## 5 Stability
### Wave Forces
\begin{table}
\begin{tabular}{l c c c} \hline \hline
**Level of Seabed (m OD)** & \(-\)**10.0** & \(-\)**14.0** & \(-\)**18.0** \\ \hline Static sea water level (m OD) & 6.50 & 6.50 & 6.50 \\ hc, Height of crest above SWL (m) & 2.00 & 2.00 & 2.00 \\ hh, depth of seabed below SWL (m) & 16.50 & 20.50 & 24.50 \\ hh’, depth of caisson below SWL (m) & 15.50 & 19.50 & 23.50 \\ dd, depth of armour protection below SWL (m) & 14.50 & 18.50 & 22.50 \\ hb\({}_{\rm b}\), water depth at 5H\({}_{1/3}\) seaward of caisson (m) & 16.74 & 20.88 & 24.91 \\ \(\alpha\)1 & 0.718 & 0.680 & 0.655 \\ \(\alpha\)2 is the minimum of & 0.011 & 0.014 & 0.010 \\ \(\alpha\)2 & 4.00 & 3.29 & 3.67 \\ \(\alpha\)2 & 0.011 & 0.014 & 0.010 \\ \(\alpha\)3 & 0.617 & 0.542 & 0.477 \\ P1 Max wave pressure at SWL (kN/m) & 52.41 & 77.43 & 80.70 \\ P2 wave pressure at seabed & 31.04 & 40.13 & 36.69 \\ P3 wave pressure at base of caissons & 32.34 & 41.95 & 38.48 \\ n\({}^{\star}\), height of wave above SWL & 10.69 & 16.59 & 18.06 \\ hc\({}^{\star}\) & 2.00 & 2.00 & 2.00 \\ P4, wave pressure at top of caisson (kN/m) & 42.61 & 68.10 & 71.77 \\ Ph, total horizontal wave force (kN/m) & 752 & 1310 & 1553 \\ Mph, moment of Ph about tow & 7058 & 15,455 & 22,134 \\ h\({}_{\rm ph}\), height of Ph above base of caisson & 9.39 & 11.80 & 14.25 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Design wave output data. \begin{table}
\begin{tabular}{l c c} \hline \hline overall height of bund (m) & 22.5 & Width of inclined bund (m) & 22.5 \\ Static depth of water on sea side d1 (m) & 21.7 & Overall width of base (m) & 57.0 \\ Depth of water on land side d2 (m) & 16.5 & Area of bund (m\({}^{2}\)) & 776.2 \\ Vertical component of horizontal wave force, & 1309 & Lever arm of vertical wave force about O, (m) & 45.2 \\ Hydro-static water pressure at base on sea side (kN/m\({}^{2}\)) & 219 & Hydro-static water pressure at base on land side (kN/m\({}^{2}\)) & 166.7 \\ Base modulus (width)\({}^{2}/6\) & 541 & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Example of stability calculation output. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Component** & \multicolumn{2}{c}{**Force (kN)**} & **Lever Arm (m)** & **Sliding/Shear (kN)** & **Moment about O (kNm)** \\ \hline
**Description** & **Vertical** & **Horizontal** & & **Acting** & **Restoring** & **Overturning** & **Restoring** \\ \hline Wt of bund, W1 & 15,758 & & 28.50 & & & & 449,096 \\ Wt of water above inland & 1375 & & 5.50 & & & 7562 \\ slope W2 & & & & & & 118,345 \\ Wt of water above sea slope & 2378 & & 49.77 & & & 118,345 \\ W3 & & 2378 & 7.23 & 2378 & 17,201 & \\ Horiz force from land H2 & & \(-\)1375 & 5.50 & & 1375 & 7562 \\ Horiz wave force Ph & & 1310 & 11.80 & 1310 & & 15,452 & \\ Vertical component of horiz & 1309 & & 45.20 & & & 59,184 \\ wave force Pv & & \(-\)4792 & 0.00 & & 4792 & 0 \\ Available base friction (kN) & \(-\)9499 & & 28.50 & & & \(-\)270,720 \\ Variable boyancy force B1 & \(-\)1497 & & 38.00 & & & \(-\)56,879 \\ Totals & 9824 & \(-\)2479 & & 3687 & 6166 & 32,653 & 314,149 \\ Factor of Safety & & & 1.67 & & 9.62 \\ Net ground bearing force & \(-\)9824 & & 28.65 & & 281,497 & \\ G1 & & & & & \\ Net ground bearing & \(-\)172 & \(+/-\) & 2.79 & & & \\ pressure (kN/m\({}^{2}\)) & & & Net ground pressure after Hansen & & & \\ eccentricity about centre of & & & & & \\ base (m) & \(-\)0.15 & Effective width of base (m) & 57.31 & Net ground bearing & \(-\)171 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Example of stability calculation output continued.