** & **Actual Grouted** & \multicolumn{3}{c}{**Grouting Quantity/m\({}^{3}\)**} & \multicolumn{3}{c}{**Grouting Quantity**} \\
**Section** & **Length/m** & **Hole Length/m** & \multicolumn{3}{c}{**SAC**} & **C-S** & **Total** & **SAC** & **Total** \\ \hline D3K279 + 910.5 & 131.5 & 129.5 & 78.03 & 56.84 & 134.87 & 0.60 & 1.04 \\ \hline D3K279 + 913 & 316.8 & 306.8 & 204.61 & 296.90 & 501.51 & 0.67 & 1.63 \\ \hline D3K279 + 915.5 & 94  
growing amount are only 13.16 m\({}^{3}\) and 15 m\({}^{3}\), because the grouting hole at the side of the section is fully grouted, the lower grouting volume can produce larger pressure.  
Figure 13c shows the grouting record of single hole grouting in the right lane of D3K279 + 925.5 section. The end pressures of No. 1 and No. 7 are 1.6 MPa and 1.7 MPa, respectively, and the end pressures of No. 4 and No. 6 hole are 1.3 MPa, are even smaller than No. 1 hole with a value of 1.6 MPa. The grouting quantity of No. 8 hole is 17.97 m\({}^{3}\) and is almost equal to the grouting quantity of No. 11 and No. 12 holes whose grouting quantity are 17.86 m\({}^{3}\) and 17.98 m\({}^{3}\), respectively. Compared with the grouting quantity of No. 1 hole, the grouting quantity of No. 6 and No. 10 is not significantly reduction. The analysis result shows that the central hole has larger end pressure and smaller grouting quantity than the side hole; the reason for the abnormal grouting volume in this section should be investigated by direct methods.  
Figure 13d shows the grouting record of D3K279 + 938 section left lane, the grouting volume of No. 1 grouting hole is larger than that of the other grouting holes with end pressure of 1.6 MPa, indicating that there is a through crack on the left side of the reinforcement region. Moreover, the data grouting amount of No. 2-No. 5 is close to the design value, which illustrates the through crack is effectively sealed by penetration grouting.